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diff --git a/old/66726-0.txt b/old/66726-0.txt deleted file mode 100644 index 32562d5..0000000 --- a/old/66726-0.txt +++ /dev/null @@ -1,4119 +0,0 @@ -The Project Gutenberg eBook of More Minor Horrors, by Arthur Everett -Shipley - -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms -of the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you -will have to check the laws of the country where you are located before -using this eBook. - -Title: More Minor Horrors - -Author: Arthur Everett Shipley - -Release Date: November 13, 2021 [eBook #66726] - -Language: English - -Character set encoding: UTF-8 - -Produced by: Peter Becker, Les Galloway and the Online Distributed - Proofreading Team at https://www.pgdp.net (This file was - produced from images generously made available by The Internet - Archive) - -*** START OF THE PROJECT GUTENBERG EBOOK MORE MINOR HORRORS *** - Transcriber’s Notes - -Obvious typographical errors have been silently corrected. Variations -in hyphenation have been standardised but all other spelling and -punctuation remains unchanged. - -Italics are represented thus _italic_. - - - - - MORE MINOR HORRORS - - - [Illustration: Mosquitos in the Colvith River delta, Arctic Alaska, - about 71° lat., July 1909. The Eskimo, Natkusiak, had stood still for - a minute or two, and refrained from brushing them off, while loading a - uomiak. (From the _American Museum Journal_.) - [_Frontispiece_]] - - - - - MORE - MINOR HORRORS - - BY - - A. E. SHIPLEY, Sc.D. - - HON. Sc.D. PRINCETON, F.R.S. - - MASTER OF CHRIST’S COLLEGE, CAMBRIDGE, AND READER IN ZOOLOGY - IN THE UNIVERSITY - - ILLUSTRATED - - LONDON - - SMITH, ELDER & CO., 15 WATERLOO PLACE - 1916 - - [All rights reserved] - - - - - EDMUNDO ALFREDO CARRINGTON - - ET - - JOHANNI TRISTRAM YARDE - - COLLEGII CHRISTI DILECTISSIMIS ALUMNIS - HUIC AB ORIENTI ILLI AB OCCIDENTI PARTE - PRO PATRIA PUGNANTIBUS - - - - - PREFACE - - -My publisher tells me that this volume will be regarded as a sequel -to ‘The Minor Horrors of War,’ and he assures me that sequels are -not a success. I have no doubt my publisher is right, because if -publishers were not invariably right, and authors invariably wrong, how -can one explain the fact that publishers are proverbially prosperous -and prominent people, whereas authors are notoriously penniless and -obscure? In spite of his warning, however, I propose to publish this -little volume, for there still ‘air some catawampous chawers in the -small way, too, as graze upon a human pretty strong’—as ‘one of them -inwading conquerors at Pawkins’s’ called them—that were unmentioned in -my earlier book. - -I am indebted to the kindness of the Editor and Proprietors of the -_British Medical Journal_ for permission to reprint Chapters I to IX -and Chapter XI, and to the Editor of _The Journal of Economic Biology_ -for permission to reprint the twelfth chapter, of this book, and I -offer them my thanks. I also thank Mr. Hugh Scott (the University -Curator in Entomology), and Professor G. H. Carpenter of the Royal -College of Science, Dublin, for much kindly help. - - A. E. SHIPLEY. - - CHRIST’S COLLEGE LODGE, CAMBRIDGE, - _April 1916._ - - - - - CONTENTS - - - CHAPTER PAGE - - I. COCKROACHES (_Periplaneta_) 1 - - II. COCKROACHES (_continued_) 16 - - III. THE BOT- OR WARBLE-FLY (_Hypoderma_) 25 - - IV. THE MOSQUITO (_Anopheles maculipennis_) 42 - - V. THE MOSQUITO (_continued_) 53 - - VI. THE MOSQUITO (_continued_) 65 - - VII. THE MOSQUITO (_continued_) 76 - - VIII. THE MOSQUITO (_continued_) 86 - - IX. THE YELLOW-FEVER MOSQUITO (_Stegomyia - calopus_) 101 - - X. THE BISCUIT-‘WEEVIL’ (_Anobium paniceum_) 111 - - XI. THE FIG-MOTH (_Ephestia cautella_) 114 - - XII. THE STABLE-FLY (_Stomoxys_) 124 - - XIII. RATS (_Mus_ or _Epimys_) 135 - - XIV. THE FIELD-MOUSE (_Apodemus sylvaticus_) 153 - - INDEX 161 - - - - - ILLUSTRATIONS - - - FIG. PAGE - - A portrait of the head of an Eskimo attacked by - mosquitos _Frontispiece_ - - 1. _Periplaneta orientalis_, male, dorsal view 2 - - 2. _P. orientalis_, male, side view 6 - - 3. Mouth parts of _P. orientalis_ 9 - - 4. _P. orientalis_, female, dissected 10 - - 5. Egg capsule of _P. orientalis_ 12 - - 6. Cast skin of the nymph stage of cockroach 18 - - 7. Nymph stage of cockroach escaping from old skin 19 - - 8. _Hypoderma bovis_ 29 - - 9. Eggs of _H. lineatum_ 33 - - 10. Eggs of _H. bovis_ 35 - - 11. Entrance hole of _H. lineatum_ 37 - - 12. Cow being chased by warble-fly 40 - - 13. Side-view of head of _Anopheles maculipennis_, female 44 - - 14. Section through proboscis of _A. maculipennis_, female 45 - - 15. Piercing-lancets of _A. maculipennis_, female 46 - - 16. _A. maculipennis_, female, sucking blood 58 - - 17. _A. maculipennis_, male 66 - - 18. Stridulating organ of _A. maculipennis_ 70 - - 19. Larva and eggs of _A. maculipennis_ 78 - - 20. Side view of the head of larva of _A. maculipennis_ 81 - - 21. Under surface of head of larva of _A. maculipennis_ 82 - - 22. Diagrams of mosquitos and gnats 85 - - 23. Side view of pupa of _A. maculipennis_ 91 - - 24. Tail of pupa of _A. maculipennis_ 93 - - 25. Imago mosquito issuing from pupa-case 95 - - 26. _Stegomyia fasciata_, female 104 - - 27. Larva and eggs of _S. fasciata_ 106 - - 28. Larva of _S. fasciata_ 107 - - 29. Egg of _S. fasciata_ 108 - - 30. The biscuit-‘weevil’ (_Anobium paniceum_) 112 - - 31. The larval and pupal stages of _A. paniceum_ 113 - - 32. Orchard of fig-trees 115 - - 33. The fig-moth (_Ephestia cautella_) 116 - - 34. Figs drying on reeds 119 - - 35. Figs packed on strings 120 - - 36. Pile of refuse-figs 122 - - 37. The stable-fly (_Stomoxys calcitrans_) 125 - - 38. _Stomoxys calcitrans_ 126 - - 39. Wings of _Musca domestica_ and of _Stomoxys calcitrans_ 127 - - 40. Side view of head of _Stomoxys calcitrans_ 128 - - 41. _Stomoxys calcitrans_. Eggs 129 - - 42. Acephalous larva of _Stomoxys calcitrans_ 130 - - 43. Coarctate pupa of _Stomoxys calcitrans_ 131 - - 44. The rat (_Mus rattus_) 136 - - 45. Head of _Mus rattus_ 138 - - 46. _Mus decumanus_ 143 - - 47. Head of _Mus decumanus_ 145 - - 48. The field-mouse (_Apodemus sylvaticus_) 156 - - 49. Diagram of burrow of field-mouse 159 - - - - - MORE MINOR HORRORS - - - - - CHAPTER I - - COCKROACHES (_Periplaneta_) - - - PART I - - _The Governess:_ And, perhaps, Mabel, as they are not black - and as they are not beetles, you will in future call them cockroaches. - _Mabel:_ Certainly, Miss Smith, although they are not cocks - and they are not roaches. (_Punch._) - - -In ‘The Minor Horrors of War,’ we rather neglected the Navy—the -senior Service, and till now the more dominant of our two magnificent -forces—partly because it is less interfered with by insect pests than -is the sister Service, though the common pests of our poor humanity—the -flea, the louse, the bug—are, like the poor, ‘always with us.’ Like -aeroplanes, insects have captured the air; like motors, they have made -a respectable show on land; but they have signally failed at sea. They -have nothing corresponding to battleships or submarines; and a certain -bug, called _Halobates_, alone hoists the insect flag on the ocean, and -that only in the warmer waters. - - [Illustration: FIG. 1.—_Periplaneta orientalis_, male. × 2. Dorsal - view. 1, Antenna; 2, palp of first maxilla; 3, prothorax; 4, anterior - wings; 5, femur of second leg; 6, tibia; 7, tarsus; 8, cerci anales; - 9, styles. (From Kükenthal.)] - -Insects are not only highly intelligent animals, but are by far the -most numerous and dominant class of the Animal Kingdom; and they have -probably come to conclusions about themselves and the sea, comparable -to those expressed by Dr. Johnson about man and the ocean: ‘To all the -inland inhabitants of every region the sea is only known as an immense -diffusion of waters, over which men pass from one country to another, -and in which life is frequently lost.’ - -But one insect at least causes more trouble to sailors than to -soldiers—and that is the cockroach. Like the bed-bug, the cockroach -came into England at the end of the sixteenth century, and, like the -bed-bug, it came from the East. It seems to have been first introduced -into England and Holland in the spacious times of Henry VIII by the -cross-sea traffic, and from about the end of the sixteenth century the -cockroach began gradually to spread throughout the Western world. Like -the rat, the bed-bug, and the domestic fly, it has become thoroughly -acclimatised to human habitations, and is indeed an associate of man. -It is very rarely found living apart from some form or other of human -activity. - -This insect seems to have been first described in England in -Moufet’s ‘Insectorum Theatrum,’ 1634, and he speaks of it as living -in flour-mills, wine-cellars, &c., in England, and he tells us how -Sir Francis Drake took, in 1584, the _San Felipe_, a Spanish East -Indiaman, laden with spices and burdened with a great multitude of -flying cockroaches on board. - -This species was _Periplaneta orientalis_; but there is another and a -larger species, which presumably came into England from the West later -than its Eastern cousin _P. americana_—which can frequently be seen in -England running about in the cages in our zoological gardens—but it is -not on exhibition, it is a by-product, and is not counted in the fee -for admission to the gardens. - -Latter tells us there are ten species of BLATTODEA which occur in -Britain; but only three of these are indigenous, and these three all -belong to the genus _Ectobia_. _Ectobias_ are smaller than cockroaches, -and do not frequent human habitations, but live in shrubs, under -rubbish heaps, &c. Some species of _Ectobia_ are, however, very -destructive and have been known to destroy in one day the whole -accumulation of dried but not properly salted fish in a Lapland -village. Of the remaining species of cockroach most are local, and -occur sporadically in particular factories, or places where food is -stored but they are not very widely spread. - -As we have said above, _P. orientalis_ is the common English cockroach, -_P. americana_ occurs especially in zoological gardens and menageries; -but a third species, _P. germanica_, sometimes gets established. -Mercifully, _P. germanica_ does not seem to spread. Neither _P. -germanica_ nor _P. americana_ seem to make much headway against _P. -orientalis_, which appears to be predominant over both these other -species. - -_P. germanica_ is probably most methodical, very thorough, very -brave, very faithful—but rather lacking in the power of understanding -the point of view of others. If it has any association with its -specific name, it illustrates the most striking example in the world’s -history of the divorce of wisdom from learning. ‘O Lord! give us -understanding,’ should be the prayer of _P. germanica_. - -Miall and Denny tell us that from the first introduction of _P. -orientalis_ into England it took two centuries before it spread far -beyond London. In 1790 Gilbert White speaks of it as ‘an unusual -insect, which he had never observed in his house till lately,’ -and, indeed, at the present moment many English villages are still -blissfully ignorant of this particular nuisance. - -As Fig. 2 shows, the cockroach is a somewhat slackly put -together insect. One might almost call it rather slatternly and -loose-jointed—and the latter it certainly is. Its head moves freely on -the thorax, and the thorax on the abdomen. The successive segments -of the latter move very freely on one another. The legs are long and -mobile, and so are the antennae with which the animal is ceaselessly -testing the ground over which it flits hither and thither in its -restless activity. - - [Illustration: FIG. 2.—_Periplaneta orientalis_, male. × 2. Side - view. 1, Antenna; 2, head; 3, prothorax; 4, anterior wing; 5, soft - skin between terga and sterna; 6, sixth abdominal tergum; 7, split - portion of tenth abdominal tergum; 8, cercianales; 9, styles; 10, coxa - of third leg; 11, trochanter; 12, femur; 13, tibia; 14, tarsus; 15, - claws. (From Kükenthal.)] - -Cockroaches are very difficult to catch. They practically never walk, -but run with a hardly believable rapidity, darting to and fro in an -apparently erratic mode of progression. Even when caught they are -not easily retained, for they have all the slipperiness of a highly -polished billiard-ball. They have great powers of flattening their -bodies, and they slip out of one’s hand with an amazing dexterity. -Besides their slipperiness they have another weapon, and that is a -wholly unpleasant and most intolerable odour, which is due to the -secretion of a couple of glands situated on the back of the abdomen. -The glands which produce this repellent odour are sunk in the soft -membrane which unites the fifth and sixth abdominal segments, and -the moment a cockroach is attacked it exudes a sticky, glue-like -fluid, which gives out this most unendurable smell. The fluid is -extraordinarily tenacious and difficult to remove from the hand of -those who have touched the insects. No doubt the cockroach, in nature, -finds safety in this from the attacks of insectivorous animals. - -Cockroaches, as has been said, very rarely walk, they nearly always -run, and they advance the first and third leg of one side at the same -time as the middle leg of the other, pulling themselves forward with -their front legs and pushing themselves forward with the hindermost. -They are thus constantly poised on a tripod. They occasionally, but not -very often, use their wings for flight. When they do so, their anterior -wings are stretched out at right angles to the body, and take no active -share in beating the air. They act in effect as monoplanes. It is the -hinder wings which really do the active flying. After a flight, the -hinder wings are shut up something in the manner of a fan. - -The flattened coxae, or thighs, of the leg are adapted for shovelling -débris back from beneath the body when the insect is enlarging its -habitation. When the cockroach gets into a dusty ‘_milieu_’ the dust -is immediately removed; the hairs on the legs act as clothes-brushes -and brush every part of the body, whilst the antennae, which attract -any dust in the neighbourhood, are repeatedly drawn through the closed -mandibles and so cleaned. A cockroach is able to walk on smooth -surfaces because it possesses between the joints of the tarsus certain -soft, white patches, very velvety, and these give the creature a good -hold, and prevent slipping even on glass. - -Cockroaches will eat pretty well everything. They are a great nuisance -on board ship, where they are said to gnaw the skin and nibble the -toe-nails of sailors. Hardly any animal or vegetable substance -is absent from their menu. It is said that they will even devour -bed-bugs, and that natives on the African shores, troubled by these -semi-parasites, will beg cockroaches as a favour from sailors in -passing ships. - - [Illustration: FIG. 3. Mouth appendages of _Periplaneta_ (magnified). - A, Mandible. B, First maxilla: 1, cardo; 2, stipes; 3, lacinia; 4, - galea; 5, palp. C, Right and left second maxillae fused to form the - labium: 1, submentum; 2, mentum; 3, ligula, corresponding to the - lacinia; 4, paraglossa, corresponding to the galea; 5, palp. (From - Latter.)] - -The mandible (Fig. 3), with its strongly toothed surface, is capable -of biting and grinding into fragments a very varied diet. The food is -moistened by the secretion of the salivary glands, which is capable of -converting starch into the more soluble sugar. The food is further -ground up by a series of hard ridges projecting into the inner face of -the gizzard (Fig. 4, 7). The secretion of the so-called hepatic caeca -is capable of emulsifying fat and rendering proteins soluble. Thus the -ordinary food substances are reduced to a condition in which they are -capable of diffusing from the lumen of the alimentary canal into the -blood which floods the body cavity. - - [Illustration: FIG. 4.—A female cockroach, _Periplaneta_, with the - dorsal exoskeleton removed, dissected to show the viscera. Magnified - about 2. 1, Head; 2, labrum; 3, antenna, cut short; 4, eye; 5, crop; - 6, nervous system of crop; 7, gizzard; 8, hepatic caeca; 9, mid-gut - or mesenteron; 10, Malpighian tubules; 11, colon; 12, rectum; 13, - salivary glands; 14, salivary receptacle; 15, brain; 16, ventral - nerve cord with ganglia; 17, ovary; 18, spermatheca; 19, oviduct; - 20, genital pouch, in which the egg-cocoon is found; 21, colleterial - glands; 22, anal cercus. (From Latter.)] - -The external movement—one might almost say ‘the panting’—which is very -obvious in the abdomen, the alternate flattening and deepening of -this part of the body, is a movement of inspiration and expiration, -the air being driven into the stigmata and so into the tracheae or -breathing-tubes. There is a considerable variation in the rate of these -pulsations, but the cockroach’s heart beats at an average rate of -seventy to eighty contractions per minute. - -Although cockroaches have fairly developed eyes, they seem to trust -very largely to tactile impressions in appreciating their relations -to the surrounding world. Their antennae and the palps of their first -and second maxillae are constantly touching the surface on which they -are resting or moving, and from time to time their antennae wildly -wave in the air in a manner which suggests that they are smelling out -the external circumstances which environ them. The 39,000 sensory -‘nerve-endings’ which are found in the antennae of the male cockroach -are almost certainly olfactory in function. At the posterior end of -the body the two ‘cerci’ are also sensitive to tactile impressions, and -probably act at the hinder end of the cockroach as the antennae act at -the forward end. Cockroaches are certainly keenly sensitive to light, -and, as every one knows, they shun the light, and when detected in -daylight or candle-light they make as quickly as they can for some dark -hole or crevice in which to hide. - - [Illustration: FIG. 5.—Egg capsule of _P. orientalis_ (magnified). A, - External view; B, opened; C, end view. (From Miall and Denny.)] - -Cockroaches breed during the summer, and their eggs are laid in packets -of sixteen in a capsule or cocoon with rounded ends, and with an upper -corrugated edge. These cocoons are very like the little hand-bags -ladies have carried since the dressmakers denied them pockets. There -are sixteen ovarian tubes in the female, and each of these deposits -one egg in each cocoon. The ventral portion of the seventh abdominal -segment in the female is shaped like the prow of a boat, and it is in -this structure that the cocoon, or egg-case, is built up. Each egg is -fertilised by a spermatozoon which has been deposited by the male in -the spermatheca of the female. The eggs are placed in a double row, -eight in each row, facing each other, and, as they gradually develop, -it becomes apparent that the ventral face of one row faces the ventral -face of the other row—just as the little choir-boys on the Gospel side -of a chancel face the little choir-boys on the Epistle side, but much -nearer together—and that their heads are all directed towards the -corrugated ridge. - -They are at first quite white, but with large black eyes, and it -has often struck me how surprised they must be when they awake -to consciousness and find themselves staring at a brother or -sister cockroach just opposite, of whom they have had hitherto no -consciousness. The ripe embryos secrete some fluid, probably saliva, -which dissolves the ridge, and it is through this dissolved or softened -ridge that they ultimately make their way into the outer world. - -Young cockroaches are very active, running about and seeking everywhere -for any food of a starchy nature. They are, in fact, miniatures of -their parents, for a cockroach, like many of the primitive insects, has -a direct development, and there are no such stages as caterpillar and -pupa in their life-history. - -But, like other insects, cockroaches change their skin from time to -time, and they lose little time before beginning this ecdysis, for -they first cast their cuticle immediately after escaping from the -egg-capsule. The second ecdysis is four weeks later, and the third at -the end of the first year, and after this time they moult annually. At -the seventh moult, when the animal is now four years old, it assumes -the form of the perfect insect, and is capable of reproduction. The -later moults fall in the summer time, and so does fertilisation and -oviposition. Male cockroaches may be distinguished from the females by -their well-developed wings and wing-covers. They stand higher on their -legs than do the females, whose abdomens often trail upon the ground. - -In spite of the noxious secretion of their abdominal glands there are -creatures who habitually feed on cockroaches—hedgehogs, for instance, -are frequently imported into our houses to check these pests. Rats, -cats, polecats, frogs, and wasps have been known to eat them, and some -few of the digging-wasps lay them down in their larders for the use -of their progeny. Some birds will also tackle them. But even the most -devoted friend of cockroaches can find little to say in their favour, -except that they are currently reported to form the basis of the -flavouring of a very popular sauce; but even wild cockroaches will not -drag from me what the name of that particular sauce is. - - - - - CHAPTER II - - COCKROACHES (_Periplaneta_) - - PART II - - In Russia the small Asiatic cockroach (_P. orientalis_) has everywhere - driven before it its greater congener (_P. germanica_). - (DARWIN, _Origin of Species_.) - - -Cockroaches do a very considerable amount of damage by consuming -food-supplies. But they do not stop at food-supplies: woollen clothing, -newspapers—not a really great loss—blacking, ink, leather, and even -emery-paper, are all to their taste, and, being of an economical frame -of mind, they devour their own cast skins and the dead bodies of their -relatives. The late Professor Moseley recorded how on one occasion, -when on the circumnavigating tour of H.M.S. _Challenger_, a number of -cockroaches took up their abode in his cabin and devoured parts of his -boots, ‘nibbling off all the margins of leather projecting beyond the -seams on the upper leathers.’ He further records:— - - One huge winged cockroach baffled me in my attempts to get rid of - him for a long time. I could not discover his retreat. At night he - came out and rested on my book-shelf at the foot of my bed, swaying - his antennae to and fro, and watching me closely. If I reached out - my hand from bed to get a stick, or raised my book to throw it at - him, he dropped at once on the deck, and was forthwith out of harm’s - way. He bothered me much, because, when my light was out, he had a - familiar habit of coming to sip the moisture from my face and lips, - which was decidedly unpleasant, and awoke me often from a doze. I - believe it was with this object that he watched me before I went to - sleep. I often had a shot at him with a book or other missile as he - sat on the book-shelf, but he always dodged and escaped. His quickness - and agility astonished me. At last I triumphed by adopting the advice - of Captain Maclear and shooting him with a pellet of paper from my - air-gun, a mode of attack for which he was evidently unprepared. - -It is on record that cargoes of cheeses have been destroyed by -cockroaches on ships. Not only did they devour great quantities of each -cheese, but they defiled every one of them with their very tenacious -fluid which has, as we have noted above, a most disgusting smell. This -the cockroaches poured out from their stink-glands, making the cheeses -of no commercial value. - -When a cockroach casts its skin a median longitudinal slit appears -on the back of the thorax, and through this slit the insect slowly -emerges. With much labour and difficulty it squeezes its body through -and pulls one limb after another from its old integument, until at last -even the long whip-like antennae are completely withdrawn. Certain -portions of its inner anatomy—such as the lining of parts of the -breathing-tubes, or tracheae—are also withdrawn. Should the discarded -skin not be eaten by the emergent insect, it remains on the floor, and -might easily be mistaken for a sedentary cockroach but for the fact -that live cockroaches never are sedentary. - - [Illustration: FIG. 6.—Cast skin of older nymph (pupa). × 2½. (From - Miall and Denny.)] - - [Illustration: FIG. 7.—Nymph (in last larval stage) escaping from old - skin. Magnified. (From Miall and Denny.)] - -The incomplete metamorphosis, the generalised character of the nervures -of the hind wings, the complete separation of the three thoracic -segments (or rather their want of that fusion so conspicuous in the -higher insects—the flies and the bees) and the undifferentiated -condition of the mouth parts—all point to the insect being of a -primitive type. But there is no doubt that, whether a primitive -insect or not, the cockroach is a very successful one; it is an -_arriviste_—as ‘our lively friend, the Gaul,’ to quote Mr. Micawber, -would say—probably owing to its attaching itself in all cases, and -with unvaried devotion to the habitation of men. Not popular with -humanity, it nevertheless ceaselessly extends its domain by slowly yet -surely entering into new and hitherto unconquered human habitations. -In spite of insect-traps and vermin-killers, it is extremely difficult -to eradicate from a house when once it is well established. It has, in -fact, gradually dislodged in most places in Great Britain and Ireland -the old domestic house-cricket. For in spite of its irritating, and to -some people quite maddening, ticking, the ‘cricket-on-the-hearth’ has -somehow established itself as a household pet, and one that has won not -only our respect but our affection. So curious is our psychology. - - The cockroach has many enemies, and the genus _Sphex_ (or _Chlorion_) - may be seen hunting about here and there, up and down the road-side - and gardens, searching for its favourite prey. It spies out a - cockroach, which appears to know intuitively that there is danger at - hand, for it shows symptoms of great fright, and seems so confused - that it cannot run away. The _Chlorion_ pounces upon the insect, - clasps it with its mandibles between the head and the corselet, and - stabs it in the body with the sting. Then it flies off for a little - distance, and awaits the effects of the poison thus introduced; and - when the convulsions of the victim have ceased, the clever little - insect seizes its stupefied prey, and drags the heavy burden with - great efforts to its nest. Usually the opening of the cavity is so - narrow that the cockroach cannot be got in, for its legs and wings - stick out and prevent its introduction. But the _Chlorion_ sets to - work and cuts off the legs and the wings, and having thus lessened - the difficulty, it strives hard to push the body into the hole; but - as this plan usually fails, the hymenopteron enters first of all, - seizes the cockroach with its mandibles, and drags it in with all its - force. As the integuments of the _Blatta_ are more or less soft and - flexible, the great insect is at last forced into the gallery, where - it never could have been expected to have entered. Such proceedings on - the part of the _Chlorion_ almost verge upon the domain of reason; and - it is difficult to explain them by the notion of that very indefinite - quality called instinct, for the manœuvres vary according to the - circumstances, and there appears to be an intelligent method of - overcoming every difficulty.[1] - -Apart from animals which eat it, there are a number of parasites -which infest it, beginning with the parasitic beetle _Symbius -blattarum_, whose wingless females attach themselves to the bodies -of the cockroaches and feed upon their tissues. Then occasionally a -round-worm, _Filaria rhytipleurites_, whose sexual stage is passed -in the rat, is found in its larval stage in the fat bodies of the -cockroach. - -Two years ago Dr. C. Conyers Morrell undertook some investigations -and observations as to what part, if any, cockroaches played in the -dissemination of pathogenic microbes, his object being, as he says, -‘first to ascertain what bacilli belonging to the colon group are -likely to be conveyed to food and milk by this insect, and secondly -to find whether known bacteria and moulds can be transmitted by the -faeces.’ Dr. Conyers Morrell’s experiments were conducted on one of the -Union Castle liners sailing to South Africa, and the insects which were -investigated were collected only from the larder or passages adjacent -to the kitchens; in no case were they taken from lavatories or from -staterooms. The general condition of the ship, which was almost new, -was one of exceptional cleanliness, and thus afforded good conditions -for the experiments. Dr. Morrell was of opinion that there was little -danger except by contamination from the faeces of the infected insect. - -[1] _The Transformation of Insects_, by P. M. Duncan. London: Cassell, -Petter, Galpin and Co., 1882. - -One of his first experiments was to prove that should cockroaches -fall into the dough which was being baked for bread the heat of the -baking entirely destroyed the bacilli that were in the alimentary canal -of the insect. With regard to infection with the colon bacillus, he -kept an infected insect under the best antiseptic conditions he could -compass until it had passed some undigested food. Of this undigested -food an emulsion was prepared, and cultures were made from it on -bile-salt medium and in litmus-milk. Afterwards special cultures were -made in gelatine and peptone solutions. Incubation was conducted in -all cases at 37° C., and cultures were made from seventeen specimens. -Five of these produced colonies of bacilli on the bile-salt medium, -with sub-culture results as follows: Four produced acidity and -clotting of milk, acid, and gas in glucose, lactose, and saccharose, -and production of indol. But the bacilli did not liquefy gelatine, -and were Gram-negative. One specimen produced gas in glucose and -lactose, and liquefied gelatine and coagulated milk. The former in its -reaction corresponded to the _Bacillus lactis aërogenes_, the latter to -_Bacillus cloacae_. In five cases greenish moulds of the _Aspergillus_ -variety were found after inoculating litmus-milk. - -Cockroaches will devour human sputum with avidity, and are frequently -to be found in spittoons (or, as the more delicately minded American -calls them, ‘cuspidors’[2]), and it is interesting to know that after -feeding the insects on infected sputum from a tuberculous patient, the -tubercle bacilli are found in the faeces within twenty-four hours; two -specimens which had been fed on staphylococci showed these pathogenic -organisms in their faeces and in the cultures on agar-agar, which were -obtained from their dejecta. - -I have quoted largely from this important paper, and now propose -to quote a good deal more, and thus I append Dr. Conyers Morrell’s -conclusion of the important experiments he conducted on the Union -Castle liner. - -[2] From the Portuguese ‘cuspidor.’ Cf. the Latin ‘conspuere.’ - -The foregoing experiments, though insufficient in number to afford a -basis for working out percentage results, are, I think, of some value, -in that they prove the following facts:— - -The common cockroach is able by contamination with its faeces (1) to -bring about the souring of milk; (2) to infect food and milk with -intestinal bacilli; (3) to transmit the tubercle bacillus; (4) to -disseminate pathogenic staphylococci; (5) to transmit from place to -place destructive moulds. - -These facts, taken in conjunction with the life-habits of the insect, -lead to the conclusion that the cockroach is able to and may possibly -play a small part in the dissemination of tuberculosis, and in -the transmission of pyogenic organisms; that the insect is in all -probability an active agent in the souring of milk kept in kitchens -and larders; and that it is undoubtedly a very important factor in -the distribution of moulds to food and to numerous other articles, -especially when they are kept in dark cupboards and cellars where -cockroaches abound. The distribution and numbers of the cockroach are -rapidly increasing, and unless preventive measures are adopted the -insect is likely in the course of time to become a very troublesome and -possibly a very dangerous domestic pest.[3] - -[3] _British Medical Journal_, 1911, ii. 1531. - - - - - CHAPTER III - - THE BOT- OR WARBLE-FLY (_Hypoderma_) - - Apropos de bottes.—(REYNARD.) - - -Britain wants many materials in this war, and as long as our back -door is open we are getting them. Petrol, rubber, zinc, copper, -molybdenum, vanadium, thorium, nickel, saltpetre, wool, cotton, -are all coming to us in greater—immeasurably greater—quantities -than those in which they can filter through neutral countries into -Germany. These things count. The shortage of leeches in Great Britain, -on which I have already dwelt, is negligible, and is entirely -over-balanced by the really serious shortage of sausage-skins in -middle Europe. I am told that our meat-salesmen at Smithfield -were offered an incredible advance on the normal rate for these -products—so-very-necessary-and-under-no-circumstances-to-be-done --without-with-casements—but the meat-salesmen at Smithfield were -patriots. In their dire extremity the Germans have been trying to make -them of cellulose. - -Amongst the things both combatants most want is leather. One of the -most impressive efforts we non-combatants have been watching, since -August 1914, is an army growing, near us and next us, with apparently -an unlimited supply of leather belts, leather trappings, leather -saddlery—leather harness for man and beast. Yet they tell me that -the price of leather since the War began has appreciated by 140 per -cent. This may be so; but, as Joseph Finsbury remarked in ‘The Wrong -Box,’ ‘there is nothing in the whole field of commerce more surprising -than the fluctuations of the leather market. Its sensitiveness may -be described as morbid.’ But Joseph was no business-man, and kept in -the background of the office a capable Scot who was understood to -have a certain talent for book-keeping. Readers of Stevenson will -remember that nobody had ever made money out of Finsbury Brothers, -Leather-merchants, except the capable Scot who retired (after his -discharge) to the neighbourhood of Banff, and built a castle with his -profits. There are still many capable Scots about, and this may, to -some extent, account for the present price of Sam Browne belts. - -There must have been well over 150,000 Sam Browne belts made since the -War began. A widespread belief—at any rate, amongst the junior members -of the Army—is that Sam Browne was an American; possibly some slight -confusion existed in their dear young minds between the inventor of the -belt and John Brown whose ‘body lies,’ &c. The inventor of this useful -cincture was, however, Sir Samuel James Browne (1824-1901), G.C.B., -K.C.S.I., the well-known Indian fighter, who lost an arm, and gained a -V.C. by his gallantry during the Mutiny. He was for a time the military -member of the Governor-General’s Council, and he commanded the first -division of the Peshawar Field Force during the Afghan War of 1878-9. -The 22nd Regiment in the Indian Army, a frontier force, is known as Sam -Browne’s Cavalry. - -The belt was first used unofficially, but it gradually found favour -with the authorities, and it is mentioned officially in the regulations -drawn up for the Straits Settlements in 1891, and for Egypt and West -Africa in 1894. It was only on April 24, 1900, that the pattern was -‘sealed,’ and adopted as a general item of equipment for all officers -on Active Service. - -Anything that seriously destroys the continuity of the integument of -our oxen, which interferes with the ‘wholeness’ of the hide which is -the basis of leather, clearly affects—and affects detrimentally—an -important munition of war. The bot- or warble-fly does this. But -it does more: its attacks materially lessen the value of the beef -which potentially lies beneath the hide, and thus in a double sense -the warble-fly is the enemy of man whether he be soldier or sailor. -Further, its attacks seriously lessen the milk-supply of the country. - -Amongst the numerous families into which the true flies (DIPTERA) are -divided, none are more harmful to human enterprise than that of the -_OESTRIDAE_, or bot-flies, inasmuch as every single species and every -single member of this family passes its larval stage within the tissues -of some vertebrate host, and frequently in those of domesticated -cattle; sometimes even in man himself. One of the commonest genera -of this family of flies is _Hypoderma_, which is represented in our -islands, and in many other parts of the world where domesticated cattle -are reared, by two species—_H. bovis_ and _H. lineatum_, both commonly -known as bot- or warble-flies. - -The harm caused by these larvae, living as they do in the tissues of -the body, beneath the skin, by piercing holes through the integument or -skin, whereby they make their exit from the ‘warble’ or subcutaneous -tumour in which they have passed their latest larval stage, is almost -incalculable. - - [Illustration: FIG. 8.—_a_, _Hypoderma bovis_; _b_, maggot of _H. - bovis_; _c_, egg of _H. bovis_; _d_, puparium of _H. bovis_; _e_, - egg of _H. lineatum_; _f_, maggot of _H. lineatum_; _g_, _Hypoderma - lineatum_. All the figures are magnified. (From F. V. Theobald’s - _Second Report on Economic Zoology_, British Museum, 1904.)] - -Miss Ormerod, who for so many years kept alight the lamp of economic -entomology in England, published some statistics on this subject -towards the end of the last century. In 1888, out of slightly over -100,000 hides dealt with in the Newcastle cattle and skin market, -60,000 were ‘warbled,’ and the loss to the trade amounted to £15,000. -The same year at Nottingham 8500 out of 35,000 hides were largely -spoiled; at Manchester 83,500 out of 250,000 suffered from the same -cause: the losses in these towns being estimated for the year in -question at about £2000 and £17,000 respectively. Taking the average -from all sources in England, Miss Ormerod estimated the fall in value -at from 5s. to 6s. on every warbled hide. The most riddled hides—that -is, those with the most punctures—come to the sale-room during April -and May, but the trouble extends from February to September. - -There is also the loss caused by the warble to the butcher—and through -the butcher to the Army Service Corps. The presence of the fly-larva, -which is quite a large creature, induces chronic inflammation in the -tissues, and a state of things known to the trade as ‘licked beef,’ -and unless the meat-salesman cuts away the affected parts the meat is -unsaleable in the market, or greatly depreciated in value. The average -loss to the butcher on a warbled carcass is estimated at 6_s._ 8_d._ - -Finally there is a loss to the stock-raiser and dairy farmer. We shall -have occasion later to refer to the curious psychological effect the -warble-fly has upon the cattle, causing them to ‘gad’ or stampede -in wild gallops, which interferes with fattening, deteriorates the -milk-supply, and is especially injurious to cows with calf. Mr. Imms, -in his most useful summary of the warble-fly, tells us that the loss -due to _H. lineatum_ in America is calculated at 28 per cent. of their -total value of all the cattle in the States. Some authorities place -the total loss to the agricultural community in England at £2,000,000, -others at £7,000,000, a year, whilst others estimate that the loss -amounts to about £1 sterling on every head of horned cattle. - -Curiously enough, the fly itself is rarely seen, and still more rarely -taken. Mr. Imms records only two specimens of _H. bovis_ in the -collections of the British Museum, and but fifteen of _H. lineatum_. A -similar scarcity of imagos in public collections obtains on the other -side of the Atlantic, where for many years the last-named species -was alone recognised. Two years ago, however, Dr. Hadwen, working in -Canada, established the widespread existence of _H. bovis_ in the -Dominion; almost certainly it also occurs in the States; but Dr. -Hadwen had to send to Dublin for specimens with which to confirm his -find. None existed in the collections in Ottawa, and a ‘request for a -specimen ... from the Bureau of Entomology at Washington, D.C., could -not be granted owing to a scarcity of specimen’! These statements are -interesting, since at present the tanneries of Canada are working night -and day to help our shortage in leather at home. - -_H. bovis_ measures ⅝ in. in length, _H. lineatum_, somewhat less -robust, ½ in.; the hairy covering of the last named is of a foxy red -at the tail end, while that of _H. bovis_ is yellow, both at the tail -end and towards the front of the body. The flies are most abundant -during July and August, though they are believed to occur throughout -the summer. At Athenry (co. Galway) _H. lineatum_ is common by the -middle of May. They fly very rapidly, and are difficult to follow with -the eye. They rejoice in warm, sunny weather, and remain in retirement -during cold or cloudy days. Hadwen describes the egg-laying by the -female ‘as a sort of frenzied process, the fly striking’ with its -ovipositor twenty or thirty times rapidly, then leaving the animal for -fifteen minutes or so, when the process was repeated. The eggs are -attached one at a time to the hairs of the cattle and very close to the -base of each hair, not near the tip, where the horse bot-fly deposits -its ova. The eggs of _H. bovis_ are scattered and isolated; those of -_H. lineatum_ are arranged in rows of some seven or more half-way up -the hair and are contiguous. The favourite region for placing the -eggs is on the hock and on the back of the knee, or on the thighs and -flanks, and hence the American cowboys call the insect the ‘heel-fly.’ -Undoubtedly by standing with their legs in water the herd is delivered -from the pest—at any rate, for the time. - - [Illustration: FIG. 9.—Eggs of _H. lineatum_, attached to hair of cow. - Five of the eggs are hatched and six unhatched. Magnified 15 times. - (From Carpenter, Hewitt, and Reddin, _Journ. Dept. Agric. Ireland_, - xv., 1914.)] - -The eggs are large, 1·25 mm. in length, and enclosed in a whitish -shell, which is prolonged behind into a brownish foot, and this foot, -which exudes some sticky excretion, adheres to the ruminant’s hairs. -The foot of the egg-shell, in fact, consists of two lobes or valves, -which clasp the hair between their sticky inner surfaces. - - [Illustration: FIG. 10.—Eggs of _H. bovis_ attached to hairs. Note - attachment near base. Slightly enlarged. (From Hadwen.)] - -Within the egg the youngest of the four larval stages is maturing. When -hatched it is less than 1 mm. long, but it is ‘a terror for its size,’ -being armed with a formidable spine and two hooks in the mouth, and -with rows of strong spines on all the body-segments. Later, we find -a second stage, very much smoother and less spiny than the first and -this lies within the tissues of the host, embedded in its muscles and -membranes, notably in the submucous coat of the gullet; and now the -question confronts us, which once confronted George III apropos of -the apple in the apple dumpling, ‘How the devil did it get in?’ There -seems to be with _Hypoderma_ but two possible modes of entrance into -the body of its host—that is, domesticated cattle: (1) The eggs, or the -newly hatched larvae, are licked up by the tongue, as are the eggs of -the horse bot-fly—and this might be held to explain the not infrequent -occurrence of the second larval stage in the walls of the oesophagus; -or (2) the larvae bore their way directly through the skin. From -experiments carried on for several years which show that cattle unable -to lick themselves are not protected from warbles, Professor G. H. -Carpenter of the Royal College of Science, Dublin, concluded that the -larvae do not enter by the mouth. During the summer of 1914, he and his -able assistant, the late Mr. T. R. Hewitt, definitely proved that ‘the -newly hatched maggot does bore through the skin of cattle’; probably -after an ecdysis they find their way to the submucous coat and muscles -of the gullet, and here for a while they rest. I quote from the account -of Carpenter and Hewitt some of their most crucial experiments carried -out at the Athenry and Ballyhaise Stations of the Irish Department of -Agriculture:— - - In July 1914, twenty-four maggots were hatched in the incubator, and - some of these were used for observations as to behaviour when placed - on a calf’s body. Glaser, in 1913, had tried to carry out observations - of this kind by placing maggots on a shaved portion of a calf’s skin; - he found that they made no effort to bore through. Instead of being - shaved, a small patch of the shoulder of one of the Ballyhaise calves - was clipped, so as to have the conditions as normal as possible, when - newly hatched maggots of _H. bovis_ were placed on it. Immediately - they started crawling down the clipped hairs to the skin, and, as soon - as they reached the surface, they began to burrow. On account of their - small size it is hard to discern them, but by carefully watching - through a lens it was seen that they enter perpendicularly to the - surface, evidently cutting into the epidermis with their mouth-hooks - and occasionally bending their bodies. Mr. R. G. Whelan, A.R.C.Sc.I., - Superintendent of the Ballyhaise Agricultural Station, kindly helped - in the observations and confirmed them. Six hours after being placed - on the calf, the maggots disappeared completely. Next morning the - spots where they had entered were marked by little pimples, like - those of the Athenry animals, easily to be seen with the naked eye. - These increased slightly in size, but soon healed up, and in less - than a week not a trace of the maggots’ entrances could be found. The - boring-in of the maggots seemed at first to cause the calf a little - pain, but the symptoms of discomfort soon passed away. - - We have still to find out what happens to the first-stage larva after - it has bored into the skin and how far it travels before it undergoes - its first moult. Gläser found that some eggs of _H. lineatum_ laid - on his trousers hatched, and that a maggot bored right through into - his own skin. From symptoms of swelling and pain in various regions - he concluded that this maggot travelled to his gullet, and he finally - extracted it (in the second stage) from his mouth.[4] - - [Illustration: FIG. 11.—Entrance hole of _H. lineatum_ maggot into - the skin of a cow. The hairs around the hole have been clipped short. - The white incrustation is due to a discharge from the hole, which has - hardened. Magnified 12 times. (From Carpenter, Hewitt, and Reddin, - _Journ. Dept. Agric., Ireland_, xv., 1914.)] - -Perhaps in the first stage they may be carried by the blood stream. -They seem in their second larval stage to wander freely through the -tissues, especially through the muscular tissues, of the body of -their host—usually working upwards, and not infrequently reaching the -neighbourhood of the vertebral column before taking up—still in the -second larval stage—their final position, where their presence gives -rise to the ‘warbles,’ or subcutaneous cysts or tumours, in which the -third and fourth larval stages are passed. - -[4] _The Irish Naturalist_, October 1914. - -It seems odd that an insect pest, which so seriously affects our supply -of leather, of meat, and of milk, should have been studied for over a -century and yet conceal its chief secret from man. But the problem is -much more difficult than the layman thinks. - -Whatever be the route the maggot travels through the body of the calf -or cow, by the spring the fourth larval stage—when it is about an inch -long, and perhaps half as much in breadth—is reached in the ‘warble’ -or cyst, under the skin. Here, nourished by the products of the -inflammation it sets up, and breathing by two spiracles at the hinder -end of its body, which are directed to the opening of the ‘warble’ -which it has pierced through the skin, the larva rests until one fine -morning it pushes its way, aided by its stout bristles, through the -opening and tumbles into the outer world. - -Apparently it does not think much of its new surroundings, for it loses -no time in hiding under some clod of earth or stone or crevice in the -soil, and straightway turns into a dark brown pupa or chrysalis. This -stage lasts three to four weeks, and then the perfect fly emerges, and -will soon be ready to lay her eggs on some new victim. - -[Illustration: FIG. 12.—Cow being chased by fly. Note terrified look of -eyes. (From Hadwen.)] - -As a rule it is the yearlings who suffer most, and then the -two-year-olds; the older cattle being comparatively immune. The -inexplicable terror which the warble-fly induces in its victims is -testified to on all hands, but has never been adequately explained. -_Hypoderma_ does not bite, neither does it sting. Many other -blood-sucking insects, whose puncture must involve some pain, are -tolerated by cattle with a flick of the tail, or are frightened off by -a gesture of the head; but the presence of the warble-fly induces a -mysterious fear which rapidly spreads through a herd, and results in -a general stampede—often referred to by cattle-breeders as the ‘gad.’ -This terror communicates itself even to the ‘stalled ox,’ and cattle -confined within cowsheds show symptoms of extraordinary unrest when the -fly is abroad amongst their kin in the pastures. The resulting evils -are, of course, far graver in the unlimited prairies of the West—the -great cattle-breeding districts of the United States and Canada—than in -our carefully hedged or fenced meadows. A great many ‘dips,’ ointments, -and chemical solutions have been recommended for the prevention of -the grubs in cattle, but none have proved entirely satisfactory. The -tedious method of removing the grub from the tumour is the only safe -one. This can be done by the mere pressure of the fingers when the -grub is nearly mature and ready to leave its host, or by the use of -small forceps should the grub be young and recalcitrant. Once removed -the grub should be immediately destroyed, and some such antiseptic as -coal-tar applied to the lips of the vacated tumour. - - - - - CHAPTER IV - - THE MOSQUITO (_Anopheles maculipennis_) - - PART I - - Where the water is stopped in a stagnant pond, - Danced over by the midge. - (R. BROWNING, _By the Fireside_.) - - -There is no zoological distinction between a mosquito, a gnat, or -a midge. But, as a matter of convenience, we might confine the -term ‘gnat’ to the genus _Culex_, the term ‘mosquito’ to the genus -_Anopheles_, and the term ‘midge’ to the genus _Ceratopogon_ and its -congeners, whose collocation with the naked knees of the Highlander is -said to have given rise to the ‘Highland Fling.’ - -There is no doubt about it that both the mosquito and the gnat are -extraordinarily beautiful insects. This fact, however, has been veiled -from the public partly owing to their small size and more especially -because of their irritating bite, which causes the sufferer to kill -a mosquito at sight rather than examine its fairy-like beauty or its -fascinating dances in the air, far surpassing in grace and agility -anything seen in the Russian ballet. But biting is the dominating note -of a mosquito, and we may as well consider, to begin with, how it bites. - -If we examine the head of a mosquito we shall find that it is shaped -like a circular cushion bearing two enormous eyes—so large that in the -male they touch above the forehead and almost meet below the chin. Each -eye consists of hundreds of facets of a brilliant green hue, set in -a darkish background, like emeralds arranged on a black surface. The -head also bears a quantity of hairs and flattened scales whose number, -shape, and arrangement are of considerable systematic value. - -The following are the appendages of the head:— - -1. A pair of antennae, which are markedly different in the two sexes. - -2. A pair of mandibles. These are absent in the male. - -3. A pair of first maxillae, each of which has a jointed tactile palp. - -4. A pair of second maxillae which have fused together to form a deeply -grooved soft process in which the other appendages lie. - -Beside these four pairs of appendages, which are in reality modified -limbs, there are two median processes, which project one from the -top, the other from the bottom, of the mouth, like elongated and -hardened upper and lower lips. These are the median labrum above—a -deeply grooved structure whose edges approximate and almost touch, thus -forming a tube along which the blood of the victim is sucked. Lastly, -there is the hypopharynx—sometimes termed the tongue—a median structure -a double-edged sword, rising from the bottom of the mouth, and it is -this that is the cause of all the trouble. - - [Illustration: FIG. 13.—Side view of the head of a female _Anopheles - maculipennis_ (magnification about 20), with the various mouth - parts separated, but in the relative position in which they lie - when enclosed in the groove of the labium. This figure shows the - characteristic cephalic scales, _a_, Antennae; _cs_, cephalic scales; - _cl_, clypeus; _lxe_, labrum + epipharynx; _mn_, mandible; _hp_, - hypopharynx; _mx_, first maxilla; _li_, labium; _mp_, maxillary palps. - (From Nuttall and Shipley.)] - - [Illustration: FIG. 14.—Transverse section through the middle of the - proboscis of a female _Anopheles maculipennis_, showing the relative - position of the parts when at rest. Two tracheae and two pairs of - extensor and flexor muscles are seen in the labrum. _lxe_, Labrum + - epipharynx; _tr_, trachea; _mus_, muscles; _hp_, hypopharynx; _sal_, - salivary duct; _mx_, first maxilla; _mn_, mandible. (From Nuttall and - Shipley.)] - -A glance at Fig. 13 will show how these various mouth appendages -can by a skilful use of dissecting needles be separated out, but in -nature they are all packed together in a case; the arrangement in the -case is shown by Fig. 14, which represents a transverse section of -the proboscis. The term ‘proboscis’ is given to the totality of all -these structures taken and packed together. With the exception of the -labium and of the tactile maxillary palps all the mouth appendages -lance into the skin. The proboscis of the male is, however, too weak -to pierce the human integument, and it is the female which does all -the damage. When a mosquito is going to bite, she alights so gently -that her approach is unperceived, and she proceeds to thrust her -arsenal of weapons into the epidermis of her victim almost unfelt; the -feeling comes later. These weapons are all guided, by the forked end -of the softened labium, just as one’s finger-tips guide the end of -a billiard-cue. These ‘mouth parts’ are exceedingly fine, extremely -sharp-edged structures, whose consistency is about that of whalebone, -and both the mandibles and the maxillae have a toothed, serrated edge -(Fig. 15). They are partly pushed in by muscles in the head, partly, -I think, by the lowering of the body, and they sink slowly and surely -into the flesh with as much ease as a paper-knife will penetrate a -cream-cheese. But as they sink deeper and deeper into the integument -the body of the mosquito approaches nearer and nearer to the skin of -the victim, and the labium is pressed farther and farther backwards -until at the end of a satisfactory puncture the distal and proximal -parts of the labium are parallel and touching. - - [Illustration: FIG. 15.—A side view of the labellae and - piercing-organs of the proboscis of a female _Anopheles maculipennis_, - dissected out to show the tips of the mandibles, maxillae, and labrum - + epipharynx. The hypopharynx is not shown, _li_, Labium; _lxe_, - labrum + epipharynx; _mx_, first maxilla; _mn_, mandible; _la_, - labellae. (From Nuttall and Shipley.)] - -It is rather an interesting point that the labium does not enter the -skin, because the larvae of certain _Filarias_—one of which produces -elephantiasis in man, and the other severe heart trouble in the dog—are -found in pairs—probably a male and a female—in the labia of mosquitos. -How exactly these nematode larvae leave the labium of the mosquito, and -enter the body of the man and the dog, has not definitely, I believe, -been cleared up; but that they do enter the human and the canine skin -seems certain. - -We have mentioned that the labrum is a grooved tube with its edges -practically in proximity, and it is up this tube that the blood of the -bitten is sucked by the well-known suctorial pharynx which occupies so -large a part of the interior of the head of a mosquito. Much the most -dangerous weapon of the whole armoury, however, is the hypopharynx. -This is shaped like a double-edged sword with a very minute groove -running down the centre; this groove is so minute that Professor -Nuttall and I and others for some time took it to be a closed tube. -It receives at its base the products of the salivary glands of the -mosquito, and it is these products which contain the organisms which -cause malaria—a disease which has probably caused more trouble and has -played a greater part in the history of the world than any other malady -to which humanity is heir. Down this minute, microscopic groove has -flowed the fluid which has closed the continent of Africa for countless -centuries to civilisation, and which has played a dominating part in -destroying the civilisations of ancient Greece and of Rome. - -When the adult mosquitos (the imagines) leave their pupa-cases they are -unable to pierce the human skin until the mouth parts have hardened, -and this takes at least six hours. In England they can undoubtedly -feed twenty-four hours after leaving the pupa-case. When feeding, -both the sensory antennae and the tactile maxillary palps are thrust -forward at right angles to the proboscis. They thus test the place -where the two-lobed extremity of the labium will guide the battery of -stylets into the substance they are feeding on. The female is much more -voracious than the male, which, as we have mentioned above, cannot -pierce the human integument, and has to be content with a vegetarian -diet. Sometimes the effort even of the female mosquito to insert its -proboscis is fruitless, and we have watched a mosquito attempt four -times to pierce the skin before it drew blood. If undisturbed during -the meal the suctorial repast may last some two or three and a half -minutes. So greedy at times is the mosquito that she resembles Baron -Munchausen’s horse after the adventure with the portcullis—what is -flowing in at one end is flowing out at the other. In fact, as Dr. -Johnson said of the boys at a school ‘where discipline was maintained -without recourse to corporal punishment,’ ‘But, sir, what they gain -at one end they lose at the other!’ After the process of biting, of -sinking-in of the piercing needles, is complete, the proboscis is -withdrawn, and to do this the mosquito braces herself on her legs and -raises her body. - -Another curious feature about the head of _Anopheles_ is that it is -pierced by two chitinous, symmetrical tunnels—tubes which are open at -each end with trumpet-shaped orifices. The use of these is probably to -act as a stay or strut to strengthen the chitinous exoskeleton of the -head; but these queer galleries or tubes also to some extent act as -attachments for muscles. - -The antennae vary very much in the two sexes. In the female there -are fifteen segments, each bearing a ring of hairs, but of small and -disproportionate size, whereas in the male the bushy character of the -hairs is conspicuous even to the naked eye. In fact, it is the easiest -criterion for judging the sex of the insect. At the base of the first -joint of the male antenna is a deep cup-shaped structure packed with -sense organs, and containing a large nerve ganglion. There are sixteen -segments in the whole antenna, one more than in the female. The hairs -are capable of movement, and as a rule are kept closed on the shaft of -the antenna whilst not in use; when evening comes on they are spread -out. There seems little doubt that these organs are auditory and help -the male in searching for the female. - -The beautiful transparent wings of the mosquito are beset with minute -spikes, which serve to break up the light and to give rise to the -many-coloured iridescence of the creature’s wings. The posterior border -of the wing bears rows of beautifully graded scales. These add much -to the symmetry and beauty of the whole structure. Just behind it are -two balancers or halteres—a name derived from the Greek word ἁλτῆρες, -meaning a kind of dumb-bells which athletes used in the stadium when -jumping. These so-called balancers project outwards and backwards from -the body when the wings are in a position of flight. - -A curious distinction between the _Culex_ and _Anopheles_ is in regard -to the position assumed by the insects when they rest. In _Anopheles_ -the proboscis and body are almost in one line, and the axis of the -body is at an angle with the surface upon which it rests. _Culex_, on -the other hand, has its proboscis at a slight angle with its body, and -its body is almost parallel to the surface upon which it is perching. -_Culex_ has a much more hump-backed appearance than _Anopheles_, and -its legs are considerably shorter and stouter. The insect generally -rests upon four out of six legs; in the former case the hinder pair are -held out and curved upwards. The hind legs not infrequently serve as a -test for food. When feeding upon sweetened milk or fruit, the moment -the hind leg touches the fluid or juice the insect will wheel round and -at once begin to feed. - -_Anopheles maculipennis_ is very widely distributed, and it has been -recorded from most parts of North America and Europe, and from many -parts of Asia. Probably the species is much more widely distributed -than we have any record, but individuals do not wander very far, -of their own accord, from the breeding-places, though they may be -dispersed by the wind. Cases are known where they have been blown as -far as ten or even twenty miles; and in camping in Africa it is always -well to keep to the windward of a native village. They are also -carried about by trains, motors, and steamers. They do not indulge in -any such voluntary migratory flights as the locusts, although some -such flights have been from time to time recorded, but these ‘swarms’ -are probably due to a high wind catching a large number of mosquitos -temporarily associated. - -In a joint paper which Professor Nuttall and I wrote some years ago, we -drew attention to a case in which mosquitos came aboard a ship some ten -miles from land, and to another in which a Spanish barque from Rio was -detained in the South Atlantic quarantine station of the United States. -The vessel was so much infested with mosquitos that it was rendered -nearly uninhabitable, and the United States quarantine officer reported -that when the forecastle was opened after fumigation ‘the mosquitos -could be scooped up by hand.’ The master of the barque was positive -that there had been no mosquitos on board until the twenty-second day -out. Howard quotes a letter from a General living in Texas in which he -states he has ‘twice seen flights of _Culicidae_,’ but as the species -and the genus are not given, much of the interest of the statement -evaporates. Generals living in Texas are not invariably remarkable for -meticulous accuracy in recondite scientific matters. - - - - - CHAPTER V - - THE MOSQUITO (_Anopheles maculipennis_) - - PART II - - There in a wailful choir the small gnats mourn - Among the river sallows, borne aloft - Or sinking as the light wind lives or dies. - (JOHN KEATS, _To Autumn_.) - - -The female imago hibernates. Finsch made observations and found it -hibernating on the frozen Siberian tundras, beneath the moss and snow. -Sterling found them in North America when the snow was melting, in -great numbers, and he and his party were subsequently terribly bitten. -There is no doubt that female imagines live throughout the winter, and -they can be found in England, hibernating in cellars, old out-houses, -chicken-houses, or disused farm buildings. These hibernating females -disappear early in May, presumably having laid their eggs. Dr. Thayer -of Baltimore describes these creatures, having found them on the roofs -and walls of barns near New Orleans. Whether the male also hibernates -is doubtful. Grassi says he never found the male of _A. maculipennis_ -in the winter, only fertilised females. But as the warm weather sets in -the female generally becomes active and bites, and the native American -Indians consider these elderly and famished females give more annoyance -than at any other stage in the life-cycle of either sex. In the warmer -climate of Southern Italy they not infrequently hibernate in grottos -and caves. At times they occur in such numbers that they can be swept -up. After depositing their eggs the hibernating females probably die. -This usually happens in May. - -In the old days we used to collect gnats, keep them in a receptacle -unprovided with any food, and when, after a couple of days, they died -of starvation we wrote poems or essays on the ‘Transitoriness of Life’ -and the ‘Evanescence of Time.’ - - The thin-winged gnats their transient time employ, - Reeling through sunbeams in a dance of joy. - (MRS. NORTON.) - -Nowadays, we feed them. Bananas, sweetened milk, pineapple, or almost -any other vegetable juice, is their diet, and in captivity they will -live for weeks. At Cambridge in 1900 (July to August), Professor -Nuttall was successful in keeping females alive on a diet of bananas -and water from two to eight weeks, but it was found essential to keep -the atmosphere fairly moist and the food fresh. Grassi found that he -could only keep _Anopheles_ alive in his laboratory in Rome for a month. - -Both _Anopheles_ and _Culex_—at any rate, in captivity—lay their eggs -early in the morning. Apparently the nature of the food has some -effect upon their fertility, certain observers stating that when male -and female are fed on vegetable food alone there is no fertilisation -and no oviposition. A diet of blood evidently assists the female to -lay her eggs, and perhaps to get them fertilised. One of our female -_Anopheles_ laid a batch of 146 eggs, and subsequently laid six more. -But, as a rule, a fertilised female does not lay a second batch unless -she receives a second meal of blood. The eggs are laid two or three -days after the meal. There is also some evidence that a meal of blood -is necessary if fertilisation is to be effected. As Austen says in -_The Report of the Sierra Leone Expedition of the Liverpool School of -Tropical Medicine_:— - - The following law is likely to hold good for the _Culicidae_ which - feed on man—at least for the common species; although these gnats can - live indefinitely on fruit, the female requires a meal of blood both - for fertilisation and for the development of the ova. In other words, - the insects need blood for the propagation of their species. - -Undoubtedly, if mosquitos ever talk, they would talk like Mr. -Waterbrook, Mrs. Henry Spiker—Hamlet’s aunt—and the ‘simpering -fellow with weak legs’ talked when David Copperfield dined with the -first-named at Ely Place, Holborn. The burden of their song was: ‘Give -us blood.’ - -But a word of caution must be given here. Most of these deductions are -based upon mosquitos in captivity; whether the same be true of them in -natural conditions is not quite certain. If it be so it is difficult to -see how these countless millions of gnats and mosquitos which dwell in -the barren regions around the polar circle ever keep going. - -It very frequently happens in the Animal Kingdom that females are much -more numerous, as well as much larger, than the males.[5] As Kipling -tells us: ‘The female of the species is more deadly than the male,’ -but Professor Nuttall and I did not notice that this was the case with -_Anopheles_. - -[5] This is a fact I have always tried to conceal from Mrs. Pankhurst; -but, sooner or later, she is bound to find it out. - -There is some evidence that the male hatches out earlier than the -female, and that in Southern Europe there may be three or four -generations in the course of the season: the first beginning in April -and the fourth taking place between the middle of September and the -middle of October. After that date no larvae were found. About four -generations also occurred in the neighbourhood of Cambridge, according -to observations of Professor Nuttall. - -Kerschbaumer has calculated that if the average number of eggs laid by -a female be 150, the number of the descendants by the fourth generation -would amount to 31 millions. This readily accounts for the fact -that in certain parts of the world they occur in perfectly enormous -numbers, and if it be true that blood is essential for fertilisation -and oviposition, very few of these potential mothers can breed. In -nature they will feed on a great number of vegetable juices—melons, -wild cherry-blossom, bananas, oranges, overripe mangoes; they suck -the ‘juices’ of allied species of insects just when the imago is -issuing from the pupa-case and before their integument is hardened, -or they pierce the soft skin of the cicada, and occasionally attack -the chrysalids of a butterfly. One of the most curious sources of food -are very young trout. The adult insect attacks these _petits poissons -filiformes_, ‘literally sucking out their unsuspective little brains -before they could escape.’ Grassi is doubtful whether the adult males -feed at all. He states that he never found any food in their stomach, -nor has he ever seen a male feed. But Professor Nuttall’s experiments -in Cambridge prove that males were seen repeatedly to feed, and to feed -hungrily, on cherries, dried fruits, dates, and bananas.[6] - -[6] Owing to the recent restrictions on imported fruit imposed by the -Government the food of these beautiful little insects will be further -diminished. But what does our Government know or care about insects? - - [Illustration: FIG. 16.—View of my arm being sucked by _Anopheles - maculipennis_ (female). (From Nuttall and Shipley.)] - -As mentioned before, the proboscis of the male is too weak to pierce -the human integument, but Howard notes that it will suck up water, -molasses, and beer; and Gray, at Santa Lucia, mentions that in that -island _Culex_ had developed a marked fondness for port wine. One -particularly favourite food is rose-buds covered with aphides—probably -due to the sweetened secretion which these insects exude. The feeding -is sometimes very ravenous, so that the insects become distended, the -bright colour of blood, or coloured sap, readily shining through the -joints of their chitinous armour. - -The reaction to heat and cold is that common to many insects. During -the winter the imagines become torpid, quiescent, and cease to worry -one. With returning warmth they become lively again, and generally -wake from their winter sleep in a state of considerable hunger. They -are insects which prefer darkness to light, and during the day-time -congregate in caverns and grottos, under the shade of trees and bushes, -beneath bridges, in barns, and so on. As the sun sinks they emerge from -their hiding-places and fly during the night. - -Cambon, writing on _A. maculipennis_ found in the Roman Campagna, says -that imagines ‘appear a few minutes after sunset and disappear a few -minutes before sunrise.’ We were able to confirm this at Cambridge. The -insects retired into the shadiest parts of the boxes in which they were -living until the time of sunset, when a loud buzzing was heard, and the -insects promptly fed on the food which they had neglected during the -day. We kept our tame mosquitos in a huge gauze tent, and at night they -invariably accumulated on the side which was illuminated by a lamp. -Such mosquitos as were kept in a glass lamp-chimney, closed with gauze -at each end, invariably flew towards the end which was held towards the -light. People who are experienced with mosquitos sometimes keep the -room in which they are sleeping dark and place a light in an adjoining -room, leaving the door ajar, and thus lure them away. It seems a -curious thing that, while these insects are repelled by the diffused -light of the sun, they are attracted by the more concentrated light of -a lamp or candle, but such is the psychology of _Anopheles_. - -It is not perhaps solely the influence of light; it may be the -influence of colour; for light is very rarely entirely colourless. In -the many experiments carried on in Cambridge on the natural history of -the mosquito, _A. maculipennis_, not the least interesting were those -directed to ascertaining the insect’s preference for colour. It had -been noticed by many observers that they frequented dark-coloured areas -rather than light: for instance, note how few mosquitos there are on -the white collar of the gentleman in the Frontispiece compared with the -number on his dark head and coat. Austen had pointed out that in a -room with a dark dado it was on the dado that the mosquitos were found -rather than on the whitened walls above. Buchanan noted that the men -when collecting _Anopheles_ in an Indian hospital found they were to -be most easily got by hanging up a dark coat or two upon the walls. A -white coat they always avoided. The proverbial yellow dog of the West -is much less bitten than the Newfoundland, and persons wearing dark -socks and black shoes are more bitten than those who wear light ones. -Natives, although they suffer less in health having acquired a certain -immunity, are undoubtedly more bitten than the Europeans. - -The experiments we carried on at Cambridge were as follows: In the -large gauze cubical tent in which the mosquitos were bred and kept, a -number of pasteboard boxes without lids, measuring 20 by 16 by 10 cm., -were piled up. The boxes were lined with seventeen different coloured -cloths, and were placed in rows one above another, and the order was -changed each day, so that no question of height from the floor or -better illumination entered into the problem. Counts were made of the -inhabitants of each box on each of seventeen consecutive days, with the -following results:— - - Average number - Colour of box of mosquitos - in each box. - Navy blue 108 - Dark red 90 - Brown (reddish) 81 - Scarlet 59 - Black 49 - Slate grey 31 - Dark green (olive) 24 - Violet 18 - Leaf green 17 - Blue 14 - Pearl grey 9 - Pale green 4 - Light blue (forget-me-not) 3 - Ochre 2 - White 2 - Orange 1 - Yellow 0 - —— - Total 512 - -It will be noted that about the level of the pearl grey there was a -marked drop. Pale green and pale light blue, ochre, white, orange, -and yellow—especially the last two colours—seem positively to repel -the insect. Our khaki-clothed soldiers have other advantages than -invisibility to the foe. This matter is worth pursuing farther, and it -might be possible to design mosquito-traps lined with navy-blue; by -periodically exposing them to chloroform or benzine, or by sweeping -out the contents, considerable numbers of mosquitos might be destroyed. -A dark blue, sticky solution might be even more effective. After -reading this chapter in the _British Medical Journal_, Mr. J. Cropper -of Chepstow wrote to me as follows:— - - Seeing your article on Colour Selection by _Anopheles_ reminds - me that I found the dark navy-blue lining of my tent this summer - (in Palestine) extremely attractive to mosquitos, almost entirely - _Anopheles_; and when the sun got hot I always noticed an increase in - their numbers, presumably as they came from the herbage and trees near - by. No one ever slept in the tent, and I never found _Anopheles_ bite - in the day-time. - -The best way of ‘downing’ mosquitos is to prevent the imago hatching, -and this, as has been indicated, can be done by killing the larvae and -the pupae, which is effected by brushing oil on the water in which -they live. The petrol or crude mineral oil should be renewed from time -to time as it evaporates. When once the mosquitos are hatched, every -effort should be made to keep them outside dwelling-houses by means of -wire screens, but if that be impracticable mosquito-nets should be used -at nights. Professor Lefroy recommends one with sixteen to eighteen -meshes ‘to the inch.’ They may be driven away from a room by burning -pyrethum powder in it, or vaporising cresol or carbolic acid, but of -course this must only be done when a window is open, through which they -can escape. As regards the human body, mosquitos may to some extent be -kept away by smearing the skin with the various essential oils—such -as eucalyptus oil or lemon-grass oil, &c. Mosquitos not infrequently -bite through the socks, but wearing two pairs of socks instead of one -pair, or inserting paper under the socks, often prevents their reaching -the skin, as the proboscis is not long enough to penetrate two woollen -socks, or strong enough to pierce the paper. - - - - - CHAPTER VI - - THE MOSQUITO (_Anopheles maculipennis_) - - PART III - - - The tiny-trumpeting gnat can break our dream - When sweetest. (TENNYSON.) - -It is now pretty well accepted that the auditory organs of the mosquito -are situated in the antennae. Sixty years ago Johnston of Baltimore -was investigating the hearing-apparatus of a gnat, and came to the -conclusion that— - - The animal may judge of the _intensity_ or _distance_ of the source - of sound by the _quantity_ of the impression; of the _pitch_, or - _quality_, by the consonance of particular whorls of stiff hairs, - according to their lengths; and of the _direction_ in which the - modulations travel, by the manner in which they strike upon the - _antennae_, or may be made to meet either _antenna_, in consequence - of an opposite movement of that part. That the male should be endowed - with superior acuteness of the sense of hearing appears from the - fact that he must seek the female for sexual union either in the dim - twilight or in the dark night, when nothing save her sharp humming - noise can serve him as a guide. - - [Illustration: FIG. 17.—A, _Anopheles maculipennis_, male, showing - large, feathered antennae. B, Head of female, showing antennae with - feathering little developed. (From Nuttall and Shipley.)] - -Johnston also notes that the male mosquito is the more difficult to -catch. The bushy, complicated antennae of the male show that of the -two sexes, with the mosquito, as with man, the male is primarily the -hearer, the one who has to listen. - -Another American, Mayer, twenty years later made some interesting -experiments confirming the views held by Johnston. He managed to cement -with shellac a species of _Culex_ on to a glass slide, and, placing -it beneath a low-powered microscope, watched the response of the -antennae to tuning-forks of varying strengths. He found that under the -influence of a fork producing 512 vibrations per second certain hairs -of the antennae vigorously vibrated, whilst others were left unmoved. -He measured the amplitudes of the vibrations of these hairs under the -influence of the sound emitted by various tuning-forks. Different hairs -were seen to vibrate to different notes. Mayer also observed that when -the sound came from a direction in line with the long axis of the -antennary hair vibrations ceased altogether. Hence he argued that the -antennae could register the direction whence the sound came. Observing -the antennae under the microscope, he confirmed the view that the -vibrations ceased when the hairs pointed towards the source of sound, -and on drawing a line in the direction in which the hair pointed, he -found that it always cut within 5° of the position of the source of -sound. He concludes:— - - The song of the female vibrates the fibrillae of one of the antennae - more forcibly than those of the other. The insect spreads the angle - between his antennae, and thus, as I have observed, brings the - fibrillae, situated within the angle formed by the antennae, in a - direction approximately parallel to the axis of the body. The mosquito - now turns his body in the direction of that antenna whose fibrils are - most affected, and thus gives greater intensity to the vibrations - of the fibrils of the other antenna. When he has thus brought the - vibrations of the antennae to equality of intensity he has placed his - body in the direction of the radiation of the sound, and he directs - his flight accordingly, and from my experiments it would appear that - he can thus guide himself to within 5° of the direction of the female. - -There has always been some divergence of opinion as to how the buzzing -sound to which the male so readily reacts is produced. Howard once -thought that it was due to vibrations of certain chitinous processes -in the large tracheae. Our experiments showed, however, that when the -wing was cut off closer and closer to its origin the sound decreased in -volume, but the note progressively rose. Unlike human beings, the male -at all times emits a higher pitched note than the female, and in both -sexes the note rises after feeding. ‘The greater the meal, the higher -the note.’ This is, however, by no means confined to mosquitos. It is -a matter which any one must have noticed when assisting at a public -dinner or when dining in a college hall. - -Three unfed females gave a note of from 240 to 270 vibrations. One -unfed female gave an abnormally low note of about 175 vibrations. Four -other females, which were arranged in the order of the distension of -the abdomen, after food gave notes corresponding to 264-281-297-317 -vibrations; whereas three unfed males all gave exactly the same note -corresponding to 880 vibrations. The explanation of the higher note -of the males is probably that their wings are markedly narrower and -shorter than those of the females. - -Whilst working at _Anopheles_ the late Mr. Edwin Wilson, the artist who -was drawing our plates, observed at the base of the wing a structure -which may possibly account for the tone which is so characteristic a -feature of the buzzing. The articulation of the wing with the body is -extremely complex. There seems to be a series of structures like minute -knuckle-bones articulated with one another, and at the outer end of the -series are two ribbed rods which may play some part in the production -of the overtones. One is a chitinous bar with some fourteen or fifteen -well-marked ridges. In certain circumstances we consider that the other -toothed rod can rasp across the ridges of the bar below it. As the wing -is raised and lowered it seems probable that the slightly movable rod -would be drawn across the ridged bar. - - [Illustration: FIG. 18.—B, Right half of thorax of _Anopheles - maculipennis_, Meig, with base of right wing and right halter, - magnified about 30. A, The same magnified about 5, to show the area - which bears the stridulator. _tb_, The teeth which rasp on the ridges - borne by _bl_; _kn_, papillae on knob; _h_, distal end of halter; - _scl_, chitinous thickenings. (From Shipley and Wilson.)] - -We have mentioned above that the mosquito’s note increased in pitch as -the wings were shortened until a very short stump was left. As long -as these stumps were left a note was heard, and these stumps would -undoubtedly include the apparatus just described, for it is next -and nighest the insertion of the wing into the body. But Dr. Nuttall -found that when this short stump was removed all perceptible sound -ceased, which is certainly an argument in favour of these rods and bars -playing some part in the production of the buzzing, and in opposition -to the view of Howard and others that the buzzing is caused by certain -chitinous structures in the tracheae. - -M. J. Perez[7] has carefully gone into the question of the production -of sound in the Diptera. He claims to have shown experimentally that -the stigmata take no part in the production of sound. ‘Les causes du -bourdonnement résident certainement dans les ailes.’ He, too, points -out that if the wings are cut short the notes become more acute, until -the _timbre_ resembles that of certain interrupters which break and -make an electric conductor. This sound we should attribute to the -stridulator described above. M. Perez definitely states that both in -the Diptera and in the Hymenoptera the buzzing is due to two causes: -‘L’une, les vibrations dont l’articulation de l’aile est le siége et -qui constituent le vrai bourdonnement; l’autre, le frottement des -ailes contre l’air, effet qui modifie plus ou moins le premier.’ The -apparatus we have described is, we believe, the mechanism by means of -which the first vibrations are produced. - -[7] _Compt. Rend. Acad. Paris_ (1878), lxxxvii, p. 378. - -In the same periodical M. Jousset de Bellesme[8] confirms the statement -that both Dipterous and Hymenopterous insects emit two sounds—one deep -and one acute, and states that the latter is usually the octave of the -former. It is this double note which gives rise to the peculiar buzzing -associated with these two orders of insects. M. de Bellesme, like M. -Perez, discards the view that acute sounds are due to any action of the -issuing air in the stigmata, and attributes it to the vibrations of -the pieces of the thorax which support the wing, and which are moved -by the muscles of flight. It is usually stated that these muscles -are not inserted into the wing, but into the sides of the thorax, to -which the wing is so attached that when the lateral walls of this -part of the body are deformed by the action of the muscles the wings -move up and down. But whether this be the case or not, it is clear -that the vibrations of the sides of the thorax caused by the muscles -of flight—and causing the vibrations of the wing—will synchronise in -number with these wing vibrations, and will give forth the same note. -The existence of the higher note —‘usually the octave’ of the one -produced by the wing vibrations—is unexplained by this view. It is, -however, easily explicable if such a stridulating organ as we have -described at the base of the wing in _Anopheles maculipennis_ be found -in other Diptera and in Hymenopterous insects. - -[8] _Compt. Rend. Acad. Paris_ (1878), lxxxvii, p. 535. - -In our paper Mr. Wilson and I thought it well to figure the upper -surface of the halter as seen under a high magnification. The drawing -showed the hinge on which the halter quivers—and certain basal -papillae, as Weinland[9] calls them. There is little doubt that the -main function of the halteres is that of balancing and orientating the -insect. They may, however, have a secondary function; in some flies -they are known to vibrate with extreme rapidity. It is just possible -that in these rapid vibrations the papillae of the concave surface -rubbing against those of the convex basal plate may produce a note. -As long ago as 1764 von Gleichen-Russworm[10] observed that when the -halteres of the common house-fly are removed the volume of the buzzing -diminished. This, however, in all probability is due to the diminished -activity of the wings. On the other hand, Professor J. Stanley Gardiner -informs us that he has noticed that mosquitos still continue to give -forth a faint note even when their wings are quite at rest, and this -note may possibly be caused by the halteres. - -[9] _Zeit. f. wissensch. Zool._ (1891), li, p. 55. - -[10] _Geschichte der gemeinen Stubenfliege._ Nuremberg, 1764. - -The part which sound plays in the life of the mosquito has not been -very fully recognised. Grassi says that people who are talking are -more liable to be bitten by _Anopheles_ than people who are silent—and -quite properly, we think; people are apt to talk too much, especially -in trains. Joly observes in Madagascar that mosquitos are attracted by -music. When he played a stringed instrument the quiescent mosquitos in -his room began to fly about, and if the windows were open mosquitos -were attracted from the outside into his room, and he notes that -mosquitos are attracted by musicians when at work, or should we say—at -play? - -Two curious instances—one recorded by Howard and the other printed -in a letter to _The Times_—of the attraction that electric buzzings -have on these insects may be given. Mr. A. de P. Weaver, an electrical -engineer, of Jackson, Miss., U.S.A., records that, when engaged in -some experiments in harmonic telegraphy, he observed that when the -note was raised to a certain number of vibrations per second, all the -mosquitos—not only in the room, but from the outside—would congregate -near the apparatus, and were, in fact, precipitated from the air -with a quite extraordinary force, hurling their frail bodies against -the buzzing machinery. This machinery formed, in conjunction with -sticky fly-paper, an excellent means of capturing them. Mr. Weaver -then devised a means of electrocuting the pests. He used a section -of unpainted wire screen mounted on a board with pins driven through -the meshes, the heads of the pins being flush with the surface of -the screen. The bodies of the pins were then electrically connected -together, the whole forming one electrode of the secondary coil of an -induction coil, whilst the wire screen formed the other electrode. An -alternating current of high potential was passed, and when the note -was sounded the insects precipitated themselves to their doom, being -electrocuted the moment they touched the apparatus. - -A somewhat similar story is told by Sir Hiram Maxim in _The Times_ of -October 29, 1901. One of the lamps in an installation which was put -up in Saratoga Springs, New York, hummed in an agreeable manner, and -he noticed that night after night this lamp was covered with small -insects. On closer examination he found that they were all mosquitos, -and all males. - - - - - CHAPTER VII - - THE MOSQUITO (_Anopheles maculipennis_) - - PART IV - - Gnats are unnoted wheresoe’er they fly, - But eagles gazed upon with every eye. - (SHAKESPEARE, _Rape of Lucrece_.) - - -The eggs of the mosquito are deposited in fresh water, and at first -they are white, but they very rapidly darken until they assume a -polished black appearance. Each egg is 0·72 mm. in length, and its -greatest breadth, which is somewhere about its middle, is 0·16 mm. The -egg is boat-shaped, and one end, as is usual in boats, is slightly -deeper and fuller than the other. The under surface is fluted, and -is marked by a minute network. The upper surface has a coarser -reticulation which divides the surface into nearly equal hexagonal -areas. The rim of the ‘boat’ is thickened, and these thickenings are -regularly ribbed; they extend over above the median third of the egg, -and recall the rounded float which runs along the edge of a life-boat: -and indeed they serve the same purpose, for they are composed of -air-cells, and their function is to keep the boat-shaped eggs right -side upward. Soon after the egg has been laid it is of a greyish-black -colour, but after a certain amount of attrition an outer membrane -splits off—the membrane which has given the egg its reticulated -appearance. This membrane scales off in fragments, and is of a grey -colour. The egg beneath it is glistening black—as shiny and as black as -patent leather. - -One curious fact that Professor Nuttall and I noticed in the -life-history of the egg is that when it is drawn by capillary forces -a little way out of the water on to the leaf of a water-plant or some -other half-submerged object, the blunt end always points downwards. Now -the blunt end is the head end, and thus, should hatching take place -whilst the egg is suspended half in the water and half in the air, the -larva will emerge into its proper element and not into the atmosphere. - - [Illustration: FIG. 19.—Larva and eggs of _Anopheles maculipennis_. - A, Egg seen from the side, × about 20; _fl_, the float. B, Egg seen - from the upper surface, × about 20; _fl_, ridge of air-chambers, which - acts as a float. C, Very young larval stage, × about 20; _st_, stigma. - D, Fully grown larva, × about 20; _b_, brush _ant_, antenna; _mp_, - palp of maxilla; _st_, stigma; _t_, tergum; _ap_, anal papillae. E, - Flabellum or flap, which overhangs the base of certain thoracic hairs. - F, A palmate hair, highly magnified. (From Nuttall and Shipley.)] - -Like other objects floating on the surface, the mosquito-egg slightly -indents the surface. The number of eggs seems to vary. According to -Grassi, each female deposits about one hundred eggs, whilst Howard puts -the number as varying from forty to one hundred. We, however, found in -captivity the female laid about one hundred and fifty. According to -Grassi, the eggs of _A. maculipennis_ lie side by side like the bridges -of boats which span the Rhine, whilst those of _A. bifurcatus_ arrange -themselves with their ends in contact, forming starlike patterns. -Unlike the eggs of the gnat (_Culex_) the eggs of _Anopheles_ do not -adhere together, and the result is they are very readily scattered -by the wind. But in sheltered places, like a laboratory aquarium, if -undisturbed, the Italian Professor found that they tended to congregate -together, as indeed do most minute objects floating on the surface of -the water. Our observations did not entirely confirm those of Grassi. -In Cambridge, at any rate, we found the eggs in our aquaria always -scattered. Very frequently empty egg-shells were met with, but they too -were scattered. As a rule, in nature, the ova are deposited in water -rich with algae or other vegetable life, and they are more frequently -in shallow than in deep water, the temperature of shallow water being -naturally somewhat higher. - -On the second or third day after oviposition (and this depends upon the -temperature), the young larva leaves the egg and begins to swim in the -water. The egg hatches by the detachment of a cap-like portion of the -anterior end of the egg-shell. There is no visible ring indicating the -limits of this operculum, but the cap is usually more or less of the -same size. Opinions differ as to how far desiccation interferes with -development of the larva in the egg-shell. They do not seem to be able -to stand more than forty-eight hours of drought. There is no evidence -that they can survive throughout the winter period. Everything that we -know indicates that the egg must pass this period within the mother’s -body, and that they only attain maturity in early spring, when the -weather becomes warmer. - -The larva of the mosquito is one of the most fascinating objects one -can watch under the microscope. It is very complex, and consists of the -usual arthropod regions of (1) the head, (2) the thorax, and (3) the -abdomen. - - [Illustration: FIG. 20.—Side view of head of a fully grown larva of - _Anopheles maculipennis_. _b_, Brush; _c_, antenna; _d_, palp of - maxilla; _m_, hooked hairs at edge of maxilla; _p_, median tuft of - hairs; _r_, thickened rim of chitinous covering to head; _s_, large, - feathered hairs which overhang head; _t_, mandible; _u_, larval eye; - _v_, eye of adult, forming above and behind _u_. (From Nuttall and - Shipley.)] - -Without going into the question of how many typical somites make up the -head, we must state that the thorax has the typical number of three, -much fused together, and the abdomen nine. The first seven of these -are very much alike; the eighth, however, bears the large stigmata or -orifices of the breathing system, and the ninth a number of beautifully -arranged hairs, by means of which the larva to a great extent steers -itself. The head resembles two-thirds of a sphere, and is covered with -a complete and clearly defined brown, chitinous case. The eyes are -lateral, and on each side we have both a simple and a compound eye. In -front of each eye is a little protuberance, which carries the antenna, -and between these two eminences a band of pigment runs across the -head, from which six symmetrically placed immovable feathered hairs -project, wreathing the head, as it were, with a halo. There are many -other hairs on the head, whose number and shape are of great systematic -importance. The anterior edge of the head carries on each side of its -under surface a conspicuous brush, very like a shaving-brush, the -constituent hairs of which are arranged in a spiral, and it is these -brushes which sweep the food into the mouth of the young and voracious -larva. The base of this brush is so arranged that when depressed and -bent towards the mouth the two brushes approximate, but each brush can -move independently and often does so: one may be depressed towards the -mouth, whilst the other remains erect. - - [Illustration: FIG. 21.—Ventral view of head of a fully grown larva - of _Anopheles maculipennis_. _b_, Brush; _c_, antenna; _d_, palp of - maxilla; _j_, stout hairs of mandible, which arrange the brush; _k_, - teeth of mandible; _m_, hooked hairs at edge of maxilla; _p_, median - tuft of hairs; _q_, the ‘underlip’ of Meinert, or metastoma; _r_, - thickened rim which passes into the soft tissues of the neck. (From - Nuttall and Shipley.)] - -The larva passes its life hanging on to the under surface of the -surface-film of the water, its dorsal surface being uppermost. In fact, -as Sidney Smith pointed out about the sloth, ‘it passes its life in a -state of suspense, like a young curate distantly related to a bishop.’ -But, since these larvae feed on any kind of organic débris that -floats up to the top and is there arrested by the surface-film, it is -obviously important that the brushes which sweep together these organic -particles and carry them to the mouth should be next the surface, and -to effect this the head must rotate through an angle of 180°; and -the head does in fact turn upside-down on the neck so sharply and -accurately that, as it comes into position, you almost think, as you -are watching it, that you hear a click, just as you do when you rotate -the diaphragm of a microscope. - -The mouth parts now begin to vibrate upwards and forwards, and the -brushes are bent downwards, backwards, and inwards. Round the mouth is -a small space, the walls of which are completed by the mandibles, and -into this space the brushes are suddenly bent back, at the same time -the mandibles and maxillae move forward to meet them. This movement may -take place as many as 180 times a minute, and it produces a current -converging in concentric curves towards the above-mentioned chamber. -The water filters out between the sides, and any particle of food is -retained by the hairs or by the mouth appendages; from time to time -the mandibles are brought together, and their stiff bristles are run -through the brushes as one’s fingers run through a beard;[11] at other -times the brushes disappear far into the mouth, and then are slowly -withdrawn, passing through the comb-like bristles on the mandibles. The -brushes are frequently swallowed, and are withdrawn in little jerks, -so that the maxillae have every opportunity of combing any nutritive -particles out of them. The whole operation is a most fascinating one to -watch. - -As far as one can judge, the currents set in motion by the action -of all these forces extend in an area equal to twice the length of -the larva, or even more. The currents are in the plane just below -the surface-film, and any organic matter lighter than water is swept -towards the mouth. In fact the larva sweeps the lower side of the -surface-film of the pond or puddle just as a careful housemaid might -sweep spiders and flies off a ceiling with a hand-brush. - -The principal food-supply of the larva consists of the spores of -fresh-water algae, diatoms, particles of _Spirogyra_, and any other -organisms which do not penetrate the surface-film. Occasionally the -larvae devour the decaying leaves of duck-weed (_Lemna_), and sometimes -they attack their dead fellows. - -[11] If you have a beard. - -Grassi found the intestine of the larva to contain protozoa, -unicellular algae, and other organic detritus. In course of time some -object too big for the larva to swallow is brought to its mouth by the -currents, but after a very short struggle this is rejected. The minuter -particles accumulate in the chamber for a certain time, and then are -swallowed by a gulp-like motion and thus pass into the oesophagus. - - [Illustration: FIG. 22.—A comparison between the various stages in the - life-history of the mosquito (_Anopheles_), on the left, and the gnat - (_Culex_), on the right. - - ANOPHELES CULEX - - _IMAGO_ - _PUPA_ - _LARVA_ - _OVA_] - - - - - CHAPTER VIII - - THE MOSQUITO (_Anopheles maculipennis_) - - PART V - - Amongst aquatic larvae, the most beautiful and delicate are those of - numerous species of gnat.—(GORING AND PRITCHARD’S _Micrographia_, - 1837.) - - -In the young larva of _Anopheles_ the head is broader and deeper than -the thorax, but in the older larvae the segments that succeed the -head have at least twice its diameter. It is a characteristic of true -flies, or Diptera, that the thorax should not exhibit that separation -into three divisions which is so usual in the less specialised -insects—such as the cockroach and this is peculiarly true of the larva -of the mosquito—at any rate, so far as its external structure goes. -The abdomen of the larva consists of nine free segments; the third, -fourth, fifth, sixth, and seventh of these bear palmate hairs on the -dorsal or upper surface, something like hands with fourteen ‘fingers’ -spread out. These hairs adhere to the under layer of the surface-film -of the water, and help to maintain the animal in a horizontal position -just below that film. When the larva relaxes its hold and sinks into -the water, it not infrequently carries with it air-bubbles enclosed by -these fourteen ‘fingers.’ - -The eighth abdominal segment bears the stigmata or the openings -of the respiratory apparatus, and the ninth segment has abandoned -the flattened and square cross-section of its predecessors, and is -cylindrical and tapering. The posterior end of the body is cut off -sharply. Round the posterior opening of the alimentary canal are -four white, soft papillae, which are well supplied with tracheae and -are capable of contracting and expanding. Above these are four very -prominent hairs, two median and two lateral, and ventrally to the ninth -abdominal segment is a fan-shaped arrangement of hairs springing from -two pieces of very complicated structures. These hairs seem to act to -some extent as a rudder, and they probably serve as an accessory organ -of locomotion. Possibly they have also a sensory or tactile function, -and act, as so many posterior filaments do in insects, as antennae -‘from behind.’ - -We have referred above to the respiratory openings, and, indeed, these -are the key to the whole situation. Close these openings— as they -can be closed by floating petrol or other oil on the surface of the -water—and ‘the trick is done.’ The larvae and the pupae can no longer -breathe, and there is thus no imago to “carry on.” In _Culex_ (the -gnat), these respiratory orifices are borne on a long tube directing -dorsalwards—a tube which is larger and longer than a segment of the -body, and whose presence gives the larva the appearance of a Y with -slightly unequal limbs. These breathing-openings are of the greatest -complexity, but the outstanding fact is that these stigmata pierce -through the watery film and put the respiratory system of the larva -into communication with the atmosphere of the whole cosmos. If anything -frightens the larva, certain side-pieces and flaps fold suddenly -backwards and over the stigmata, the connexion through the surface-film -is broken, and the little larva, like a German submarine when it -sights an English battleship, darts below, frequently carrying with it -the drop of air attached to the rim of the respiratory recess which -surrounds the openings of the two stigmata. - -Not infrequently the larva ceases to lie parallel to the surface of the -water, its palmate hairs are put out of action, and then its body hangs -down into the water, but it still maintains its respiratory connexion -with the outer air through these breathing-pores. From time to time -the hairs mentioned above are brushed over by the mouth parts and -cleaned of any débris. - -The larvae, when they leave the surface-film sink by their own -weight; but they not infrequently swim actively downwards, their -swimming action being very like that of an eel. When returning -to the surface they are entirely dependent upon their powers of -swimming, being slightly heavier than water. When the tail reaches the -surface-film the larvae are at once arrested, and immediately cease -their swimming-movements. They invariably move tail forwards, and -the hairs which we have mentioned above at the posterior end of the -body undoubtedly act as ‘buffers’ or ‘fenders.’ As a rule, when they -are above, they are actively engaged in feeding; but at the bottom -they lay inert, as though feigning to be dead. Kept in a glass beaker -they are apt to lie with their respiratory apparatus attached to the -concave film, which capillary attraction draws up on the surface of the -glass. Their heads then point towards the surface of the beaker. If -forcibly kept below—say, by submerging them under a watch-glass—they -are frequently enabled to breathe by attaching the openings of their -respiratory apparatus to an air-bubble. - -The general colour of the larva is a mottled brown, darkening where the -chitin thickens. The older larvae are to some extent green, possibly -due to their food; but this green colour is not by any means confined -to the alimentary tract. After moulting, the issuing larva is a uniform -light lavender colour, which, however, very soon darkens. - -A strong wind passing over a pool where _Anopheles_ eggs, larvae, or -pupae are floating, will gradually pile them all up on the side towards -which it is blowing. The _Anopheles_ larvae undoubtedly are braver than -those of the _Culex_—that is to say, a disturbance which will send all -the _Culex_ larvae scurrying to the bottom will leave the _Anopheles_ -larvae unmoved. - -When first hatched the larvae measure somewhere about 0·7 mm. to 0·95 -mm., but when ready to pupate they have attained the length of 7 mm. -The rate of development is greatly influenced by the temperature, and -a few cold days will markedly retard the larval growth. In warm sunny -weather, larvae will pupate between the second and third week, but -larvae taken in August (if the autumn be cold) do not attain their full -growth until November. The young larvae undoubtedly die in considerable -numbers, and the act of pupating is also attended with certain and -varying dangers. Out of 834 larvae and pupae caught in Cambridgeshire, -636 were small larvae, measuring less than 4 mm.; 181 were large -larvae, measuring up to 7 mm. But only 17 pupae were taken. There are -other facts which show that the larvae under natural conditions succumb -in very considerable numbers. - -[Illustration: FIG. 23.—Side view of late pupal stage of _Anopheles -maculipennis_. _f_, The stigma opening at end of trumpet-like -projections. (From Nuttall and Shipley.)] - -When the larva is about to turn into a pupa it comes to rest, and now -the thoracic regions are more swollen than ever. Soon a dorsal slit -appears along the larval cuticle and the pupa slowly, but gradually, -emerges through this slit and leaves the larval chitinous cuticle -behind it. On first emerging, the pupa measures about 6·5 mm., the head -and thorax making up one-third of this. During the last larval stage -many of the pupal organs have been re-forming and are more or less -visible through the cuticle. The mouth parts and limbs of the third -stage—the future imago—show no relation to those of the larva. They -are there enclosed in their respective sheaths, but these are quite -independent of the larval ‘appendages.’ The respiratory trumpets, -which, as in the larva, pierce the surface-film, are ready to act as -breathing-organs. Whereas the larvae breathe through two stigmata -at the posterior end of the abdomen, the pupae breathe through two -respiratory trumpets issuing from the anterior dorsal surface, and it -is these trumpets, together with certain palmate hairs, which support -the pupae in the right position and put the respiratory organs at this -stage into communication with the outer atmosphere. During the pupa -stage _Anopheles_, like the pupa of other insects, takes no food. - -The pupa is something like a tadpole, with its tail bent under its -body and flapping up and down, instead of from side to side. The whole -pupa is enclosed in a thin semitransparent membrane, through which the -organs of the adult can readily be seen. As it grows older its colour -darkens. Until about the time when it will give rise to the fly, the -pupa floats quietly at the surface, breathing through its respiratory -trumpets. When disturbed it shows considerable activity, and it is by -no means always easy to capture by means of a pipette. At the least -sign of danger it darts below with a series of intermittent strokes -and rests at the bottom of the water. Its own buoyancy brings it back -to the surface, as, unlike the larva, it is lighter than water. Not -only has it a certain amount of air in its tracheae, but there is a -reservoir of air at the posterior end of the thorax which acts as a -very efficient float. When retreating below the surface the respiratory -trumpets usually carry down with them two minute air-bubbles. - -[Illustration: FIG. 24.—A, Side view, B, ventral view, of the pupa of -a male _Anopheles maculipennis_; C and D, the same views of the female -pupa.] - -The sex of the pupa can be determined by the lobes at the posterior -end of the tail: A and B (Fig. 24) representing the male, and C and D -the corresponding parts of the female. The duration of the pupal life -is generally three to four days, but conditions of temperature and the -state of the natural surroundings exert considerable influence upon -the rate of development. Howard has pointed out that the addition of -creosote or creosote-oil to the water in which the larvae are living -hastens the metamorphosis into pupae, and the pupa stage is passed -through in as short a time as fifteen hours instead of the normal -forty-eight hours of the warm waters of the Southern States in America. -It has also been observed that showery weather hastens the rate of -development. - -When the adult mosquito is about to emerge, a certain amount of -air is secreted under the chitinous casing of the pupa. A fine -streak containing air appears along the back, extending between the -respiratory trumpets and the base of the head. This central streak -gradually passes backwards until it reaches the seventh abdominal -segment, and then suddenly the pupa extends its abdomen so that it -floats parallel to the surface of the water instead of being under the -rest of the pupa’s body. The chitinous integument now splits along the -median dorsal line, and through the slit thus made the thorax of the -adult mosquito now protrudes. By gradually pressing its abdomen against -the pupa-case, the body of the perfect insect is slowly but gradually -raised above the surface of the water. The head is pulled backwards -and upwards, and millimetre by millimetre the mouth parts, the palps, -and antennae are withdrawn, and at first remain bent backwards beneath -the body of the insect. Gradually the bases of the wings and the -abdomen emerge, and soon the wings are freed and immediately flatten -out and begin to harden. The legs and the tip of the abdomen alone now -remain to be dealt with. At this stage the insect projects far beyond -the anterior end of the pupa encasement, and somewhat resembles an -exaggerated figurehead on a ship. The pupa-case is still filled with -air, and acts as a float to support the emerging insect. At last the -front legs are being freed, the second and third pair of legs soon -follow, and now the insect is standing on the surface of the water -raised on its tarsal joints, the tip of the abdomen being the last part -to free itself from the pupa-case. - - [Illustration: FIG. 25.—Imago of a mosquito extracting itself from the - pupa-case, which floats on the surface of the water. Magnified. (From - Guiart.)] - -The exit of the fly is naturally a very critical period in its -life-history, and in many cases it is fatal. The freeing process takes -between five and ten minutes. When undisturbed the emergent fly rests -for a time until its wings and limbs are sufficiently hardened to -enable it to fly, or at least to walk about. Sometimes the mosquito -takes its first flight straight from the pupa-case; at other times -it rests awhile before taking to the air. The young imago is pale in -colour, the thorax being brown and the abdomen transparent, with a -greenish tinge. At first the abdomen is much longer than it is later, -for, almost immediately after the mosquito’s exit from the pupa-case -its abdomen begins to contract, and from its hinder end four or five -drops of a glistening, greenish-white fluid are exuded. - -The newly born imagines generally take to flight between five and ten -minutes after they have emerged, and they at once begin to darken in -colour, and in two hours assume the normal dusky colour of the adult. -If anything hinders the insect from properly extending its limbs -immediately on issuing from the pupa-case, the parts harden and remain -distorted throughout life. - - * * * * * - -Anyone who has spent a day or two in Lille or Bruges, or other towns -in Picardy and in Southern Belgium, will understand why, as my Uncle -Toby has it, ‘Our army swore terribly in Flanders.’ The incessant and -tireless biting of mosquitos would make any army swear, even though -they were ignorant—as my Uncle Toby’s army certainly was ignorant—that -the gnats, as they called them, conveyed tertian and quartan ague. In -Europe the trouble is a summer or early autumn trouble; but our troops -are fighting in many tropical and sub-tropical countries, where the -mosquitos—like the poor—are always with them. - -That the plague can now be checked is shown by the making of the Panama -Canal; and that this check is due to British science is shown by the -work on the life-history of the malarial organism, first investigated -by Sir Ronald Ross, and later, as regards the human parasites, by -certain Italian savants. It is also due to the public health services -of one or two British medical officers of health in the East. _Their_ -methods have been applied and improved by those responsible for the -elusive channel which now at times separates North from South America. - -We have seen that the larva and the pupa hang on to the surface-film -of the water by means of certain suspensory hairs, and by the -openings of their breathing-apparatus. Anything which prevents the -breathing-tubes reaching the air ensures the death of the larva and -pupa, and then there is no issuing adult—hence the use of paraffin on -the pools or breeding-places. It, or any other oily fluid, spreads as -a thin layer over the surface of the pools and puddles and clogs the -respiratory-pores and the larvae or pupae die of suffocation. - -In Ismailia the disease has been reduced to an amazing extent, and -remarkable results have followed the use of these preventive measures -at Port Swettenham in the Federated Malay States. Within two months -of the opening of the port in 1902, 41 out of 49 of the Government -quarters were infected, and 118 out of 196 Government servants were -ill. Now, after filling up all pools and cleaning the jungle, no single -officer has suffered from malaria since July 1904, and the number of -cases amongst the children fell from 34·8 to 0·77 per cent. The only -melancholy feature about this wonderful alleviation of suffering, due -to the untiring efforts of the district surgeon, Dr. Malcolm Watson, is -that his fees for attending malarial cases dropped to zero. - -Thus, even ten years ago, a considerable degree of success had attended -the efforts of the sanitary authorities—largely at the instigation of -Sir Ronald Ross—all over the world, to diminish the mosquito-plague. -It is, of course, equally important to try to destroy the parasite -in man by means of quinine. This is, however, a matter of great -difficulty. In Africa and in the East nearly all native children -are infected with malaria, though they suffer little, and gradually -acquire a high degree of immunity. Still, they are always a source of -infection; and soldiers stationed in malarious districts should always -place their dwellings to the windward of the native settlements. - -Knowing the cause, we can now guard against malaria; mosquito-nets and -wire-protected windows and doors are a sufficient check on the access -of _Anopheles_ to man. If the mosquito and man could only be kept -permanently apart, we might hope for the disappearance of the parasite -from our fauna. In relieving man from this world-wide pest, all genuine -lovers of animals will rejoice that we are also relieving the far more -serious lesions of one of the most delicate and beautiful insects that -we know. - -It has always been a source of surprise to me that the great resources -and the very evident enthusiasm of the anti-vivisection societies have -not been turned in this direction. In the malarial parasite, we have a -most potent vivisector of the entrails of one of the most charming and -graceful of creatures, whose poetry of movement is hardly approached -and never equalled by the ladies of the front row of the ballet. A -little help, a very little help, would free these fascinating flies -from a form of trouble far worse than that the human alternative host -suffers. Yet, as far as I know, these societies and the societies for -the prevention of cruelty to animals have declined to help in any -way, and have knowingly allowed thousands of millions of animals to -perish annually by a most painful death, and have never stretched out a -helping hand to the fairy-like and fascinating mosquito. - - - - - CHAPTER IX - - THE YELLOW-FEVER MOSQUITO (_Stegomyia calopus_) - - ... et nova febrium - Terris incubuit cohors. - (HORACE.) - - -Like other branches of human activity disease has its romantic and its -unromantic side. Nobody can regard mumps or measles as romantic. On the -other hand, yellow fever calls up all the romance of slave-trading, -pirates and the Spanish Main, buccaneers, maroonings and other grisly -horrors, whose sole redeeming feature was a touch of romance. Lovers -of pirate stories—and who are not?—will always remember their graphic -description of Yellow Jack in the West Indies. - -We have probably always had disease with us since the creation of the -world—that act of ‘_impardonnable imprudence_,’ as Anatole France calls -it; but the first description of yellow fever only dates back to 1647, -when an outbreak occurred in the Barbados. Then, as now, it devastated -the shipping of the port, and was soon introduced by ships into St. -Christopher and, later, into Guadeloupe. The following year it was in -Cuba, and in 1655 in Jamaica, and it gradually spread throughout the -whole of the West Indies until a century or more later it reached the -Island of St. Thomas. - -One of the peculiarities of the disease is that it frequently -disappears from a given locality for long periods of time. For -instance, it was absent in Barbados after the first outbreak until -1690, and when it recurred it was at first not recognised as being the -same disease which devastated the islands forty-three years before. In -the eighteenth century there was another break of fifty-four years, and -similar breaks can be recorded in most of the West Indian islands. - -Besides the West Indies, it is at present endemic in Brazil and -on the west coast of Africa, and is common in Mexico. Whether the -disease arose primarily in Africa and is part of the toll the American -continent has had to pay for the slave-trade, or whether it was brought -to the west coast of Africa from the other side of the Atlantic, is not -certain. It apparently appeared as a regular disease in Brazil in the -year 1849, and from that time onwards, with the exception of one year, -has been a permanent trouble at Rio. From time to time the disease has -been carried to neighbouring parts of America, especially to the Gulf, -Central America, and the northern coast of South America. It has been -introduced more than once into Monte Video and Buenos Ayres, and has -even penetrated up the Parana as far as Asunçion. Every few years it -extends into the Southern States and has even reached Philadelphia and -Boston. With the exception of an outbreak in Leghorn in 1804, European -epidemics have been confined to Portugal, Spain, and the Balearic -Islands. - -It will have been noticed that most of these outbreaks occur on the -coast and then pass up the rivers. It is thus most probable that the -disease is one which is brought mainly by ships. It is obviously a -disease which must be guarded against by our troops fighting near the -coast in West Africa, as well as such troops as are left in the West -Indies. But, above all, it must be guarded against in relation to our -shipping fleet and our Navy, operating off the South American coasts. -The danger, now the Panama Canal is open, of introducing the disease -from America to Asia is a danger that should carefully be considered. - -Yellow fever is a disease which requires a winter temperature of at -least 68° F., for it is a mosquito-borne disease, and the yellow-fever -mosquito flourishes best at about this temperature. It can be -introduced into a new locality by the arrival of an infected mosquito, -or by the arrival of an infected human being. In the former case the -disease breaks out within a few days; in the latter at least ten or -twelve days elapse before new cases arise, for, as we shall see later, -the organism, whatever it is, that causes the fever is not capable of -passing from the mosquito until it has been in its body for ten or -twelve days. - - [Illustration: FIG. 26.—_Stegomyia fasciata._ Female, lateral view - (magnified.) Note hump-backed outline, and also the position of the - posterior pair of legs.] - -Thirty-six years ago Finlay of Havana suggested that the virus of -yellow fever was inoculated by mosquitos; but it was not until the -publication of the discoveries by Sir Ronald Ross and others, that -malaria is transferred by _Anopheles_, that a thorough investigation -of yellow fever was made. In the last year of the last century -an American Commission, consisting of Drs. Walter Reed, Carroll, -Agramonte, and Lazear, investigated the whole subject, and, taking -extraordinary risks, were able to prove that the infection was not -conveyed by contact or through the air, or from bedding or clothes -soiled by the dejecta of yellow-fever patients, but by a mosquito of -the genus _Stegomyia_. Whatever the virus is, it is invisible, even -under the highest powers of the microscope. It can be filtered through -a Berkefeld filter. It is destroyed by heating to 55° C. If the blood -of a yellow fever patient, during the first three days, be inoculated -into a healthy man he gets yellow fever, and it is only during the -first three days that the blood is infective. On the other hand, the -mosquito is incapable of transferring the disease until the unknown -organism has been in its own body for at least ten or twelve days. - -The mosquito in question belongs to the species _Stegomyia calopus_ -(Blanchard), or, as it is more often called in English textbooks, -_Stegomyia fasciata_ (Fabricius). The genus _Stegomyia_ differs from -other _Culicidae_ in having a dark grey or black colour, whilst the -_Culicidae_ are as a rule browner. _Stegomyia_ also has silver-white -spots and silver glistening scales, especially on the back of the legs -and on the abdomen. The grown-up mosquito is comparatively small, and -very elegant. Its length is some 3 to 4 mm., but if the mouth parts be -added is some 6 to 6½ mm. long. As is usual, the male is smaller and -feebler than the female. When settled—as, for instance, whilst sucking -the blood of its host—it rests upon its first four legs only, the two -hindmost being stretched out abaft like pennants waving in the air; but -in general it has the hump-backed appearance of _Culex_ and not the -straight outline of _Anopheles_. The colour is greyish black, modified -by numerous white spots and rings. There is a white rim round the eyes, -and a very characteristic lyre-like pattern on the dorsal surface of -the thorax. The structure of the mouth parts is much the same as that -of any other _Culicidae_. The antennae have fourteen joints, the last -two of which in the male are longer than the others. As is again usual, -the antennae of the male have long brush-like hairs, organs by means of -which they find the female. The legs are banded alternately with white -and black rings. It is this character, indeed, which has given this -mosquito the name of the ‘tiger-gnat.’ The wings are very iridescent. - - [Illustration: FIG. 27.—_Stegomyia fasciata._ Above, the larvae; - below, the eggs. Both natural size.] - -The pupa of _Stegomyia_ is darker and blacker than that of _Culex_, -and, seen from the side, the head and the thorax are somewhat more -triangular than the same parts in _Culex_. As the pupa grows older it -grows darker. The length of the larva is 4 to 6 mm., somewhat larger -than that of the gnat. But, like that, it has a respiratory-tube -stretching out from the last segment of the abdomen, almost at right -angles to the rest of the body. This respiratory-tube is much shorter -than that of _Culex_, but is long enough to enable the larva to hang -obliquely down into the water. The eggs are very large. They are -covered by a mass of small ‘cells’ containing air, and they never tend -to form a conglomerate mass like those of _Culex_, but are laid singly, -and remain isolated until the larvae hatch. After floating a certain -time they usually sink to the bottom of the water. Their length may -be about a millimetre, and their colour is almost black. When the egg -hatches, the anterior third of the shell splits off and the larva at -once emerges. - - [Illustration: FIG. 28.—Larva of _Stegomyia fasciata_ breathing on the - surface of the water. Highly magnified.] - -As is so often the case with mosquitos, it is the female alone -which bites. The male nourishes itself on plant-juices, saps, and -so on—especially they like sugary secretions—and in the absence of -blood the female is reduced to a similar diet. Hence _Stegomyia_ is -comparatively common in dwellings where sweetstuffs are—bakeries, -sugar-refineries, and so on. These mosquitos are, like the cockroach, -the fly, and the bed-bug, inhabitants of human dwellings. They are -indeed domesticated, and are always to be found in the neighbourhood of -human houses or buildings or ships, and are very rarely indeed found -far away from the sphere of man’s activities. - - [Illustration: FIG. 29.—Egg of _Stegomyia fasciata_ (highly - magnified). Notice the air-‘cells.’] - -They are very apt to bite one in the neck, creeping along the darker -parts of the clothing until an unprotected region of the body is -reached. Unless one has very thick socks they frequently bite the -ankle, and they are as tireless in their pesterings as ever Mrs. -Pardiggle was—no sooner are they driven away than they return to the -attack. The bite is painful, and in many people raises a considerable -swelling. - -The _Stegomyia_ bite not only during the night, but also during the -day. According to R. O. and O. Neumann—in Brazil, at any rate—they are -capable of biting not only during the twilight, but at any times. The -bite lasts twenty to thirty seconds, after which the mosquito rests -a bit, waving its third pair of legs in the sun. After this rest she -flies away to some sheltered spot, and whilst blood is being digested -the mosquito takes nothing but water—a very proper dietetic measure. -After three or four days the female is ready for another meal. - -In the absence of man these mosquitos will suck blood from other -animals, and in confinement they are generally fed on rats or canaries, -and they will even suck up a drop of blood presented on a piece of -cotton-wool. - -If the female mosquito has been fertilised before the sucking of blood -she will commence egg-laying two or three days later, and two or three -days later again the larva will emerge. The larval stage lasts from -nine to twelve days, and the pupa stage three to four, so that the -whole metamorphosis takes from sixteen to twenty-two days. Hence, -during warm weather, many generations succeed each other, but one must -have a temperature of at least 20° to 27° C. Below that temperature -the processes tend to slow down, and under a temperature near -freezing-point the regular development is definitely interrupted. But -the interruption is only a suspense, and living activities are resumed -should the temperature rise again. - -It is a disputed point whether these mosquitos must have a meal of -blood before they can lay eggs, and on this point the evidence is not -yet sufficient to make a dogmatic statement. These mosquitos are very -indifferent where their eggs are laid. The smallest collection of water -in an empty sardine-tin, a broken tumbler, a puddle in the street, a -gutter-pipe, is good enough for _Stegomyia calopus_. She will even lay -her eggs on moist cotton-wool. - -Although _Stegomyia_ bites freely during the day-time, it, as a rule, -avoids the light and seeks some dark shelter. Contrary to the habits -of _Anopheles_, it prefers a light ground to rest upon. The larvae -live on algae, vegetable-matter, or plant-detritus, or, in captivity, -on white bread or Indian corn. They can remain for a considerable time -without food, and this without materially diminishing the rate of their -development. _Stegomyia_ breeds well in ships, and is occasionally -found in one part only of the ship—such as the engine-room or cook’s -galley, where the conditions seem to be most favourable to its -development. Thus it comes about that at times certain quarters of a -ship provide the greatest percentage of yellow-fever cases. - - - - - CHAPTER X - - THE BISCUIT-‘WEEVIL’[12] (_Anobium paniceum_) - - ‘Let us be merry,’ said Mr. Pecksniff. Here he took a captain’s - biscuit. ‘It is a poor heart that never rejoices; your hearts are not - poor. No!’—(DICKENS, _Martin Chuzzlewit_.) - -The first things to notice about the biscuit-‘weevil,’ so familiar -to readers of Marryat’s novels, is that it is not a weevil at all, -and that it attacks a great many other comestibles besides biscuits. -The so-called biscuit-‘weevil’ is in truth an _Anobium_—_Anobium -paniceum_—a member of the family _PTINIDAE_ and is closely allied -to _A. striatum_, which makes the little round holes in worm-eaten -furniture, so cleverly imitated by the second-hand furniture-dealers. -Another species of _Anobium_ (recently re-christened _Xestobium -tessellatum_), a somewhat larger insect, is destructive in churches, -libraries, and old houses. Their mysterious tappings (which are really -efforts to attract the other sex—mere flirtations) are the cause of -much superstitious dread in the nervous, and this species is known as -the ‘greater death-watch.’ - -[12] Modern systematists now call the biscuit-‘weevil’ _Sitodrepa -panicea_. - - [Illustration: FIG. 30.—Biscuit-‘weevil,’ _Anobium paniceum_. (From - David Sharp, _The Cambridge Natural History_, vol. vi.)] - -But to return to the biscuit-‘weevil.’ The mature insect is about a -quarter of an inch long, and lives at large; it is the larva which -burrows into and attacks the dried biscuit—the ‘hard-tack’ of the -Navy. Less of a woodborer than its allies, it nevertheless attacks -almost any vegetable substance; and Butler tells us that ‘rhubarb-root, -ginger, wafers, and even so unlikely a substance as Cayenne pepper -have been greedily devoured by it.’ Several generations have been -known to flourish on a diet of opium, and it has been found in tablets -of compressed meat. Vegetable matter, even in an altered state—such -as paper—affords it an ample meal; and in one case the larva of -an _Anobium paniceum_ bored steadily in a straight line through -twenty-seven folio volumes in a public library, and so straight was the -tunnel that a string could be passed through it from end to end. In -one of our libraries at Cambridge some Arabic manuscripts were almost -entirely destroyed by the larvae, which do not hesitate to browse on -drawings and paintings and the dried paper of herbaria. - - [Illustration: FIG. 31.—Early stages of _Anobium paniceum_. A, Eggs, - variable in form; B, larva; C, pupa; D, asymmetrical processes - terminating body of pupa. This larva is probably the ‘book-worm’ of - librarians. (From David Sharp, _The Cambridge Natural History_, vol. - vi.)] - -The larva of this beetle is in truth a book-worm. Its interest for us -in the present series is, however, the disastrous infestation of ships’ -biscuits, which frequently is so severe that the sailors ‘hard-tack’ -is rendered uneatable. Heating, of course, kills it; but the biscuits -are still uneatable. The dead larvae are as unpalatable as the living. -The contrivance of biscuit-tins since Marryat’s time has done much -to lessen the evils. Tradition has it that a great firm and a great -fortune had their foundations laid, during the first half of the last -century, by the accidental contiguity of a baker’s shop and that of a -tinsmith. - - - - - CHAPTER XI - - THE FIG-MOTH[13] (_Ephestia cautella_) - - All’ amico mondagli il fico. - (_Italian Proverb._) - - -The extension of the War to Turkey and Asia Minor has drawn attention -to the existence of certain insects whose larvae exercise a very -deleterious effect on valuable food-supplies in the Near East. The -inhabitants of Asiatic Turkey, without knowing it, have from time -immemorial adopted the advice of Captain Cuttle: ‘Train up a fig-tree -in the way it should go, and when you are old sit under the shade on -it. Overhaul the—— Well,’ said the Captain, ‘on second thoughts, I -ain’t quite certain where that’s to be found, but when found, make a -note of.’ - -[13] The figures illustrating this article are taken from _The Report -of the Fig-moth in Smyrna_, Bul. 104. Bureau of Entomology, Washington, -1911. - -Asia Minor may indeed be described as the fig-ground of the East, and -anything that interferes with the fig as a food is likely to interfere -with the well-being of our troops in Egypt and the Near East. In -‘The Minor Horrors of War,’ I described a species of moth, _Ephestia -kühniella_, a member of the family Pyralidae, which infests and -destroys Army biscuits; but this other species, _E. cautella_, which -attacks figs, is even more troublesome than the one described in the -above-mentioned book.[14] - -[14] It might be well to repeat the fact that the genus _Ephestia_ -belongs to the family _PYRALIDAE_, which is by most authorities -included in the _Microlepidoptera_. The Speaker’s sneer at the -entomologists who work at this group (see his letter in _The Times_ -of February 2, 1916) is hardly worthy of one of the chief trustees of -the British Museum. As a chief trustee, he must have been aware of the -exhibit of the Microlepidoptera, _E. kühniella_, and its devastating -action on the biscuits supplied to our soldiers by the War Office, -which has for many months occupied a prominent position in the middle -of the central hall of the Natural History Museum at South Kensington. -This exhibit showed how closely the study of the Microlepidoptera is -associated with the food-supply of our soldiers in many parts of the -world. - - [Illustration: FIG. 32.—Typical Smyrna fig-orchard in Meander Valley, - Asia Minor, whence come the best figs for export.] - - [Illustration: FIG. 33.—The fig-moth (_Ephestia cautella_). _a_, Moth - with expanded wings; _b_, denuded wings showing venation; _c_, larva, - full grown, dorsal view; _d_, two egg masses, _a_, _b_, _c_, About - four times natural size; _d_, more enlarged.] - -Whoever has attentively eaten dried figs must from time to time have -become aware that there is something very defective in their flavour, -and on close inspection little clusters of débris will be observed -on the outside of the dried fruit—the dejecta of the larva burrowing -within—and numerous round holes can be detected through which the -larvae have made their entrance. If cut open and carefully examined, -one or two small white grubs may be found, which give the fig a -singularly sour-bitter and most unpleasant taste. This is the larva -of the moth, _Ephestia cautella_ which has for the last four or five -years been attracting much attention in the Levant market. From 15 to -50 per cent. of the figs exported from Smyrna, the great centre of the -fig-trade, are infected with this ‘worm,’ and active steps were being -taken before the War spread to the Near East to check its ravages. The -moth itself is very like _E. kühniella_, but readily distinguished by -an entomologist. Originally, it seems to have come from Asiatic Turkey, -but by the aid of commerce it has been distributed in a broad belt -all round the world within certain limits of temperature. Wide as its -distribution now is, it is equally catholic in its tastes. Perhaps it -does as much harm to the chocolate trade as to any other, attacking -the cacao-bean as well as the prepared article; all sorts of nuts are -infested. At one time it was thought that the oil of the nuts was the -attraction, but the larvae flourish just as well on rice and bran, on -dried apples, dried insects, maize, and a great variety of other more -or less nutritive substances. - -But to return to the figs. So serious was the trouble felt to be in -the American fig-market that, in 1910, the authorities at Washington -sent Mr. E. G. Smyth of the Bureau of Entomology to investigate the -insect in Asia Minor, where the figs come from, and from his report the -following account is taken:— - - The manner of the fig-harvest is as follows: During August the - figs are ripening on the trees, and are gradually dropping off to - be collected from the ground and laid on strips of reeds, called - ‘serghi,’ a yard broad; and here for two to five days they dry in - the sun. When dried, they are packed in goats’-hair bags or woven - willow baskets, and carried by horse or by camel to the fig-depots - in the neighbouring villages. Here they are collected from the - whole district, mixed together, and re-sacked for transmission by - railroad to the coast. At Smyrna they are graded and prepared for - the market: the better kind being either ‘layered’ or ‘pulled,’ - whilst the inferior fruits are strung on strings or exported in the - form of a mashed cake to make the ‘strawberry’ jam of the Western - breakfast-table. - - [Illustration: FIG. 34.—‘Serghi’ of reeds laid in long rows, used in - large orchards. Over these the moths congregate by thousands at night.] - -Mr. Smyth’s object was first to find out at what stage the figs become -infected by the moth, and then if possible to suggest preventive -or remedial measures. He minutely investigated every stage in the -preservation of figs, from the ripe fruit on the tree to the preserved -figs in the hold on the steamer bound for New York, and the conclusion -he came to is this: With very rare exceptions the eggs are never -laid on the fruit whilst on the tree. The first and by far the most -important infection is when the figs are gathered and exposed on the -reed ‘serghi.’ Then about seven in the evening the moths begin to -appear, and steadily increase in number as the evening wears on. The -actual deposition of the ova cannot be observed, for the moths get -down amongst the reeds and lay their eggs on the under surface of the -fruit—usually in some crack or abrasion—so that the newly hatched larva -can more easily make an entrance into the fig. From some ‘counts’ made -at Tchifte Kaive it appears that after an exposure of one night 29 per -cent. of figs were infested, after two nights 38·5 per cent., and after -three nights 44·5 per cent. - - [Illustration: FIG. 35.—Figs packed by string method (reduced).] - -A second and serious source of infection is at the village depots. -Before the figs arrive, there seem to be no specimens of the _Ephestia_ -in the buildings; but with their arrival the moth appears, and so -favourable is the shelter from the heat and the wind, and so abundant -is the supply of figs as sack after sack is emptied on to the floor, -that soon the moth is more abundant in the depots than amongst the -‘serghi,’ and the wonder is that a single fig escapes infestation. -Fortunately, the time spent in the depots is short, often only a night; -were it much longer, the whole crop would suffer. On their way down to -the coast again there is little or no risk of the moth, but arriving -at Smyrna we pick up the insect again in the ‘khans,’ where the figs -are prepared for export, but in the larval form. Here, in August and -September, little trace of the insect is seen, the larvae are then too -small to emerge and pupate; but by October many full-grown larvae -may be found on the fig-heaps or crawling up the walls; a few pupate -inside the figs, and these probably produce the few imagines found in -the ‘khans,’ at the port of shipping. The unpleasantness of the larvae -crawling all about the ship greatly detracts from the pleasure of a -voyage on a vessel laden with Smyrna figs. - - [Illustration: FIG. 36.—Pile of refuse-figs in a Smyrna ‘khan:’ On the - wall, above these figs, fig-moth larvae congregate in large numbers.] - -With regard to preventive measures, there seems in many parts of Asia -Minor to be two crops of figs—one in May and June and one later. The -former produces a large, watery fig, unfit for sale. It is left to -rot on the ground, but it serves as food for the larvae which will -produce the myriad swarms of moths in the early autumn. Obviously -these worthless figs should be destroyed as completely as possible. -Equally obvious are the suggestions that the figs should be covered at -night with some cheap covering whilst on the ‘serghi,’ and screened -from the moth whilst in the depots, and their sojourn there should be -as short as possible. Measures for destroying the larvae in the fig -usually take the form of heat—either hot air, hot water, or steam. -Each is effective, and each has certain advantages and disadvantages; -still, the more progressive merchants of Smyrna were, before the War, -experimenting trying to find the best means of destroying the larvae, -and in time a uniform system will probably emerge. - - - - - CHAPTER XII - - THE STABLE-FLY (_Stomoxys_) - - Fly! Thy brisk unmeaning buzz - Would have roused the man of Uz; - And, besides thy buzzing, I - Fancy thou’rt a stinging-fly. - Fly—who’rt peering, I am certain, - At me now from yonder curtain: - Busy, curious, thirsty fly - (As thou’rt clept, I well know why)— - Cease, if only for a single - Hour, to make my being tingle! - Flee to some loved haunt of thine; - To the valleys where the kine, - Udder-deep in grasses cool, - Or the rushy margined pool, - Strive to lash thy murmurous kin - (Vainly) from their dappled skin! - (CALVERLEY; _The Poet and the Fly_.) - - -The common names for common insects in English are confusing. Not -only are the same insects frequently known by different names on -different sides of the Atlantic, but in many cases quite different -insects—insects even belonging to different genera—are connoted -by the same common name. In this respect matters are different in -Germany: partly, perhaps, because the Germans on the whole are more -scientifically inclined than we are, but partly, I suspect, because the -German language lends itself more easily to express in one word—however -long—the characteristics of any given insect. - - [Illustration: FIG. 37.—The Stable-fly (_Stomoxys calcitrans_).] - - [Illustration: FIG. 38.—_Stomoxys calcitrans_ × 5. Left antenna right - × 1, resting position. (From Graham Smith.)] - -The genus _Stomoxys_ is generally called in Great Britain the -‘stable-fly,’ but there are other ‘stable-flies.’ One of the commonest -species of the genus is _S. calcitrans_, a two-winged muscid fly, not -at all unlike the common domestic fly, _Musca domestica_; but there -are one or two points which readily distinguish it from the commoner -insect. To begin with: it has a hard, firm, chitinous, piercing -proboscis, which when at rest stretches forward in front of the head, -and when in action is pressed down at right angles to the longitudinal -axis of the body; then, again, when resting, its wings diverge; those -of the house-fly approximate. Like other flies, the _Stomoxys_ varies -somewhat in length, between 5·5-7 mm. The thorax has on its back four -longitudinal, dark stripes, broken by a transverse suture; and, as -the accompanying figure shows, the third of the great, long veins -which traverse the wing is much more slightly bent than is the case -in _Musca domestica_. Further, whereas the hinder edge of the eye in -the house-fly is straight that of the stable-fly is concave, and the -antennae bear hairs on the upper side only and not above and below as -they do in the domestic fly. - -As a biting-fly and a blood-sucking fly, the habits of _Stomoxys_ -naturally differ from those of _Musca domestica_; but, like the latter, -its distribution is almost world-wide. It is found in all temperate -and tropical countries, and extends as far north as Lapland. But it is -perhaps most abundant (or shall we say it has been most observed?) in -temperate climates and during the summer months. - - [Illustration: FIG. 39.—Wing of _Musca domestica_ above, and of - _Stomoxys calcitrans_ below.] - -In any farm or country house large numbers of _Stomoxys calcitrans_ are -found in and about the cowsheds and stables, and in warm weather the -same is true wherever cattle are grazing in the field. Later in the -year, at the beginning of autumn, they are frequently found indoors, -and in some ‘fly counts’ they have furnished quite 50 per cent. of the -flies of a country house, the remaining 50 per cent. being made up -of many other species and genera. When resting on a vertical surface -_Stomoxys_ generally has its head pointing upwards, whereas, as a rule, -the house-fly rests upside down. The adult fly feeds upon any decaying -matter; but whenever it can, it sucks the blood of vertebrates, and -at times is a real nuisance to animals as well as human beings. So -voracious are they that should a well-fed one be injured, the others -immediately attack it and suck up every drop of blood which it had -secured for its own food. - - [Illustration: FIG. 40.—Side view of head of _Stomoxys calcitrans_. A, - Proboscis in resting position; B, proboscis extended. (After Graham - Smith.)] - -It has often been disputed whether a meal of blood is essential to the -female mosquito before oviposition, but it seems perfectly clear that -the female _Stomoxys_ can produce fertilised eggs without having had a -meal of blood. - -The female lays a number of white, banana-shaped eggs a few inches -below the surface of any decaying organic matter; fermenting grass from -the lawn, decaying garden stuff, stable manure—each forms a favourable -nidus. The eggs are laid in a heap like those of the house-fly, each -heap containing from fifty to seventy. The egg is 1 mm. in length and -has a grooved side, through the thicker end of which the larva escapes -when the egg-shell splits. - - [Illustration: FIG. 41.—_Stomoxys calcitrans._ Eggs. (After Newstead.)] - -The issuing larva is almost transparent. It not only has no head, -but the anterior end dwindles almost to a point. When fully grown -it attains a length of 11 mm., and the larval stage usually lasts -from two to three weeks; but development may be retarded by adverse -circumstances up to eleven or twelve weeks, and in such cases the -full-grown larvae are often stunted in size. In these circumstances -the pupae they produce are markedly smaller than those which have -followed a more normal course of development. As is true of the egg -and of the larva, the pupa resembles the pupa of the house-fly, being -barrel-shaped and of a chestnut-brown colour; it is 5 to 5·5 mm. in -length. The pupa stage lasts from nine to thirteen days, but this -period is prolonged by cold. - - [Illustration: FIG. 42.—Acephalous larva of _Stomoxys calcitrans_. - (After Newstead.)] - -On emerging from the pupa-case the insect has to push its way to the -surface of the rotting vegetation in which it has been produced. -This it does partly by the alternate inflation and deflation of the -so-called ‘frontal sac,’ and by actively pushing forward the body by -means of its legs. Once on the surface the insect begins to clean -itself, pumps air into its body, forces it along the tracheae in -the wings, which expand and ultimately harden. In the processes of -unfolding they are aided by the hind legs. For a time the insect is -immobile, gradually stiffening; but when the integument has hardened it -flies off to explore the outer world. Under normal conditions the whole -life-cycle varies from twenty-seven to thirty-seven days. - -The chief interest of _Stomoxys_ to the public, rests upon the fact -that it is a very potent carrier of disease. There are certain forms -of _Trypanosoma_ which, under experimental conditions, are undoubtedly -transferred by this species. But opinion is still unsettled as -to whether the transference of these protozoa occurs in nature. -The _Surra_ diseases of horses and camels is, according to some -authorities, transferred by _Stomoxys_, and so is the _Surra_ disease -of cattle; and there are others, all fully set forth in Mr. Hindle’s -work on ‘Flies and Disease.’ - - [Illustration: FIG. 43.—Coarctate pupa of _Stomoxys calcitrans_. - (After Newstead.)] - -Certain thread-worms—for instance, _Filaria labiato-papillosa_—which -occur in the peritoneal cavity, and sometimes in the eyes of cattle -and deer in India, are undoubtedly conveyed by _Stomoxys calcitrans_. -The superficial vessels of the cattle swarm with the larvae of these -thread-worms, which readily pass through the proboscis of the insect -into its stomach. They then wriggle through the walls of the stomach -and make their way into the thoracic muscles; here they undergo a -‘rest-cure,’ and after a time they are readily transferred to a new and -possibly uninfected host. - -But by far the worst infection which is attributed to this fly is acute -epidemic poliomyelitis, or infantile paralysis. That this disease -occurs in epidemics has been known—especially in Scandinavia—for some -time; and eight years ago it attracted serious attention in North -America and in our country. In 1907 there were many local outbreaks in -the United States and Canada, and it is thought that the infection was -first introduced from Scandinavia along the Atlantic coast, and later, -inland, as far as the State of Minnesota, by the numerous Scandinavian -immigrants that settle there. - -The disease is one of those which are apparently due to a protozoon too -small to be visible under the highest power of the microscope, and so -small as to be able to pass through a Berkefeld filter. It can readily -be artificially transmitted to monkeys. It is thought that the disease -is by no means transmitted only by means of the biting _Stomoxys_, and -that it may be directly transmitted from one person to another without -the aid of any intermediate host. But there seems little doubt that it -can be, and is, transmitted by _Stomoxys_, and therefore it is of the -highest importance to reduce the number of these insects. - -The most efficient way of controlling this pest is to destroy or put -out of action its breeding-places. All decaying vegetable matter should -be either removed or burnt or buried, or covered with some agent which -will prevent the larvae living. In fact, the methods that have been -advocated for the common house-fly are applicable to _Stomoxys_. If -stable manure were carefully removed, from May to October, at least -every seven days, the number of flies would be materially reduced. -Where this is impracticable, manure-heaps should be covered with -some insecticide, so as to destroy the eggs and larvae. Experiments -are still being made with the view of finding a substance capable -of killing the eggs, larvae, and pupae, which will be at once cheap -and unharmful to the fertilising value of the manure. The American -experts recommend borax or colemanite (crude calcium borate), calcined, -powdered, and applied by a flour-dredger. The proportions which seem -most effective are 0·62 lb. of borax and 0·75 lb. of colemanite to -10 cubic feet, or 8 bushels of manure. Two or three gallons of water -should then be sprinkled over the manure-heap. - - - - - CHAPTER XIII - - RATS[15] (_Mus_ or _Epimys_) - - Now, Muse, let’s sing of rats! - (GRAINGER.) - - -The overwhelming majority of rats fall under two species: (i) _Mus -rattus_, the black rat, and (ii) _Mus decumanus_, the brown rat. The -original home of both species is, according to Dr. Blandford, Mongolia; -but the date of their first appearance in our islands is a matter of -some uncertainty. According to Helm, _M. rattus_ passed into Europe -at the time of the _Völkerwanderung_, and doubtless accompanied the -migrating Asiatic hordes on their journeys westward. The name rat -appears in early High-Dutch glossaries, it is mentioned by Albertus -Magnus, and occurs in early Anglo-Saxon writings in England. This -evidence is, however, not conclusive that in those times the rat had -entered Great Britain; indeed, according to Bell,[16] the black rat -was not known here until before the middle of the sixteenth century: -at least, he says, no author more ancient than that period has -described, or even alluded to, it as being in Great Britain, Gesner -being the first to do so. Jenyns, in his ‘Manual of British Vertebrate -Animals,’[17] describes _M. rattus_ as ‘truly indigenous’; but this is -in comparison with the brown rat, whose comparatively recently arrival -he chronicles. _M. rattus_ is said to have been common on the continent -of Europe in the thirteenth century. - -[15] The modern systematist now calls the black rat _Epimys rattus_, -and distinguishes two varieties—_E. rattus alexandrinus_ and _E. rattus -rattus_; the brown rat is now _E. norvegicus_. - -[16] _A History of British Quadrupeds_, 2nd ed. London, 1874. - -[17] London, 1833. - - [Illustration: FIG. 44.—_Mus rattus._ (From Pennant.)] - -_M. rattus_ has, as a rule, greyish-black fur above, ash-coloured -below, with a tail a little longer than the body and head. It is -smaller and more elegantly built than the brown rat; its snout is -longer and more slender, and the long, thin, scaly tail is about eight -or nine inches in length. The British forms average in length seven -inches from the tip of the nose to the origin of the tail. Although -known as the black rat, its bluish, or greyish-black colour is, both in -the East and in Northern America, frequently replaced by brown on the -upper surface, and by white fur on the lower, or by a yellowish-brown -rufous colour. The ears, feet, and tail are black. When kept as -pets—and they frequently are—white and piebald varieties are often -bred. The ears are larger in proportion than in _M. decumanus_, the -rings of scales on the tail better marked, and spines in the fur are -not uncommon. - -The black rat, or Old-English rat, begins to breed under the age of -one year, and goes with young six weeks; it breeds frequently during -the year, but does not commence in Bombay, according to the Plague -Commission, until it has attained the weight of at least 70 grammes. -In India they breed all the year round. In Britain they produce six -to eleven young at a time; in India the average is 5·2; the largest -number found by the Plague Commission having been nine. In Bombay it -is noteworthy that in both species the percentage of young rats to -the total rat population is greater during the warmer months—from June -to October—than at other times of the year. It is also noteworthy that -the fall in fertility begins before the onset of the plague epizootic, -though, later, it roughly coincides with it. In Britain they increase -so fast as to overstock their abode, and thus they are forced, from -deficiency of food, to devour one another, and this alone, Pennant -thinks, ‘prevents even the human race from becoming a prey to them, not -but there are instances of their gnawing the extremities of infants in -their sleep.’ - - [Illustration: FIG. 45.—Head of _Mus rattus_. (From Flower and - Lyddeker.)] - -The black rat is catholic as to its diet, omnivorous, and it devours -every kind of human food. It is more domesticated than its congener, -more devoted to human habitations, and it does immense damage to stored -grain, seeds, and cereals. It is a better climber than _M. decumanus_, -which accounts for its being _par excellence_ the ship-rat, since it -can climb hawsers and more readily ‘comes on board.’ It makes its way -up to the higher rooms of the tenement houses in Indian cities, where -it nests and breeds undisturbed by the human inhabitants. - - Day by day we passed them— - Met them unaware, - Shambling through the lobbies, - Squatting on the stair. - - Not a rat among them - Moved to give us place, - Staring with its cruel eye - And its aged face. - (F. LANGRIDGE.) - -Pennant[18] draws attention to the harm the black rat causes by gnawing -and devouring not only edibles, but paper, cloth, water-pipes, and even -furniture. In England it makes a lodge—either for the day’s residence -or a nest for its young—near a chimney, and ‘improves the warmth by -forming in it a magazine of wool, bits of cloth, hay, or straw.’ In -the East it nests in the indescribable rubbish and ‘unconsidered -trifles’ the natives accumulate in their rooms, and is seldom, if ever, -interfered with. - -[18] _British Zoology._ London, 1812. - -Its climbing-habits enable it to ascend trees, and in India it -frequently nests among the branches. In some tropical islands _M. -rattus_ lives exclusively in the crowns of coco-nut palms, feeding -almost entirely on their fruit. - -Contrary to the opinion of Blandford, Oldfield Thomas thinks that the -black rat originally came from India, and thence spread all over the -world, exterminating the indigenous rats of other countries, only to -be exterminated later by the arrival of the stronger _M. decumanus_. -At the present time the last-named species is not yet established in -some countries—for instance, in those of western South America. On that -continent, _M. alexandrinus_, a tropical variety of _M. rattus_, is -waging war on the less highly organised native rice-rats (_Sigmodon_). -_M. alexandrinus_ has a grey or rufous back, and a white belly. - -_M. rattus_ has a milder, more amenable, and tameable character -than _M. decumanus_, and the white, or pied varieties, so dear to -schoolboys, are of this species. It is cleanly in its habits, and the -skin is kept in excellent order. Like other rats, it holds its food in -its hands whilst eating, and it drinks by lapping. - -Although the black rat is tending to be driven out by the brown rat, -it still lingers on in some warehouses in London, at Yarmouth, in -Sutherlandshire, I believe in Lundy Island, and I have been told it -occurred not so very long ago on the island in the Serpentine. It -doubtless occurs in many other places. - -_Mus decumanus_, the so-called brown rat, undoubtedly comes from -Central Asia; and at the present time there is a rat in China described -under the name _M. humiliatus_, which is so little distinguishable from -the brown rat that it is thought to be the parent form. - -The migration westward of the brown rat certainly took place much later -than that of _M. rattus_. Its first appearance is difficult to date. -Undoubtedly large hordes of them crossed the Volga in the year 1727, -and continued their journey towards Central Europe. The following year, -according to Pennant, brown rats, appeared in England—Jenyns says not -till 1730—and almost certainly they came in ships, for on its journey -overland it only reached Paris about the year 1750. Reaching England -about the year of the second George’s accession, and but thirteen years -after the first of the House of Hanover succeeded to the throne, it was -called—probably by the adherents of the Stuart cause—the Hanoverian -rat. It was also called the Norwegian rat—possibly from the mistaken -idea that it reached these islands from that country. It has now passed -to the northern half of the New World, where it is gradually driving -out many of its weaker brethren. Its numbers are, however, kept within -certain limits by wolves, lynxes, raccoons, coyotes, opossums, and -other carnivora, and especially by the skunks, which enter barns and -out-houses in search of it. - -Until the discovery of America, the rat and mouse were unknown in the -New World, and the first rats who ever saw it are said to have been -introduced in a ship from Antwerp.[19] - -The brown rat is of a greyish-brown colour, tinged with yellow and -white beneath. The tail is not so long as the body. It is a larger rat -than _M. rattus_, has shorter ears, a more powerful skull, and ten to -twelve mammae. Its ears, feet, and tail are flesh-coloured. Like _M. -rattus_, colour varieties occur often: the melanistic variety, not -uncommon in Ireland, being sometimes mistaken for the black rat. It -is a larger animal than its congener, more heavily built, with a more -powerful head, and blunter jaws. The head and body measure some eight -to nine inches, but the tail, as a rule, does not surpass the length of -the body alone. Its weight averages about nine ounces. It is extremely -fierce and extremely cunning, and in the struggle for existence with -allied species has hitherto been consistently successful in the fight. - -[19] Ovalle’s ‘History of Chili,’ in _Churchill’s Voyages_, vol. iii, -p. 45. - -_Mus decumanus_ is very prolific, and produces several litters a year, -each averaging eight to ten in number, but twelve or even fourteen -young are not very uncommonly born at one time. It begins breeding -young—a half-grown female producing a litter of three or four; but -in Bombay the sexes do not breed until they have attained at least a -weight of 100 grammes. The young are naked, i.e. without hairs, and -of a beautiful pink colour. They are blind, and their ears are gummed -down over the auditory meatus. They are very weak and helpless, and -need that maternal care, which, to do the female rat justice, is never -withheld. - - [Illustration: FIG. 46.—_Mus decumanus._ (From Pennant.)] - -_M. decumanus_ is less attached to the dwellings of man than _M. -rattus_; still, it does live in houses, though, owing to a lack of -climbing power, it is never found above the third floor. It is largely -a burrowing animal, and makes its nests in its burrows. _M. rattus_ can -also burrow, but not so readily, and it nests not in the burrow, but in -some obscure corner. A curious instance of the nesting habits of this -species was found during the rebuilding of my ‘lodgings’ in 1911. In -searching under the boards of the floor of the rooms of our Foundress -the Lady Margaret, Mother of Henry VII, now the drawing-room, the -workmen found the mummified remains of four rats, which had taken to -themselves coverings or shrouds; and upon investigation these proved to -consist of a vellum deed relating to the College, some paper documents -relating to Thomas Thompson, who was Master of the College from 1510 to -1517, and some fragments of printed matter which turned out to be part -of an early Virgil; four leaves of a Horace; two leaves of a primer of -Wynkyn de Worde; and finally a leaf of a work by Caxton. In addition, -four playing-cards of the sixteenth century were found. - -The brown rat frequents barns, granaries, stables, slaughter-houses, -rivers, ponds, ditches, drains, gullies, and sewers—it is, in fact, -sometimes called the sewer-rat. It is less particular in its food than -the black rat, which is more usually found in grain-stores. Although in -Bombay the relative numbers of _M. rattus_ and _M. decumanus_ caught -was as seven is to three, in open spaces, gardens, &c., the latter -was much the commoner. Yet the report of the Plague Commission states -that the authors ‘do not think it an exaggeration to state that every -inhabited building in Bombay City and Island, not excepting even the -better-class bungalows, shelters its colony of _M. rattus_.’ - - [Illustration: FIG. 47.—Head of _Mus decumanus_. (From Flower and - Lyddeker.)] - -Both species readily take to water, though _M. rattus_, being the -better climber, more readily gets on shipboard. They will swim rivers -and arms of the sea. The rats which infest the London Zoological -Gardens are said to swim nightly the canal in Regent’s Park. Rats -constantly make their way to coastal islands, and in a comparative -short time clear the place of indigenous rabbits and birds. Puffin -Island, off the coast of Anglesea, and the Copeland Islands, in Belfast -Bay, are two examples of islands at one time leased for the sake of -their rabbits to people who had to give up the lease after the rats had -landed on them. Similar cases are known off Denmark. They greedily eat -birds’ eggs, and are said to convey them over considerable distances, -though how they do this is not very clear. After the destruction of -the vertebrate land-fauna, they fall back upon the dwellers in the -littoral, and live on prawns, shrimps, and molluscs. They are very fond -of fish, and Lyddeker, in the ‘Royal Natural History,’ states that they -occasionally catch and eat young eels. As their parasites show, they -eat insects such as the meal-beetle, and when in the field they eat -land-snails, insect larvae, and other food, which conveys into their -bodies the same tape-worms, &c., which we find in the hedgehog and in -the smaller carnivora. - -They are, in fact, omnivorous, and nothing in the way of human food -is alien to them. They do enormous harm to corn-ricks and to stored -grain. They are inveterate enemies of the hen-roost, the pigeon-house, -and, as we have seen, of the rabbit-warren. When pressed by hunger, -they readily turn cannibal, and the brown rat easily masters the black. -There are stories of some few specimens of each species being left -in a cage overnight; on the following morning there were only brown -rats in that cage. To some extent they help to keep down one of the -field-mice (Genus _Microtus_), and this is especially the case in North -America;[20] but the benefit is doubtful since they are held to be at -least as destructive to the crops as the field-mice, and probably more -so. - -The ferocity with which they defend themselves when attacked is well -known, and at times, when they are driven by hunger, they do not -hesitate to attack man. They are said to nibble the extremities of -infants, and in one—apparently authentic—instance they overcame and -devoured a man who had entered a disused coal-mine tenanted by starving -rats. The bite is said to be severe (they will bite through a man’s -thumb-nail into the flesh), and the bite is long in healing. - -[20] ‘An Economic Study of Field-mice (Genus _Microtus_).’ By Dr. -Lantz, in _U.S. Dept. of Agric., Biol. Survey_, Bull. 31. - -Rats eat much garbage and offal, and readily feed upon dead bodies. -About sixty years ago there stood, at Monfaucon, a slaughter-house for -horses, and this it was proposed to remove still farther from Paris. It -is stated that the carcasses of the horses slaughtered—which sometimes -amounted to thirty-five a day—were cleared to the bone by rats in the -course of the following night. This excited the attention of a M. -Dusaussois, who made the following experiment: He placed the carcasses -of two or three horses in an enclosure, which permitted the entrance of -rats by certain known and closable paths. Towards midnight, he and some -workmen entered the enclosure, closed the rat-holes, and in the course -of that night killed 2650 rats. He repeated the experiment, and by the -end of four days had killed 9101 rats, and by the end of a month 16,050 -rats. During the process of these experiments other carcasses were -exposed in the neighbourhood, so that in all probability M. Dusaussois -attracted to his enclosure but a small proportion of the total -available number of rats. All around this slaughter-house the country -was riddled with extensive burrows, so that the earth was constantly -falling in. In one place the rodents had formed a pathway, 500 yards -long, leading to a distant burrow. - -A rat census can never be taken; but, estimating that there is one rat -for every human being on these islands, or less than one rat for every -acre of ground, a moderate estimate would give us 40,000,000 rats at -any one time. It has been calculated that a rat does at least 7_s._ -6_d._ worth of damage during the course of the year: hence in Great -Britain and Ireland, we may annually charge them with a loss of at -least £15,000,000! - -From what has been said it is obvious that rats cause enormous damage -to humanity, which is counterbalanced by the almost infinitesimal good -they do as scavengers. I do not propose to consider in detail the harm -they do as disease-carriers, but one cannot forget that the rat is the -primary host of _Trichinella spiralis_, which, when conveyed from the -rat to the pig, and—by eating uncooked or imperfectly cooked pork—from -the pig to man, causes severe and very fatal epidemics, and enforces -the expenditure of large annual sums on meat inspection. They further -convey a virulent form of equine influenza from one stable to another, -and also the ‘foot-and-mouth’ disease. But what is infinitely more -important to man than all the other injuries put together is the harm -they bring to suffering humanity by conveying the bubonic plague from -one patient to another. The plague under which India and great parts of -Burma are ‘groaning and travailing,’ is caused by a specific bacillus -discovered in 1894 by Yersin at Hong-Kong. It flourishes in other -vertebrates besides man and the rat, but, owing to the migratory habits -of the latter, the rat is the most effective agent in the spread of the -disease. Both species of rat seem about equally susceptible, and the -presence of the microbe showed no special relation to either the age -or the sex of either species. The microbe is conveyed from rat to rat -and from rat to man by a flea. - -The destruction of the rat is now being urged on all hands, and in the -near future we shall probably see a considerable diminution in their -numbers in the more civilised countries of the world. This will mean -a considerable upset in the balance of power of the almost hidden -fauna which surrounds us on all hands. It may even, as the Medical -Officer of Health for Bristol has pointed out, lead to an increase -of immigration of ship-rats—those most likely to be infected by -plague—to take up the places vacated on land by the slain. By one of -those commercial agencies—I do not propose to go into the merits of -any one of them—which the enterprise of our merchants is now pressing -on the public, a large landed proprietor a few months ago completely -freed his buildings of rats and mice. A few weeks later his house and -out-buildings were overrun by swarms of what to him—for in the time -of the rats and mice he had never seen one—was a new and formidable -insect. He sought the aid of the Royal Agricultural Society, who -referred the matter to their scientific adviser, who pronounced the -insects to be cockroaches! - -Mr. H. Warner Allen, the representative of the British Press with the -French Army, writes as follows in the _Morning Post_:— - - Of the smaller trench annoyances few are more worrying than the plague - of rats. Shelters and trenches, no matter where they are made, whether - in woods or open fields or on the mountainside, become immediately - infested with the objectionable creatures. In one case within my own - personal knowledge they drove a French officer out of a comfortable - and commodious dug-out into a damp and melancholy shelter, which was - to some extent protected from them by sheets of corrugated iron. The - plague had attained considerable dimensions before a really organised - attempt was made to deal with it, and there were many cases of rats - actually biting men who were chasing them down the trenches. - - Terriers have proved of considerable assistance. Trains full of - dogs have been dispatched to the Front, and poison has been fairly - effective. Lately, a reward has been offered for every dead rat - brought in by men in the trenches, and regular battues have been - organised. In a single fortnight one army corps alone has disposed of - no fewer than 8000 rats. At a halfpenny a rat this has involved an - expense of £16, and it was certainly money well spent. The sport of - rat-catching on such very advantageous terms has proved very popular - among the men, who now suggest that the standing reward offered for - the more dangerous and more exciting form of sport involved in the - capture of a German machine-gun should be raised to a higher figure. - -Ferrets have been largely used in the British trenches, but their price -is now very high, and the supply is very limited. The method which has -had some success in combatting the rabbit-plague of Australia—killing -all captured females and let all captured males loose—is certainly -worth a trial. Rats will gnaw through concrete, but not if plenty of -pieces of broken glass be mixed with the concrete. They will never -cross a band of tar which has been kept liquid by mixing with grease. -In the French trenches, special rat-runs are dug and these are provided -with ‘live’ wires. On touching one of these the rat is electrocuted. - -In the eighteenth century, among the officers of his ‘Britannic -Majesty,’ was an official rat-catcher, whose special uniform was -scarlet, embroidered in yellow worsted with figures of field-mice -destroying wheat-sheaves. Inquiry at the Lord Chamberlain’s office has -satisfied me that the officer still exists and still catches rats, but -I fear the uniform has been abolished. However, a book has recently -appeared dealing officially and exhaustively with all matters of this -kind, and as soon as I can come by it, I will look the matter up. -Should this dignified uniform have really disappeared, might not a -humble petition be presented that it be revived? Surely, never more -than at the present time should the honour and glory of the rat-catcher -be exalted! - - - - - CHAPTER XIV - - THE FIELD-MOUSE (_Apodemus sylvaticus_) - - TO A FIELD-MOUSE - ON TURNING HER UP IN HER NEST WITH THE PLOUGH, NOVEMBER 1785. - - Wee, sleekit, cowrin’, tim’rous beastie, - Oh, what a panic’s in thy breastie! - Thou needna start awa’ sae hasty, - Wi’ bickering brattle! - I wad be laith to rin an’ chase thee, - Wi’ murd’ring pattle! - - I’m truly sorry man’s dominion - Has broken Nature’s social union, - An’ justifies that ill opinion - Which maks thee startle - At me, thy poor earth-born companion, - An’ fellow mortal! - - I doubt na, whyles, but thou may thieve; - What then? poor beastie, thou maun live! - A daimen icker in a thrave - ’S a sma’ request; - I’ll get a blessin’ wi’ the lave, - An’ never miss ’t! - - Thy wee bit housie, too, in ruin! - Its silly wa’s the win’s are strewin’! - An’ naething now to big a new ane - O’ foggage green! - An’ bleak December’s win’s ensuin’, - Baith snell an’ keen! - - Thou saw the fields laid bare an’ waste, - An’ weary winter comin’ fast, - An’ cozie here, beneath the blast, - Thou thought to dwell, - Till, crash! the cruel coulter past - Out thro’ thy cell. - - That wee bit heap o’ leaves an’ stibble, - Has cost thee mony a weary nibble! - Now thou’s turn’d out for a’ thy trouble, - But house or hauld, - To thole the winter’s sleety dribble, - An’ cranreuch cauld! - - But, Mousie, thou art no thy lane, - In proving foresight may be vain: - The best-laid schemes o’ mice an’ men - Gang aft a-gley, - An’ lea’e us nought but grief an’ pain - For promis’d joy. - - Still thou art blest, compared wi’ me! - The present only touches thee: - But, och! I backward cast my ee - On prospects drear! - An’ forward, tho’ I canna see, - I guess an’ fear. - (BURNS.) - - -Another member of the _MURIDAE_, the field-mouse (_Apodemus -sylvaticus_), is almost as great a nuisance in the trenches as the rat. -The field-mouse is very like the house-mouse, with some of its features -seen under a lens. The hind feet and ears and eyes are larger than -are those of the house-mouse. Perhaps its much longer hind legs help -most easily to differentiate the two species. The tail is of about -the same length as the body and head added together, and is annulated, -presenting some 150 rings. The hands have five-palmar pads, and the -feet six pads. There are six mammae in the female, the anterior pair -being pectoral. - -The general colour of the dorsal surface is described as wood-brown, -which pales at the front end and towards the shoulders and flanks, -and grows to a more reddish tinge at the posterior end. The whole -of the lower surface is of dull, white, silvery colour, and on some -well-developed specimens there is a spot of buff, or orange, on the -throat, which sometimes lengthens out to form a collar. Moulting seems -to be rare—at any rate but a few cases have been recorded. - -The field-mouse occurs all over Europe, and extends into parts of Asia. -It is found all the way from Iceland, southward to Algiers, and from -Ireland to India. In the Himalayas it has been taken at a height of -11,500 feet, and in the mountains of Europe it frequently occurs at a -height of 7000 feet. It is certainly the most universally distributed -of European animals, and the number of individual specimens probably -far exceeds that of any other mammal which occurs in its district. - - [Illustration: FIG. 48.—The field-mouse (_Apodemus sylvaticus_). (From - Barrett Hamilton.)] - -The field-mouse does not hibernate like the dor-mouse, but is active -and hardy at all seasons of the year. Although, like other _MURIDAE_, -it is probably vegetarian by ancestry, it is, in effect, quite -omnivorous. It causes considerable loss in cornfields and gardens, -especially to early-sown peas; it eagerly eats dandelions and any -kind of grain or nut, or berry, or fruit, or bulb, or bud. Even fungi -have been found in their winter stores; and one family was discovered -which had eaten considerable quantities of putty with apparently no -deleterious effect. Their fondness for bulbs is a great nuisance to the -Dutch tulip-merchants. As many as 300 have been trapped in a fortnight -in a single crocus-bed. They are also a nuisance to bee-keepers, -inasmuch as they enter the hive and eat the honeycomb, especially -during the winter. Whilst feeding in the hedgerows, or undergrowth, -they frequently establish themselves in birds’ nests, and occasionally -such nests become their permanent home. - - In the hedge-sparrow’s nest he sits, - When the summer brood is fled, - And picks the berries from the bough - Of the hawthorn overhead. - (_Sketches of Natural History_, 1834.) - -They are not above sucking the birds’ eggs, or even devouring the -young birds. They will sometimes enter disused tunnels and devour -hibernating flies and other insects. Unlike rats, they seldom enter -human habitations, and they are quite innocent of the peculiar odour -which is so disagreeable in the house-mouse; and unlike the house-mouse -and the harvest-mouse they are seldom found in stacks of corn. Their -preference for berries explains the fact that they generally haunt -woods and hedgerows, and their passion for growing corn accounts for -the fact that they swarm in cornfields towards harvest-time. - -The field-mouse, however, does not neglect open and barren districts, -and is found from the sea-beach to the mountain-tops. It seems to -flourish equally well in the flower-beds of the London parks and on the -lonely hills of Scotland. Its activities are largely confined to the -night-time, which may account for the exceptional size of its eyes. -It is described ‘as bounding along in a peculiar zig-zag and erratic -manner, remotely resembling the movements of a kangaroo or jerboa.’ -Its spoor is very characteristic. The hind feet pressing nearly on the -same spot as the fore feet, but less lightly than the latter. From time -to time it sits upright, pricking its ears; and obviously its sense of -hearing is very acute, for it distinguishes sounds inaudible to the -human ear. It is mild in manner, gentle and inoffensive, extremely -timid, and most easily trapped. It is to some extent gregarious, as -many as fourteen or fifteen sometimes being found in the same burrow. - -As Fig. 49 shows, the burrow generally has an entrance which is marked -by a little heap of excavated earth. This leads down into the nest -where food is often stored. - - saepe exiguus mus - Sub terris posuitque domos atque horrea fecit. - (VIRGIL, _Georgics_, i. 18 b.) - -At the other end of the nest there are generally a couple of -bolt-holes separated from one another by an angle of nearly ninety -degrees. - - The mouse that always trusts to one poor hole - Can never be a mouse of any soul. - (POPE, _The Wife of Bath_.) - - [Illustration: FIG. 49.—Diagram of burrow of field-mouse.] - -The field-mouse is prolific, the female producing several litters -throughout the greater part of the year. The mother carries the -young-born litter about for two or three weeks, nipping the skin of her -offspring at the side, half-way between the fore and hind legs. The -average number of young born at one time is probably somewhere about -five, though litters of nine are by no means unknown. All predaceous -animals naturally eat field-mice, and they are the favourite food—at -any rate, in some localities—of owls. - - - - - INDEX - - - Agramonte, Dr., 105 - - Albertus Magnus, 135 - - Allen, H. Warner, 151 - - _Anobium paniceum_ (biscuit-‘weevil’), 111, 112 - - _A. striatum_, 111 - - _Apodemus sylvaticus_ (field-mouse), 153, 154 - - _Anopheles maculipennis_, 42, 65, 106; - head of, 49; - distribution of, 51; - hibernation of, 54; - breeding habits of, 55-6; - sensibility to light, 59; - and colour, 60-3, 110; - extermination of, 63; - buzzing of, 73-4; - eggs of, 78; - larva, 86 - - Austen, 55 - - - _Bacillus lactis aerogenes_, _B. cloacae_, 23 - - Bell, 135 - - Bellesme, Jousset de, 72 - - Biscuit-‘weevil,’ 111-13 - - Blandford, Dr., 135, 140 - - _Blattodea_, 4 - - Bombay Plague Commission, 137, 145 - - Bot- or warble-fly, 25, 27; - effect on cattle, 40; - cure for, 41 - - _British Medical Journal_, 24, 63 - - Browne, Sir Samuel James, 27 - - - Cambon, 59 - - Canada, 31, 32 - - Carpenter, Prof. G. H., 36 - - Carroll, Dr., 105 - - _Ceratopogon_, 42 - - _Challenger_, H.M.S., 16 - - _Churchill’s Voyages_, 142 _n._ - - Cropper, J., 63 - - Cockroaches (Periplaneta), 1, 3; - food of, 8, 11, 13, 17 - - _Culex_, 42, 50, 51, 55, 58, 79, 88, 90, 106-7 - - - Duncan, P. M., 21 _n._ - - Dusaussois, 148 - - - _Ectobia_, 4 - - Elephantiasis, 47 - - Entomology, Washington Bureau of, 114, 118 - - _Ephestia cautella_, 114, 115, 117, 121 - - _E. kühniella_, 115, 116, 117 - - - Field-mouse, 154-9 - - Fig-moth, 114; - ravages of, 117-22; - prevention of infection by, 123 - - _Filaria_, 47 - - _Filaria rhytipleurites_, 21 - - _Filaria labiato-papillosa_, 131 - - Finlay (of Havana), 104 - - Finsch, 53 - - - Gardiner, J. Stanley, 73 - - Gesner, 136 - - Gleichen-Russworm, von, 73 - - Grassi, 54, 55, 68, 77, 78, 79, 84 - - Gray, 58 - - - Hadwen, Dr., 31, 32 - - _Halobates_, 2 - - Helm, 135 - - Hewitt, T. R., 36 - - Hindle, Mr., 131 - - Howard, 58, 71, 74, 77, 94 - - _Hypoderma_, 25, 28 - - _Hypoderma bovis_, 31, 32; - eggs of, 34 - - _Hypoderma lineatum_, 31, 32; - eggs of, 34, 38 - - - Imms, Mr., 31 - - Infantile paralysis (poliomyelitis), 132 - - Irish Department of Agriculture, 36 - - Ismailia, 98 - - - Jenyns, 136, 141 - - Johnston (of Baltimore), 65, 66, 67 - - Joly, 74 - - - Kerschbaumer, 57 - - - Lantz, Dr., 147 _n._ - - Larva, of bot-flies, 28, 35; - of mosquitos, 80-5, 90, 91, 97; - of yellow-fever mosquito, 107; - of stable-fly, 130 - - Latter, 4 - - Lazear, Dr., 105 - - Lefroy, Prof., 63 - - Liverpool School of Tropical Medicine, 55 - - Lyddeker, 146 - - - Malaria, 48, 104; - prevention of, 98 - - Maxim, Sir Hiram, 75 - - Mayer, 67 - - Miall and Denny, 5 - - _Microlepidoptera_, 116 _n._ - - Morrell, Dr. C. Conyers, 21, 23 - - Moseley, Prof., 16 - - Mosquitos, biting apparatus, 43; - wings, 50; - hibernation of female, 54; - food of, 64-7; - experiments with, 60-3, 67-8; - how to avoid, 63-4; - auditory organs of, 65; - buzzing of, 68-74; - eggs of, 76 - - Moufet, 3 - - _Muridae_, 154, 156 - - _Mus_ or _Epimys_, 135 - - _Mus rattus_ or _Epimys rattus_, 135 _n._, 136, 139, 144, 145 - - _M. decumanus_ or _Norvegicus_, 135 _n._, 137, 140, 141, 142, 145 - - _M. alexandrinus_, 140 - - _Musca domestica_, 125, 126 - - - Neumann, R. O. and O., 109 - - Nuttall, Professor, 47, 52, 54, 56, 57, 58, 71, 77 - - - Ormerod, Miss, 28, 30 - - _Oestridae_ (bot-flies), 28 - - - Pennant, 138, 139, 141 - - Perez, J., 71, 72 - - _Periplaneta orientalis_, 4, 5, 16 - - _P. americana_, 4 - - _P. germanica_, 5, 16 - - Plague conveyed by rats, 149 - - Port Swettenham, 98 - - _Ptinidae_, 111 - - Pupa of mosquitos, 92-5, 97 - - _Pyralidae_, 116 _n._ - - - Rats, black, or Old-English, 137; - brown, 141; - ravages of 145-9; - estimated annual damage by, 149; - diseases conveyed by, 149; - destruction of, 150, 152; - in the trenches, 151 - - Reed, Dr. Walter, 105 - - Ross, Sir Ronald, 97, 98, 104 - - - Sam Browne belts, 26 - - _Sigmodon_ (rice-rat), 140 - - Smyrna, Report of the fig-moth in, 114 _n._ - - Smyth, E. G., 118 - - _Sphex_ (or _Chlorion_), 20 - - _Spirogyra_, 84 - - Stable-fly, 125; - food of, 128; - diseases conveyed by, 131, 132 - - _Stegomyia calopus_ or _fasciata_, 101, 105; - domesticated, 108; - bites of, 108, 110 - - _Stomoxys calcitrans_ (stable-fly), 125; - distribution of, 127; - eggs of, 129; - diseases conveyed by, 131, 132, 133; - extermination of, 133 - - _Symbius blattarum_, 21 - - - Thayer, Dr., 53 - - Thomas, Oldfield, 140 - - _Trichinella spiralis_, 149 - - _Trypanosoma_, 131 - - - ‘Warbled’ hides, 30 - - Watson, Dr. Malcolm, 98 - - Weaver, A. de P., 74, 75 - - Weinland, 73 - - Whelan, R. G., 37 - - White, Gilbert, 5 - - Wilson, Edwin, 69, 73 - - - _Xestobium tessellatum_, 111 - - - Yellow-fever, 101-3; - localities affected by, American commission on, 105 - - Yellow-fever mosquito, 101, 104; - metamorphosis of, 109 - - Yersin, 149 - - - AT THE BALLANTYNE PRESS - PRINTED BY SPOTTISWOODE, BALLANTYNE AND CO. 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- color: black; - font-size:smaller; - padding:0.5em; - margin-bottom:5em; - font-family:sans-serif, serif; - } - -/* Illustration classes */ -.illowp100 {width: 100%;} -.illowp20 {width: 20%;} -.illowp30 {width: 30%;} -.illowp35 {width: 35%;} -.illowp36 {width: 36%;} -.illowp40 {width: 40%;} -.illowp42 {width: 42%;} -.illowp45 {width: 45%;} -.illowp48 {width: 48%;} -.illowp50 {width: 50%;} -.illowp63 {width: 63%;} -.illowp66 {width: 66%;} -.illowp68 {width: 68%;} -.illowp70 {width: 70%;} -.illowp71 {width: 71%;} -.illowp74 {width: 74%;} -.illowp75 {width: 75%;} -.illowp79 {width: 79%;} -.illowp80 {width: 80%;} -.illowp90 {width: 90%;} -.illowp94 {width: 94%;} - - - </style> - </head> -<body> - -<div style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of More Minor Horrors, by Arthur Everett Shipley</div> - -<div style='display:block; margin:1em 0'> -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms -of the Project Gutenberg License included with this eBook or online -at <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you -are not located in the United States, you will have to check the laws of the -country where you are located before using this eBook. -</div> - -<p style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: More Minor Horrors</p> - -<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Author: Arthur Everett Shipley</div> - -<div style='display:block; margin:1em 0'>Release Date: November 13, 2021 [eBook #66726]</div> - -<div style='display:block; margin:1em 0'>Language: English</div> - -<div style='display:block; margin:1em 0'>Character set encoding: UTF-8</div> - -<div style='display:block; margin-left:2em; text-indent:-2em'>Produced by: Peter Becker, Les Galloway and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)</div> - -<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK MORE MINOR HORRORS ***</div> - -<div class="transnote"> -<h3>Transcriber’s Notes</h3> - -<p>Obvious typographical errors have been silently corrected. Variations -in hyphenation have been standardised but all other spelling and -punctuation remains unchanged.</p> - -</div> - -<p class="half-title">MORE MINOR HORRORS</p> - -<div class="chapter"></div> - -<div class="figcenter illowp75" id="frontispiece" style="max-width: 62.5em;"> - <img class="w100" src="images/frontispiece.jpg" alt="" /> - <div class="captionl"><p>Mosquitos in the Colvith River delta, Arctic -Alaska, about 71° lat., July 1909. The Eskimo, Natkusiak, had stood -still for a minute or two, and refrained from brushing them off, while -loading a uomiak. (From the <i>American Museum Journal</i>.)</p> -<p class="center"><i>Frontispiece</i></p> -</div> -</div> - - - - -<h1> -MORE<br /> -MINOR HORRORS</h1> - -<p class="center"><small>BY</small></p> - -<p class="center">A. E. SHIPLEY, Sc.D.<br /> - -<span class="smcap"><small>Hon.Sc.D. Princeton, F.R.S.</small></span></p> - -<p class="center xs">MASTER OF CHRIST’S COLLEGE, CAMBRIDGE, AND READER IN ZOOLOGY<br /> -IN THE UNIVERSITY</p> - -<p class="center spaced">ILLUSTRATED</p> - -<p class="center">LONDON<br /> - -SMITH, ELDER & CO., 15 WATERLOO PLACE<br /> -<small>1916</small></p> - -<p class="center xs">[All rights reserved]</p> - - - - -<p class="center"> -EDMUNDO ALFREDO CARRINGTON<br /> - -ET<br /> - -JOHANNI TRISTRAM YARDE</p> -<p class="center"> -<small>COLLEGII CHRISTI DILECTISSIMIS ALUMNIS<br /> -HUIC AB ORIENTI ILLI AB OCCIDENTI PARTE<br /> -PRO PATRIA PUGNANTIBUS</small></p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="PREFACE">PREFACE</h2> -</div> - - -<p>My publisher tells me that this volume will -be regarded as a sequel to ‘The Minor Horrors -of War,’ and he assures me that sequels -are not a success. I have no doubt my -publisher is right, because if publishers were -not invariably right, and authors invariably -wrong, how can one explain the fact that -publishers are proverbially prosperous and -prominent people, whereas authors are notoriously -penniless and obscure? In spite of -his warning, however, I propose to publish -this little volume, for there still ‘air some -catawampous chawers in the small way, too, -as graze upon a human pretty strong’—as -‘one of them inwading conquerors at Pawkins’s’ -called them—that were unmentioned -in my earlier book.</p> - -<p>I am indebted to the kindness of the -Editor and Proprietors of the <i>British Medical -Journal</i> for permission to reprint Chapters I to -IX and Chapter XI, and to the Editor of <i>The<span class="pagenum" id="Page_ii">[Pg ii]</span> -Journal of Economic Biology</i> for permission to -reprint the twelfth chapter, of this book, and -I offer them my thanks. I also thank Mr. -Hugh Scott (the University Curator in Entomology), -and Professor G. H. Carpenter of the -Royal College of Science, Dublin, for much -kindly help.</p> - -<p class="psig">A. E. SHIPLEY.</p> - -<p><span class="smcap small">Christ’s College Lodge, Cambridge,</span><br /> -<i>April 1916.</i></p> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_iii">[Pg iii]</span></p> - -<h2 class="nobreak" id="CONTENTS">CONTENTS</h2> -</div> - -<table class="standard" summary=""> -<tr> -<th class="tdr">CHAPTER</th> -<td></td> -<th class="tdr">PAGE</th> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_I">I</a>.</td> -<td class="tdl"><span class="smcap">Cockroaches</span> (<i>Periplaneta</i>)</td> -<td class="tdr">1</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_II">II</a>.</td> -<td class="tdl"><span class="smcap">Cockroaches</span> (<i>continued</i>)</td> -<td class="tdr">16</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_III">III</a>.</td> -<td class="tdl"><span class="smcap">The Bot- or Warble-Fly</span> (<i>Hypoderma</i>)</td> -<td class="tdr">25</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_IV">IV</a>.</td> -<td class="tdl"><span class="smcap">The Mosquito</span> (<i>Anopheles maculipennis</i>)</td> -<td class="tdr">42</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_V">V</a>.</td> -<td class="tdl"><span class="smcap">The Mosquito</span> (<i>continued</i>)</td> -<td class="tdr">53</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_VI">VI</a>.</td> -<td class="tdl"><span class="smcap">The Mosquito</span> (<i>continued</i>)</td> -<td class="tdr">65</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_VII">VII</a>.</td> -<td class="tdl"><span class="smcap">The Mosquito</span> (<i>continued</i>)</td> -<td class="tdr">76</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_VIII">VIII</a>.</td> -<td class="tdl"><span class="smcap">The Mosquito</span> (<i>continued</i>)</td> -<td class="tdr">86</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_IX">IX</a>.</td> -<td class="tdl"><span class="smcap">The Yellow-Fever Mosquito</span> (<i>Stegomyia -calopus</i>)</td> -<td class="tdr">101</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_X">X</a>.</td> -<td class="tdl"><span class="smcap">The Biscuit-‘Weevil’</span> (<i>Anobium paniceum</i>)</td> -<td class="tdr">111</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_XI">XI</a>.</td> -<td class="tdl"><span class="smcap">The Fig-Moth</span> (<i>Ephestia cautella</i>)</td> -<td class="tdr">114</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_XII">XII</a>.</td> -<td class="tdl"><span class="smcap">The Stable-Fly</span> (<i>Stomoxys</i>)</td> -<td class="tdr">124</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_XIII">XIII</a>.</td> -<td class="tdl"><span class="smcap">Rats</span> (<i>Mus</i> or <i>Epimys</i>)</td> -<td class="tdr">135</td> -</tr> -<tr> -<td class="tdr"><a href="#CHAPTER_XIV">XIV</a>.</td> -<td class="tdl"><span class="smcap">The Field-Mouse</span> (<i>Apodemus sylvaticus</i>)</td> -<td class="tdr">153</td> -</tr> -<tr> -<td></td> -<td class="tdl"><span class="smcap"><a href="#INDEX">Index</a></span></td> -<td class="tdr">161</td> -</tr> -</table> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_v">[Pg v]</span></p> - -<h2 class="nobreak" id="ILLUSTRATIONS">ILLUSTRATIONS</h2> -</div> - - - -<table class="standard" summary=""> -<tr> -<th class="tdr">FIG.</th> -<th></th> -<th class="tdr">PAGE</th> -</tr> -<tr> -<td></td> -<td class="tdr">A portrait of the head of an Eskimo attacked by mosquitos</td> -<td class="tdr"><i>Frontispiece</i></td> -</tr> -<tr> -<td class="tdr"><a href="#fig1">1</a>.</td> -<td class="tdl"><i>Periplaneta orientalis</i>, male, dorsal view</td> -<td class="tdr">2</td> -</tr> -<tr> -<td class="tdr"><a href="#fig2">2</a>.</td> -<td class="tdl"><i>P. orientalis</i>, male, side view</td> -<td class="tdr">6</td> -</tr> -<tr> -<td class="tdr"><a href="#fig3">3</a>.</td> -<td class="tdl">Mouth parts of <i>P. orientalis</i></td> -<td class="tdr">9</td> -</tr> -<tr> -<td class="tdr"><a href="#fig4">4</a>.</td> -<td class="tdl"><i>P. orientalis</i>, female, dissected</td> -<td class="tdr">10</td> -</tr> -<tr> -<td class="tdr"><a href="#fig5">5</a>.</td> -<td class="tdl">Egg capsule of <i>P. orientalis</i></td> -<td class="tdr">12</td> -</tr> -<tr> -<td class="tdr"><a href="#fig6">6</a>.</td> -<td class="tdl">Cast skin of the nymph stage of cockroach</td> -<td class="tdr">18</td> -</tr> -<tr> -<td class="tdr"><a href="#fig7">7</a>.</td> -<td class="tdl">Nymph stage of cockroach escaping from old skin</td> -<td class="tdr">19</td> -</tr> -<tr> -<td class="tdr"><a href="#fig8">8</a>.</td> -<td class="tdl"><i>Hypoderma bovis</i></td> -<td class="tdr">29</td> -</tr> -<tr> -<td class="tdr"><a href="#fig9">9</a>.</td> -<td class="tdl">Eggs of <i>H. lineatum</i></td> -<td class="tdr">33</td> -</tr> -<tr> -<td class="tdr"><a href="#fig10">10</a>.</td> -<td class="tdl">Eggs of <i>H. bovis</i></td> -<td class="tdr">35</td> -</tr> -<tr> -<td class="tdr"><a href="#fig11">11</a>.</td> -<td class="tdl">Entrance hole of <i>H. lineatum</i></td> -<td class="tdr">37</td> -</tr> -<tr> -<td class="tdr"><a href="#fig12">12</a>.</td> -<td class="tdl">Cow being chased by warble-fly</td> -<td class="tdr">40</td> -</tr> -<tr> -<td class="tdr"><a href="#fig13">13</a>.</td> -<td class="tdl">Side-view of head of <i>Anopheles maculipennis</i>, female</td> -<td class="tdr">44</td> -</tr> -<tr> -<td class="tdr"><a href="#fig14">14</a>.</td> -<td class="tdl">Section through proboscis of <i>A. maculipennis</i>, female</td> -<td class="tdr">45</td> -</tr> -<tr> -<td class="tdr"><a href="#fig15">15</a>.</td> -<td class="tdl">Piercing-lancets of <i>A. maculipennis</i>, female</td> -<td class="tdr">46</td> -</tr> -<tr> -<td class="tdr"><a href="#fig16">16</a>.</td> -<td class="tdl"><i>A. maculipennis</i>, female, sucking blood</td> -<td class="tdr">58</td> -</tr> -<tr> -<td class="tdr"><a href="#fig17">17</a>.</td> -<td class="tdl"><i>A. maculipennis</i>, male</td> -<td class="tdr">66</td> -</tr> -<tr> -<td class="tdr"><a href="#fig18">18</a>.</td> -<td class="tdl">Stridulating organ of <i>A. maculipennis</i></td> -<td class="tdr">70</td> -</tr> -<tr> -<td class="tdr"><a href="#fig19">19</a>.</td> -<td class="tdl">Larva and eggs of <i>A. maculipennis</i></td> -<td class="tdr">78</td> -</tr> -<tr> -<td class="tdr"><a href="#fig20">20</a>.</td> -<td class="tdl">Side view of the head of larva of <i>A. maculipennis</i></td> -<td class="tdr">81</td> -</tr> -<tr> -<td class="tdr"><a href="#fig21">21</a>.</td> -<td class="tdl">Under surface of head of larva of <i>A. maculipennis</i></td> -<td class="tdr">82<span class="pagenum" id="Page_vi">[Pg vi]</span></td> -</tr> -<tr> -<td class="tdr"><a href="#fig22">22</a>.</td> -<td class="tdl">Diagrams of mosquitos and gnats</td> -<td class="tdr">85</td> -</tr> -<tr> -<td class="tdr"><a href="#fig23">23</a>.</td> -<td class="tdl">Side view of pupa of <i>A. maculipennis</i></td> -<td class="tdr">91</td> -</tr> -<tr> -<td class="tdr"><a href="#fig24">24</a>.</td> -<td class="tdl">Tail of pupa of <i>A. maculipennis</i></td> -<td class="tdr">93</td> -</tr> -<tr> -<td class="tdr"><a href="#fig25">25</a>.</td> -<td class="tdl">Imago mosquito issuing from pupa-case</td> -<td class="tdr">95</td> -</tr> -<tr> -<td class="tdr"><a href="#fig26">26</a>.</td> -<td class="tdl"><i>Stegomyia fasciata</i>, female</td> -<td class="tdr">104</td> -</tr> -<tr> -<td class="tdr"><a href="#fig27">27</a>.</td> -<td class="tdl">Larva and eggs of <i>S. fasciata</i></td> -<td class="tdr">106</td> -</tr> -<tr> -<td class="tdr"><a href="#fig28">28</a>.</td> -<td class="tdl">Larva of <i>S. fasciata</i></td> -<td class="tdr">107</td> -</tr> -<tr> -<td class="tdr"><a href="#fig29">29</a>.</td> -<td class="tdl">Egg of <i>S. fasciata</i></td> -<td class="tdr">108</td> -</tr> -<tr> -<td class="tdr"><a href="#fig30">30</a>.</td> -<td class="tdl">The biscuit-‘weevil’ (<i>Anobium paniceum</i>)</td> -<td class="tdr">112</td> -</tr> -<tr> -<td class="tdr"><a href="#fig31">31</a>.</td> -<td class="tdl">The larval and pupal stages of <i>A. paniceum</i></td> -<td class="tdr">113</td> -</tr> -<tr> -<td class="tdr"><a href="#fig32">32</a>.</td> -<td class="tdl">Orchard of fig-trees</td> -<td class="tdr">115</td> -</tr> -<tr> -<td class="tdr"><a href="#fig33">33</a>.</td> -<td class="tdl">The fig-moth (<i>Ephestia cautella</i>)</td> -<td class="tdr">116</td> -</tr> -<tr> -<td class="tdr"><a href="#fig34">34</a>.</td> -<td class="tdl">Figs drying on reeds</td> -<td class="tdr">119</td> -</tr> -<tr> -<td class="tdr"><a href="#fig35">35</a>.</td> -<td class="tdl">Figs packed on strings</td> -<td class="tdr">120</td> -</tr> -<tr> -<td class="tdr"><a href="#fig36">36</a>.</td> -<td class="tdl">Pile of refuse-figs</td> -<td class="tdr">122</td> -</tr> -<tr> -<td class="tdr"><a href="#fig37">37</a>.</td> -<td class="tdl">The stable-fly (<i>Stomoxys calcitrans</i>)</td> -<td class="tdr">125</td> -</tr> -<tr> -<td class="tdr"><a href="#fig38">38</a>.</td> -<td class="tdl"><i>Stomoxys calcitrans</i></td> -<td class="tdr">126</td> -</tr> -<tr> -<td class="tdr"><a href="#fig39">39</a>.</td> -<td class="tdl">Wings of <i>Musca domestica</i> and of <i>Stomoxys calcitrans</i></td> -<td class="tdr">127</td> -</tr> -<tr> -<td class="tdr"><a href="#fig40">40</a>.</td> -<td class="tdl">Side view of head of <i>Stomoxys calcitrans</i></td> -<td class="tdr">128</td> -</tr> -<tr> -<td class="tdr"><a href="#fig41">41</a>.</td> -<td class="tdl"><i>Stomoxys calcitrans</i>. Eggs</td> -<td class="tdr">129</td> -</tr> -<tr> -<td class="tdr"><a href="#fig42">42</a>.</td> -<td class="tdl">Acephalous larva of <i>Stomoxys calcitrans</i></td> -<td class="tdr">130</td> -</tr> -<tr> -<td class="tdr"><a href="#fig43">43</a>.</td> -<td class="tdl">Coarctate pupa of <i>Stomoxys calcitrans</i></td> -<td class="tdr">131</td> -</tr> -<tr> -<td class="tdr"><a href="#fig44">44</a>.</td> -<td class="tdl">The rat (<i>Mus rattus</i>)</td> -<td class="tdr">136</td> -</tr> -<tr> -<td class="tdr"><a href="#fig45">45</a>.</td> -<td class="tdl">Head of <i>Mus rattus</i></td> -<td class="tdr">138</td> -</tr> -<tr> -<td class="tdr"><a href="#fig46">46</a>.</td> -<td class="tdl"><i>Mus decumanus</i></td> -<td class="tdr">143</td> -</tr> -<tr> -<td class="tdr"><a href="#fig47">47</a>.</td> -<td class="tdl">Head of <i>Mus decumanus</i></td> -<td class="tdr">145</td> -</tr> -<tr> -<td class="tdr"><a href="#fig48">48</a>.</td> -<td class="tdl">The field-mouse (<i>Apodemus sylvaticus</i>)</td> -<td class="tdr">156</td> -</tr> -<tr> -<td class="tdr"><a href="#fig49">49</a>.</td> -<td class="tdl">Diagram of burrow of field-mouse</td> -<td class="tdr">159</td> -</tr> -</table> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_1">[Pg 1]</span></p> - -<p class="half-title">MORE MINOR HORRORS</p> - - -<h2 class="nobreak" id="CHAPTER_I">CHAPTER I<br /> - -<small>COCKROACHES (<i>Periplaneta</i>)</small></h2></div> - - -<p class="center"><span class="smcap">Part</span> I</p> - -<p> -<i>The Governess:</i> And, perhaps, Mabel, as they are not black -and as they are not beetles, you will in future call them cockroaches.</p> -<p><i>Mabel:</i> Certainly, Miss Smith, although they are not cocks -and they are not roaches.</p> -<p class="psig">(<i>Punch.</i>)</p> - - -<p>In ‘The Minor Horrors of War,’ we rather -neglected the Navy—the senior Service, and -till now the more dominant of our two magnificent -forces—partly because it is less interfered -with by insect pests than is the sister -Service, though the common pests of our -poor humanity—the flea, the louse, the bug—are, -like the poor, ‘always with us.’ Like -aeroplanes, insects have captured the air; -like motors, they have made a respectable -show on land; but they have signally failed -at sea. They have nothing corresponding -to battleships or submarines; and a certain<span class="pagenum" id="Page_2">[Pg 2]</span> -bug, called <i>Halobates</i>, alone hoists the insect -flag on the ocean, and that only in the warmer -waters.</p> - - -<div class="figcenter illowp100" id="fig1" style="max-width: 75em;"> - <img class="w100" src="images/fig1.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 1.</span>—<i>Periplaneta orientalis</i>, male. × 2. Dorsal view. 1, -Antenna; 2, palp of first maxilla; 3, prothorax; 4, anterior wings; -5, femur of second leg; 6, tibia; 7, tarsus; 8, cerci anales; -9, styles. (From Kükenthal.)</div> -</div> - -<p>Insects are not only highly intelligent -animals, but are by far the most numerous -and dominant class of the Animal Kingdom;<span class="pagenum" id="Page_3">[Pg 3]</span> -and they have probably come to conclusions -about themselves and the sea, comparable to -those expressed by Dr. Johnson about man -and the ocean: ‘To all the inland inhabitants -of every region the sea is only known as an -immense diffusion of waters, over which men -pass from one country to another, and in -which life is frequently lost.’</p> - -<p>But one insect at least causes more -trouble to sailors than to soldiers—and that -is the cockroach. Like the bed-bug, the cockroach -came into England at the end of the -sixteenth century, and, like the bed-bug, it -came from the East. It seems to have been -first introduced into England and Holland -in the spacious times of Henry VIII by the -cross-sea traffic, and from about the end of -the sixteenth century the cockroach began -gradually to spread throughout the Western -world. Like the rat, the bed-bug, and the -domestic fly, it has become thoroughly acclimatised -to human habitations, and is indeed -an associate of man. It is very rarely found -living apart from some form or other of -human activity.</p> - -<p>This insect seems to have been first -described in England in Moufet’s ‘Insectorum -Theatrum,’ 1634, and he speaks of it as living -in flour-mills, wine-cellars, &c., in England, -and he tells us how Sir Francis Drake took,<span class="pagenum" id="Page_4">[Pg 4]</span> -in 1584, the <i>San Felipe</i>, a Spanish East -Indiaman, laden with spices and burdened -with a great multitude of flying cockroaches -on board.</p> - -<p>This species was <i>Periplaneta orientalis</i>; but -there is another and a larger species, which -presumably came into England from the West -later than its Eastern cousin <i>P. americana</i>—which -can frequently be seen in England -running about in the cages in our zoological -gardens—but it is not on exhibition, it is a -by-product, and is not counted in the fee -for admission to the gardens.</p> - -<p>Latter tells us there are ten species of -<span class="smcap">Blattodea</span> which occur in Britain; but only -three of these are indigenous, and these three -all belong to the genus <i>Ectobia</i>. <i>Ectobias</i> are -smaller than cockroaches, and do not frequent -human habitations, but live in shrubs, under -rubbish heaps, &c. Some species of <i>Ectobia</i> are, -however, very destructive and have been known -to destroy in one day the whole accumulation -of dried but not properly salted fish in a Lapland -village. Of the remaining species of cockroach -most are local, and occur sporadically -in particular factories, or places where food is -stored but they are not very widely spread.</p> - -<p>As we have said above, <i>P. orientalis</i> is -the common English cockroach, <i>P. americana</i> -occurs especially in zoological gardens and<span class="pagenum" id="Page_5">[Pg 5]</span> -menageries; but a third species, <i>P. germanica</i>, -sometimes gets established. Mercifully, <i>P. -germanica</i> does not seem to spread. Neither -<i>P. germanica</i> nor <i>P. americana</i> seem to make -much headway against <i>P. orientalis</i>, which -appears to be predominant over both these -other species.</p> - -<p><i>P. germanica</i> is probably most methodical, -very thorough, very brave, very faithful—but -rather lacking in the power of understanding -the point of view of others. If it -has any association with its specific name, it -illustrates the most striking example in the -world’s history of the divorce of wisdom from -learning. ‘O Lord! give us understanding,’ -should be the prayer of <i>P. germanica</i>.</p> - -<p>Miall and Denny tell us that from the first -introduction of <i>P. orientalis</i> into England -it took two centuries before it spread far -beyond London. In 1790 Gilbert White -speaks of it as ‘an unusual insect, which he -had never observed in his house till lately,’ -and, indeed, at the present moment many -English villages are still blissfully ignorant -of this particular nuisance.</p> - -<p>As Fig. 2 shows, the cockroach is a somewhat -slackly put together insect. One might -almost call it rather slatternly and loose-jointed—and -the latter it certainly is. Its -head moves freely on the thorax, and the<span class="pagenum" id="Page_6">[Pg 6]</span> -thorax on the abdomen. The successive segments -of the latter move very freely on -one another. The legs are long and mobile, -and so are the antennae with which the -animal is ceaselessly testing the ground over<span class="pagenum" id="Page_7">[Pg 7]</span> -which it flits hither and thither in its restless -activity.</p> - -<div class="figcenter illowp100" id="fig2" style="max-width: 112.5em;"> - <img src="images/fig2.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 2.</span>—<i>Periplaneta orientalis</i>, male. × 2. Side view. 1, Antenna; 2, head; -3, prothorax; 4, anterior wing; 5, soft skin between terga and sterna; 6, sixth abdominal -tergum; 7, split portion of tenth abdominal tergum; 8, cercianales; 9, styles; -10, coxa of third leg; 11, trochanter; 12, femur; 13, tibia; 14, tarsus; 15, claws. -(From Kükenthal.)</div> -</div> - -<p>Cockroaches are very difficult to catch. -They practically never walk, but run with -a hardly believable rapidity, darting to and -fro in an apparently erratic mode of progression. -Even when caught they are not -easily retained, for they have all the slipperiness -of a highly polished billiard-ball. They -have great powers of flattening their bodies, -and they slip out of one’s hand with an amazing -dexterity. Besides their slipperiness they -have another weapon, and that is a wholly -unpleasant and most intolerable odour, which -is due to the secretion of a couple of glands -situated on the back of the abdomen. The -glands which produce this repellent odour -are sunk in the soft membrane which unites -the fifth and sixth abdominal segments, and -the moment a cockroach is attacked it exudes -a sticky, glue-like fluid, which gives out this -most unendurable smell. The fluid is extraordinarily -tenacious and difficult to remove -from the hand of those who have touched -the insects. No doubt the cockroach, in -nature, finds safety in this from the attacks of -insectivorous animals.</p> - -<p>Cockroaches, as has been said, very rarely -walk, they nearly always run, and they advance -the first and third leg of one side at<span class="pagenum" id="Page_8">[Pg 8]</span> -the same time as the middle leg of the other, -pulling themselves forward with their front -legs and pushing themselves forward with the -hindermost. They are thus constantly poised -on a tripod. They occasionally, but not very -often, use their wings for flight. When they -do so, their anterior wings are stretched out -at right angles to the body, and take no -active share in beating the air. They act -in effect as monoplanes. It is the hinder -wings which really do the active flying. After -a flight, the hinder wings are shut up something -in the manner of a fan.</p> - -<p>The flattened coxae, or thighs, of the -leg are adapted for shovelling débris back -from beneath the body when the insect is -enlarging its habitation. When the cockroach -gets into a dusty ‘<i>milieu</i>’ the dust is immediately -removed; the hairs on the legs -act as clothes-brushes and brush every part -of the body, whilst the antennae, which attract -any dust in the neighbourhood, are repeatedly -drawn through the closed mandibles and so -cleaned. A cockroach is able to walk on -smooth surfaces because it possesses between -the joints of the tarsus certain soft, white -patches, very velvety, and these give the -creature a good hold, and prevent slipping -even on glass.</p> - -<p>Cockroaches will eat pretty well every<span class="pagenum" id="Page_9">[Pg 9]</span>thing. -They are a great nuisance on board -ship, where they are said to gnaw the skin -and nibble the toe-nails of sailors. Hardly -any animal or vegetable substance is absent -from their menu. It is said that they will even -devour bed-bugs, and that natives on the -African shores, troubled by these semi-parasites, -will beg cockroaches as a favour from sailors -in passing ships.</p> - -<div class="figcenter illowp100" id="fig3" style="max-width: 75em;"> - <img src="images/fig3.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 3.</span> Mouth appendages of <i>Periplaneta</i> (magnified). <span class="allsmcap">A</span>, Mandible. -<span class="allsmcap">B</span>, First maxilla: 1, cardo; 2, stipes; 3, lacinia; 4, galea; 5, -palp. <span class="allsmcap">C</span>, Right and left second maxillae fused to form the labium: -1, submentum; 2, mentum; 3, ligula, corresponding to the lacinia; -4, paraglossa, corresponding to the galea; 5, palp. (From Latter.) -</div> -</div> - -<p>The mandible (Fig. 3), with its strongly -toothed surface, is capable of biting and -grinding into fragments a very varied diet. -The food is moistened by the secretion of -the salivary glands, which is capable of con<span class="pagenum" id="Page_10">[Pg 10]</span>verting -starch into the more soluble sugar. -The food is further ground up by a series -of hard ridges projecting into the inner face -of the gizzard (Fig. 4, 7). The secretion -of the so-called hepatic caeca is capable of<span class="pagenum" id="Page_11">[Pg 11]</span> -emulsifying fat and rendering proteins soluble. -Thus the ordinary food substances are reduced -to a condition in which they are capable of -diffusing from the lumen of the alimentary -canal into the blood which floods the body -cavity.</p> - -<div class="figcenter illowp80" id="fig4" style="max-width: 75em;"> - <img class="w100" src="images/fig4.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 4.</span>—A female -cockroach, <i>Periplaneta</i>, with the dorsal exoskeleton removed, -dissected to show the viscera. Magnified about 2.1, Head; 2, labrum; -3, antenna, cut short; 4, eye; 5, crop; 6, nervous system of crop; 7, -gizzard; 8, hepatic caeca; 9, mid-gut or mesenteron; 10, Malpighian -tubules; 11, colon; 12, rectum; 13, salivary glands; 14, salivary -receptacle; 15, brain; 16, ventral nerve cord with ganglia; 17, -ovary; 18, spermatheca; 19, oviduct; 20, genital pouch, in which the -egg-cocoon is found; 21, colleterial glands; 22, anal cercus. (From -Latter.)</div> -</div> - -<p>The external movement—one might almost -say ‘the panting’—which is very -obvious in the abdomen, the alternate -flattening and deepening of this part of the -body, is a movement of inspiration and expiration, -the air being driven into the stigmata -and so into the tracheae or breathing-tubes. -There is a considerable variation in the rate -of these pulsations, but the cockroach’s heart -beats at an average rate of seventy to eighty -contractions per minute.</p> - -<p>Although cockroaches have fairly developed -eyes, they seem to trust very largely to tactile -impressions in appreciating their relations to -the surrounding world. Their antennae and -the palps of their first and second maxillae -are constantly touching the surface on which -they are resting or moving, and from time to -time their antennae wildly wave in the air in -a manner which suggests that they are smelling -out the external circumstances which environ -them. The 39,000 sensory ‘nerve-endings’ -which are found in the antennae of the male -cockroach are almost certainly olfactory in<span class="pagenum" id="Page_12">[Pg 12]</span> -function. At the posterior end of the body -the two ‘cerci’ are also sensitive to tactile -impressions, and probably act at the hinder -end of the cockroach as the antennae act -at the forward end. Cockroaches are certainly -keenly sensitive to light, and, as every one -knows, they shun the light, and when detected -in daylight or candle-light they make as -quickly as they can for some dark hole or -crevice in which to hide.</p> - -<div class="figcenter illowp100" id="fig5" style="max-width: 75em;"> - <img src="images/fig5.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 5.</span>—Egg capsule of <i>P. orientalis</i> -(magnified). <span class="allsmcap">A</span>, External view; <span -class="allsmcap">B</span>, opened; <span class="allsmcap">C</span>, end -view. (From Miall and Denny.)</div> -</div> - -<p>Cockroaches breed during the summer, -and their eggs are laid in packets of sixteen -in a capsule or cocoon with rounded ends, and -with an upper corrugated edge. These cocoons -are very like the little hand-bags ladies have -carried since the dressmakers denied them -pockets. There are sixteen ovarian tubes in the -female, and each of these deposits one egg in each -cocoon. The ventral portion of the seventh abdominal -segment in the female is shaped like the -prow of a boat, and it is in this structure that<span class="pagenum" id="Page_13">[Pg 13]</span> -the cocoon, or egg-case, is built up. Each egg -is fertilised by a spermatozoon which has been -deposited by the male in the spermatheca -of the female. The eggs are placed in a -double row, eight in each row, facing each -other, and, as they gradually develop, it -becomes apparent that the ventral face of one -row faces the ventral face of the other row—just -as the little choir-boys on the Gospel -side of a chancel face the little choir-boys on -the Epistle side, but much nearer together—and -that their heads are all directed towards the -corrugated ridge.</p> - -<p>They are at first quite white, but with large -black eyes, and it has often struck me how -surprised they must be when they awake -to consciousness and find themselves staring -at a brother or sister cockroach just opposite, -of whom they have had hitherto no consciousness. -The ripe embryos secrete some -fluid, probably saliva, which dissolves the -ridge, and it is through this dissolved or -softened ridge that they ultimately make -their way into the outer world.</p> - -<p>Young cockroaches are very active, running -about and seeking everywhere for any food -of a starchy nature. They are, in fact, -miniatures of their parents, for a cockroach, -like many of the primitive insects, has a -direct development, and there are no such<span class="pagenum" id="Page_14">[Pg 14]</span> -stages as caterpillar and pupa in their life-history.</p> - -<p>But, like other insects, cockroaches change -their skin from time to time, and they lose -little time before beginning this ecdysis, for -they first cast their cuticle immediately after -escaping from the egg-capsule. The second -ecdysis is four weeks later, and the third at the -end of the first year, and after this time they -moult annually. At the seventh moult, when -the animal is now four years old, it assumes -the form of the perfect insect, and is capable -of reproduction. The later moults fall in -the summer time, and so does fertilisation -and oviposition. Male cockroaches may -be distinguished from the females by their -well-developed wings and wing-covers. They -stand higher on their legs than do the -females, whose abdomens often trail upon -the ground.</p> - -<p>In spite of the noxious secretion of their -abdominal glands there are creatures who -habitually feed on cockroaches—hedgehogs, -for instance, are frequently imported into -our houses to check these pests. Rats, cats, -polecats, frogs, and wasps have been known -to eat them, and some few of the digging-wasps -lay them down in their larders for -the use of their progeny. Some birds will -also tackle them. But even the most devoted<span class="pagenum" id="Page_15">[Pg 15]</span> -friend of cockroaches can find little to say in -their favour, except that they are currently -reported to form the basis of the flavouring -of a very popular sauce; but even wild cockroaches -will not drag from me what the -name of that particular sauce is.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_16">[Pg 16]</span></p> - -<h2 class="nobreak" id="CHAPTER_II">CHAPTER II<br /> - -<small>COCKROACHES (<i>Periplaneta</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part II</span></p> - -<div class="blockquote"> - -<p>In Russia the small Asiatic cockroach (<i>P. orientalis</i>) has -everywhere driven before it its greater congener (<i>P. germanica</i>).</p> - -<p class="psig"> -(<span class="smcap">Darwin</span>, <i>Origin of Species</i>.)<br /> -</p> -</div> - - -<p>Cockroaches do a very considerable amount -of damage by consuming food-supplies. But -they do not stop at food-supplies: woollen -clothing, newspapers—not a really great loss—blacking, -ink, leather, and even emery-paper, -are all to their taste, and, being of an economical -frame of mind, they devour their own cast -skins and the dead bodies of their relatives. -The late Professor Moseley recorded how on -one occasion, when on the circumnavigating -tour of H.M.S. <i>Challenger</i>, a number of cockroaches -took up their abode in his cabin and -devoured parts of his boots, ‘nibbling off all -the margins of leather projecting beyond the -seams on the upper leathers.’ He further -records:—</p> - -<p><span class="pagenum" id="Page_17">[Pg 17]</span></p> - -<div class="blockquote"> - -<p>One huge winged cockroach baffled me in my -attempts to get rid of him for a long time. I could -not discover his retreat. At night he came out -and rested on my book-shelf at the foot of my bed, -swaying his antennae to and fro, and watching -me closely. If I reached out my hand from bed -to get a stick, or raised my book to throw it at him, -he dropped at once on the deck, and was forthwith -out of harm’s way. He bothered me much, because, -when my light was out, he had a familiar habit -of coming to sip the moisture from my face and -lips, which was decidedly unpleasant, and awoke -me often from a doze. I believe it was with this -object that he watched me before I went to sleep. -I often had a shot at him with a book or other missile -as he sat on the book-shelf, but he always dodged -and escaped. His quickness and agility astonished -me. At last I triumphed by adopting the advice -of Captain Maclear and shooting him with a pellet -of paper from my air-gun, a mode of attack for -which he was evidently unprepared.</p> -</div> - -<p>It is on record that cargoes of cheeses -have been destroyed by cockroaches on ships. -Not only did they devour great quantities -of each cheese, but they defiled every one of -them with their very tenacious fluid which -has, as we have noted above, a most disgusting -smell. This the cockroaches poured out from -their stink-glands, making the cheeses of no -commercial value.</p> - -<div class="figleft illowp42" id="fig6" style="max-width: 18.75em;"> - <img src="images/fig6.jpg" alt="" /> -<div class="captionl"><span class="smcap">Fig. 6.</span>—Cast skin of -older nymph (pupa). × 2½. (From Miall and Denny.</div> -</div> - -<p>When a cockroach casts its skin a median -longitudinal slit appears on the back of the<span class="pagenum" id="Page_18">[Pg 18]</span> -thorax, and through this slit the insect slowly -emerges. With much labour and difficulty -it squeezes its body through and pulls one -limb after another from its old integument, -until at last even the long -whip-like antennae are -completely withdrawn. -Certain portions of its -inner anatomy—such as -the lining of parts of the -breathing-tubes, or tracheae—are -also withdrawn. -Should the discarded skin -not be eaten by the emergent -insect, it remains on -the floor, and might easily -be mistaken for a sedentary -cockroach but for the fact -that live cockroaches never -are sedentary.</p> - -<div class="figcenter illowp100" id="fig7" style="max-width: 75em;"> - <img src="images/fig7.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 7.</span>—Nymph (in -last larval stage) escaping from old skin. Magnified. (From Miall and -Denny.)</div> -</div> - -<p>The incomplete metamorphosis, -the generalised -character of the nervures of the hind wings, -the complete separation of the three thoracic -segments (or rather their want of that -fusion so conspicuous in the higher insects—the -flies and the bees) and the undifferentiated -condition of the mouth parts—all -point to the insect being of a primitive type. -But there is no doubt that, whether a primi<span class="pagenum" id="Page_19">[Pg 19]</span>tive -insect or not, the cockroach is a very -successful one; it is an <i>arriviste</i>—as ‘our -lively friend, the Gaul,’ to quote Mr. Micawber, -would say—probably owing to its attaching -itself in all cases, and with unvaried devotion -to the habitation of men. Not popular with -humanity, it nevertheless ceaselessly extends -its domain by slowly yet surely entering into -new and hitherto unconquered human habitations. -In spite of insect-traps and vermin-killers, -it is extremely difficult to eradicate -from a house when once it is well established. -It has, in fact, gradually dislodged in most -places in Great Britain and Ireland the old -domestic house-cricket. For in spite of its -irritating, and to some people quite maddening, -ticking, the ‘cricket-on-the-hearth’ has -somehow established itself as a household -pet, and one that has won not only our<span class="pagenum" id="Page_20">[Pg 20]</span> -respect but our affection. So curious is our -psychology.</p> - -<div class="blockquote"> - -<p>The cockroach has many enemies, and the genus -<i>Sphex</i> (or <i>Chlorion</i>) may be seen hunting about -here and there, up and down the road-side and -gardens, searching for its favourite prey. It spies -out a cockroach, which appears to know intuitively -that there is danger at hand, for it shows symptoms -of great fright, and seems so confused that it cannot -run away. The <i>Chlorion</i> pounces upon the insect, -clasps it with its mandibles between the head and -the corselet, and stabs it in the body with the sting. -Then it flies off for a little distance, and awaits the -effects of the poison thus introduced; and when -the convulsions of the victim have ceased, the clever -little insect seizes its stupefied prey, and drags the -heavy burden with great efforts to its nest. Usually -the opening of the cavity is so narrow that the -cockroach cannot be got in, for its legs and wings -stick out and prevent its introduction. But the -<i>Chlorion</i> sets to work and cuts off the legs and the -wings, and having thus lessened the difficulty, it -strives hard to push the body into the hole; but as -this plan usually fails, the hymenopteron enters -first of all, seizes the cockroach with its mandibles, -and drags it in with all its force. As the integuments -of the <i>Blatta</i> are more or less soft and flexible, the -great insect is at last forced into the gallery, where -it never could have been expected to have entered. -Such proceedings on the part of the <i>Chlorion</i> almost -verge upon the domain of reason; and it is difficult -to explain them by the notion of that very indefinite -quality called instinct, for the manœuvres vary<span class="pagenum" id="Page_21">[Pg 21]</span> -according to the circumstances, and there appears -to be an intelligent method of overcoming every -difficulty.<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a></p> -</div> - -<p>Apart from animals which eat it, there -are a number of parasites which infest it, -beginning with the parasitic beetle <i>Symbius -blattarum</i>, whose wingless females attach -themselves to the bodies of the cockroaches -and feed upon their tissues. Then occasionally -a round-worm, <i>Filaria rhytipleurites</i>, -whose sexual stage is passed in the rat, is -found in its larval stage in the fat bodies of -the cockroach.</p> - -<p>Two years ago Dr. C. Conyers Morrell -undertook some investigations and observations -as to what part, if any, cockroaches -played in the dissemination of pathogenic -microbes, his object being, as he says, ‘first -to ascertain what bacilli belonging to the -colon group are likely to be conveyed to food -and milk by this insect, and secondly to find -whether known bacteria and moulds can be -transmitted by the faeces.’ Dr. Conyers Morrell’s -experiments were conducted on one of -the Union Castle liners sailing to South Africa, -and the insects which were investigated were -collected only from the larder or passages<span class="pagenum" id="Page_22">[Pg 22]</span> -adjacent to the kitchens; in no case were -they taken from lavatories or from staterooms. -The general condition of the ship, -which was almost new, was one of exceptional -cleanliness, and thus afforded good -conditions for the experiments. Dr. Morrell -was of opinion that there was little danger -except by contamination from the faeces of -the infected insect.</p> - -<p>One of his first experiments was to prove -that should cockroaches fall into the dough -which was being baked for bread the heat of -the baking entirely destroyed the bacilli that -were in the alimentary canal of the insect. -With regard to infection with the colon bacillus, -he kept an infected insect under the best -antiseptic conditions he could compass until -it had passed some undigested food. Of -this undigested food an emulsion was prepared, -and cultures were made from it on -bile-salt medium and in litmus-milk. Afterwards -special cultures were made in gelatine -and peptone solutions. Incubation was conducted -in all cases at 37° C., and cultures -were made from seventeen specimens. Five -of these produced colonies of bacilli on the -bile-salt medium, with sub-culture results as -follows: Four produced acidity and clotting -of milk, acid, and gas in glucose, lactose, and -saccharose, and production of indol. But the<span class="pagenum" id="Page_23">[Pg 23]</span> -bacilli did not liquefy gelatine, and were -Gram-negative. One specimen produced gas -in glucose and lactose, and liquefied gelatine -and coagulated milk. The former in its reaction -corresponded to the <i>Bacillus lactis -aërogenes</i>, the latter to <i>Bacillus cloacae</i>. -In five cases greenish moulds of the <i>Aspergillus</i> -variety were found after inoculating -litmus-milk.</p> - -<p>Cockroaches will devour human sputum -with avidity, and are frequently to be found -in spittoons (or, as the more delicately -minded American calls them, ‘cuspidors’<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a>), -and it is interesting to know that after feeding -the insects on infected sputum from a tuberculous -patient, the tubercle bacilli are found -in the faeces within twenty-four hours; two -specimens which had been fed on staphylococci -showed these pathogenic organisms in -their faeces and in the cultures on agar-agar, -which were obtained from their dejecta.</p> - -<p>I have quoted largely from this important -paper, and now propose to quote a good deal -more, and thus I append Dr. Conyers Morrell’s -conclusion of the important experiments -he conducted on the Union Castle liner.</p> - -<p>The foregoing experiments, though insufficient -in number to afford a basis for working out per<span class="pagenum" id="Page_24">[Pg 24]</span>centage -results, are, I think, of some value, in that -they prove the following facts:—</p> - -<p>The common cockroach is able by contamination -with its faeces (1) to bring about the souring -of milk; (2) to infect food and milk with intestinal -bacilli; (3) to transmit the tubercle bacillus; (4) to -disseminate pathogenic staphylococci; (5) to transmit -from place to place destructive moulds.</p> - -<p>These facts, taken in conjunction with the life-habits -of the insect, lead to the conclusion that -the cockroach is able to and may possibly play a -small part in the dissemination of tuberculosis, -and in the transmission of pyogenic organisms; -that the insect is in all probability an active agent -in the souring of milk kept in kitchens and larders; -and that it is undoubtedly a very important factor -in the distribution of moulds to food and to numerous -other articles, especially when they are kept in -dark cupboards and cellars where cockroaches abound. -The distribution and numbers of the cockroach are -rapidly increasing, and unless preventive measures -are adopted the insect is likely in the course of time -to become a very troublesome and possibly a very -dangerous domestic pest.<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a></p> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_25">[Pg 25]</span></p> -<h2 class="nobreak" id="CHAPTER_III">CHAPTER III<br /> - -<small>THE BOT- OR WARBLE-FLY (<i>Hypoderma</i>)</small></h2></div> - -<p class="center">Apropos de bottes.—(<span class="smcap">Reynard.</span>)</p> - - -<p>Britain wants many materials in this war, -and as long as our back door is open we are -getting them. Petrol, rubber, zinc, copper, -molybdenum, vanadium, thorium, nickel, saltpetre, -wool, cotton, are all coming to us -in greater—immeasurably greater—quantities -than those in which they can filter through -neutral countries into Germany. These things -count. The shortage of leeches in Great Britain, -on which I have already dwelt, is negligible, -and is entirely over-balanced by the really -serious shortage of sausage-skins in middle -Europe. I am told that our meat-salesmen -at Smithfield were offered an incredible -advance on the normal rate for these products—so-very-necessary-and-under-no-circumstances-to-be-done-without-with-casements—but -the meat-salesmen at Smithfield -were patriots. In their dire extremity the Germans -have been trying to make them of cellulose.</p> - -<p><span class="pagenum" id="Page_26">[Pg 26]</span></p> - -<p>Amongst the things both combatants most -want is leather. One of the most impressive -efforts we non-combatants have been watching, -since August 1914, is an army growing, -near us and next us, with apparently an unlimited -supply of leather belts, leather trappings, -leather saddlery—leather harness for -man and beast. Yet they tell me that the -price of leather since the War began has appreciated -by 140 per cent. This may be so; but, -as Joseph Finsbury remarked in ‘The Wrong -Box,’ ‘there is nothing in the whole field -of commerce more surprising than the fluctuations -of the leather market. Its sensitiveness -may be described as morbid.’ But Joseph -was no business-man, and kept in the background -of the office a capable Scot who was -understood to have a certain talent for book-keeping. -Readers of Stevenson will remember -that nobody had ever made money -out of Finsbury Brothers, Leather-merchants, -except the capable Scot who retired (after -his discharge) to the neighbourhood of Banff, -and built a castle with his profits. There -are still many capable Scots about, and this -may, to some extent, account for the present -price of Sam Browne belts.</p> - -<p>There must have been well over 150,000 -Sam Browne belts made since the War began. -A widespread belief—at any rate, amongst<span class="pagenum" id="Page_27">[Pg 27]</span> -the junior members of the Army—is that -Sam Browne was an American; possibly some -slight confusion existed in their dear young -minds between the inventor of the belt and -John Brown whose ‘body lies,’ &c. The -inventor of this useful cincture was, however, -Sir Samuel James Browne (1824-1901), G.C.B., -K.C.S.I., the well-known Indian fighter, who -lost an arm, and gained a V.C. by his gallantry -during the Mutiny. He was for a time the -military member of the Governor-General’s -Council, and he commanded the first division -of the Peshawar Field Force during the Afghan -War of 1878-9. The 22nd Regiment in the -Indian Army, a frontier force, is known as -Sam Browne’s Cavalry.</p> - -<p>The belt was first used unofficially, but it -gradually found favour with the authorities, -and it is mentioned officially in the regulations -drawn up for the Straits Settlements in -1891, and for Egypt and West Africa in 1894. -It was only on April 24, 1900, that the pattern -was ‘sealed,’ and adopted as a general item -of equipment for all officers on Active Service.</p> - -<p>Anything that seriously destroys the continuity -of the integument of our oxen, which -interferes with the ‘wholeness’ of the hide -which is the basis of leather, clearly affects—and -affects detrimentally—an important -munition of war. The bot- or warble-fly does<span class="pagenum" id="Page_28">[Pg 28]</span> -this. But it does more: its attacks materially -lessen the value of the beef which potentially -lies beneath the hide, and thus in a double sense -the warble-fly is the enemy of man whether -he be soldier or sailor. Further, its attacks -seriously lessen the milk-supply of the -country.</p> - -<p>Amongst the numerous families into which -the true flies (<span class="smcap">Diptera</span>) are divided, none are -more harmful to human enterprise than that -of the <i><span class="smcap">Oestridae</span></i>, or bot-flies, inasmuch as -every single species and every single member -of this family passes its larval stage within -the tissues of some vertebrate host, and frequently -in those of domesticated cattle; sometimes -even in man himself. One of the -commonest genera of this family of flies is -<i>Hypoderma</i>, which is represented in our -islands, and in many other parts of the world -where domesticated cattle are reared, by two -species—<i>H. bovis</i> and <i>H. lineatum</i>, both commonly -known as bot- or warble-flies.</p> - -<p>The harm caused by these larvae, living -as they do in the tissues of the body, beneath -the skin, by piercing holes through the integument -or skin, whereby they make their exit -from the ‘warble’ or subcutaneous tumour -in which they have passed their latest larval -stage, is almost incalculable.</p> - -<p><span class="pagenum" id="Page_29">[Pg 29]</span></p> - -<div class="figcenter illowp100" id="fig8" style="max-width: 75em;"> - <img src="images/fig8.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 8.</span>—<i>a</i>, -<i>Hypoderma bovis</i>; <i>b</i>, maggot of <i>H. bovis</i>; <i>c</i>, -egg of <i>H. bovis</i>; <i>d</i>, puparium of <i>H. bovis</i>; -<i>e</i>, egg of <i>H. lineatum</i>; <i>f</i>, maggot of <i>H. -lineatum</i>; <i>g</i>, <i>Hypoderma lineatum</i>. All the figures -are magnified. (From F. V. Theobald’s <i>Second Report on Economic -Zoology</i>, British Museum, 1904.)</div> -</div> - -<p><span class="pagenum" id="Page_30">[Pg 30]</span></p> - -<p>Miss Ormerod, who for so many years -kept alight the lamp of economic entomology -in England, published some statistics on this -subject towards the end of the last century. In -1888, out of slightly over 100,000 hides dealt -with in the Newcastle cattle and skin market, -60,000 were ‘warbled,’ and the loss to the -trade amounted to £15,000. The same year -at Nottingham 8500 out of 35,000 hides were -largely spoiled; at Manchester 83,500 out of -250,000 suffered from the same cause: the -losses in these towns being estimated for -the year in question at about £2000 and -£17,000 respectively. Taking the average -from all sources in England, Miss Ormerod -estimated the fall in value at from 5s. to 6s. -on every warbled hide. The most riddled -hides—that is, those with the most punctures—come -to the sale-room during April and May, -but the trouble extends from February to -September.</p> - -<p>There is also the loss caused by the warble -to the butcher—and through the butcher -to the Army Service Corps. The presence -of the fly-larva, which is quite a large creature, -induces chronic inflammation in the -tissues, and a state of things known to the -trade as ‘licked beef,’ and unless the meat-salesman -cuts away the affected parts the -meat is unsaleable in the market, or greatly -depreciated in value. The average loss to<span class="pagenum" id="Page_31">[Pg 31]</span> -the butcher on a warbled carcass is estimated -at 6<i>s.</i> 8<i>d.</i></p> - -<p>Finally there is a loss to the stock-raiser -and dairy farmer. We shall have occasion -later to refer to the curious psychological -effect the warble-fly has upon the cattle, -causing them to ‘gad’ or stampede in wild -gallops, which interferes with fattening, deteriorates -the milk-supply, and is especially -injurious to cows with calf. Mr. Imms, in -his most useful summary of the warble-fly, -tells us that the loss due to <i>H. lineatum</i> in -America is calculated at 28 per cent. of their -total value of all the cattle in the States. -Some authorities place the total loss to -the agricultural community in England at -£2,000,000, others at £7,000,000, a year, whilst -others estimate that the loss amounts to about -£1 sterling on every head of horned cattle.</p> - -<p>Curiously enough, the fly itself is rarely -seen, and still more rarely taken. Mr. Imms -records only two specimens of <i>H. bovis</i> in the -collections of the British Museum, and but -fifteen of <i>H. lineatum</i>. A similar scarcity -of imagos in public collections obtains on the -other side of the Atlantic, where for many -years the last-named species was alone recognised. -Two years ago, however, Dr. Hadwen, -working in Canada, established the widespread -existence of <i>H. bovis</i> in the Dominion;<span class="pagenum" id="Page_32">[Pg 32]</span> -almost certainly it also occurs in the States; -but Dr. Hadwen had to send to Dublin for -specimens with which to confirm his find. -None existed in the collections in Ottawa, -and a ‘request for a specimen ... from the -Bureau of Entomology at Washington, D.C., -could not be granted owing to a scarcity -of specimen’! These statements are interesting, -since at present the tanneries of -Canada are working night and day to help -our shortage in leather at home.</p> - -<p><i>H. bovis</i> measures ⅝ in. in length, <i>H. -lineatum</i>, somewhat less robust, ½ in.; the -hairy covering of the last named is of a foxy -red at the tail end, while that of <i>H. bovis</i> is -yellow, both at the tail end and towards the -front of the body. The flies are most abundant -during July and August, though they are -believed to occur throughout the summer. -At Athenry (co. Galway) <i>H. lineatum</i> is common -by the middle of May. They fly very -rapidly, and are difficult to follow with the -eye. They rejoice in warm, sunny weather, -and remain in retirement during cold or -cloudy days. Hadwen describes the egg-laying -by the female ‘as a sort of frenzied -process, the fly striking’ with its ovipositor -twenty or thirty times rapidly, then leaving -the animal for fifteen minutes or so, when -the process was repeated. The eggs are<span class="pagenum" id="Page_33">[Pg 33]</span> -attached one at a time to the hairs of the -cattle and very close to the base of each hair, -not near the tip, where the horse bot-fly<span class="pagenum" id="Page_34">[Pg 34]</span> -deposits its ova. The eggs of <i>H. bovis</i> are -scattered and isolated; those of <i>H. lineatum</i> -are arranged in rows of some seven or more -half-way up the hair and are contiguous. -The favourite region for placing the eggs is on -the hock and on the back of the knee, or on -the thighs and flanks, and hence the American -cowboys call the insect the ‘heel-fly.’ Undoubtedly -by standing with their legs in water -the herd is delivered from the pest—at any -rate, for the time.</p> - -<div class="figcenter illowp48" id="fig9" style="max-width: 62.5em;"> - <img class="w100" src="images/fig9.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig.</span> 9.—Eggs of <i>H. -lineatum</i>, attached to hair of cow. Five of the eggs are hatched and -six unhatched. Magnified 15 times. (From Carpenter, Hewitt, and Reddin, -<i>Journ. Dept. Agric. Ireland</i>, xv., 1914.)</div> -</div> - -<p>The eggs are large, 1·25 mm. in length, -and enclosed in a whitish shell, which is prolonged -behind into a brownish foot, and this -foot, which exudes some sticky excretion, -adheres to the ruminant’s hairs. The foot of -the egg-shell, in fact, consists of two lobes or -valves, which clasp the hair between their -sticky inner surfaces.</p> - -<div class="figcenter illowp79" id="fig10" style="max-width: 62.5em;"> - <img class="w100" src="images/fig10.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig.</span> 10.—Eggs of <i>H. -bovis</i> attached to hairs. Note attachment near base. Slightly -enlarged. (From Hadwen.)</div> -</div> - -<p>Within the egg the youngest of the four -larval stages is maturing. When hatched it is -less than 1 mm. long, but it is ‘a terror for its -size,’ being armed with a formidable spine and -two hooks in the mouth, and with rows of -strong spines on all the body-segments. Later, -we find a second stage, very much smoother -and less spiny than the first and this lies -within the tissues of the host, embedded in its -muscles and membranes, notably in the submucous -coat of the gullet; and now the<span class="pagenum" id="Page_35">[Pg 35]</span> -question confronts us, which once confronted -George III apropos of the apple in the apple -dumpling, ‘How the devil did it get in?’ -There seems to be with <i>Hypoderma</i> but two -possible modes of entrance into the body -of its host—that is, domesticated cattle: (1) -The eggs, or the newly hatched larvae, are -licked up by the tongue, as are the eggs of the -horse bot-fly—and this might be held to -explain the not infrequent occurrence of the -second larval stage in the walls of the oesophagus; -or (2) the larvae bore their way directly -through the skin. From experiments carried<span class="pagenum" id="Page_36">[Pg 36]</span> -on for several years which show that cattle -unable to lick themselves are not protected -from warbles, Professor G. H. Carpenter of the -Royal College of Science, Dublin, concluded that -the larvae do not enter by the mouth. During -the summer of 1914, he and his able assistant, -the late Mr. T. R. Hewitt, definitely proved -that ‘the newly hatched maggot does bore -through the skin of cattle’; probably after -an ecdysis they find their way to the submucous -coat and muscles of the gullet, and -here for a while they rest. I quote from the -account of Carpenter and Hewitt some of -their most crucial experiments carried out -at the Athenry and Ballyhaise Stations of -the Irish Department of Agriculture:—</p> - -<div class="blockquote"> - -<p>In July 1914, twenty-four maggots were hatched -in the incubator, and some of these were used for -observations as to behaviour when placed on a -calf’s body. Glaser, in 1913, had tried to carry out -observations of this kind by placing maggots on a -shaved portion of a calf’s skin; he found that they -made no effort to bore through. Instead of being -shaved, a small patch of the shoulder of one of the -Ballyhaise calves was clipped, so as to have the conditions -as normal as possible, when newly hatched maggots -of <i>H. bovis</i> were placed on it. Immediately they -started crawling down the clipped hairs to the -skin, and, as soon as they reached the surface, they -began to burrow. On account of their small size -it is hard to discern them, but by carefully watching<span class="pagenum" id="Page_37">[Pg 37]</span> -through a lens it was seen that they enter perpendicularly -to the surface, evidently cutting into the -epidermis with their mouth-hooks and occasionally -bending their bodies. Mr. R. G. Whelan, A.R.C.Sc.I., -Superintendent of the Ballyhaise Agricultural -Station, kindly helped in the observations and confirmed -them. Six hours after being placed on the -calf, the maggots disappeared completely. Next -morning the spots where they had entered were<span class="pagenum" id="Page_38">[Pg 38]</span> -marked by little pimples, like those of the Athenry -animals, easily to be seen with the naked eye. These -increased slightly in size, but soon healed up, and -in less than a week not a trace of the maggots’ -entrances could be found. The boring-in of the -maggots seemed at first to cause the calf a little -pain, but the symptoms of discomfort soon passed -away.</p> - -<p>We have still to find out what happens to the -first-stage larva after it has bored into the skin -and how far it travels before it undergoes its -first moult. Gläser found that some eggs of <i>H. -lineatum</i> laid on his trousers hatched, and that a -maggot bored right through into his own skin. -From symptoms of swelling and pain in various -regions he concluded that this maggot travelled -to his gullet, and he finally extracted it (in the -second stage) from his mouth.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a></p> -</div> - -<div class="figcenter illowp63" id="fig11" style="max-width: 53.125em;"> - <img class="w100" src="images/fig11.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 11.</span>—Entrance hole -of <i>H. lineatum</i> maggot into the skin of a cow. The hairs around -the hole have been clipped short. The white incrustation is due to a -discharge from the hole, which has hardened. Magnified 12 times. (From -Carpenter, Hewitt, and Reddin, <i>Journ. Dept. Agric., Ireland</i>, -xv., 1914.)</div> -</div> - -<p>Perhaps in the first stage they may be -carried by the blood stream. They seem in their -second larval stage to wander freely through -the tissues, especially through the muscular -tissues, of the body of their host—usually -working upwards, and not infrequently reaching -the neighbourhood of the vertebral column -before taking up—still in the second larval -stage—their final position, where their presence -gives rise to the ‘warbles,’ or subcutaneous -cysts or tumours, in which the third and fourth -larval stages are passed.</p> -<p><span class="pagenum" id="Page_39">[Pg 39]</span></p> -<p>It seems odd that an insect pest, which -so seriously affects our supply of leather, of -meat, and of milk, should have been studied -for over a century and yet conceal its chief -secret from man. But the problem is much -more difficult than the layman thinks.</p> - -<p>Whatever be the route the maggot travels -through the body of the calf or cow, by the -spring the fourth larval stage—when it is about -an inch long, and perhaps half as much in -breadth—is reached in the ‘warble’ or cyst, -under the skin. Here, nourished by the -products of the inflammation it sets up, and -breathing by two spiracles at the hinder end -of its body, which are directed to the opening -of the ‘warble’ which it has pierced through -the skin, the larva rests until one fine morning -it pushes its way, aided by its stout bristles, -through the opening and tumbles into the -outer world.</p> - -<p>Apparently it does not think much of its -new surroundings, for it loses no time in hiding -under some clod of earth or stone or crevice -in the soil, and straightway turns into a dark -brown pupa or chrysalis. This stage lasts three -to four weeks, and then the perfect fly emerges, -and will soon be ready to lay her eggs on some -new victim.</p> - -<div class="figcenter illowp71" id="fig12" style="max-width: 50em;"> - <img class="w100" src="images/fig12.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 12.</span>—Cow being -chased by fly. Note terrified look of eyes. (From Hadwen.)</div> -</div> - -<p>As a rule it is the yearlings who suffer -most, and then the two-year-olds; the older<span class="pagenum" id="Page_40">[Pg 40]</span> -cattle being comparatively immune. The inexplicable -terror which the warble-fly induces -in its victims is testified to on all hands, but -has never been adequately explained. <i>Hypoderma</i> -does not bite, neither does it sting. -Many other blood-sucking insects, whose puncture -must involve some pain, are tolerated -by cattle with a flick of the tail, or are frightened -off by a gesture of the head; but the -presence of the warble-fly induces a mysterious -fear which rapidly spreads through a herd, -and results in a general stampede—often -referred to by cattle-breeders as the ‘gad.’ -This terror communicates itself even to the<span class="pagenum" id="Page_41">[Pg 41]</span> -‘stalled ox,’ and cattle confined within cowsheds -show symptoms of extraordinary unrest -when the fly is abroad amongst their kin in -the pastures. The resulting evils are, of -course, far graver in the unlimited prairies of -the West—the great cattle-breeding districts -of the United States and Canada—than in -our carefully hedged or fenced meadows. A -great many ‘dips,’ ointments, and chemical -solutions have been recommended for the prevention -of the grubs in cattle, but none have -proved entirely satisfactory. The tedious -method of removing the grub from the tumour -is the only safe one. This can be done by -the mere pressure of the fingers when the grub -is nearly mature and ready to leave its host, -or by the use of small forceps should the grub -be young and recalcitrant. Once removed the -grub should be immediately destroyed, and -some such antiseptic as coal-tar applied to the -lips of the vacated tumour.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_42">[Pg 42]</span></p> - -<h2 class="nobreak" id="CHAPTER_IV">CHAPTER IV<br /> - -<small>THE MOSQUITO (<i>Anopheles maculipennis</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part I</span></p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">Where the water is stopped in a stagnant pond,</div> - <div class="verse indent4">Danced over by the midge.</div> - - <div class="verse indent10">(<span class="smcap">R. Browning</span>, <i>By the Fireside</i>.)</div> - </div> -</div> -</div> - - -<p>There is no zoological distinction between -a mosquito, a gnat, or a midge. But, as a -matter of convenience, we might confine the -term ‘gnat’ to the genus <i>Culex</i>, the term -‘mosquito’ to the genus <i>Anopheles</i>, and the -term ‘midge’ to the genus <i>Ceratopogon</i> and -its congeners, whose collocation with the -naked knees of the Highlander is said to have -given rise to the ‘Highland Fling.’</p> - -<p>There is no doubt about it that both the -mosquito and the gnat are extraordinarily -beautiful insects. This fact, however, has -been veiled from the public partly owing to -their small size and more especially because -of their irritating bite, which causes the -sufferer to kill a mosquito at sight rather than -examine its fairy-like beauty or its fascinating<span class="pagenum" id="Page_43">[Pg 43]</span> -dances in the air, far surpassing in grace and -agility anything seen in the Russian ballet. -But biting is the dominating note of a mosquito, -and we may as well consider, to begin -with, how it bites.</p> - -<p>If we examine the head of a mosquito we -shall find that it is shaped like a circular -cushion bearing two enormous eyes—so large -that in the male they touch above the forehead -and almost meet below the chin. Each -eye consists of hundreds of facets of a brilliant -green hue, set in a darkish background, like -emeralds arranged on a black surface. The -head also bears a quantity of hairs and flattened -scales whose number, shape, and arrangement -are of considerable systematic value.</p> - -<p>The following are the appendages of the -head:—</p> - -<p>1. A pair of antennae, which are markedly -different in the two sexes.</p> - -<p>2. A pair of mandibles. These are absent -in the male.</p> - -<p>3. A pair of first maxillae, each of which -has a jointed tactile palp.</p> - -<p>4. A pair of second maxillae which have -fused together to form a deeply grooved soft -process in which the other appendages lie.</p> - -<p>Beside these four pairs of appendages, -which are in reality modified limbs, there are -two median processes, which project one from<span class="pagenum" id="Page_44">[Pg 44]</span> -the top, the other from the bottom, of the -mouth, like elongated and hardened upper -and lower lips. These are the median labrum -above—a deeply grooved structure whose edges -approximate and almost touch, thus forming a -tube along which the blood of the victim is -sucked. Lastly, there is the hypopharynx—sometimes -termed the tongue—a median -structure a double-edged sword, rising from -the bottom of the mouth, and it is this that -is the cause of all the trouble.</p> - -<div class="figcenter illowp100" id="fig13" style="max-width: 75em;"> - <img src="images/fig13.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 13.</span>—Side view -of the head of a female <i>Anopheles maculipennis</i> (magnification -about 20), with the various mouth parts separated, but in the relative -position in which they lie when enclosed in the groove of the labium. -This figure shows the characteristic cephalic scales, <i>a</i>, -Antennae; <i>cs</i>, cephalic scales; <i>cl</i>, clypeus; <i>lxe</i>, -labrum + epipharynx; <i>mn</i>, mandible; <i>hp</i>, hypopharynx; -<i>mx</i>, first maxilla; <i>li</i>, labium; <i>mp</i>, maxillary -palps. (From Nuttall and Shipley.)</div> -</div> - -<p><span class="pagenum" id="Page_45">[Pg 45]</span></p> - -<div class="figcenter illowp80" id="fig14" style="max-width: 50em;"> - <img class="w100" src="images/fig14.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 14.</span>—Transverse -section through the middle of the proboscis of a female <i>Anopheles -maculipennis</i>, showing the relative position of the parts when -at rest. Two tracheae and two pairs of extensor and flexor muscles -are seen in the labrum. <i>lxe</i>, Labrum + epipharynx; <i>tr</i>, -trachea; <i>mus</i>, muscles; <i>hp</i>, hypopharynx; <i>sal</i>, -salivary duct; <i>mx</i>, first maxilla; <i>mn</i>, mandible. (From -Nuttall and Shipley.)</div> -</div> - -<p>A glance at Fig. 13 will show how these -various mouth appendages can by a skilful -use of dissecting needles be separated out, -but in nature they are all packed together in -a case; the arrangement in the case is shown -by Fig. 14, which represents a transverse section -of the proboscis. The term ‘proboscis’ is -given to the totality of all these structures -taken and packed together. With the exception -of the labium and of the tactile maxillary -palps all the mouth appendages lance into -the skin. The proboscis of the male is, how<span class="pagenum" id="Page_46">[Pg 46]</span>ever, -too weak to pierce the human integument, -and it is the female which does all the -damage. When a mosquito is going to bite, -she alights so gently that -her approach is unperceived, -and she proceeds -to thrust her arsenal of -weapons into the epidermis -of her victim almost -unfelt; the feeling -comes later. These -weapons are all guided, -by the forked end of the -softened labium, just as -one’s finger-tips guide -the end of a billiard-cue. -These ‘mouth parts’ are -exceedingly fine, extremely -sharp-edged -structures, whose consistency -is about that of -whalebone, and both the -mandibles and the maxillae -have a toothed, -serrated edge (Fig. 15). They are partly -pushed in by muscles in the head, partly, I -think, by the lowering of the body, and they -sink slowly and surely into the flesh with as -much ease as a paper-knife will penetrate a -cream-cheese. But as they sink deeper and<span class="pagenum" id="Page_47">[Pg 47]</span> -deeper into the integument the body of the -mosquito approaches nearer and nearer to the -skin of the victim, and the labium is pressed -farther and farther backwards until at the end of -a satisfactory puncture the distal and proximal -parts of the labium are parallel and touching.</p> - -<div class="figleft illowp45" id="fig15" style="max-width: 18.75em;"> - <img src="images/fig15.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 15.</span>—A side view -of the labellae and piercing-organs of the proboscis of a female -<i>Anopheles maculipennis</i>, dissected out to show the tips of the -mandibles, maxillae, and labrum + epipharynx. The hypopharynx is not -shown, <i>li</i>, Labium; <i>lxe</i>, labrum + epipharynx; <i>mx</i>, -first maxilla; <i>mn</i>, mandible; <i>la</i>, labellae. (From Nuttall -and Shipley.)</div> -</div> - -<p>It is rather an interesting point that the -labium does not enter the skin, because the -larvae of certain <i>Filarias</i>—one of which produces -elephantiasis in man, and the other -severe heart trouble in the dog—are found in -pairs—probably a male and a female—in the -labia of mosquitos. How exactly these nematode -larvae leave the labium of the mosquito, -and enter the body of the man and the dog, -has not definitely, I believe, been cleared up; -but that they do enter the human and the -canine skin seems certain.</p> - -<p>We have mentioned that the labrum is a -grooved tube with its edges practically in -proximity, and it is up this tube that the blood -of the bitten is sucked by the well-known -suctorial pharynx which occupies so large a -part of the interior of the head of a mosquito. -Much the most dangerous weapon of the whole -armoury, however, is the hypopharynx. This -is shaped like a double-edged sword with a -very minute groove running down the centre; -this groove is so minute that Professor Nuttall -and I and others for some time took it to be a<span class="pagenum" id="Page_48">[Pg 48]</span> -closed tube. It receives at its base the products -of the salivary glands of the mosquito, and it -is these products which contain the organisms -which cause malaria—a disease which has -probably caused more trouble and has played -a greater part in the history of the world -than any other malady to which humanity -is heir. Down this minute, microscopic groove -has flowed the fluid which has closed the -continent of Africa for countless centuries -to civilisation, and which has played a dominating -part in destroying the civilisations -of ancient Greece and of Rome.</p> - -<p>When the adult mosquitos (the imagines) -leave their pupa-cases they are unable to pierce -the human skin until the mouth parts have -hardened, and this takes at least six hours. -In England they can undoubtedly feed -twenty-four hours after leaving the pupa-case. -When feeding, both the sensory antennae and -the tactile maxillary palps are thrust forward -at right angles to the proboscis. They thus -test the place where the two-lobed extremity of -the labium will guide the battery of stylets into -the substance they are feeding on. The female -is much more voracious than the male, which, -as we have mentioned above, cannot pierce -the human integument, and has to be content -with a vegetarian diet. Sometimes the effort -even of the female mosquito to insert its<span class="pagenum" id="Page_49">[Pg 49]</span> -proboscis is fruitless, and we have watched -a mosquito attempt four times to pierce the -skin before it drew blood. If undisturbed -during the meal the suctorial repast may last -some two or three and a half minutes. So -greedy at times is the mosquito that she -resembles Baron Munchausen’s horse after the -adventure with the portcullis—what is flowing -in at one end is flowing out at the other. -In fact, as Dr. Johnson said of the boys at -a school ‘where discipline was maintained -without recourse to corporal punishment,’ -‘But, sir, what they gain at one end they -lose at the other!’ After the process of biting, -of sinking-in of the piercing needles, is complete, -the proboscis is withdrawn, and to do -this the mosquito braces herself on her legs -and raises her body.</p> - -<p>Another curious feature about the head -of <i>Anopheles</i> is that it is pierced by two chitinous, -symmetrical tunnels—tubes which are -open at each end with trumpet-shaped orifices. -The use of these is probably to act as a stay or -strut to strengthen the chitinous exoskeleton of -the head; but these queer galleries or tubes also -to some extent act as attachments for muscles.</p> - -<p>The antennae vary very much in the two -sexes. In the female there are fifteen segments, -each bearing a ring of hairs, but of -small and disproportionate size, whereas in<span class="pagenum" id="Page_50">[Pg 50]</span> -the male the bushy character of the hairs is -conspicuous even to the naked eye. In fact, -it is the easiest criterion for judging the sex -of the insect. At the base of the first joint -of the male antenna is a deep cup-shaped -structure packed with sense organs, and containing -a large nerve ganglion. There are -sixteen segments in the whole antenna, one -more than in the female. The hairs are -capable of movement, and as a rule are kept -closed on the shaft of the antenna whilst not -in use; when evening comes on they are -spread out. There seems little doubt that -these organs are auditory and help the male -in searching for the female.</p> - -<p>The beautiful transparent wings of the -mosquito are beset with minute spikes, which -serve to break up the light and to give rise -to the many-coloured iridescence of the creature’s -wings. The posterior border of the -wing bears rows of beautifully graded scales. -These add much to the symmetry and beauty -of the whole structure. Just behind it are -two balancers or halteres—a name derived from -the Greek word ἁλτῆρες, meaning a kind of -dumb-bells which athletes used in the stadium -when jumping. These so-called balancers -project outwards and backwards from the body -when the wings are in a position of flight.</p> - -<p>A curious distinction between the <i>Culex</i><span class="pagenum" id="Page_51">[Pg 51]</span> -and <i>Anopheles</i> is in regard to the position -assumed by the insects when they rest. In -<i>Anopheles</i> the proboscis and body are -almost in one line, and the axis of the body -is at an angle with the surface upon which it -rests. <i>Culex</i>, on the other hand, has its proboscis -at a slight angle with its body, and -its body is almost parallel to the surface -upon which it is perching. <i>Culex</i> has a much -more hump-backed appearance than <i>Anopheles</i>, -and its legs are considerably shorter and -stouter. The insect generally rests upon four -out of six legs; in the former case the hinder -pair are held out and curved upwards. The -hind legs not infrequently serve as a test for -food. When feeding upon sweetened milk -or fruit, the moment the hind leg touches the -fluid or juice the insect will wheel round and -at once begin to feed.</p> - -<p><i>Anopheles maculipennis</i> is very widely -distributed, and it has been recorded from -most parts of North America and Europe, and -from many parts of Asia. Probably the species -is much more widely distributed than we have -any record, but individuals do not wander very -far, of their own accord, from the breeding-places, -though they may be dispersed by the -wind. Cases are known where they have been -blown as far as ten or even twenty miles; and -in camping in Africa it is always well to keep to<span class="pagenum" id="Page_52">[Pg 52]</span> -the windward of a native village. They are also -carried about by trains, motors, and steamers. -They do not indulge in any such voluntary -migratory flights as the locusts, although -some such flights have been from time to time -recorded, but these ‘swarms’ are probably due -to a high wind catching a large number of -mosquitos temporarily associated.</p> - -<p>In a joint paper which Professor Nuttall -and I wrote some years ago, we drew attention -to a case in which mosquitos came aboard a -ship some ten miles from land, and to another -in which a Spanish barque from Rio was detained -in the South Atlantic quarantine station -of the United States. The vessel was so much -infested with mosquitos that it was rendered -nearly uninhabitable, and the United States -quarantine officer reported that when the -forecastle was opened after fumigation ‘the -mosquitos could be scooped up by hand.’ -The master of the barque was positive that -there had been no mosquitos on board until -the twenty-second day out. Howard quotes -a letter from a General living in Texas in -which he states he has ‘twice seen flights of -<i>Culicidae</i>,’ but as the species and the genus -are not given, much of the interest of the -statement evaporates. Generals living in -Texas are not invariably remarkable for meticulous -accuracy in recondite scientific matters.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_53">[Pg 53]</span></p> - -<h2 class="nobreak" id="CHAPTER_V">CHAPTER V<br /> - -<small>THE MOSQUITO (<i>Anopheles maculipennis</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part II</span></p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">There in a wailful choir the small gnats mourn</div> - <div class="verse indent0">Among the river sallows, borne aloft</div> - <div class="verse indent0">Or sinking as the light wind lives or dies.</div> - <div class="verse indent10">(<span class="smcap">John Keats</span>, <i>To Autumn</i>.)</div> - </div> -</div> -</div> - - -<p>The female imago hibernates. Finsch made -observations and found it hibernating on -the frozen Siberian tundras, beneath the moss -and snow. Sterling found them in North -America when the snow was melting, in great -numbers, and he and his party were subsequently -terribly bitten. There is no doubt that -female imagines live throughout the winter, -and they can be found in England, hibernating -in cellars, old out-houses, chicken-houses, or -disused farm buildings. These hibernating -females disappear early in May, presumably -having laid their eggs. Dr. Thayer of Baltimore -describes these creatures, having found -them on the roofs and walls of barns near -New Orleans. Whether the male also hiber<span class="pagenum" id="Page_54">[Pg 54]</span>nates -is doubtful. Grassi says he never found -the male of <i>A. maculipennis</i> in the winter, -only fertilised females. But as the warm -weather sets in the female generally becomes -active and bites, and the native American -Indians consider these elderly and famished -females give more annoyance than at any other -stage in the life-cycle of either sex. In the -warmer climate of Southern Italy they not -infrequently hibernate in grottos and caves. At -times they occur in such numbers that they -can be swept up. After depositing their eggs the -hibernating females probably die. This usually -happens in May.</p> - -<p>In the old days we used to collect gnats, -keep them in a receptacle unprovided with -any food, and when, after a couple of days, -they died of starvation we wrote poems or -essays on the ‘Transitoriness of Life’ and -the ‘Evanescence of Time.’</p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">The thin-winged gnats their transient time employ,</div> - <div class="verse indent0">Reeling through sunbeams in a dance of joy.</div> - <div class="verse indent10">(<span class="smcap">Mrs. Norton.</span>)</div> - </div> -</div> -</div> - -<p>Nowadays, we feed them. Bananas, -sweetened milk, pineapple, or almost any -other vegetable juice, is their diet, and in -captivity they will live for weeks. At Cambridge -in 1900 (July to August), Professor -Nuttall was successful in keeping females alive<span class="pagenum" id="Page_55">[Pg 55]</span> -on a diet of bananas and water from two to -eight weeks, but it was found essential to keep -the atmosphere fairly moist and the food -fresh. Grassi found that he could only keep -<i>Anopheles</i> alive in his laboratory in Rome -for a month.</p> - -<p>Both <i>Anopheles</i> and <i>Culex</i>—at any rate, in -captivity—lay their eggs early in the morning. -Apparently the nature of the food has some -effect upon their fertility, certain observers -stating that when male and female are fed -on vegetable food alone there is no fertilisation -and no oviposition. A diet of blood evidently -assists the female to lay her eggs, and perhaps to -get them fertilised. One of our female <i>Anopheles</i> -laid a batch of 146 eggs, and subsequently -laid six more. But, as a rule, a fertilised -female does not lay a second batch unless -she receives a second meal of blood. The -eggs are laid two or three days after the meal. -There is also some evidence that a meal -of blood is necessary if fertilisation is to -be effected. As Austen says in <i>The Report -of the Sierra Leone Expedition of the Liverpool -School of Tropical Medicine</i>:—</p> - -<div class="blockquote"> - -<p>The following law is likely to hold good for the -<i>Culicidae</i> which feed on man—at least for the common -species; although these gnats can live indefinitely -on fruit, the female requires a meal of blood both -for fertilisation and for the development of the<span class="pagenum" id="Page_56">[Pg 56]</span> -ova. In other words, the insects need blood for -the propagation of their species.</p> -</div> - -<p>Undoubtedly, if mosquitos ever talk, they -would talk like Mr. Waterbrook, Mrs. Henry -Spiker—Hamlet’s aunt—and the ‘simpering -fellow with weak legs’ talked when David -Copperfield dined with the first-named at Ely -Place, Holborn. The burden of their song -was: ‘Give us blood.’</p> - -<p>But a word of caution must be given here. -Most of these deductions are based upon -mosquitos in captivity; whether the same -be true of them in natural conditions is not -quite certain. If it be so it is difficult to -see how these countless millions of gnats -and mosquitos which dwell in the barren -regions around the polar circle ever keep -going.</p> - -<p>It very frequently happens in the Animal -Kingdom that females are much more numerous, -as well as much larger, than the males.<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">[5]</a> As -Kipling tells us: ‘The female of the species -is more deadly than the male,’ but Professor -Nuttall and I did not notice that this -was the case with <i>Anopheles</i>.</p> - -<p>There is some evidence that the male hatches -out earlier than the female, and that in Southern<span class="pagenum" id="Page_57">[Pg 57]</span> -Europe there may be three or four generations -in the course of the season: the first beginning -in April and the fourth taking place between -the middle of September and the middle of -October. After that date no larvae were -found. About four generations also occurred -in the neighbourhood of Cambridge, according -to observations of Professor Nuttall.</p> - -<p>Kerschbaumer has calculated that if the -average number of eggs laid by a female be 150, -the number of the descendants by the fourth -generation would amount to 31 millions. This -readily accounts for the fact that in certain -parts of the world they occur in perfectly -enormous numbers, and if it be true that -blood is essential for fertilisation and oviposition, -very few of these potential mothers -can breed. In nature they will feed on a -great number of vegetable juices—melons, -wild cherry-blossom, bananas, oranges, overripe -mangoes; they suck the ‘juices’ of -allied species of insects just when the imago -is issuing from the pupa-case and before their -integument is hardened, or they pierce the -soft skin of the cicada, and occasionally -attack the chrysalids of a butterfly. One -of the most curious sources of food are very -young trout. The adult insect attacks these -<i>petits poissons filiformes</i>, ‘literally sucking out -their unsuspective little brains before they<span class="pagenum" id="Page_58">[Pg 58]</span> -could escape.’ Grassi is doubtful whether -the adult males feed at all. He states that -he never found any food in their stomach, -nor has he ever seen a male feed. But Professor -Nuttall’s experiments in Cambridge prove -that males were seen repeatedly to feed, and -to feed hungrily, on cherries, dried fruits, -dates, and bananas.<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">[6]</a></p> - -<div class="figcenter illowp100" id="fig16" style="max-width: 75em;"> - <img class="w100" src="images/fig16.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 16.</span>—View of my arm -being sucked by <i>Anopheles maculipennis</i> (female). (From Nuttall -and Shipley.)</div> -</div> - -<p>As mentioned before, the proboscis of -the male is too weak to pierce the human -integument, but Howard notes that it will -suck up water, molasses, and beer; and Gray, -at Santa Lucia, mentions that in that island -<i>Culex</i> had developed a marked fondness for -port wine. One particularly favourite food<span class="pagenum" id="Page_59">[Pg 59]</span> -is rose-buds covered with aphides—probably -due to the sweetened secretion which these -insects exude. The feeding is sometimes very -ravenous, so that the insects become distended, -the bright colour of blood, or coloured sap, -readily shining through the joints of their -chitinous armour.</p> - -<p>The reaction to heat and cold is that -common to many insects. During the winter -the imagines become torpid, quiescent, and -cease to worry one. With returning warmth -they become lively again, and generally wake -from their winter sleep in a state of considerable -hunger. They are insects which prefer -darkness to light, and during the day-time -congregate in caverns and grottos, under the -shade of trees and bushes, beneath bridges, -in barns, and so on. As the sun sinks they -emerge from their hiding-places and fly during -the night.</p> - -<p>Cambon, writing on <i>A. maculipennis</i> found -in the Roman Campagna, says that imagines -‘appear a few minutes after sunset and -disappear a few minutes before sunrise.’ We -were able to confirm this at Cambridge. The -insects retired into the shadiest parts of the -boxes in which they were living until the -time of sunset, when a loud buzzing was -heard, and the insects promptly fed on the -food which they had neglected during the<span class="pagenum" id="Page_60">[Pg 60]</span> -day. We kept our tame mosquitos in a -huge gauze tent, and at night they invariably -accumulated on the side which was illuminated -by a lamp. Such mosquitos as were kept -in a glass lamp-chimney, closed with gauze -at each end, invariably flew towards the end -which was held towards the light. People -who are experienced with mosquitos sometimes -keep the room in which they are sleeping -dark and place a light in an adjoining room, -leaving the door ajar, and thus lure them away. -It seems a curious thing that, while these -insects are repelled by the diffused light of -the sun, they are attracted by the more -concentrated light of a lamp or candle, but -such is the psychology of <i>Anopheles</i>.</p> - -<p>It is not perhaps solely the influence of -light; it may be the influence of colour; -for light is very rarely entirely colourless. -In the many experiments carried on in Cambridge -on the natural history of the mosquito, -<i>A. maculipennis</i>, not the least interesting -were those directed to ascertaining the insect’s -preference for colour. It had been noticed -by many observers that they frequented dark-coloured -areas rather than light: for instance, -note how few mosquitos there are on the -white collar of the gentleman in the Frontispiece -compared with the number on his dark -head and coat. Austen had pointed out that<span class="pagenum" id="Page_61">[Pg 61]</span> -in a room with a dark dado it was on the -dado that the mosquitos were found rather -than on the whitened walls above. Buchanan -noted that the men when collecting <i>Anopheles</i> -in an Indian hospital found they were to be -most easily got by hanging up a dark -coat or two upon the walls. A white coat -they always avoided. The proverbial yellow -dog of the West is much less bitten than the -Newfoundland, and persons wearing dark socks -and black shoes are more bitten than those -who wear light ones. Natives, although they -suffer less in health having acquired a certain -immunity, are undoubtedly more bitten than -the Europeans.</p> - -<p>The experiments we carried on at Cambridge -were as follows: In the large gauze -cubical tent in which the mosquitos were -bred and kept, a number of pasteboard -boxes without lids, measuring 20 by 16 by -10 cm., were piled up. The boxes were lined -with seventeen different coloured cloths, and -were placed in rows one above another, and -the order was changed each day, so that no -question of height from the floor or better -illumination entered into the problem. Counts -were made of the inhabitants of each box on -each of seventeen consecutive days, with the -following results:—</p> - -<p><span class="pagenum" id="Page_62">[Pg 62]</span></p> - - -<table class="standard" summary=""> -<tr> -<th class="tdl">Colour of box</th> -<th class="tdr">Average number<br />of mosquitos<br />in each box.</th> -</tr> -<tr> -<td class="tdl">Navy blue</td> -<td class="tdr">108</td> -</tr> -<tr> -<td class="tdl">Dark red</td> -<td class="tdr">90</td> -</tr> -<tr> -<td class="tdl">Brown (reddish)</td> -<td class="tdr">81</td> -</tr> -<tr> -<td class="tdl">Scarlet</td> -<td class="tdr">59</td> -</tr> -<tr> -<td class="tdl">Black</td> -<td class="tdr">49</td> -</tr> -<tr> -<td class="tdl">Slate grey</td> -<td class="tdr">31</td> -</tr> -<tr> -<td class="tdl">Dark green (olive)</td> -<td class="tdr">24</td> -</tr> -<tr> -<td class="tdl">Violet</td> -<td class="tdr">18</td> -</tr> -<tr> -<td class="tdl">Leaf green</td> -<td class="tdr">17</td> -</tr> -<tr> -<td class="tdl">Blue</td> -<td class="tdr">14</td> -</tr> -<tr> -<td class="tdl">Pearl grey</td> -<td class="tdr">9</td> -</tr> -<tr> -<td class="tdl">Pale green</td> -<td class="tdr">4</td> -</tr> -<tr> -<td class="tdl">Light blue (forget-me-not)</td> -<td class="tdr">3</td> -</tr> -<tr> -<td class="tdl">Ochre</td> -<td class="tdr">2</td> -</tr> -<tr> -<td class="tdl">White</td> -<td class="tdr">2</td> -</tr> -<tr> -<td class="tdl">Orange</td> -<td class="tdr">1</td> -</tr> -<tr> -<td class="tdl">Yellow</td> -<td class="tdr">0</td> -</tr> -<tr> -<td></td> -<td class="tdr">———</td> -</tr> -<tr> -<td class="tdc">Total</td> -<td class="tdr">512</td> -</tr> -</table> - - -<p>It will be noted that about the level of -the pearl grey there was a marked drop. -Pale green and pale light blue, ochre, white, -orange, and yellow—especially the last two -colours—seem positively to repel the insect. -Our khaki-clothed soldiers have other advantages -than invisibility to the foe. This -matter is worth pursuing farther, and it -might be possible to design mosquito-traps -lined with navy-blue; by periodically exposing <span class="pagenum" id="Page_63">[Pg 63]</span> -them to chloroform or benzine, or by -sweeping out the contents, considerable numbers -of mosquitos might be destroyed. A dark -blue, sticky solution might be even more -effective. After reading this chapter in the -<i>British Medical Journal</i>, Mr. J. Cropper of -Chepstow wrote to me as follows:—</p> - -<div class="blockquote"> - -<p>Seeing your article on Colour Selection by <i>Anopheles</i> -reminds me that I found the dark navy-blue -lining of my tent this summer (in Palestine) -extremely attractive to mosquitos, almost entirely -<i>Anopheles</i>; and when the sun got hot I always -noticed an increase in their numbers, presumably -as they came from the herbage and trees near by. -No one ever slept in the tent, and I never found -<i>Anopheles</i> bite in the day-time.</p> -</div> - -<p>The best way of ‘downing’ mosquitos -is to prevent the imago hatching, and this, -as has been indicated, can be done by killing -the larvae and the pupae, which is effected -by brushing oil on the water in which they -live. The petrol or crude mineral oil should -be renewed from time to time as it evaporates. -When once the mosquitos are hatched, every -effort should be made to keep them outside -dwelling-houses by means of wire screens, -but if that be impracticable mosquito-nets -should be used at nights. Professor Lefroy recommends -one with sixteen to eighteen meshes -‘to the inch.’ They may be driven away from<span class="pagenum" id="Page_64">[Pg 64]</span> -a room by burning pyrethum powder in it, -or vaporising cresol or carbolic acid, but of -course this must only be done when a window -is open, through which they can escape. -As regards the human body, mosquitos may -to some extent be kept away by smearing -the skin with the various essential oils—such -as eucalyptus oil or lemon-grass oil, &c. -Mosquitos not infrequently bite through the -socks, but wearing two pairs of socks instead -of one pair, or inserting paper under the socks, -often prevents their reaching the skin, as the -proboscis is not long enough to penetrate two -woollen socks, or strong enough to pierce the -paper.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_65">[Pg 65]</span></p> - -<h2 class="nobreak" id="CHAPTER_VI">CHAPTER VI<br /> - -<small>THE MOSQUITO (<i>Anopheles maculipennis</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part III</span></p> - -<div class="poetry-container"> -<div class="poetry"> -<div class="stanza"> -<div class="verse indent0">The tiny-trumpeting gnat can break our dream</div> -<div class="verse indent0">When sweetest.</div> -<div class="verse indent10">(<span class="smcap">Tennyson.</span>)</div> -</div></div></div> - - -<p>It is now pretty well accepted that the auditory -organs of the mosquito are situated in the -antennae. Sixty years ago Johnston of Baltimore -was investigating the hearing-apparatus of -a gnat, and came to the conclusion that—</p> - -<div class="blockquote"> - -<p>The animal may judge of the <i>intensity</i> or <i>distance</i> -of the source of sound by the <i>quantity</i> of the impression; -of the <i>pitch</i>, or <i>quality</i>, by the consonance -of particular whorls of stiff hairs, according -to their lengths; and of the <i>direction</i> in which the -modulations travel, by the manner in which they -strike upon the <i>antennae</i>, or may be made to meet -either <i>antenna</i>, in consequence of an opposite movement -of that part. That the male should be endowed -with superior acuteness of the sense of hearing -appears from the fact that he must seek the female -for sexual union either in the dim twilight or in the -dark night, when nothing save her sharp humming -noise can serve him as a guide.</p></div> - -<p><span class="pagenum" id="Page_66">[Pg 66]</span></p> - -<div class="figcenter illowp70" id="fig17" style="max-width: 50em;"> - <img class="w100" src="images/fig17.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 17.</span>—<span -class="allsmcap">A</span>, <i>Anopheles maculipennis</i>, male, showing -large, feathered antennae. <span class="allsmcap">B</span>, Head of -female, showing antennae with feathering little developed. (From -Nuttall and Shipley.)</div> -</div> - -<p>Johnston also notes that the male mosquito -is the more difficult to catch. The bushy, -complicated antennae of the male show that -of the two sexes, with the mosquito, as with<span class="pagenum" id="Page_67">[Pg 67]</span> -man, the male is primarily the hearer, the -one who has to listen.</p> - -<p>Another American, Mayer, twenty years -later made some interesting experiments confirming -the views held by Johnston. He managed -to cement with shellac a species of <i>Culex</i> -on to a glass slide, and, placing it beneath a -low-powered microscope, watched the response -of the antennae to tuning-forks of varying -strengths. He found that under the influence -of a fork producing 512 vibrations per second -certain hairs of the antennae vigorously -vibrated, whilst others were left unmoved. -He measured the amplitudes of the vibrations -of these hairs under the influence of the -sound emitted by various tuning-forks. Different -hairs were seen to vibrate to different -notes. Mayer also observed that when the -sound came from a direction in line with the -long axis of the antennary hair vibrations -ceased altogether. Hence he argued that the -antennae could register the direction whence -the sound came. Observing the antennae -under the microscope, he confirmed the view -that the vibrations ceased when the hairs -pointed towards the source of sound, and on -drawing a line in the direction in which the hair -pointed, he found that it always cut within 5° -of the position of the source of sound. He -concludes:—</p> - -<p><span class="pagenum" id="Page_68">[Pg 68]</span></p> - -<div class="blockquote"> - -<p>The song of the female vibrates the fibrillae -of one of the antennae more forcibly than those -of the other. The insect spreads the angle between -his antennae, and thus, as I have observed, brings -the fibrillae, situated within the angle formed by -the antennae, in a direction approximately parallel -to the axis of the body. The mosquito now turns -his body in the direction of that antenna whose -fibrils are most affected, and thus gives greater -intensity to the vibrations of the fibrils of the other -antenna. When he has thus brought the vibrations -of the antennae to equality of intensity he has placed -his body in the direction of the radiation of the sound, -and he directs his flight accordingly, and from my -experiments it would appear that he can thus guide -himself to within 5° of the direction of the female.</p> -</div> - -<p>There has always been some divergence -of opinion as to how the buzzing sound to -which the male so readily reacts is produced. -Howard once thought that it was due to vibrations -of certain chitinous processes in the large -tracheae. Our experiments showed, however, -that when the wing was cut off closer and -closer to its origin the sound decreased in -volume, but the note progressively rose. Unlike -human beings, the male at all times emits -a higher pitched note than the female, and in -both sexes the note rises after feeding. ‘The -greater the meal, the higher the note.’ This -is, however, by no means confined to mosquitos. -It is a matter which any one must have noticed<span class="pagenum" id="Page_69">[Pg 69]</span> -when assisting at a public dinner or when dining -in a college hall.</p> - -<p>Three unfed females gave a note of from -240 to 270 vibrations. One unfed female -gave an abnormally low note of about 175 -vibrations. Four other females, which were -arranged in the order of the distension of the -abdomen, after food gave notes corresponding -to 264-281-297-317 vibrations; whereas -three unfed males all gave exactly the same -note corresponding to 880 vibrations. The -explanation of the higher note of the males is -probably that their wings are markedly narrower -and shorter than those of the females.</p> - -<p>Whilst working at <i>Anopheles</i> the late Mr. -Edwin Wilson, the artist who was drawing -our plates, observed at the base of the wing -a structure which may possibly account for -the tone which is so characteristic a feature -of the buzzing. The articulation of the wing -with the body is extremely complex. There -seems to be a series of structures like minute -knuckle-bones articulated with one another, -and at the outer end of the series are two -ribbed rods which may play some part in the -production of the overtones. One is a chitinous -bar with some fourteen or fifteen well-marked -ridges. In certain circumstances we consider -that the other toothed rod can rasp across -the ridges of the bar below it. As the wing is<span class="pagenum" id="Page_70">[Pg 70]</span> -raised and lowered it seems probable that the -slightly movable rod would be drawn across -the ridged bar.</p> - - -<div class="figcenter illowp68" id="fig18" style="max-width: 62.5em;"> - <img class="w100" src="images/fig18.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 18.</span>—<span -class="allsmcap">B</span>, Right half of thorax of <i>Anopheles -maculipennis</i>, Meig, with base of right wing and right halter, -magnified about 30. <span class="allsmcap">A</span>, The same magnified -about 5, to show the area which bears the stridulator. <i>tb</i>, -The teeth which rasp on the ridges borne by <i>bl</i>; <i>kn</i>, -papillae on knob; <i>h</i>, distal end of halter; <i>scl</i>, chitinous -thickenings. (From Shipley and Wilson.)</div> -</div> - -<p>We have mentioned above that the mosquito’s -note increased in pitch as the wings -were shortened until a very short stump was -left. As long as these stumps were left a -note was heard, and these stumps would -undoubtedly include the apparatus just<span class="pagenum" id="Page_71">[Pg 71]</span> -described, for it is next and nighest the -insertion of the wing into the body. But -Dr. Nuttall found that when this short -stump was removed all perceptible sound -ceased, which is certainly an argument in -favour of these rods and bars playing some -part in the production of the buzzing, and -in opposition to the view of Howard and -others that the buzzing is caused by certain -chitinous structures in the tracheae.</p> - -<p>M. J. Perez<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">[7]</a> has carefully gone into the -question of the production of sound in the -Diptera. He claims to have shown experimentally -that the stigmata take no part in -the production of sound. ‘Les causes du -bourdonnement résident certainement dans -les ailes.’ He, too, points out that if the -wings are cut short the notes become more -acute, until the <i>timbre</i> resembles that of certain -interrupters which break and make an electric -conductor. This sound we should attribute to -the stridulator described above. M. Perez definitely -states that both in the Diptera and in -the Hymenoptera the buzzing is due to two -causes: ‘L’une, les vibrations dont l’articulation -de l’aile est le siége et qui constituent -le vrai bourdonnement; l’autre, le frottement -des ailes contre l’air, effet qui modifie -plus ou moins le premier.’ The apparatus we<span class="pagenum" id="Page_72">[Pg 72]</span> -have described is, we believe, the mechanism -by means of which the first vibrations are -produced.</p> - -<p>In the same periodical M. Jousset de -Bellesme<a id="FNanchor_8" href="#Footnote_8" class="fnanchor">[8]</a> confirms the statement that both -Dipterous and Hymenopterous insects emit -two sounds—one deep and one acute, and -states that the latter is usually the octave -of the former. It is this double note which -gives rise to the peculiar buzzing associated -with these two orders of insects. M. de -Bellesme, like M. Perez, discards the view that -acute sounds are due to any action of the -issuing air in the stigmata, and attributes -it to the vibrations of the pieces of the thorax -which support the wing, and which are moved -by the muscles of flight. It is usually stated -that these muscles are not inserted into the -wing, but into the sides of the thorax, to -which the wing is so attached that when the -lateral walls of this part of the body are -deformed by the action of the muscles the -wings move up and down. But whether this -be the case or not, it is clear that the vibrations -of the sides of the thorax caused by the -muscles of flight—and causing the vibrations -of the wing—will synchronise in number with -these wing vibrations, and will give forth the -same note. The existence of the higher note<span class="pagenum" id="Page_73">[Pg 73]</span> -—‘usually the octave’ of the one produced -by the wing vibrations—is unexplained by -this view. It is, however, easily explicable if -such a stridulating organ as we have described -at the base of the wing in <i>Anopheles maculipennis</i> -be found in other Diptera and in -Hymenopterous insects.</p> - -<p>In our paper Mr. Wilson and I thought -it well to figure the upper surface of the -halter as seen under a high magnification. -The drawing showed the hinge on which the -halter quivers—and certain basal papillae, as -Weinland<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">[9]</a> calls them. There is little doubt -that the main function of the halteres is that -of balancing and orientating the insect. They -may, however, have a secondary function; -in some flies they are known to vibrate with -extreme rapidity. It is just possible that -in these rapid vibrations the papillae of the -concave surface rubbing against those of the -convex basal plate may produce a note. As -long ago as 1764 von Gleichen-Russworm<a id="FNanchor_10" href="#Footnote_10" class="fnanchor">[10]</a> -observed that when the halteres of the common -house-fly are removed the volume of the -buzzing diminished. This, however, in all -probability is due to the diminished activity -of the wings. On the other hand, Professor -J. Stanley Gardiner informs us that he has<span class="pagenum" id="Page_74">[Pg 74]</span> -noticed that mosquitos still continue to give -forth a faint note even when their wings are -quite at rest, and this note may possibly be -caused by the halteres.</p> - -<p>The part which sound plays in the life of -the mosquito has not been very fully recognised. -Grassi says that people who are talking -are more liable to be bitten by <i>Anopheles</i> -than people who are silent—and quite properly, -we think; people are apt to talk too much, -especially in trains. Joly observes in Madagascar -that mosquitos are attracted by music. -When he played a stringed instrument the -quiescent mosquitos in his room began to -fly about, and if the windows were open -mosquitos were attracted from the outside into -his room, and he notes that mosquitos are -attracted by musicians when at work, or should -we say—at play?</p> - -<p>Two curious instances—one recorded by -Howard and the other printed in a letter -to <i>The Times</i>—of the attraction that electric -buzzings have on these insects may be given. -Mr. A. de P. Weaver, an electrical engineer, -of Jackson, Miss., U.S.A., records that, when -engaged in some experiments in harmonic -telegraphy, he observed that when the note -was raised to a certain number of vibrations -per second, all the mosquitos—not only in the -room, but from the outside—would congregate<span class="pagenum" id="Page_75">[Pg 75]</span> -near the apparatus, and were, in fact, precipitated -from the air with a quite extraordinary -force, hurling their frail bodies against the -buzzing machinery. This machinery formed, -in conjunction with sticky fly-paper, an excellent -means of capturing them. Mr. Weaver -then devised a means of electrocuting the -pests. He used a section of unpainted wire -screen mounted on a board with pins driven -through the meshes, the heads of the pins -being flush with the surface of the screen. -The bodies of the pins were then electrically -connected together, the whole forming one -electrode of the secondary coil of an induction -coil, whilst the wire screen formed the -other electrode. An alternating current of -high potential was passed, and when the note -was sounded the insects precipitated themselves -to their doom, being electrocuted the -moment they touched the apparatus.</p> - -<p>A somewhat similar story is told by Sir -Hiram Maxim in <i>The Times</i> of October 29, -1901. One of the lamps in an installation -which was put up in Saratoga Springs, New -York, hummed in an agreeable manner, and -he noticed that night after night this lamp -was covered with small insects. On closer -examination he found that they were all -mosquitos, and all males.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_76">[Pg 76]</span></p> - -<h2 class="nobreak" id="CHAPTER_VII">CHAPTER VII<br /> - -<small>THE MOSQUITO (<i>Anopheles maculipennis</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part IV</span></p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">Gnats are unnoted wheresoe’er they fly,</div> - <div class="verse indent0">But eagles gazed upon with every eye.</div> - <div class="verse indent10">(<span class="smcap">Shakespeare</span>, <i>Rape of Lucrece</i>.)</div> - </div> -</div> -</div> - - -<p>The eggs of the mosquito are deposited -in fresh water, and at first they are white, -but they very rapidly darken until they -assume a polished black appearance. Each -egg is 0·72 mm. in length, and its greatest -breadth, which is somewhere about its middle, -is 0·16 mm. The egg is boat-shaped, and -one end, as is usual in boats, is slightly deeper -and fuller than the other. The under surface -is fluted, and is marked by a minute network. -The upper surface has a coarser reticulation -which divides the surface into nearly equal -hexagonal areas. The rim of the ‘boat’ is -thickened, and these thickenings are regularly -ribbed; they extend over above the median -third of the egg, and recall the rounded float -which runs along the edge of a life-boat:<span class="pagenum" id="Page_77">[Pg 77]</span> -and indeed they serve the same purpose, -for they are composed of air-cells, and their -function is to keep the boat-shaped eggs -right side upward. Soon after the egg has -been laid it is of a greyish-black colour, but -after a certain amount of attrition an outer -membrane splits off—the membrane which has -given the egg its reticulated appearance. This -membrane scales off in fragments, and is of a -grey colour. The egg beneath it is glistening -black—as shiny and as black as patent leather.</p> - -<p>One curious fact that Professor Nuttall -and I noticed in the life-history of the egg -is that when it is drawn by capillary forces -a little way out of the water on to the leaf -of a water-plant or some other half-submerged -object, the blunt end always points -downwards. Now the blunt end is the head -end, and thus, should hatching take place -whilst the egg is suspended half in the water -and half in the air, the larva will emerge -into its proper element and not into the -atmosphere.</p> - -<div class="figcenter illowp66" id="fig19" style="max-width: 118.0625em;"> - <img class="w100" src="images/fig19.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 19.</span>—Larva and eggs -of <i>Anopheles maculipennis</i>. <span class="allsmcap">A</span>, -Egg seen from the side, × about 20; <i>fl</i>, the float. <span -class="allsmcap">B</span>, Egg seen from the upper surface, × about -20; <i>fl</i>, ridge of air-chambers, which acts as a float. <span -class="allsmcap">C</span>, Very young larval stage, × about 20; -<i>st</i>, stigma. <span class="allsmcap">D</span>, Fully grown larva, -× about 20; <i>b</i>, brush <i>ant</i>, antenna; <i>mp</i>, palp of -maxilla; <i>st</i>, stigma; <i>t</i>, tergum; <i>ap</i>, anal papillae. -<span class="allsmcap">E</span>, Flabellum or flap, which overhangs -the base of certain thoracic hairs. <span class="allsmcap">F</span>, A -palmate hair, highly magnified. (From Nuttall and Shipley.)</div> -</div> - - -<p>Like other objects floating on the surface, -the mosquito-egg slightly indents the surface. -The number of eggs seems to vary. According -to Grassi, each female deposits about one -hundred eggs, whilst Howard puts the number -as varying from forty to one hundred. -We, however, found in captivity the female<span class="pagenum" id="Page_78">[Pg 78]</span> -laid about one hundred and fifty. According -to Grassi, the eggs of <i>A. maculipennis</i> lie -side by side like the bridges of boats which -span the Rhine, whilst those of <i>A. bifurcatus</i> -arrange themselves with their ends in<span class="pagenum" id="Page_79">[Pg 79]</span> -contact, forming starlike patterns. Unlike the -eggs of the gnat (<i>Culex</i>) the eggs of <i>Anopheles</i> -do not adhere together, and the result is they -are very readily scattered by the wind. But -in sheltered places, like a laboratory aquarium, -if undisturbed, the Italian Professor found -that they tended to congregate together, as -indeed do most minute objects floating on -the surface of the water. Our observations -did not entirely confirm those of Grassi. In -Cambridge, at any rate, we found the eggs in -our aquaria always scattered. Very frequently -empty egg-shells were met with, but they too -were scattered. As a rule, in nature, the ova -are deposited in water rich with algae or -other vegetable life, and they are more frequently -in shallow than in deep water, the -temperature of shallow water being naturally -somewhat higher.</p> - -<p>On the second or third day after oviposition -(and this depends upon the temperature), -the young larva leaves the egg and -begins to swim in the water. The egg hatches -by the detachment of a cap-like portion of -the anterior end of the egg-shell. There is -no visible ring indicating the limits of this -operculum, but the cap is usually more or -less of the same size. Opinions differ as to -how far desiccation interferes with development -of the larva in the egg-shell. They do<span class="pagenum" id="Page_80">[Pg 80]</span> -not seem to be able to stand more than forty-eight -hours of drought. There is no evidence -that they can survive throughout the winter -period. Everything that we know indicates -that the egg must pass this period within the -mother’s body, and that they only attain -maturity in early spring, when the weather -becomes warmer.</p> - -<p>The larva of the mosquito is one of -the most fascinating objects one can watch -under the microscope. It is very complex, -and consists of the usual arthropod regions -of (1) the head, (2) the thorax, and (3) the -abdomen.</p> - -<div class="figcenter illowp90" id="fig20" style="max-width: 62.5em;"> - <img class="w100" src="images/fig20.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 20.</span>—Side view of -head of a fully grown larva of <i>Anopheles maculipennis</i>. <i>b</i>, -Brush; <i>c</i>, antenna; <i>d</i>, palp of maxilla; <i>m</i>, hooked -hairs at edge of maxilla; <i>p</i>, median tuft of hairs; <i>r</i>, -thickened rim of chitinous covering to head; <i>s</i>, large, feathered -hairs which overhang head; <i>t</i>, mandible; <i>u</i>, larval eye; -<i>v</i>, eye of adult, forming above and behind <i>u</i>. (From -Nuttall and Shipley.)</div> -</div> - -<p>Without going into the question of how -many typical somites make up the head, -we must state that the thorax has the typical -number of three, much fused together, and -the abdomen nine. The first seven of these -are very much alike; the eighth, however, -bears the large stigmata or orifices of the -breathing system, and the ninth a number -of beautifully arranged hairs, by means of -which the larva to a great extent steers -itself. The head resembles two-thirds of a -sphere, and is covered with a complete and -clearly defined brown, chitinous case. The -eyes are lateral, and on each side we have -both a simple and a compound eye. In front -of each eye is a little protuberance, which<span class="pagenum" id="Page_81">[Pg 81]</span> -carries the antenna, and between these two -eminences a band of pigment runs across -the head, from which six symmetrically placed -immovable feathered hairs project, wreathing -the head, as it were, with a halo. There are -many other hairs on the head, whose number -and shape are of great systematic importance. -The anterior edge of the head carries on each -side of its under surface a conspicuous brush, -very like a shaving-brush, the constituent -hairs of which are arranged in a spiral, and<span class="pagenum" id="Page_82">[Pg 82]</span> -it is these brushes which sweep the food -into the mouth of the young and voracious -larva. The base of this brush is so arranged -that when depressed and bent towards the -mouth the two brushes approximate, but -each brush can move independently and -often does so: one may be depressed towards -the mouth, whilst the other remains erect.</p> - -<div class="figcenter illowp94" id="fig21" style="max-width: 75em;"> - <img class="w100" src="images/fig21.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 21.</span>—Ventral view of head of a fully grown larva of -<i>Anopheles maculipennis</i>. <i>b</i>, Brush; <i>c</i>, antenna; <i>d</i>, palp of -maxilla; <i>j</i>, stout hairs of mandible, which arrange the brush; -<i>k</i>, teeth of mandible; <i>m</i>, hooked hairs at edge of maxilla; -<i>p</i>, median tuft of hairs; <i>q</i>, the ‘underlip’ of Meinert, or -metastoma; <i>r</i>, thickened rim which passes into the soft -tissues of the neck. (From Nuttall and Shipley.)</div> -</div> - - -<p>The larva passes its life hanging on to -the under surface of the surface-film of the -water, its dorsal surface being uppermost. -In fact, as Sidney Smith pointed out about<span class="pagenum" id="Page_83">[Pg 83]</span> -the sloth, ‘it passes its life in a state of -suspense, like a young curate distantly related -to a bishop.’ But, since these larvae -feed on any kind of organic débris that floats -up to the top and is there arrested by the -surface-film, it is obviously important that -the brushes which sweep together these -organic particles and carry them to the -mouth should be next the surface, and to -effect this the head must rotate through an -angle of 180°; and the head does in fact -turn upside-down on the neck so sharply and -accurately that, as it comes into position, you -almost think, as you are watching it, that you -hear a click, just as you do when you rotate the -diaphragm of a microscope.</p> - -<p>The mouth parts now begin to vibrate upwards -and forwards, and the brushes are bent -downwards, backwards, and inwards. Round -the mouth is a small space, the walls of which -are completed by the mandibles, and into -this space the brushes are suddenly bent -back, at the same time the mandibles and -maxillae move forward to meet them. This -movement may take place as many as 180 -times a minute, and it produces a current -converging in concentric curves towards the -above-mentioned chamber. The water filters -out between the sides, and any particle of -food is retained by the hairs or by the mouth -appendages; from time to time the mandibles<span class="pagenum" id="Page_84">[Pg 84]</span> -are brought together, and their stiff bristles -are run through the brushes as one’s fingers -run through a beard;<a id="FNanchor_11" href="#Footnote_11" class="fnanchor">[11]</a> at other times the -brushes disappear far into the mouth, and -then are slowly withdrawn, passing through -the comb-like bristles on the mandibles. The -brushes are frequently swallowed, and are -withdrawn in little jerks, so that the maxillae -have every opportunity of combing any -nutritive particles out of them. The whole -operation is a most fascinating one to watch.</p> - -<p>As far as one can judge, the currents set -in motion by the action of all these forces -extend in an area equal to twice the length -of the larva, or even more. The currents -are in the plane just below the surface-film, -and any organic matter lighter than water -is swept towards the mouth. In fact the -larva sweeps the lower side of the surface-film -of the pond or puddle just as a careful housemaid -might sweep spiders and flies off a ceiling -with a hand-brush.</p> - -<p>The principal food-supply of the larva -consists of the spores of fresh-water algae, -diatoms, particles of <i>Spirogyra</i>, and any other -organisms which do not penetrate the surface-film. -Occasionally the larvae devour the decaying -leaves of duck-weed (<i>Lemna</i>), and sometimes -they attack their dead fellows.</p> - -<p>Grassi found the intestine of the larva<span class="pagenum" id="Page_85">[Pg 85]</span> -to contain protozoa, unicellular algae, and -other organic detritus. In course of time -some object too big for the larva to swallow -is brought to its mouth by the currents, but -after a very short struggle this is rejected. -The minuter particles accumulate in the -chamber for a certain time, and then are -swallowed by a gulp-like motion and thus -pass into the oesophagus.</p> - -<div class="figcenter illowp74" id="fig22" style="max-width: 75em;"> - <img class="w100" src="images/fig22.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 22.</span>—A comparison -between the various stages in the life-history of the mosquito -(<i>Anopheles</i>), on the left, and the gnat (<i>Culex</i>), on the -right. (<small>including Imago, Pupa, Larva and Ova</small>)</div> -</div> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_86">[Pg 86]</span></p> - -<h2 class="nobreak" id="CHAPTER_VIII">CHAPTER VIII<br /> - -<small>THE MOSQUITO (<i>Anopheles maculipennis</i>)</small></h2></div> - -<p class="center"><span class="smcap">Part V</span></p> - -<div class="blockquote"> - -<p>Amongst aquatic larvae, the most beautiful and delicate -are those of numerous species of gnat.—(<span class="smcap">Goring and Pritchard’s</span> -<i>Micrographia</i>, 1837.)</p> -</div> - - -<p>In the young larva of <i>Anopheles</i> the head -is broader and deeper than the thorax, but -in the older larvae the segments that succeed -the head have at least twice its diameter. -It is a characteristic of true flies, or Diptera, -that the thorax should not exhibit that -separation into three divisions which is so -usual in the less specialised insects—such as -the cockroach and this is peculiarly true -of the larva of the mosquito—at any rate, -so far as its external structure goes. The -abdomen of the larva consists of nine free -segments; the third, fourth, fifth, sixth, and -seventh of these bear palmate hairs on the -dorsal or upper surface, something like -hands with fourteen ‘fingers’ spread out. -These hairs adhere to the under layer of the<span class="pagenum" id="Page_87">[Pg 87]</span> -surface-film of the water, and help to maintain -the animal in a horizontal position just below -that film. When the larva relaxes its hold and -sinks into the water, it not infrequently -carries with it air-bubbles enclosed by these -fourteen ‘fingers.’</p> - -<p>The eighth abdominal segment bears the -stigmata or the openings of the respiratory -apparatus, and the ninth segment has abandoned -the flattened and square cross-section -of its predecessors, and is cylindrical and -tapering. The posterior end of the body is -cut off sharply. Round the posterior opening -of the alimentary canal are four white, soft -papillae, which are well supplied with tracheae -and are capable of contracting and expanding. -Above these are four very prominent hairs, -two median and two lateral, and ventrally -to the ninth abdominal segment is a fan-shaped -arrangement of hairs springing from -two pieces of very complicated structures. -These hairs seem to act to some extent as -a rudder, and they probably serve as an -accessory organ of locomotion. Possibly they -have also a sensory or tactile function, and -act, as so many posterior filaments do in -insects, as antennae ‘from behind.’</p> - -<p>We have referred above to the respiratory -openings, and, indeed, these are the key to -the whole situation. Close these openings—<span class="pagenum" id="Page_88">[Pg 88]</span> -as they can be closed by floating petrol or -other oil on the surface of the water—and -‘the trick is done.’ The larvae and the -pupae can no longer breathe, and there is thus -no imago to “carry on.” In <i>Culex</i> (the gnat), -these respiratory orifices are borne on a long -tube directing dorsalwards—a tube which is -larger and longer than a segment of the body, -and whose presence gives the larva the appearance -of a <b>Y</b> with slightly unequal limbs. -These breathing-openings are of the greatest -complexity, but the outstanding fact is that -these stigmata pierce through the watery -film and put the respiratory system of the -larva into communication with the atmosphere -of the whole cosmos. If anything frightens -the larva, certain side-pieces and flaps fold -suddenly backwards and over the stigmata, -the connexion through the surface-film is -broken, and the little larva, like a German -submarine when it sights an English battleship, -darts below, frequently carrying with -it the drop of air attached to the rim of the -respiratory recess which surrounds the openings -of the two stigmata.</p> - -<p>Not infrequently the larva ceases to lie -parallel to the surface of the water, its -palmate hairs are put out of action, and then -its body hangs down into the water, but it -still maintains its respiratory connexion with<span class="pagenum" id="Page_89">[Pg 89]</span> -the outer air through these breathing-pores. -From time to time the hairs mentioned above -are brushed over by the mouth parts and -cleaned of any débris.</p> - -<p>The larvae, when they leave the surface-film -sink by their own weight; but they not -infrequently swim actively downwards, their -swimming action being very like that of an -eel. When returning to the surface they are -entirely dependent upon their powers of -swimming, being slightly heavier than water. -When the tail reaches the surface-film the -larvae are at once arrested, and immediately -cease their swimming-movements. They invariably -move tail forwards, and the hairs -which we have mentioned above at the posterior -end of the body undoubtedly act as ‘buffers’ -or ‘fenders.’ As a rule, when they are above, -they are actively engaged in feeding; but at -the bottom they lay inert, as though feigning -to be dead. Kept in a glass beaker they are -apt to lie with their respiratory apparatus -attached to the concave film, which capillary -attraction draws up on the surface of the -glass. Their heads then point towards the -surface of the beaker. If forcibly kept below—say, -by submerging them under a watch-glass—they -are frequently enabled to breathe by -attaching the openings of their respiratory -apparatus to an air-bubble.</p> - -<p><span class="pagenum" id="Page_90">[Pg 90]</span></p> - -<p>The general colour of the larva is a mottled -brown, darkening where the chitin thickens. -The older larvae are to some extent green, -possibly due to their food; but this green -colour is not by any means confined to the -alimentary tract. After moulting, the issuing -larva is a uniform light lavender colour, -which, however, very soon darkens.</p> - -<p>A strong wind passing over a pool where -<i>Anopheles</i> eggs, larvae, or pupae are floating, -will gradually pile them all up on the side -towards which it is blowing. The <i>Anopheles</i> -larvae undoubtedly are braver than those -of the <i>Culex</i>—that is to say, a disturbance -which will send all the <i>Culex</i> larvae scurrying -to the bottom will leave the <i>Anopheles</i> larvae -unmoved.</p> - -<p>When first hatched the larvae measure -somewhere about 0·7 mm. to 0·95 mm., but -when ready to pupate they have attained -the length of 7 mm. The rate of development -is greatly influenced by the temperature, and -a few cold days will markedly retard the -larval growth. In warm sunny weather, larvae -will pupate between the second and third -week, but larvae taken in August (if the -autumn be cold) do not attain their full -growth until November. The young larvae -undoubtedly die in considerable numbers, and -the act of pupating is also attended with<span class="pagenum" id="Page_91">[Pg 91]</span> -certain and varying dangers. Out of 834 -larvae and pupae caught in Cambridgeshire, -636 were small larvae, measuring less than -4 mm.; 181 were large larvae, measuring -up to 7 mm. But only 17 pupae were taken. -There are other facts -which show that the -larvae under natural -conditions succumb -in very considerable -numbers.</p> - -<div class="figright illowp50" id="fig23" style="max-width: 37.5em;"> - <img src="images/fig23.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 23.</span>—Side view -of late pupal stage of <i>Anopheles maculipennis</i>. <i>f</i>, The -stigma opening at end of trumpet-like projections. (From Nuttall and -Shipley.)</div> -</div> - -<p>When the larva -is about to turn into -a pupa it comes to -rest, and now the -thoracic regions are -more swollen than -ever. Soon a dorsal -slit appears along -the larval cuticle -and the pupa slowly, but gradually, emerges -through this slit and leaves the larval chitinous -cuticle behind it. On first emerging, the -pupa measures about 6·5 mm., the head and -thorax making up one-third of this. During -the last larval stage many of the pupal organs -have been re-forming and are more or less -visible through the cuticle. The mouth parts -and limbs of the third stage—the future -imago—show no relation to those of the<span class="pagenum" id="Page_92">[Pg 92]</span> -larva. They are there enclosed in their respective -sheaths, but these are quite independent -of the larval ‘appendages.’ The respiratory -trumpets, which, as in the larva, pierce the -surface-film, are ready to act as breathing-organs. -Whereas the larvae breathe through -two stigmata at the posterior end of the -abdomen, the pupae breathe through two -respiratory trumpets issuing from the anterior -dorsal surface, and it is these trumpets, together -with certain palmate hairs, which -support the pupae in the right position and -put the respiratory organs at this stage -into communication with the outer atmosphere. -During the pupa stage <i>Anopheles</i>, like the -pupa of other insects, takes no food.</p> - -<p>The pupa is something like a tadpole, -with its tail bent under its body and flapping -up and down, instead of from side to side. -The whole pupa is enclosed in a thin semitransparent -membrane, through which the -organs of the adult can readily be seen. As -it grows older its colour darkens. Until about -the time when it will give rise to the fly, the -pupa floats quietly at the surface, breathing -through its respiratory trumpets. When disturbed -it shows considerable activity, and -it is by no means always easy to capture -by means of a pipette. At the least sign -of danger it darts below with a series of inter<span class="pagenum" id="Page_93">[Pg 93]</span>mittent -strokes and rests at the bottom of -the water. Its own buoyancy brings it back -to the surface, as, unlike the larva, it is lighter -than water. Not only has it a certain amount -of air in its tracheae, but there is a reservoir -of air at the posterior end of the thorax -which acts as a very efficient float. When -retreating below the surface the respiratory -trumpets usually carry down with them two -minute air-bubbles.</p> - -<div class="figcenter illowp100" id="fig24" style="max-width: 62.5em;"> - <img class="w100" src="images/fig24.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 24.</span>—<span -class="allsmcap">A</span>, Side view, <span class="allsmcap">B</span>, -ventral view, of the pupa of a male <i>Anopheles maculipennis</i>; -<span class="allsmcap">C</span> and <span class="allsmcap">D</span>, -the same views of the female pupa.</div> -</div> - -<p>The sex of the pupa can be determined -by the lobes at the posterior end of the tail: -<span class="allsmcap">A</span> and <span class="allsmcap">B</span> (Fig. 24) representing the male, and -<span class="allsmcap">C</span> and <span class="allsmcap">D</span> the corresponding parts of the female. -The duration of the pupal life is generally -three to four days, but conditions of temperature -and the state of the natural surroundings -exert considerable influence upon the rate<span class="pagenum" id="Page_94">[Pg 94]</span> -of development. Howard has pointed out -that the addition of creosote or creosote-oil -to the water in which the larvae are living -hastens the metamorphosis into pupae, and -the pupa stage is passed through in as short -a time as fifteen hours instead of the normal -forty-eight hours of the warm waters of -the Southern States in America. It has also -been observed that showery weather hastens -the rate of development.</p> - -<p>When the adult mosquito is about to -emerge, a certain amount of air is secreted -under the chitinous casing of the pupa. A fine -streak containing air appears along the back, -extending between the respiratory trumpets -and the base of the head. This central streak -gradually passes backwards until it reaches -the seventh abdominal segment, and then -suddenly the pupa extends its abdomen so -that it floats parallel to the surface of the -water instead of being under the rest of the -pupa’s body. The chitinous integument now -splits along the median dorsal line, and through -the slit thus made the thorax of the adult -mosquito now protrudes. By gradually pressing -its abdomen against the pupa-case, the body -of the perfect insect is slowly but gradually -raised above the surface of the water. The -head is pulled backwards and upwards, and -millimetre by millimetre the mouth parts, the<span class="pagenum" id="Page_95">[Pg 95]</span> -palps, and antennae are withdrawn, and at first -remain bent backwards beneath the body of -the insect. Gradually the bases of the wings -and the abdomen emerge, and soon the wings -are freed and immediately flatten out and -begin to harden. The legs and the tip of -the abdomen alone -now remain to be -dealt with. At -this stage the insect -projects far -beyond the anterior -end of the -pupa encasement, -and somewhat -resembles an exaggerated -figurehead -on a ship. -The pupa-case is -still filled with air, -and acts as a float to support the emerging -insect. At last the front legs are being -freed, the second and third pair of legs soon -follow, and now the insect is standing on -the surface of the water raised on its tarsal -joints, the tip of the abdomen being the last -part to free itself from the pupa-case.</p> - -<div class="figright illowp50" id="fig25" style="max-width: 43.6875em;"> - <img src="images/fig25.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 25.</span>—Imago of a -mosquito extracting itself from the pupa-case, which floats on the -surface of the water. Magnified. (From Guiart.)</div> -</div> - -<p>The exit of the fly is naturally a very -critical period in its life-history, and in many -cases it is fatal. The freeing process takes<span class="pagenum" id="Page_96">[Pg 96]</span> -between five and ten minutes. When undisturbed -the emergent fly rests for a time -until its wings and limbs are sufficiently -hardened to enable it to fly, or at least to -walk about. Sometimes the mosquito takes -its first flight straight from the pupa-case; -at other times it rests awhile before taking -to the air. The young imago is pale in colour, -the thorax being brown and the abdomen -transparent, with a greenish tinge. At first -the abdomen is much longer than it is later, for, -almost immediately after the mosquito’s exit -from the pupa-case its abdomen begins to -contract, and from its hinder end four or five -drops of a glistening, greenish-white fluid are -exuded.</p> - -<p>The newly born imagines generally take to -flight between five and ten minutes after -they have emerged, and they at once begin -to darken in colour, and in two hours assume -the normal dusky colour of the adult. If -anything hinders the insect from properly -extending its limbs immediately on issuing -from the pupa-case, the parts harden and -remain distorted throughout life.</p> - -<hr class="tb" /> - -<p>Anyone who has spent a day or two in -Lille or Bruges, or other towns in Picardy -and in Southern Belgium, will understand -why, as my Uncle Toby has it, ‘Our army<span class="pagenum" id="Page_97">[Pg 97]</span> -swore terribly in Flanders.’ The incessant -and tireless biting of mosquitos would make -any army swear, even though they were -ignorant—as my Uncle Toby’s army certainly -was ignorant—that the gnats, as they called -them, conveyed tertian and quartan ague. -In Europe the trouble is a summer or early -autumn trouble; but our troops are fighting -in many tropical and sub-tropical countries, -where the mosquitos—like the poor—are -always with them.</p> - -<p>That the plague can now be checked is -shown by the making of the Panama Canal; -and that this check is due to British science -is shown by the work on the life-history of -the malarial organism, first investigated by Sir -Ronald Ross, and later, as regards the human -parasites, by certain Italian savants. It is also -due to the public health services of one or two -British medical officers of health in the East. -<i>Their</i> methods have been applied and improved -by those responsible for the elusive channel -which now at times separates North from -South America.</p> - -<p>We have seen that the larva and the pupa -hang on to the surface-film of the water by -means of certain suspensory hairs, and by -the openings of their breathing-apparatus. -Anything which prevents the breathing-tubes -reaching the air ensures the death of the<span class="pagenum" id="Page_98">[Pg 98]</span> -larva and pupa, and then there is no issuing -adult—hence the use of paraffin on the -pools or breeding-places. It, or any other -oily fluid, spreads as a thin layer over the -surface of the pools and puddles and clogs -the respiratory-pores and the larvae or pupae -die of suffocation.</p> - -<p>In Ismailia the disease has been reduced -to an amazing extent, and remarkable results -have followed the use of these preventive -measures at Port Swettenham in the Federated -Malay States. Within two months of the -opening of the port in 1902, 41 out of 49 -of the Government quarters were infected, -and 118 out of 196 Government servants -were ill. Now, after filling up all pools and -cleaning the jungle, no single officer has -suffered from malaria since July 1904, and -the number of cases amongst the children -fell from 34·8 to 0·77 per cent. The only -melancholy feature about this wonderful alleviation -of suffering, due to the untiring efforts -of the district surgeon, Dr. Malcolm Watson, -is that his fees for attending malarial cases -dropped to zero.</p> - -<p>Thus, even ten years ago, a considerable -degree of success had attended the efforts -of the sanitary authorities—largely at the -instigation of Sir Ronald Ross—all over the -world, to diminish the mosquito-plague. It<span class="pagenum" id="Page_99">[Pg 99]</span> -is, of course, equally important to try to -destroy the parasite in man by means of -quinine. This is, however, a matter of great -difficulty. In Africa and in the East nearly -all native children are infected with malaria, -though they suffer little, and gradually acquire -a high degree of immunity. Still, they are -always a source of infection; and soldiers -stationed in malarious districts should always -place their dwellings to the windward of -the native settlements.</p> - -<p>Knowing the cause, we can now guard -against malaria; mosquito-nets and wire-protected -windows and doors are a sufficient -check on the access of <i>Anopheles</i> to man. -If the mosquito and man could only be kept -permanently apart, we might hope for the -disappearance of the parasite from our fauna. -In relieving man from this world-wide pest, -all genuine lovers of animals will rejoice that -we are also relieving the far more serious -lesions of one of the most delicate and -beautiful insects that we know.</p> - -<p>It has always been a source of surprise -to me that the great resources and the very -evident enthusiasm of the anti-vivisection -societies have not been turned in this direction. -In the malarial parasite, we have a most potent -vivisector of the entrails of one of the most -charming and graceful of creatures, whose<span class="pagenum" id="Page_100">[Pg 100]</span> -poetry of movement is hardly approached and -never equalled by the ladies of the front row of -the ballet. A little help, a very little help, -would free these fascinating flies from a form -of trouble far worse than that the human -alternative host suffers. Yet, as far as I -know, these societies and the societies for the -prevention of cruelty to animals have declined -to help in any way, and have knowingly -allowed thousands of millions of animals to -perish annually by a most painful death, and -have never stretched out a helping hand to the -fairy-like and fascinating mosquito.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_101">[Pg 101]</span></p> - -<h2 class="nobreak" id="CHAPTER_IX">CHAPTER IX<br /> - -<small>THE YELLOW-FEVER MOSQUITO (<i>Stegomyia calopus</i>)</small></h2></div> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent7">... et nova febrium</div> - <div class="verse indent0">Terris incubuit cohors.</div> - <div class="verse indent10">(<span class="smcap">Horace.</span>)</div> - </div></div></div> - -<p>Like other branches of human activity disease -has its romantic and its unromantic side. Nobody -can regard mumps or measles as romantic. -On the other hand, yellow fever calls up all -the romance of slave-trading, pirates and the -Spanish Main, buccaneers, maroonings and -other grisly horrors, whose sole redeeming -feature was a touch of romance. Lovers of -pirate stories—and who are not?—will always -remember their graphic description of Yellow -Jack in the West Indies.</p> - -<p>We have probably always had disease with -us since the creation of the world—that act -of ‘<i>impardonnable imprudence</i>,’ as Anatole -France calls it; but the first description of -yellow fever only dates back to 1647, when -an outbreak occurred in the Barbados. Then, -as now, it devastated the shipping of the port,<span class="pagenum" id="Page_102">[Pg 102]</span> -and was soon introduced by ships into St. -Christopher and, later, into Guadeloupe. The -following year it was in Cuba, and in 1655 in -Jamaica, and it gradually spread throughout -the whole of the West Indies until a century -or more later it reached the Island of St. -Thomas.</p> - -<p>One of the peculiarities of the disease is -that it frequently disappears from a given -locality for long periods of time. For instance, -it was absent in Barbados after the first -outbreak until 1690, and when it recurred it -was at first not recognised as being the same -disease which devastated the islands forty-three -years before. In the eighteenth century -there was another break of fifty-four years, -and similar breaks can be recorded in most -of the West Indian islands.</p> - -<p>Besides the West Indies, it is at present -endemic in Brazil and on the west coast of -Africa, and is common in Mexico. Whether -the disease arose primarily in Africa and is -part of the toll the American continent has -had to pay for the slave-trade, or whether it -was brought to the west coast of Africa from -the other side of the Atlantic, is not certain. -It apparently appeared as a regular disease -in Brazil in the year 1849, and from that time -onwards, with the exception of one year, has -been a permanent trouble at Rio. From time<span class="pagenum" id="Page_103">[Pg 103]</span> -to time the disease has been carried to neighbouring -parts of America, especially to the -Gulf, Central America, and the northern coast -of South America. It has been introduced -more than once into Monte Video and Buenos -Ayres, and has even penetrated up the Parana -as far as Asunçion. Every few years it extends -into the Southern States and has even -reached Philadelphia and Boston. With the -exception of an outbreak in Leghorn in 1804, -European epidemics have been confined to -Portugal, Spain, and the Balearic Islands.</p> - -<p>It will have been noticed that most of these -outbreaks occur on the coast and then pass -up the rivers. It is thus most probable -that the disease is one which is brought mainly -by ships. It is obviously a disease which -must be guarded against by our troops fighting -near the coast in West Africa, as well as such -troops as are left in the West Indies. But, above -all, it must be guarded against in relation to -our shipping fleet and our Navy, operating off -the South American coasts. The danger, -now the Panama Canal is open, of introducing -the disease from America to Asia is a danger -that should carefully be considered.</p> - -<p>Yellow fever is a disease which requires a -winter temperature of at least 68° F., for it is a -mosquito-borne disease, and the yellow-fever -mosquito flourishes best at about this tempera<span class="pagenum" id="Page_104">[Pg 104]</span>ture. -It can be introduced into a new locality -by the arrival of an infected mosquito, or by -the arrival of an infected human being. In -the former case the disease breaks out within -a few days; in the latter at least ten or twelve -days elapse before new cases arise, for, as we -shall see later, the organism, whatever it is, -that causes the fever is not capable of passing -from the mosquito until it has been in its body -for ten or twelve days.</p> - -<div class="figcenter illowp100" id="fig26" style="max-width: 62.5em;"> - <img class="w100" src="images/fig26.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 26.</span>—<i>Stegomyia -fasciata.</i> Female, lateral view (magnified.) Note hump-backed -outline, and also the position of the posterior pair of legs.</div> -</div> - -<p>Thirty-six years ago Finlay of Havana -suggested that the virus of yellow fever was -inoculated by mosquitos; but it was not until -the publication of the discoveries by Sir -Ronald Ross and others, that malaria is transferred -by A<i>nopheles</i>, that a thorough investigation -of yellow fever was made. In the last<span class="pagenum" id="Page_105">[Pg 105]</span> -year of the last century an American Commission, -consisting of Drs. Walter Reed, Carroll, Agramonte, -and Lazear, investigated the whole -subject, and, taking extraordinary risks, were -able to prove that the infection was not -conveyed by contact or through the air, or -from bedding or clothes soiled by the dejecta -of yellow-fever patients, but by a mosquito -of the genus <i>Stegomyia</i>. Whatever the virus -is, it is invisible, even under the highest powers -of the microscope. It can be filtered through -a Berkefeld filter. It is destroyed by heating -to 55° C. If the blood of a yellow fever -patient, during the first three days, be inoculated -into a healthy man he gets yellow fever, -and it is only during the first three days that -the blood is infective. On the other hand, the -mosquito is incapable of transferring the -disease until the unknown organism has been -in its own body for at least ten or twelve days.</p> - -<div class="figleft illowp50" id="fig27" style="max-width: 18.75em;"> - <img src="images/fig27.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 27.</span>—<i>Stegomyia -fasciata.</i> Above, the larvae; below, the eggs. Both natural -size.</div> -</div> - -<p>The mosquito in question belongs to the -species <i>Stegomyia calopus</i> (Blanchard), or, as -it is more often called in English textbooks, -<i>Stegomyia fasciata</i> (Fabricius). The genus -<i>Stegomyia</i> differs from other <i>Culicidae</i> in having -a dark grey or black colour, whilst the <i>Culicidae</i> -are as a rule browner. <i>Stegomyia</i> also has -silver-white spots and silver glistening scales, -especially on the back of the legs and on the -abdomen. The grown-up mosquito is com<span class="pagenum" id="Page_106">[Pg 106]</span>paratively -small, and very elegant. Its length -is some 3 to 4 mm., but if the mouth parts be -added is some 6 to 6½ mm. long. As is usual, -the male is smaller and feebler than the female. -When settled—as, for instance, whilst sucking -the blood of its host—it rests upon its first four -legs only, the two hindmost being stretched out -abaft like pennants waving -in the air; but in general -it has the hump-backed -appearance of <i>Culex</i> and not -the straight outline of -<i>Anopheles</i>. The colour is -greyish black, modified by -numerous white spots and -rings. There is a white rim -round the eyes, and a very -characteristic lyre-like -pattern on the dorsal surface of the thorax. -The structure of the mouth parts is much -the same as that of any other <i>Culicidae</i>. -The antennae have fourteen joints, the last -two of which in the male are longer than -the others. As is again usual, the antennae -of the male have long brush-like hairs, -organs by means of which they find the female. -The legs are banded alternately with white and -black rings. It is this character, indeed, which -has given this mosquito the name of the -‘tiger-gnat.’ The wings are very iridescent.</p> - -<p><span class="pagenum" id="Page_107">[Pg 107]</span></p> - -<div class="figright illowp40" id="fig28" style="max-width: 25em;"> - <img src="images/fig28.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 28.</span>—Larva of -<i>Stegomyia fasciata</i> breathing on the surface of the water. Highly -magnified.</div> -</div> - -<p>The pupa of <i>Stegomyia</i> is darker and -blacker than that of <i>Culex</i>, and, seen from the -side, the head and the thorax are somewhat -more triangular than the same parts in <i>Culex</i>. -As the pupa grows older it grows darker. -The length of the larva is 4 to 6 mm., somewhat -larger than that of the -gnat. But, like that, it -has a respiratory-tube -stretching out from the -last segment of the abdomen, -almost at right angles -to the rest of the body. -This respiratory-tube is -much shorter than that -of <i>Culex</i>, but is long enough -to enable the larva to -hang obliquely down into -the water. The eggs are -very large. They are covered by a mass -of small ‘cells’ containing air, and they never -tend to form a conglomerate mass like those -of <i>Culex</i>, but are laid singly, and remain -isolated until the larvae hatch. After floating -a certain time they usually sink to the bottom -of the water. Their length may be about a -millimetre, and their colour is almost black. -When the egg hatches, the anterior third of -the shell splits off and the larva at once -emerges.</p> - -<p><span class="pagenum" id="Page_108">[Pg 108]</span></p> - -<p>As is so often the case with mosquitos, it -is the female alone which bites. The male -nourishes itself on plant-juices, saps, and so on—especially -they like sugary secretions—and -in the absence of blood the female is reduced -to a similar diet. Hence <i>Stegomyia</i> is -comparatively common in dwellings where -sweetstuffs are—bakeries, sugar-refineries, -and so on. These mosquitos -are, like the cockroach, -the fly, and the bed-bug, inhabitants -of human dwellings. They -are indeed domesticated, and are -always to be found in the neighbourhood -of human houses or -buildings or ships, and are very -rarely indeed found far away from -the sphere of man’s activities.</p> - -<div class="figleft illowp30" id="fig29" style="max-width: 12.5em;"> - <img class="w100" src="images/fig29.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 29.</span>—Egg of <i>Stegomyia fasciata</i> -(highly magnified). Notice the air-‘cells.’.</div> -</div> - -<p>They are very apt to bite one in the neck, -creeping along the darker parts of the -clothing until an unprotected region of the -body is reached. Unless one has very thick -socks they frequently bite the ankle, and they -are as tireless in their pesterings as ever Mrs. -Pardiggle was—no sooner are they driven -away than they return to the attack. The -bite is painful, and in many people raises a -considerable swelling.</p> - -<p>The <i>Stegomyia</i> bite not only during the night, -but also during the day. According to R. O.<span class="pagenum" id="Page_109">[Pg 109]</span> -and O. Neumann—in Brazil, at any rate—they -are capable of biting not only during the twilight, -but at any times. The bite lasts twenty to thirty -seconds, after which the mosquito rests a bit, -waving its third pair of legs in the sun. After -this rest she flies away to some sheltered spot, -and whilst blood is being digested the mosquito -takes nothing but water—a very proper -dietetic measure. After three or four days -the female is ready for another meal.</p> - -<p>In the absence of man these mosquitos -will suck blood from other animals, and in -confinement they are generally fed on rats -or canaries, and they will even suck up a -drop of blood presented on a piece of cotton-wool.</p> - -<p>If the female mosquito has been fertilised -before the sucking of blood she will commence -egg-laying two or three days later, and two or -three days later again the larva will emerge. -The larval stage lasts from nine to twelve -days, and the pupa stage three to four, so that -the whole metamorphosis takes from sixteen -to twenty-two days. Hence, during warm -weather, many generations succeed each other, -but one must have a temperature of at least -20° to 27° C. Below that temperature the -processes tend to slow down, and under a -temperature near freezing-point the regular -development is definitely interrupted. But<span class="pagenum" id="Page_110">[Pg 110]</span> -the interruption is only a suspense, and living -activities are resumed should the temperature -rise again.</p> - -<p>It is a disputed point whether these mosquitos -must have a meal of blood before they -can lay eggs, and on this point the evidence is -not yet sufficient to make a dogmatic statement. -These mosquitos are very indifferent -where their eggs are laid. The smallest collection -of water in an empty sardine-tin, a broken -tumbler, a puddle in the street, a gutter-pipe, -is good enough for <i>Stegomyia calopus</i>. She will -even lay her eggs on moist cotton-wool.</p> - -<p>Although <i>Stegomyia</i> bites freely during -the day-time, it, as a rule, avoids the light -and seeks some dark shelter. Contrary to the -habits of <i>Anopheles</i>, it prefers a light ground -to rest upon. The larvae live on algae, -vegetable-matter, or plant-detritus, or, in -captivity, on white bread or Indian corn. -They can remain for a considerable time -without food, and this without materially -diminishing the rate of their development. -<i>Stegomyia</i> breeds well in ships, and is occasionally -found in one part only of the ship—such -as the engine-room or cook’s galley, where -the conditions seem to be most favourable -to its development. Thus it comes about that -at times certain quarters of a ship provide the -greatest percentage of yellow-fever cases.</p> -<hr class="chap x-ebookmaker-drop" /> - - - -<div class="chapter"> -<p><span class="pagenum" id="Page_111">[Pg 111]</span></p> - -<h2 class="nobreak" id="CHAPTER_X">CHAPTER X<br /> - - -<small>THE BISCUIT-‘WEEVIL’<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">[12]</a> - (<i>Anobium paniceum</i>)</small></h2> -</div> - -<div class="blockquote"> - -<p>‘Let us be merry,’ said Mr. Pecksniff. Here he took a captain’s -biscuit. ‘It is a poor heart that never rejoices; your hearts -are not poor. No!’—(<span class="smcap">Dickens</span>, <i>Martin Chuzzlewit</i>.)</p> -</div> - - -<p>The first things to notice about the biscuit-‘weevil,’ -so familiar to readers of Marryat’s -novels, is that it is not a weevil at all, and that -it attacks a great many other comestibles -besides biscuits. The so-called biscuit-‘weevil’ -is in truth an <i>Anobium</i>—<i>Anobium -paniceum</i>—a member of the family <i><span class="smcap">Ptinidae</span></i> -and is closely allied to <i>A. striatum</i>, which makes -the little round holes in worm-eaten furniture, -so cleverly imitated by the second-hand -furniture-dealers. Another species of <i>Anobium</i> -(recently re-christened <i>Xestobium tessellatum</i>), -a somewhat larger insect, is destructive in -churches, libraries, and old houses. Their -mysterious tappings (which are really efforts -to attract the other sex—mere flirtations) -are the cause of much superstitious dread in<span class="pagenum" id="Page_112">[Pg 112]</span> -the nervous, and this species is known as the -‘greater death-watch.’</p> - -<div class="figleft illowp40" id="fig30" style="max-width: 18.75em;"> - <img src="images/fig30.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. -30.</span>—Biscuit-‘weevil,’ <i>Anobium paniceum</i>. (From David -Sharp, <i>The Cambridge Natural History</i>, vol. vi.)</div> -</div> - -<p>But to return to the biscuit-‘weevil.’ -The mature insect is about a quarter of an inch -long, and lives at large; it is the larva which -burrows into and attacks the -dried biscuit—the ‘hard-tack’ -of the Navy. Less of a woodborer -than its allies, it nevertheless -attacks almost any vegetable -substance; and Butler tells us -that ‘rhubarb-root, ginger, -wafers, and even so unlikely a -substance as Cayenne pepper -have been greedily devoured -by it.’ Several generations -have been known to flourish -on a diet of opium, and it has -been found in tablets of compressed -meat. Vegetable matter, even in an -altered state—such as paper—affords it an -ample meal; and in one case the larva of -an <i>Anobium paniceum</i> bored steadily in a -straight line through twenty-seven folio -volumes in a public library, and so straight -was the tunnel that a string could be -passed through it from end to end. In one -of our libraries at Cambridge some Arabic -manuscripts were almost entirely destroyed -by the larvae, which do not hesitate to browse<span class="pagenum" id="Page_113">[Pg 113]</span> -on drawings and paintings and the dried -paper of herbaria.</p> - -<div class="figcenter illowp100" id="fig31" style="max-width: 75em;"> - <img src="images/fig31.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 31.</span>—Early stages -of <i>Anobium paniceum</i>. <span class="allsmcap">A</span>, Eggs, -variable in form; <span class="allsmcap">B</span>, larva; <span -class="allsmcap">C</span>, pupa; <span class="allsmcap">D</span>, -asymmetrical processes terminating body of pupa. This larva is probably -the ‘book-worm’ of librarians. (From David Sharp, <i>The Cambridge -Natural History</i>, vol. vi.)</div> -</div> - -<p>The larva of this beetle is in truth a book-worm. -Its interest for us in the present series -is, however, the disastrous infestation of ships’ -biscuits, which frequently is so severe that -the sailors ‘hard-tack’ is rendered uneatable. -Heating, of course, kills it; but the biscuits are -still uneatable. The dead larvae are as unpalatable -as the living. The contrivance of -biscuit-tins since Marryat’s time has done -much to lessen the evils. Tradition has it -that a great firm and a great fortune had -their foundations laid, during the first half of -the last century, by the accidental contiguity -of a baker’s shop and that of a tinsmith.</p> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_114">[Pg 114]</span></p> - -<h2 class="nobreak" id="CHAPTER_XI">CHAPTER XI<br /> - -<small>THE FIG-MOTH<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">[13]</a> -(<i>Ephestia cautella</i>)</small></h2> -</div> - - -<p class="center"> -All’ amico mondagli il fico.</p> -<p class="psig"> -(<i>Italian Proverb.</i>)</p> - - -<p>The extension of the War to Turkey and -Asia Minor has drawn attention to the existence -of certain insects whose larvae exercise -a very deleterious effect on valuable food-supplies -in the Near East. The inhabitants -of Asiatic Turkey, without knowing it, have -from time immemorial adopted the advice -of Captain Cuttle: ‘Train up a fig-tree in -the way it should go, and when you are old -sit under the shade on it. Overhaul the—— -Well,’ said the Captain, ‘on second thoughts, -I ain’t quite certain where that’s to be found, -but when found, make a note of.’</p> - -<p>Asia Minor may indeed be described as -the fig-ground of the East, and anything that -interferes with the fig as a food is likely to -interfere with the well-being of our troops</p> - -<p><span class="pagenum" id="Page_115">[Pg 115]</span></p> - -<div class="figcenter illowp100" id="fig32" style="max-width: 75em;"> - <img src="images/fig32.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 32.</span>—Typical Smyrna -fig-orchard in Meander Valley, Asia Minor, whence come the best figs -for export.</div> -</div> - - -<div class="figcenter illowp100" id="fig33" style="max-width: 75em;"> - <img src="images/fig33.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 33.</span>—The fig-moth -(<i>Ephestia cautella</i>). <i>a</i>, Moth with expanded wings; -<i>b</i>, denuded wings showing venation; <i>c</i>, larva, full grown, -dorsal view; <i>d</i>, two egg masses, <i>a</i>, <i>b</i>, <i>c</i>, -About four times natural size; <i>d</i>, more enlarged.</div> -</div> - -<p>in Egypt and the Near East. In ‘The Minor -Horrors of War,’ I described a species of moth, -<i>Ephestia kühniella</i>, a member of the family -Pyralidae, which infests and destroys Army -biscuits; but this other species, <i>E. cautella</i>, -which attacks figs, is even more troublesome<span class="pagenum" id="Page_116">[Pg 116]</span> -than the one described in the above-mentioned -book.<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">[14]</a></p> - -<p>Whoever has attentively eaten dried figs -must from time to time have become aware -that there is something very defective in -their flavour, and on close inspection little<span class="pagenum" id="Page_117">[Pg 117]</span> -clusters of débris will be observed on the -outside of the dried fruit—the dejecta of -the larva burrowing within—and numerous -round holes can be detected through which -the larvae have made their entrance. If -cut open and carefully examined, one or -two small white grubs may be found, which -give the fig a singularly sour-bitter and most -unpleasant taste. This is the larva of the -moth, <i>Ephestia cautella</i> which has for the -last four or five years been attracting much -attention in the Levant market. From 15 -to 50 per cent. of the figs exported from -Smyrna, the great centre of the fig-trade, are -infected with this ‘worm,’ and active steps -were being taken before the War spread to -the Near East to check its ravages. The -moth itself is very like <i>E. kühniella</i>, but -readily distinguished by an entomologist. -Originally, it seems to have come from Asiatic -Turkey, but by the aid of commerce it has -been distributed in a broad belt all round -the world within certain limits of temperature. -Wide as its distribution now is, it is equally -catholic in its tastes. Perhaps it does as -much harm to the chocolate trade as to any -other, attacking the cacao-bean as well as -the prepared article; all sorts of nuts -are infested. At one time it was thought -that the oil of the nuts was the attraction,<span class="pagenum" id="Page_118">[Pg 118]</span> -but the larvae flourish just as well on rice -and bran, on dried apples, dried insects, maize, -and a great variety of other more or less -nutritive substances.</p> - -<p>But to return to the figs. So serious -was the trouble felt to be in the American -fig-market that, in 1910, the authorities at -Washington sent Mr. E. G. Smyth of the -Bureau of Entomology to investigate the -insect in Asia Minor, where the figs come -from, and from his report the following -account is taken:—</p> - -<div class="blockquote"> - -<p>The manner of the fig-harvest is as follows: -During August the figs are ripening on the trees, -and are gradually dropping off to be collected from -the ground and laid on strips of reeds, called ‘serghi,’ -a yard broad; and here for two to five days they -dry in the sun. When dried, they are packed in -goats’-hair bags or woven willow baskets, and carried -by horse or by camel to the fig-depots in the neighbouring -villages. Here they are collected from the -whole district, mixed together, and re-sacked for -transmission by railroad to the coast. At Smyrna -they are graded and prepared for the market: the -better kind being either ‘layered’ or ‘pulled,’ whilst -the inferior fruits are strung on strings or exported -in the form of a mashed cake to make the ‘strawberry’ -jam of the Western breakfast-table.</p> -</div> - -<div class="figcenter illowp100" id="fig34" style="max-width: 75em;"> - <img src="images/fig34.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 34.</span>—‘Serghi’ of -reeds laid in long rows, used in large orchards. Over these the moths -congregate by thousands at night.</div> -</div> - -<p>Mr. Smyth’s object was first to find out -at what stage the figs become infected by the -moth, and then if possible to suggest pre<span class="pagenum" id="Page_119">[Pg 119]</span>ventive -or remedial measures. He minutely -investigated every stage in the preservation -of figs, from the ripe fruit on the tree to the -preserved figs in the hold on the steamer -bound for New York, and the conclusion -he came to is this: With very rare exceptions<span class="pagenum" id="Page_120">[Pg 120]</span> -the eggs are never laid on the fruit whilst -on the tree. The first and by far the most -important infection is when the figs are gathered -and exposed on the reed ‘serghi.’ Then<span class="pagenum" id="Page_121">[Pg 121]</span> -about seven in the evening the moths begin -to appear, and steadily increase in number -as the evening wears on. The actual deposition -of the ova cannot be observed, for -the moths get down amongst the reeds and -lay their eggs on the under surface of the -fruit—usually in some crack or abrasion—so -that the newly hatched larva can more -easily make an entrance into the fig. From -some ‘counts’ made at Tchifte Kaive it -appears that after an exposure of one night -29 per cent. of figs were infested, after two -nights 38·5 per cent., and after three nights -44·5 per cent.</p> - - -<div class="figcenter illowp36" id="fig35" style="max-width: 37.5em;"> - <img class="w100" src="images/fig35.jpg" alt="" /> -<div class="captionl"><p><span class="smcap">Fig. 35.</span>—Figs packed -by string method (reduced).</p></div> -</div> - -<p>A second and serious source of infection -is at the village depots. Before the figs -arrive, there seem to be no specimens of the -<i>Ephestia</i> in the buildings; but with their -arrival the moth appears, and so favourable -is the shelter from the heat and the wind, -and so abundant is the supply of figs as sack -after sack is emptied on to the floor, that soon -the moth is more abundant in the depots -than amongst the ‘serghi,’ and the wonder -is that a single fig escapes infestation. -Fortunately, the time spent in the depots -is short, often only a night; were it much -longer, the whole crop would suffer. On their -way down to the coast again there is little -or no risk of the moth, but arriving at Smyrna<span class="pagenum" id="Page_122">[Pg 122]</span> -we pick up the insect again in the ‘khans,’ -where the figs are prepared for export, but -in the larval form. Here, in August and -September, little trace of the insect is seen, -the larvae are then too small to emerge and -pupate; but by October many full-grown<span class="pagenum" id="Page_123">[Pg 123]</span> -larvae may be found on the fig-heaps or -crawling up the walls; a few pupate inside -the figs, and these probably produce the -few imagines found in the ‘khans,’ at the -port of shipping. The unpleasantness of the -larvae crawling all about the ship greatly -detracts from the pleasure of a voyage on a -vessel laden with Smyrna figs.</p> - -<div class="figcenter illowp90" id="fig36" style="max-width: 75em;"> - <img class="w100" src="images/fig36.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 36.</span>—Pile of -refuse-figs in a Smyrna ‘khan:’ On the wall, above these figs, fig-moth -larvae congregate in large numbers.</div> -</div> - -<p>With regard to preventive measures, there -seems in many parts of Asia Minor to be -two crops of figs—one in May and June and -one later. The former produces a large, -watery fig, unfit for sale. It is left to rot -on the ground, but it serves as food for the -larvae which will produce the myriad swarms -of moths in the early autumn. Obviously -these worthless figs should be destroyed as -completely as possible. Equally obvious are -the suggestions that the figs should be covered -at night with some cheap covering whilst -on the ‘serghi,’ and screened from the moth -whilst in the depots, and their sojourn there -should be as short as possible. Measures -for destroying the larvae in the fig usually -take the form of heat—either hot air, hot -water, or steam. Each is effective, and each -has certain advantages and disadvantages; -still, the more progressive merchants of Smyrna -were, before the War, experimenting trying to -find the best means of destroying the larvae, and -in time a uniform system will probably emerge.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_124">[Pg 124]</span></p> - -<h2 class="nobreak" id="CHAPTER_XII">CHAPTER XII<br /> - -<small>THE STABLE-FLY (<i>Stomoxys</i>)</small></h2> -</div> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">Fly! Thy brisk unmeaning buzz</div> - <div class="verse indent0">Would have roused the man of Uz;</div> - <div class="verse indent0">And, besides thy buzzing, I</div> - <div class="verse indent0">Fancy thou’rt a stinging-fly.</div> - <div class="verse indent0">Fly—who’rt peering, I am certain,</div> - <div class="verse indent0">At me now from yonder curtain:</div> - <div class="verse indent0">Busy, curious, thirsty fly</div> - <div class="verse indent0">(As thou’rt clept, I well know why)—</div> - <div class="verse indent0">Cease, if only for a single</div> - <div class="verse indent0">Hour, to make my being tingle!</div> - <div class="verse indent0">Flee to some loved haunt of thine;</div> - <div class="verse indent0">To the valleys where the kine,</div> - <div class="verse indent0">Udder-deep in grasses cool,</div> - <div class="verse indent0">Or the rushy margined pool,</div> - <div class="verse indent0">Strive to lash thy murmurous kin</div> - <div class="verse indent0">(Vainly) from their dappled skin!</div> - <div class="verse indent10">(<span class="smcap">Calverley</span>; <i>The Poet and the Fly</i>.)</div> - </div></div> -</div> - - - -<p>The common names for common insects in -English are confusing. Not only are the -same insects frequently known by different -names on different sides of the Atlantic, but in -many cases quite different insects—insects even -belonging to different genera—are connoted -by the same common name. In this respect -matters are different in Germany: partly,<span class="pagenum" id="Page_125">[Pg 125]</span> -perhaps, because the Germans on the whole -are more scientifically inclined than we are, -but partly, I suspect, because the German -language lends itself more easily to express -in one word—however long—the characteristics -of any given insect.</p> - -<div class="figcenter illowp90" id="fig37" style="max-width: 75em;"> - <img class="w100" src="images/fig37.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 37.</span>—The Stable-fly -(<i>Stomoxys calcitrans</i>).</div> -</div> - -<div class="figcenter illowp100" id="fig38" style="max-width: 62.5em;"> - <img class="w100" src="images/fig38.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 38.</span>—<i>Stomoxya -calcitrans</i> × 5. Left antenna right × 1, resting position. (From -Graham Smith.)</div> -</div> - -<p>The genus <i>Stomoxys</i> is generally called -in Great Britain the ‘stable-fly,’ but there -are other ‘stable-flies.’ One of the commonest -species of the genus is <i>S. calcitrans</i>, a two-winged -muscid fly, not at all unlike the common -domestic fly, <i>Musca domestica</i>; but there are -one or two points which readily distinguish<span class="pagenum" id="Page_126">[Pg 126]</span> -it from the commoner insect. To begin with: -it has a hard, firm, chitinous, piercing proboscis, -which when at rest stretches forward -in front of the head, and when in action is -pressed down at right angles to the longitudinal -axis of the body; then, again, when -resting, its wings diverge; those of the house-fly -approximate. Like other flies, the <i>Stomoxys</i> -varies somewhat in length, between 5·5-7 mm. -The thorax has on its back four longitudinal, -dark stripes, broken by a transverse suture; -and, as the accompanying figure shows, the -third of the great, long veins which traverse -the wing is much more slightly bent than -is the case in <i>Musca domestica</i>. Further, -whereas the hinder edge of the eye in the -house-fly is straight that of the stable-fly<span class="pagenum" id="Page_127">[Pg 127]</span> -is concave, and the antennae bear hairs on -the upper side only and not above and below -as they do in the domestic fly.</p> - -<div class="figcenter illowp90" id="fig39" style="max-width: 37.5em;"> - <img class="w100" src="images/fig39.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 39.</span>—Wing of -<i>Musca domestica</i> above, and of <i>Stomoxys calcitrans</i> -below.</div> -</div> - - -<p>As a biting-fly and a blood-sucking fly, -the habits of <i>Stomoxys</i> naturally differ from -those of <i>Musca domestica</i>; but, like the latter, -its distribution is almost world-wide. It is -found in all temperate and tropical countries, -and extends as far north as Lapland. But it -is perhaps most abundant (or shall we say -it has been most observed?) in temperate -climates and during the summer months.</p> - -<div class="figleft illowp50" id="fig40" style="max-width: 25em;"> - <img src="images/fig40.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 40.</span>—Side view of -head of <i>Stomoxys calcitrans</i>. <span class="allsmcap">A</span>, -Proboscis in resting position; <span class="allsmcap">B</span>, -proboscis extended. (After Graham Smith.)</div> -</div> - -<p>In any farm or country house large numbers -of <i>Stomoxys calcitrans</i> are found in and about -the cowsheds and stables, and in warm weather -the same is true wherever cattle are grazing<span class="pagenum" id="Page_128">[Pg 128]</span> -in the field. Later in the year, at the -beginning of autumn, they are frequently -found indoors, and in some ‘fly counts’ they -have furnished quite 50 per cent. of the -flies of a country house, the remaining 50 per -cent. being made up of many other species and -genera. When resting -on a vertical surface -<i>Stomoxys</i> generally has its -head pointing upwards, -whereas, as a rule, the -house-fly rests upside -down. The adult fly -feeds upon any decaying -matter; but whenever it -can, it sucks the blood of -vertebrates, and at times -is a real nuisance to -animals as well as human -beings. So voracious are -they that should a well-fed -one be injured, the others immediately -attack it and suck up every drop of blood -which it had secured for its own food.</p> - -<p>It has often been disputed whether a -meal of blood is essential to the female mosquito -before oviposition, but it seems perfectly clear -that the female <i>Stomoxys</i> can produce fertilised -eggs without having had a meal of -blood.</p> - -<p><span class="pagenum" id="Page_129">[Pg 129]</span></p> - -<div class="figcenter illowp75" id="fig41" style="max-width: 62.5em;"> - <img class="w100" src="images/fig41.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 41.</span>—<i>Stomoxys -calcitrans.</i> Eggs. (After Newstead.)</div> -</div> - -<p>The female lays a number of white, banana-shaped -eggs a few inches below the surface -of any decaying organic matter; fermenting -grass from the lawn, decaying garden stuff, -stable manure—each forms a favourable nidus. -The eggs are laid in a heap like those of the -house-fly, each heap containing from fifty -to seventy. The egg is 1 mm. in length -and has a grooved side, through the thicker -end of which the larva escapes when the -egg-shell splits.</p> - -<div class="figleft illowp20" id="fig42" style="max-width: 12.5em;"> - <img src="images/fig42.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 42.</span>—Acephalous -larva of <i>Stomoxys calcitrans</i>. (After Newstead.)</div> -</div> - -<p>The issuing larva is almost transparent. -It not only has no head, but the anterior -end dwindles almost to a point. When fully<span class="pagenum" id="Page_130">[Pg 130]</span> -grown it attains a length of 11 mm., and the -larval stage usually lasts from two to three -weeks; but development may be retarded -by adverse circumstances up -to eleven or twelve weeks, -and in such cases the full-grown -larvae are often -stunted in size. In these circumstances -the pupae they -produce are markedly smaller -than those which have followed -a more normal course -of development. As is true -of the egg and of the larva, -the pupa resembles the pupa -of the house-fly, being barrel-shaped -and of a chestnut-brown -colour; it is 5 to 5·5 -mm. in length. The pupa -stage lasts from nine to thirteen -days, but this period is -prolonged by cold.</p> - -<p>On emerging from the -pupa-case the insect has to push its way to the -surface of the rotting vegetation in which it has -been produced. This it does partly by the -alternate inflation and deflation of the so-called -‘frontal sac,’ and by actively pushing forward -the body by means of its legs. Once on the -surface the insect begins to clean itself, pumps<span class="pagenum" id="Page_131">[Pg 131]</span> -air into its body, forces it along the tracheae in -the wings, which expand and ultimately harden. -In the processes of unfolding they are aided -by the hind legs. For a time the insect is -immobile, gradually stiffening; but when the -integument has hardened it flies off to explore -the outer world. Under normal conditions -the whole life-cycle varies from -twenty-seven to thirty-seven -days.</p> - -<div class="figright illowp35" id="fig43" style="max-width: 12.5em;"> - <img class="w100" src="images/fig43.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 43.</span>—Coarctate pupa -of <i>Stomoxys calcitrans</i>. (After Newstead.)</div> -</div> - -<p>The chief interest of <i>Stomoxys</i> -to the public, rests upon the fact -that it is a very potent carrier -of disease. There are certain -forms of <i>Trypanosoma</i> which, -under experimental conditions, -are undoubtedly transferred by -this species. But opinion is still -unsettled as to whether the transference -of these protozoa occurs in nature. The -<i>Surra</i> diseases of horses and camels is, according -to some authorities, transferred by <i>Stomoxys</i>, -and so is the <i>Surra</i> disease of cattle; and -there are others, all fully set forth in Mr. -Hindle’s work on ‘Flies and Disease.’</p> - -<p>Certain thread-worms—for instance, <i>Filaria -labiato-papillosa</i>—which occur in the peritoneal -cavity, and sometimes in the eyes -of cattle and deer in India, are undoubtedly -conveyed by <i>Stomoxys calcitrans</i>. The super<span class="pagenum" id="Page_132">[Pg 132]</span>ficial -vessels of the cattle swarm with the -larvae of these thread-worms, which readily -pass through the proboscis of the insect into -its stomach. They then wriggle through the -walls of the stomach and make their way -into the thoracic muscles; here they undergo -a ‘rest-cure,’ and after a time they are readily -transferred to a new and possibly uninfected -host.</p> - -<p>But by far the worst infection which -is attributed to this fly is acute epidemic -poliomyelitis, or infantile paralysis. That this -disease occurs in epidemics has been known—especially -in Scandinavia—for some time; and -eight years ago it attracted serious attention -in North America and in our country. In -1907 there were many local outbreaks in -the United States and Canada, and it is -thought that the infection was first introduced -from Scandinavia along the Atlantic -coast, and later, inland, as far as the State -of Minnesota, by the numerous Scandinavian -immigrants that settle there.</p> - -<p>The disease is one of those which are -apparently due to a protozoon too small -to be visible under the highest power of the -microscope, and so small as to be able to -pass through a Berkefeld filter. It can readily -be artificially transmitted to monkeys. It -is thought that the disease is by no means<span class="pagenum" id="Page_133">[Pg 133]</span> -transmitted only by means of the biting -<i>Stomoxys</i>, and that it may be directly transmitted -from one person to another without -the aid of any intermediate host. But there -seems little doubt that it can be, and is, -transmitted by <i>Stomoxys</i>, and therefore it is -of the highest importance to reduce the -number of these insects.</p> - -<p>The most efficient way of controlling this -pest is to destroy or put out of action -its breeding-places. All decaying vegetable -matter should be either removed or burnt -or buried, or covered with some agent which -will prevent the larvae living. In fact, the -methods that have been advocated for the -common house-fly are applicable to <i>Stomoxys</i>. -If stable manure were carefully removed, -from May to October, at least every seven -days, the number of flies would be materially -reduced. Where this is impracticable, manure-heaps -should be covered with some insecticide, -so as to destroy the eggs and larvae. -Experiments are still being made with the -view of finding a substance capable of killing -the eggs, larvae, and pupae, which will be -at once cheap and unharmful to the fertilising -value of the manure. The American experts -recommend borax or colemanite (crude calcium -borate), calcined, powdered, and applied by -a flour-dredger. The proportions which seem<span class="pagenum" id="Page_134">[Pg 134]</span> -most effective are 0·62 lb. of borax and 0·75 lb. -of colemanite to 10 cubic feet, or 8 bushels -of manure. Two or three gallons of water -should then be sprinkled over the manure-heap.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_135">[Pg 135]</span></p> - -<h2 class="nobreak" id="CHAPTER_XIII">CHAPTER XIII<br /> - - -<small>RATS<a id="FNanchor_15" href="#Footnote_15" class="fnanchor">[15]</a> -(<i>Mus</i> or <i>Epimys</i>)</small></h2> -</div> - -<p class="center"> -Now, Muse, let’s sing of rats!</p> -<p class="psig">(<span class="smcap">Grainger.</span>)</p> - - -<p>The overwhelming majority of rats fall under -two species: (i) <i>Mus rattus</i>, the black rat, and -(ii) <i>Mus decumanus</i>, the brown rat. The -original home of both species is, according -to Dr. Blandford, Mongolia; but the date of -their first appearance in our islands is a matter -of some uncertainty. According to Helm, <i>M. -rattus</i> passed into Europe at the time of the -<i>Völkerwanderung</i>, and doubtless accompanied -the migrating Asiatic hordes on their journeys -westward. The name rat appears in early High-Dutch -glossaries, it is mentioned by Albertus -Magnus, and occurs in early Anglo-Saxon -writings in England. This evidence is, however, -not conclusive that in those times the rat had entered -Great Britain; indeed, according to Bell,<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">[16]</a><span class="pagenum" id="Page_136">[Pg 136]</span> -the black rat was not known here until before -the middle of the sixteenth century: at -least, he says, no author more ancient than -that period has described, or even alluded -to, it as being in Great Britain, Gesner being -the first to do so. Jenyns, in his ‘Manual -of British Vertebrate Animals,’<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">[17]</a> describes <i>M. -rattus</i> as ‘truly indigenous’; but this is in -comparison with the brown rat, whose comparatively -recently arrival he chronicles. <i>M. -rattus</i> is said to have been common on the -continent of Europe in the thirteenth century.</p> - -<div class="figcenter illowp100" id="fig44" style="max-width: 75em;"> - <img src="images/fig44.jpg" alt="" /> - <div class="caption"><span class="smcap">Fig. 44.</span>—<i>Mus -rattus.</i> (From Pennant.)</div> -</div> - -<p><i>M. rattus</i> has, as a rule, greyish-black -fur above, ash-coloured below, with a tail a<span class="pagenum" id="Page_137">[Pg 137]</span> -little longer than the body and head. It is -smaller and more elegantly built than the -brown rat; its snout is longer and more slender, -and the long, thin, scaly tail is about eight or -nine inches in length. The British forms -average in length seven inches from the tip of -the nose to the origin of the tail. Although -known as the black rat, its bluish, or greyish-black -colour is, both in the East and in Northern -America, frequently replaced by brown on the -upper surface, and by white fur on the lower, -or by a yellowish-brown rufous colour. The -ears, feet, and tail are black. When kept as -pets—and they frequently are—white and -piebald varieties are often bred. The ears are -larger in proportion than in <i>M. decumanus</i>, -the rings of scales on the tail better marked, -and spines in the fur are not uncommon.</p> - -<p>The black rat, or Old-English rat, begins -to breed under the age of one year, and goes -with young six weeks; it breeds frequently -during the year, but does not commence in -Bombay, according to the Plague Commission, -until it has attained the weight of at least -70 grammes. In India they breed all the year -round. In Britain they produce six to eleven -young at a time; in India the average is 5·2; -the largest number found by the Plague Commission -having been nine. In Bombay it is -noteworthy that in both species the percentage<span class="pagenum" id="Page_138">[Pg 138]</span> -of young rats to the total rat population is -greater during the warmer months—from June -to October—than at other times of the year. -It is also noteworthy that the fall in fertility -begins before the onset of the plague epizootic, -though, later, it roughly coincides with it. -In Britain they increase so fast as to overstock -their abode, and thus they are forced, from -deficiency of food, to devour one another, and -this alone, Pennant thinks, ‘prevents even -the human race from becoming a prey to them, -not but there are instances of their gnawing -the extremities of infants in their sleep.’</p> - -<div class="figcenter illowp100" id="fig45" style="max-width: 46.875em;"> - <img src="images/fig45.jpg" alt="" /> - <div class="caption"><span class="smcap">Fig. 45.</span>—Head of <i>Mus -rattus</i>. (From Flower and Lyddeker.)</div> -</div> - -<p>The black rat is catholic as to its diet, -omnivorous, and it devours every kind of -human food. It is more domesticated than -its congener, more devoted to human habitations, -and it does immense damage to stored -grain, seeds, and cereals. It is a better -climber than <i>M. decumanus</i>, which accounts -for its being <i>par excellence</i> the ship-rat, since -it can climb hawsers and more readily ‘comes<span class="pagenum" id="Page_139">[Pg 139]</span> -on board.’ It makes its way up to the higher -rooms of the tenement houses in Indian cities, -where it nests and breeds undisturbed by the -human inhabitants.</p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">Day by day we passed them—</div> - <div class="verse indent2">Met them unaware,</div> - <div class="verse indent0">Shambling through the lobbies,</div> - <div class="verse indent2">Squatting on the stair.</div> - </div> - <div class="stanza"> - <div class="verse indent0">Not a rat among them</div> - <div class="verse indent2">Moved to give us place,</div> - <div class="verse indent0">Staring with its cruel eye</div> - <div class="verse indent2">And its aged face.</div> - <div class="verse indent10">(<span class="smcap">F. Langridge.</span>)</div> - </div> -</div> -</div> - -<p>Pennant<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">[18]</a> draws attention to the harm the -black rat causes by gnawing and devouring -not only edibles, but paper, cloth, water-pipes, -and even furniture. In England it makes a -lodge—either for the day’s residence or a nest -for its young—near a chimney, and ‘improves -the warmth by forming in it a magazine of -wool, bits of cloth, hay, or straw.’ In the -East it nests in the indescribable rubbish and -‘unconsidered trifles’ the natives accumulate -in their rooms, and is seldom, if ever, interfered -with.</p> - -<p>Its climbing-habits enable it to ascend trees, -and in India it frequently nests among the -branches. In some tropical islands <i>M. rattus</i><span class="pagenum" id="Page_140">[Pg 140]</span> -lives exclusively in the crowns of coco-nut -palms, feeding almost entirely on their fruit.</p> - -<p>Contrary to the opinion of Blandford, -Oldfield Thomas thinks that the black rat -originally came from India, and thence spread -all over the world, exterminating the indigenous -rats of other countries, only to be exterminated -later by the arrival of the stronger <i>M. decumanus</i>. -At the present time the last-named -species is not yet established in some countries—for -instance, in those of western South -America. On that continent, <i>M. alexandrinus</i>, -a tropical variety of <i>M. rattus</i>, is waging war -on the less highly organised native rice-rats -(<i>Sigmodon</i>). <i>M. alexandrinus</i> has a grey or -rufous back, and a white belly.</p> - -<p><i>M. rattus</i> has a milder, more amenable, -and tameable character than <i>M. decumanus</i>, -and the white, or pied varieties, so dear to -schoolboys, are of this species. It is cleanly -in its habits, and the skin is kept in excellent -order. Like other rats, it holds its food in its -hands whilst eating, and it drinks by lapping.</p> - -<p>Although the black rat is tending to be -driven out by the brown rat, it still lingers -on in some warehouses in London, at Yarmouth, -in Sutherlandshire, I believe in Lundy Island, -and I have been told it occurred not so very -long ago on the island in the Serpentine. It -doubtless occurs in many other places.</p> - -<p><span class="pagenum" id="Page_141">[Pg 141]</span></p> - -<p><i>Mus decumanus</i>, the so-called brown rat, -undoubtedly comes from Central Asia; and -at the present time there is a rat in China -described under the name <i>M. humiliatus</i>, -which is so little distinguishable from the brown -rat that it is thought to be the parent form.</p> - -<p>The migration westward of the brown -rat certainly took place much later than that -of <i>M. rattus</i>. Its first appearance is -difficult to date. Undoubtedly large hordes -of them crossed the Volga in the year 1727, -and continued their journey towards Central -Europe. The following year, according to -Pennant, brown rats, appeared in England—Jenyns -says not till 1730—and almost certainly -they came in ships, for on its journey overland -it only reached Paris about the year 1750. -Reaching England about the year of the -second George’s accession, and but thirteen -years after the first of the House of Hanover -succeeded to the throne, it was called—probably -by the adherents of the Stuart cause—the -Hanoverian rat. It was also called the -Norwegian rat—possibly from the mistaken -idea that it reached these islands from that -country. It has now passed to the northern -half of the New World, where it is gradually -driving out many of its weaker brethren. Its -numbers are, however, kept within certain -limits by wolves, lynxes, raccoons, coyotes,<span class="pagenum" id="Page_142">[Pg 142]</span> -opossums, and other carnivora, and especially -by the skunks, which enter barns and out-houses -in search of it.</p> - -<p>Until the discovery of America, the rat -and mouse were unknown in the New World, -and the first rats who ever saw it are said to -have been introduced in a ship from Antwerp.<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">[19]</a></p> - -<p>The brown rat is of a greyish-brown colour, -tinged with yellow and white beneath. The -tail is not so long as the body. It is a larger -rat than <i>M. rattus</i>, has shorter ears, a more -powerful skull, and ten to twelve mammae. Its -ears, feet, and tail are flesh-coloured. Like <i>M. -rattus</i>, colour varieties occur often: the melanistic -variety, not uncommon in Ireland, being -sometimes mistaken for the black rat. It -is a larger animal than its congener, more -heavily built, with a more powerful head, and -blunter jaws. The head and body measure -some eight to nine inches, but the tail, as a -rule, does not surpass the length of the body -alone. Its weight averages about nine ounces. -It is extremely fierce and extremely cunning, -and in the struggle for existence with allied -species has hitherto been consistently successful -in the fight.</p> - -<p><i>Mus decumanus</i> is very prolific, and produces -several litters a year, each averaging eight -to ten in number, but twelve or even fourteen<span class="pagenum" id="Page_143">[Pg 143]</span> -young are not very uncommonly born at one -time. It begins breeding young—a half-grown -female producing a litter of three or four; -but in Bombay the sexes do not breed until -they have attained at least a weight of -100 grammes. The young are naked, i.e. -without hairs, and of a beautiful pink colour. -They are blind, and their ears are gummed -down over the auditory meatus. They are -very weak and helpless, and need that maternal -care, which, to do the female rat justice, is -never withheld.</p> - -<div class="figcenter illowp100" id="fig46" style="max-width: 75em;"> - <img src="images/fig46.jpg" alt="" /> - <div class="caption"><span class="smcap">Fig. 46.</span>—<i>Mus -decumanus.</i> (From Pennant.)</div> -</div> - -<p><i>M. decumanus</i> is less attached to the dwellings -of man than <i>M. rattus</i>; still, it does live -in houses, though, owing to a lack of climbing -power, it is never found above the third floor.<span class="pagenum" id="Page_144">[Pg 144]</span> -It is largely a burrowing animal, and makes -its nests in its burrows. <i>M. rattus</i> can also -burrow, but not so readily, and it nests not -in the burrow, but in some obscure corner. -A curious instance of the nesting habits of -this species was found during the rebuilding -of my ‘lodgings’ in 1911. In searching under -the boards of the floor of the rooms of our -Foundress the Lady Margaret, Mother of Henry -VII, now the drawing-room, the workmen found -the mummified remains of four rats, which -had taken to themselves coverings or shrouds; -and upon investigation these proved to consist -of a vellum deed relating to the College, some -paper documents relating to Thomas Thompson, -who was Master of the College from 1510 to -1517, and some fragments of printed matter -which turned out to be part of an early Virgil; -four leaves of a Horace; two leaves of a -primer of Wynkyn de Worde; and finally a -leaf of a work by Caxton. In addition, four -playing-cards of the sixteenth century were -found.</p> - -<p>The brown rat frequents barns, granaries, -stables, slaughter-houses, rivers, ponds, ditches, -drains, gullies, and sewers—it is, in fact, -sometimes called the sewer-rat. It is less -particular in its food than the black rat, -which is more usually found in grain-stores. -Although in Bombay the relative numbers<span class="pagenum" id="Page_145">[Pg 145]</span> -of <i>M. rattus</i> and <i>M. decumanus</i> caught was as -seven is to three, in open spaces, gardens, -&c., the latter was much the commoner. -Yet the report of the Plague Commission -states that the authors ‘do not think it an -exaggeration to state that every inhabited -building in Bombay City and Island, not -excepting even the better-class bungalows, -shelters its colony of <i>M. rattus</i>.’</p> - -<div class="figcenter illowp100" id="fig47" style="max-width: 46.875em;"> - <img class="w100" src="images/fig47.jpg" alt="" /> - <div class="caption"><span class="smcap">Fig. 47.</span>—Head of <i>Mus -decumanus</i>. (From Flower and Lyddeker.)</div> -</div> - -<p>Both species readily take to water, though -<i>M. rattus</i>, being the better climber, more -readily gets on shipboard. They will swim -rivers and arms of the sea. The rats which -infest the London Zoological Gardens are -said to swim nightly the canal in Regent’s -Park. Rats constantly make their way to -coastal islands, and in a comparative short -time clear the place of indigenous rabbits -and birds. Puffin Island, off the coast of -Anglesea, and the Copeland Islands, in Belfast -Bay, are two examples of islands at one time<span class="pagenum" id="Page_146">[Pg 146]</span> -leased for the sake of their rabbits to people -who had to give up the lease after the rats -had landed on them. Similar cases are known -off Denmark. They greedily eat birds’ eggs, -and are said to convey them over considerable -distances, though how they do this is -not very clear. After the destruction of the -vertebrate land-fauna, they fall back upon -the dwellers in the littoral, and live on prawns, -shrimps, and molluscs. They are very fond -of fish, and Lyddeker, in the ‘Royal Natural -History,’ states that they occasionally catch -and eat young eels. As their parasites show, -they eat insects such as the meal-beetle, -and when in the field they eat land-snails, -insect larvae, and other food, which conveys -into their bodies the same tape-worms, &c., -which we find in the hedgehog and in the -smaller carnivora.</p> - -<p>They are, in fact, omnivorous, and nothing -in the way of human food is alien to them. -They do enormous harm to corn-ricks and -to stored grain. They are inveterate enemies -of the hen-roost, the pigeon-house, and, as -we have seen, of the rabbit-warren. When -pressed by hunger, they readily turn cannibal, -and the brown rat easily masters the black. -There are stories of some few specimens of -each species being left in a cage overnight; -on the following morning there were only<span class="pagenum" id="Page_147">[Pg 147]</span> -brown rats in that cage. To some extent they -help to keep down one of the field-mice (Genus -<i>Microtus</i>), and this is especially the case in -North America;<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">[20]</a> but the benefit is doubtful -since they are held to be at least as destructive -to the crops as the field-mice, and probably -more so.</p> - -<p>The ferocity with which they defend themselves -when attacked is well known, and -at times, when they are driven by hunger, -they do not hesitate to attack man. They are -said to nibble the extremities of infants, and -in one—apparently authentic—instance they -overcame and devoured a man who had entered -a disused coal-mine tenanted by starving -rats. The bite is said to be severe (they will -bite through a man’s thumb-nail into the -flesh), and the bite is long in healing.</p> - -<p>Rats eat much garbage and offal, and readily -feed upon dead bodies. About sixty years -ago there stood, at Monfaucon, a slaughter-house -for horses, and this it was proposed -to remove still farther from Paris. It is -stated that the carcasses of the horses -slaughtered—which sometimes amounted to -thirty-five a day—were cleared to the bone -by rats in the course of the following night. -This excited the attention of a M. Dusaussois,<span class="pagenum" id="Page_148">[Pg 148]</span> -who made the following experiment: He -placed the carcasses of two or three horses -in an enclosure, which permitted the entrance -of rats by certain known and closable paths. -Towards midnight, he and some workmen -entered the enclosure, closed the rat-holes, -and in the course of that night killed 2650 -rats. He repeated the experiment, and by -the end of four days had killed 9101 rats, -and by the end of a month 16,050 rats. During -the process of these experiments other carcasses -were exposed in the neighbourhood, -so that in all probability M. Dusaussois -attracted to his enclosure but a small proportion -of the total available number of -rats. All around this slaughter-house the -country was riddled with extensive burrows, -so that the earth was constantly falling in. In -one place the rodents had formed a pathway, -500 yards long, leading to a distant burrow.</p> - -<p>A rat census can never be taken; but, -estimating that there is one rat for every human -being on these islands, or less than one rat -for every acre of ground, a moderate estimate -would give us 40,000,000 rats at any one time. -It has been calculated that a rat does at least -7<i>s.</i> 6<i>d.</i> worth of damage during the course of -the year: hence in Great Britain and Ireland, -we may annually charge them with a loss of at -least £15,000,000!</p> - -<p><span class="pagenum" id="Page_149">[Pg 149]</span></p> - -<p>From what has been said it is obvious -that rats cause enormous damage to humanity, -which is counterbalanced by the almost -infinitesimal good they do as scavengers. I do -not propose to consider in detail the harm -they do as disease-carriers, but one cannot -forget that the rat is the primary host of -<i>Trichinella spiralis</i>, which, when conveyed -from the rat to the pig, and—by eating uncooked -or imperfectly cooked pork—from the -pig to man, causes severe and very fatal -epidemics, and enforces the expenditure of -large annual sums on meat inspection. They -further convey a virulent form of equine -influenza from one stable to another, and also -the ‘foot-and-mouth’ disease. But what is -infinitely more important to man than all the -other injuries put together is the harm they -bring to suffering humanity by conveying -the bubonic plague from one patient to -another. The plague under which India and -great parts of Burma are ‘groaning and -travailing,’ is caused by a specific bacillus -discovered in 1894 by Yersin at Hong-Kong. -It flourishes in other vertebrates besides man -and the rat, but, owing to the migratory -habits of the latter, the rat is the most effective -agent in the spread of the disease. Both -species of rat seem about equally susceptible, -and the presence of the microbe showed no<span class="pagenum" id="Page_150">[Pg 150]</span> -special relation to either the age or the sex of -either species. The microbe is conveyed from -rat to rat and from rat to man by a flea.</p> - -<p>The destruction of the rat is now being -urged on all hands, and in the near future -we shall probably see a considerable diminution -in their numbers in the more civilised countries -of the world. This will mean a considerable -upset in the balance of power of the almost -hidden fauna which surrounds us on all hands. -It may even, as the Medical Officer of Health -for Bristol has pointed out, lead to an increase -of immigration of ship-rats—those most likely -to be infected by plague—to take up the -places vacated on land by the slain. By one -of those commercial agencies—I do not propose -to go into the merits of any one of them—which -the enterprise of our merchants is -now pressing on the public, a large landed -proprietor a few months ago completely freed -his buildings of rats and mice. A few weeks -later his house and out-buildings were overrun -by swarms of what to him—for in the -time of the rats and mice he had never seen one—was -a new and formidable insect. He sought -the aid of the Royal Agricultural Society, who -referred the matter to their scientific adviser, -who pronounced the insects to be cockroaches!</p> - -<p>Mr. H. Warner Allen, the representative -of the British Press with the French Army, -writes as follows in the <i>Morning Post</i>:—</p> - -<p><span class="pagenum" id="Page_151">[Pg 151]</span></p> - -<div class="blockquote"> - -<p>Of the smaller trench annoyances few are more -worrying than the plague of rats. Shelters and -trenches, no matter where they are made, whether -in woods or open fields or on the mountainside, -become immediately infested with the objectionable -creatures. In one case within my own personal -knowledge they drove a French officer out of a -comfortable and commodious dug-out into a damp -and melancholy shelter, which was to some extent -protected from them by sheets of corrugated iron. -The plague had attained considerable dimensions -before a really organised attempt was made to deal -with it, and there were many cases of rats actually -biting men who were chasing them down the trenches.</p> - -<p>Terriers have proved of considerable assistance. -Trains full of dogs have been dispatched to the -Front, and poison has been fairly effective. Lately, -a reward has been offered for every dead rat brought -in by men in the trenches, and regular battues have -been organised. In a single fortnight one army corps -alone has disposed of no fewer than 8000 rats. At -a halfpenny a rat this has involved an expense of -£16, and it was certainly money well spent. The -sport of rat-catching on such very advantageous terms -has proved very popular among the men, who now -suggest that the standing reward offered for the more -dangerous and more exciting form of sport involved -in the capture of a German machine-gun should be -raised to a higher figure.</p> -</div> - -<p>Ferrets have been largely used in the -British trenches, but their price is now very -high, and the supply is very limited. The -method which has had some success in<span class="pagenum" id="Page_152">[Pg 152]</span> -combatting the rabbit-plague of Australia—killing -all captured females and let all captured -males loose—is certainly worth a trial. Rats -will gnaw through concrete, but not if plenty -of pieces of broken glass be mixed with the -concrete. They will never cross a band of tar -which has been kept liquid by mixing with -grease. In the French trenches, special rat-runs -are dug and these are provided with -‘live’ wires. On touching one of these the -rat is electrocuted.</p> - -<p>In the eighteenth century, among the -officers of his ‘Britannic Majesty,’ was an -official rat-catcher, whose special uniform was -scarlet, embroidered in yellow worsted with -figures of field-mice destroying wheat-sheaves. -Inquiry at the Lord Chamberlain’s office -has satisfied me that the officer still exists -and still catches rats, but I fear the uniform -has been abolished. However, a book has -recently appeared dealing officially and exhaustively -with all matters of this kind, and -as soon as I can come by it, I will look the -matter up. Should this dignified uniform -have really disappeared, might not a humble -petition be presented that it be revived? -Surely, never more than at the present time -should the honour and glory of the rat-catcher -be exalted!</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_153">[Pg 153]</span></p> - -<h2 class="nobreak" id="CHAPTER_XIV">CHAPTER XIV<br /> - -<small>THE FIELD-MOUSE (<i>Apodemus sylvaticus</i>)</small></h2></div> - -<p class="center">TO A FIELD-MOUSE</p> - -<p class="center"><span class="smcap">On turning Her up in Her Nest with the Plough, -November 1785.</span></p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">Wee, sleekit, cowrin’, tim’rous beastie,</div> - <div class="verse indent0">Oh, what a panic’s in thy breastie!</div> - <div class="verse indent0">Thou needna start awa’ sae hasty,</div> - <div class="verse indent16">Wi’ bickering brattle!</div> - <div class="verse indent0">I wad be laith to rin an’ chase thee,</div> - <div class="verse indent16">Wi’ murd’ring pattle!</div> - </div> - <div class="stanza"> - <div class="verse indent0">I’m truly sorry man’s dominion</div> - <div class="verse indent0">Has broken Nature’s social union,</div> - <div class="verse indent0">An’ justifies that ill opinion</div> - <div class="verse indent16">Which maks thee startle</div> - <div class="verse indent0">At me, thy poor earth-born companion,</div> - <div class="verse indent16">An’ fellow mortal!</div> - </div> - <div class="stanza"> - <div class="verse indent0">I doubt na, whyles, but thou may thieve;</div> - <div class="verse indent0">What then? poor beastie, thou maun live!</div> - <div class="verse indent0">A daimen icker in a thrave</div> - <div class="verse indent16">’S a sma’ request;</div> - <div class="verse indent0">I’ll get a blessin’ wi’ the lave,</div> - <div class="verse indent16">An’ never miss ’t!</div> - </div> - <div class="stanza"> - <div class="verse indent0">Thy wee bit housie, too, in ruin!</div> - <div class="verse indent0">Its silly wa’s the win’s are strewin’!</div> - <div class="verse indent0">An’ naething now to big a new ane</div> - <div class="verse indent16">O’ foggage green!</div> - <div class="verse indent0">An’ bleak December’s win’s ensuin’,</div> - <div class="verse indent16">Baith snell an’ keen!</div><span class="pagenum" id="Page_154">[Pg 154]</span> - </div> - <div class="stanza"> - <div class="verse indent0">Thou saw the fields laid bare an’ waste,</div> - <div class="verse indent0">An’ weary winter comin’ fast,</div> - <div class="verse indent0">An’ cozie here, beneath the blast,</div> - <div class="verse indent16">Thou thought to dwell,</div> - <div class="verse indent0">Till, crash! the cruel coulter past</div> - <div class="verse indent16">Out thro’ thy cell.</div> - </div> - <div class="stanza"> - <div class="verse indent0">That wee bit heap o’ leaves an’ stibble,</div> - <div class="verse indent0">Has cost thee mony a weary nibble!</div> - <div class="verse indent0">Now thou’s turn’d out for a’ thy trouble,</div> - <div class="verse indent16">But house or hauld,</div> - <div class="verse indent0">To thole the winter’s sleety dribble,</div> - <div class="verse indent16">An’ cranreuch cauld!</div> - </div> - <div class="stanza"> - <div class="verse indent0">But, Mousie, thou art no thy lane,</div> - <div class="verse indent0">In proving foresight may be vain:</div> - <div class="verse indent0">The best-laid schemes o’ mice an’ men</div> - <div class="verse indent16">Gang aft a-gley,</div> - <div class="verse indent0">An’ lea’e us nought but grief an’ pain</div> - <div class="verse indent16">For promis’d joy.</div> - </div> - <div class="stanza"> - <div class="verse indent0">Still thou art blest, compared wi’ me!</div> - <div class="verse indent0">The present only touches thee:</div> - <div class="verse indent0">But, och! I backward cast my ee</div> - <div class="verse indent16">On prospects drear!</div> - <div class="verse indent0">An’ forward, tho’ I canna see,</div> - <div class="verse indent16">I guess an’ fear.</div> - <div class="verse indent20">(<span class="smcap">Burns.</span>)</div> - </div> -</div> -</div> - - -<p>Another member of the <i><span class="smcap">Muridae</span></i>, the field-mouse -(<i>Apodemus sylvaticus</i>), is almost as -great a nuisance in the trenches as the rat. -The field-mouse is very like the house-mouse, -with some of its features seen under a lens. -The hind feet and ears and eyes are larger -than are those of the house-mouse. Perhaps -its much longer hind legs help most easily to -differentiate the two species. The tail is of<span class="pagenum" id="Page_155">[Pg 155]</span> -about the same length as the body and head -added together, and is annulated, presenting -some 150 rings. The hands have five-palmar -pads, and the feet six pads. There -are six mammae in the female, the anterior -pair being pectoral.</p> - -<p>The general colour of the dorsal surface -is described as wood-brown, which pales at the -front end and towards the shoulders and flanks, -and grows to a more reddish tinge at the posterior -end. The whole of the lower surface -is of dull, white, silvery colour, and on some -well-developed specimens there is a spot of -buff, or orange, on the throat, which sometimes -lengthens out to form a collar. Moulting -seems to be rare—at any rate but a few cases -have been recorded.</p> - -<p>The field-mouse occurs all over Europe, -and extends into parts of Asia. It is found -all the way from Iceland, southward to Algiers, -and from Ireland to India. In the Himalayas -it has been taken at a height of 11,500 feet, -and in the mountains of Europe it frequently -occurs at a height of 7000 feet. It is certainly -the most universally distributed of European -animals, and the number of individual specimens -probably far exceeds that of any other -mammal which occurs in its district.</p> - -<div class="figcenter illowp80" id="fig48" style="max-width: 75em;"> - <img src="images/fig48.jpg" alt="" /> - <div class="captionl"><span class="smcap">Fig. 48.</span>—The -field-mouse (<i>Apodemus sylvaticus</i>). (From Barrett Hamilton.)</div> -</div> - -<p>The field-mouse does not hibernate like -the dor-mouse, but is active and hardy at<span class="pagenum" id="Page_156">[Pg 156]</span> -all seasons of the year. Although, like other -<i><span class="smcap">Muridae</span></i>, it is probably vegetarian by ancestry, -it is, in effect, quite omnivorous. It -causes considerable loss in cornfields and -gardens, especially to early-sown peas; it -eagerly eats dandelions and any kind of grain or -nut, or berry, or fruit, or bulb, or bud. Even -fungi have been found in their winter stores; -and one family was discovered which had eaten -considerable quantities of putty with appar<span class="pagenum" id="Page_157">[Pg 157]</span>ently -no deleterious effect. Their fondness for -bulbs is a great nuisance to the Dutch tulip-merchants. -As many as 300 have been trapped -in a fortnight in a single crocus-bed. They -are also a nuisance to bee-keepers, inasmuch -as they enter the hive and eat the honeycomb, -especially during the winter. Whilst feeding -in the hedgerows, or undergrowth, they frequently -establish themselves in birds’ nests, and -occasionally such nests become their permanent -home.</p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">In the hedge-sparrow’s nest he sits,</div> - <div class="verse indent2">When the summer brood is fled,</div> - <div class="verse indent0">And picks the berries from the bough</div> - <div class="verse indent2">Of the hawthorn overhead.</div> - <div class="verse indent10">(<i>Sketches of Natural History</i>, 1834.)</div> - </div> -</div> -</div> - -<p>They are not above sucking the birds’ eggs, -or even devouring the young birds. They -will sometimes enter disused tunnels and -devour hibernating flies and other insects. -Unlike rats, they seldom enter human habitations, -and they are quite innocent of the -peculiar odour which is so disagreeable in -the house-mouse; and unlike the house-mouse -and the harvest-mouse they are seldom found -in stacks of corn. Their preference for berries -explains the fact that they generally haunt -woods and hedgerows, and their passion for -growing corn accounts for the fact that they -swarm in cornfields towards harvest-time.</p> - -<p><span class="pagenum" id="Page_158">[Pg 158]</span></p> - -<p>The field-mouse, however, does not neglect -open and barren districts, and is found from -the sea-beach to the mountain-tops. It seems -to flourish equally well in the flower-beds of -the London parks and on the lonely hills of -Scotland. Its activities are largely confined -to the night-time, which may account for the -exceptional size of its eyes. It is described -‘as bounding along in a peculiar zig-zag and -erratic manner, remotely resembling the movements -of a kangaroo or jerboa.’ Its spoor is -very characteristic. The hind feet pressing -nearly on the same spot as the fore feet, but -less lightly than the latter. From time to -time it sits upright, pricking its ears; and -obviously its sense of hearing is very acute, -for it distinguishes sounds inaudible to the -human ear. It is mild in manner, gentle and -inoffensive, extremely timid, and most easily -trapped. It is to some extent gregarious, -as many as fourteen or fifteen sometimes -being found in the same burrow.</p> - -<p>As Fig. 49 shows, the burrow generally -has an entrance which is marked by a little -heap of excavated earth. This leads down -into the nest where food is often stored.</p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent18">saepe exiguus mus</div> - <div class="verse indent0">Sub terris posuitque domos atque horrea fecit.</div> - <div class="verse indent10">(<span class="smcap">Virgil</span>, <i>Georgics</i>, i. 18 b.)</div> - </div> -</div> -</div> - -<p>At the other end of the nest there are gene<span class="pagenum" id="Page_159">[Pg 159]</span>rally -a couple of bolt-holes separated from one -another by an angle of nearly ninety degrees.</p> - -<div class="poetry-container"> -<div class="poetry"> - <div class="stanza"> - <div class="verse indent0">The mouse that always trusts to one poor hole</div> - <div class="verse indent0">Can never be a mouse of any soul.</div> - <div class="verse indent10">(<span class="smcap">Pope</span>, <i>The Wife of Bath</i>.)</div> - </div> -</div> -</div> - -<div class="figcenter illowp100" id="fig49" style="max-width: 75em;"> - <img src="images/fig49.jpg" alt="" /> - <div class="caption"><span class="smcap">Fig. 49.</span>—Diagram of -burrow of field-mouse.</div> -</div> - -<p>The field-mouse is prolific, the female producing -several litters throughout the greater -part of the year. The mother carries the young-born -litter about for two or three weeks, nipping -the skin of her offspring at the side, half-way -between the fore and hind legs. The -average number of young born at one time -is probably somewhere about five, though -litters of nine are by no means unknown. All -predaceous animals naturally eat field-mice, -and they are the favourite food—at any rate, -in some localities—of owls.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_161">[Pg 161]</span></p> - -<h2 class="nobreak" id="INDEX">INDEX</h2> -</div> - - -<div class="index"> -<ul class="index"> -<li class="ifrst">Agramonte, Dr., <a href='#Page_105'>105</a></li> - -<li>Albertus Magnus, <a href='#Page_135'>135</a></li> - -<li class="indx">Allen, H. Warner, <a href='#Page_151'>151</a></li> - -<li class="indx"><i>Anobium paniceum</i> (biscuit-‘weevil’), <a href='#Page_111'>111</a>, <a href='#Page_112'>112</a></li> - -<li class="indx"><i>A. striatum</i>, <a href='#Page_111'>111</a></li> - -<li class="indx"><i>Apodemus sylvaticus</i> (field-mouse), <a href='#Page_153'>153</a>, <a href='#Page_154'>154</a></li> - -<li class="indx"><i>Anopheles maculipennis</i>, <a href='#Page_42'>42</a>, <a href='#Page_65'>65</a>, <a href='#Page_106'>106</a>;</li> -<li class="isub1">head of, <a href='#Page_49'>49</a>;</li> -<li class="isub1">distribution of, <a href='#Page_51'>51</a>;</li> -<li class="isub1">hibernation of, <a href='#Page_54'>54</a>;</li> -<li class="isub1">breeding habits of, <a href='#Page_55'>55</a>-6;</li> -<li class="isub1">sensibility to light, <a href='#Page_59'>59</a>;</li> -<li class="isub1">and colour, <a href='#Page_60'>60</a>-3, <a href='#Page_110'>110</a>;</li> -<li class="isub1">extermination of, <a href='#Page_63'>63</a>;</li> -<li class="isub1">buzzing of, <a href='#Page_73'>73</a>-4;</li> -<li class="isub1">eggs of, <a href='#Page_78'>78</a>;</li> -<li class="isub1">larva, <a href='#Page_86'>86</a></li> - -<li class="indx">Austen, <a href='#Page_55'>55</a></li> - - -<li class="ifrst"><i>Bacillus lactis aerogenes</i>, <i>B. cloacae</i>, <a href='#Page_23'>23</a></li> - -<li class="indx">Bell, <a href='#Page_135'>135</a></li> - -<li class="indx">Bellesme, Jousset de, <a href='#Page_72'>72</a></li> - -<li class="indx">Biscuit-‘weevil,’ <a href='#Page_111'>111</a>-13</li> - -<li class="indx">Blandford, Dr., <a href='#Page_135'>135</a>, <a href='#Page_140'>140</a></li> - -<li class="indx"><i>Blattodea</i>, <a href='#Page_4'>4</a></li> - -<li class="indx">Bombay Plague Commission, <a href='#Page_137'>137</a>, <a href='#Page_145'>145</a></li> - -<li class="indx">Bot- or warble-fly, <a href='#Page_25'>25</a>, <a href='#Page_27'>27</a>;</li> -<li class="isub1">effect on cattle, <a href='#Page_40'>40</a>;</li> -<li class="isub1">cure for, <a href='#Page_41'>41</a></li> - -<li class="indx"><i>British Medical Journal</i>, <a href='#Page_24'>24</a>, <a href='#Page_63'>63</a></li> - -<li class="indx">Browne, Sir Samuel James, <a href='#Page_27'>27</a></li> - - -<li class="ifrst">Cambon, <a href='#Page_59'>59</a></li> - -<li class="indx">Canada, <a href='#Page_31'>31</a>, <a href='#Page_32'>32</a></li> - -<li class="indx">Carpenter, Prof. G. H., <a href='#Page_36'>36</a></li> - -<li class="indx">Carroll, Dr., <a href='#Page_105'>105</a></li> - -<li class="indx"><i>Ceratopogon</i>, <a href='#Page_42'>42</a></li> - -<li class="indx"><i>Challenger</i>, H.M.S., <a href='#Page_16'>16</a></li> - -<li class="indx"><i>Churchill’s Voyages</i>, <a href='#Page_142'>142</a> <i>n.</i></li> - -<li class="indx">Cropper, J., <a href='#Page_63'>63</a></li> - -<li class="indx">Cockroaches (Periplaneta), <a href='#Page_1'>1</a>, <a href='#Page_3'>3</a>;</li> -<li class="isub1">food of, <a href='#Page_8'>8</a>, <a href='#Page_11'>11</a>, <a href='#Page_13'>13</a>, <a href='#Page_17'>17</a></li> - -<li class="indx"><i>Culex</i>, <a href='#Page_42'>42</a>, <a href='#Page_50'>50</a>, <a href='#Page_51'>51</a>, <a href='#Page_55'>55</a>, <a href='#Page_58'>58</a>, <a href='#Page_79'>79</a>, <a href='#Page_88'>88</a>, <a href='#Page_90'>90</a>, <a href='#Page_106'>106</a>-7</li> - - -<li class="ifrst">Duncan, P. M., <a href='#Page_21'>21</a> <i>n.</i></li> - -<li class="indx">Dusaussois, <a href='#Page_148'>148</a></li> - - -<li class="ifrst"><i>Ectobia</i>, <a href='#Page_4'>4</a></li> - -<li class="indx">Elephantiasis, <a href='#Page_47'>47</a></li> - -<li class="indx">Entomology, Washington Bureau of, <a href='#Page_114'>114</a>, <a href='#Page_118'>118</a></li> - -<li class="indx"><i>Ephestia cautella</i>, <a href='#Page_114'>114</a>, <a href='#Page_115'>115</a>, <a href='#Page_117'>117</a>, <a href='#Page_121'>121</a></li> - -<li class="indx"><i>E. kühniella</i>, <a href='#Page_115'>115</a>, <a href='#Page_116'>116</a>, <a href='#Page_117'>117</a></li> - - -<li class="ifrst">Field-mouse, <a href='#Page_154'>154</a>-9</li> - -<li class="indx">Fig-moth, <a href='#Page_114'>114</a>;</li> -<li class="isub1">ravages of, <a href='#Page_117'>117</a>-22;</li> -<li class="isub1">prevention of infection by, <a href='#Page_123'>123</a></li> - -<li class="indx"><i>Filaria</i>, <a href='#Page_47'>47</a></li> - -<li class="indx"><i>Filaria rhytipleurites</i>, <a href='#Page_21'>21</a></li> - -<li class="indx"><i>Filaria labiato-papillosa</i>, <a href='#Page_131'>131</a></li> - -<li class="indx">Finlay (of Havana), <a href='#Page_104'>104</a></li> - -<li class="indx">Finsch, <a href='#Page_53'>53</a></li> - - -<li class="ifrst">Gardiner, J. Stanley, <a href='#Page_73'>73</a></li> - -<li class="indx">Gesner, <a href='#Page_136'>136</a></li> - -<li class="indx">Gleichen-Russworm, von, <a href='#Page_73'>73</a></li> - -<li class="indx">Grassi, <a href='#Page_54'>54</a>, <a href='#Page_55'>55</a>, <a href='#Page_68'>68</a>, <a href='#Page_77'>77</a>, <a href='#Page_78'>78</a>, <a href='#Page_79'>79</a>, <a href='#Page_84'>84</a></li> - -<li class="indx">Gray, <a href='#Page_58'>58</a><span class="pagenum" id="Page_162">[Pg 162]</span></li> - - -<li class="ifrst">Hadwen, Dr., <a href='#Page_31'>31</a>, <a href='#Page_32'>32</a></li> - -<li class="indx"><i>Halobates</i>, <a href='#Page_2'>2</a></li> - -<li class="indx">Helm, <a href='#Page_135'>135</a></li> - -<li class="indx">Hewitt, T. R., <a href='#Page_36'>36</a></li> - -<li class="indx">Hindle, Mr., <a href='#Page_131'>131</a></li> - -<li class="indx">Howard, <a href='#Page_58'>58</a>, <a href='#Page_71'>71</a>, <a href='#Page_74'>74</a>, <a href='#Page_77'>77</a>, <a href='#Page_94'>94</a></li> - -<li class="indx"><i>Hypoderma</i>, <a href='#Page_25'>25</a>, <a href='#Page_28'>28</a></li> - -<li class="indx"><i>Hypoderma bovis</i>, <a href='#Page_31'>31</a>, <a href='#Page_32'>32</a>;</li> -<li class="isub1">eggs of, <a href='#Page_34'>34</a></li> - -<li class="indx"><i>Hypoderma lineatum</i>, <a href='#Page_31'>31</a>, <a href='#Page_32'>32</a>;</li> -<li class="isub1">eggs of, <a href='#Page_34'>34</a>, <a href='#Page_38'>38</a></li> - - -<li class="ifrst">Imms, Mr., <a href='#Page_31'>31</a></li> - -<li class="indx">Infantile paralysis (poliomyelitis), <a href='#Page_132'>132</a></li> - -<li class="indx">Irish Department of Agriculture, <a href='#Page_36'>36</a></li> - -<li class="indx">Ismailia, <a href='#Page_98'>98</a></li> - - -<li class="ifrst">Jenyns, <a href='#Page_136'>136</a>, <a href='#Page_141'>141</a></li> - -<li class="indx">Johnston (of Baltimore), <a href='#Page_65'>65</a>, <a href='#Page_66'>66</a>, <a href='#Page_67'>67</a></li> - -<li class="indx">Joly, <a href='#Page_74'>74</a></li> - - -<li class="ifrst">Kerschbaumer, <a href='#Page_57'>57</a></li> - - -<li class="ifrst">Lantz, Dr., <a href='#Page_147'>147</a> <i>n.</i></li> - -<li class="indx">Larva, of bot-flies, <a href='#Page_28'>28</a>, <a href='#Page_35'>35</a>;</li> -<li class="isub1">of mosquitos, <a href='#Page_80'>80</a>-5, <a href='#Page_90'>90</a>, <a href='#Page_91'>91</a>, <a href='#Page_97'>97</a>;</li> -<li class="isub1">of yellow-fever mosquito, <a href='#Page_107'>107</a>;</li> -<li class="isub1">of stable-fly, <a href='#Page_130'>130</a></li> - -<li class="indx">Latter, <a href='#Page_4'>4</a></li> - -<li class="indx">Lazear, Dr., <a href='#Page_105'>105</a></li> - -<li class="indx">Lefroy, Prof., <a href='#Page_63'>63</a></li> - -<li class="indx">Liverpool School of Tropical Medicine, <a href='#Page_55'>55</a></li> - -<li class="indx">Lyddeker, <a href='#Page_146'>146</a></li> - - -<li class="ifrst">Malaria, <a href='#Page_48'>48</a>, <a href='#Page_104'>104</a>;</li> -<li class="isub1">prevention of, <a href='#Page_98'>98</a></li> - -<li class="indx">Maxim, Sir Hiram, <a href='#Page_75'>75</a></li> - -<li class="indx">Mayer, <a href='#Page_67'>67</a></li> - -<li class="indx">Miall and Denny, <a href='#Page_5'>5</a></li> - -<li class="indx"><i>Microlepidoptera</i>, <a href='#Page_116'>116</a> <i>n.</i></li> - -<li class="indx">Morrell, Dr. C. Conyers, <a href='#Page_21'>21</a>, <a href='#Page_23'>23</a></li> - -<li class="indx">Moseley, Prof., <a href='#Page_16'>16</a></li> - -<li class="indx">Mosquitos, biting apparatus, <a href='#Page_43'>43</a>;</li> -<li class="isub1">wings, <a href='#Page_50'>50</a>;</li> -<li class="isub1">hibernation of female, <a href='#Page_54'>54</a>;</li> -<li class="isub1">food of, <a href='#Page_64'>64</a>-7;</li> -<li class="isub1">experiments with, <a href='#Page_60'>60</a>-3, <a href='#Page_67'>67</a>-8;</li> -<li class="isub1">how to avoid, <a href='#Page_63'>63</a>-4;</li> -<li class="isub1">auditory organs of, <a href='#Page_65'>65</a>;</li> -<li class="isub1">buzzing of, <a href='#Page_68'>68</a>-74;</li> -<li class="isub1">eggs of, <a href='#Page_76'>76</a></li> - -<li class="indx">Moufet, <a href='#Page_3'>3</a></li> - -<li class="indx"><i>Muridae</i>, <a href='#Page_154'>154</a>, <a href='#Page_156'>156</a></li> - -<li class="indx"><i>Mus</i> or <i>Epimys</i>, <a href='#Page_135'>135</a></li> - -<li class="indx"><i>Mus rattus</i> or <i>Epimys rattus</i>, <a href='#Page_135'>135</a> <i>n.</i>, <a href='#Page_136'>136</a>, <a href='#Page_139'>139</a>, <a href='#Page_144'>144</a>, <a href='#Page_145'>145</a></li> - -<li class="indx"><i>M. decumanus</i> or <i>Norvegicus</i>, <a href='#Page_135'>135</a> <i>n.</i>, <a href='#Page_137'>137</a>, <a href='#Page_140'>140</a>, <a href='#Page_141'>141</a>, <a href='#Page_142'>142</a>, <a href='#Page_145'>145</a></li> - -<li class="indx"><i>M. alexandrinus</i>, <a href='#Page_140'>140</a></li> - -<li class="indx"><i>Musca domestica</i>, <a href='#Page_125'>125</a>, <a href='#Page_126'>126</a></li> - - -<li class="ifrst">Neumann, R. O. and O., <a href='#Page_109'>109</a></li> - -<li class="indx">Nuttall, Professor, <a href='#Page_47'>47</a>, <a href='#Page_52'>52</a>, <a href='#Page_54'>54</a>, <a href='#Page_56'>56</a>, <a href='#Page_57'>57</a>, <a href='#Page_58'>58</a>, <a href='#Page_71'>71</a>, <a href='#Page_77'>77</a></li> - - -<li class="ifrst">Ormerod, Miss, <a href='#Page_28'>28</a>, <a href='#Page_30'>30</a></li> - -<li class="indx"><i>Oestridae</i> (bot-flies), <a href='#Page_28'>28</a></li> - - -<li class="ifrst">Pennant, <a href='#Page_138'>138</a>, <a href='#Page_139'>139</a>, <a href='#Page_141'>141</a></li> - -<li class="indx">Perez, J., <a href='#Page_71'>71</a>, <a href='#Page_72'>72</a></li> - -<li class="indx"><i>Periplaneta orientalis</i>, <a href='#Page_4'>4</a>, <a href='#Page_5'>5</a>, <a href='#Page_16'>16</a></li> - -<li class="indx"><i>P. americana</i>, <a href='#Page_4'>4</a></li> - -<li class="indx"><i>P. germanica</i>, <a href='#Page_5'>5</a>, <a href='#Page_16'>16</a></li> - -<li class="indx">Plague conveyed by rats, <a href='#Page_149'>149</a></li> - -<li class="indx">Port Swettenham, <a href='#Page_98'>98</a></li> - -<li class="indx"><i>Ptinidae</i>, <a href='#Page_111'>111</a></li> - -<li class="indx">Pupa of mosquitos, <a href='#Page_92'>92</a>-5, <a href='#Page_97'>97</a></li> - -<li class="indx"><i>Pyralidae</i>, <a href='#Page_116'>116</a> <i>n.</i></li> - - -<li class="ifrst">Rats, black, or Old-English, <a href='#Page_137'>137</a>;</li> -<li class="isub1">brown, <a href='#Page_141'>141</a>;</li> -<li class="isub1">ravages of <a href='#Page_145'>145</a>-9;</li> -<li class="isub1">estimated annual damage by, <a href='#Page_149'>149</a>;</li> -<li class="isub1">diseases conveyed by, <a href='#Page_149'>149</a>;</li> -<li class="isub1">destruction of, <a href='#Page_150'>150</a>, <a href='#Page_152'>152</a>;</li> -<li class="isub1">in the trenches, <a href='#Page_151'>151</a></li> - -<li class="indx">Reed, Dr. Walter, <a href='#Page_105'>105</a></li> - -<li class="indx">Ross, Sir Ronald, <a href='#Page_97'>97</a>, <a href='#Page_98'>98</a>, <a href='#Page_104'>104</a></li> - - -<li class="ifrst">Sam Browne belts, <a href='#Page_26'>26</a></li> - -<li class="indx"><i>Sigmodon</i> (rice-rat), <a href='#Page_140'>140</a> -<span class="pagenum" id="Page_163">[Pg 163]</span></li> -<li class="indx">Smyrna, Report of the fig-moth in, <a href='#Page_114'>114</a> <i>n.</i></li> - -<li class="indx">Smyth, E. G., <a href='#Page_118'>118</a></li> - -<li class="indx"><i>Sphex</i> (or <i>Chlorion</i>), <a href='#Page_20'>20</a></li> - -<li class="indx"><i>Spirogyra</i>, <a href='#Page_84'>84</a></li> - -<li class="indx">Stable-fly, <a href='#Page_125'>125</a>;</li> -<li class="isub1">food of, <a href='#Page_128'>128</a>;</li> -<li class="isub1">diseases conveyed by, <a href='#Page_131'>131</a>, <a href='#Page_132'>132</a></li> - -<li class="indx"><i>Stegomyia calopus</i> or <i>fasciata</i>, <a href='#Page_101'>101</a>, <a href='#Page_105'>105</a>;</li> -<li class="isub1">domesticated, <a href='#Page_108'>108</a>;</li> -<li class="isub1">bites of, <a href='#Page_108'>108</a>, <a href='#Page_110'>110</a></li> - -<li class="indx"><i>Stomoxys calcitrans</i> (stable-fly), <a href='#Page_125'>125</a>;</li> -<li class="isub1">distribution of, <a href='#Page_127'>127</a>;</li> -<li class="isub1">eggs of, <a href='#Page_129'>129</a>;</li> -<li class="isub1">diseases conveyed by, <a href='#Page_131'>131</a>, <a href='#Page_132'>132</a>, <a href='#Page_133'>133</a>;</li> -<li class="isub1">extermination of, <a href='#Page_133'>133</a></li> - -<li class="indx"><i>Symbius blattarum</i>, <a href='#Page_21'>21</a></li> - - -<li class="ifrst">Thayer, Dr., <a href='#Page_53'>53</a></li> - -<li class="indx">Thomas, Oldfield, <a href='#Page_140'>140</a></li> - -<li class="indx"><i>Trichinella spiralis</i>, <a href='#Page_149'>149</a></li> - -<li class="indx"><i>Trypanosoma</i>, <a href='#Page_131'>131</a></li> - - -<li class="ifrst">‘Warbled’ hides, <a href='#Page_30'>30</a></li> - -<li class="indx">Watson, Dr. Malcolm, <a href='#Page_98'>98</a></li> - -<li class="indx">Weaver, A. de P., <a href='#Page_74'>74</a>, <a href='#Page_75'>75</a></li> - -<li class="indx">Weinland, <a href='#Page_73'>73</a></li> - -<li class="indx">Whelan, R. G., <a href='#Page_37'>37</a></li> - -<li class="indx">White, Gilbert, <a href='#Page_5'>5</a></li> - -<li class="indx">Wilson, Edwin, <a href='#Page_69'>69</a>, <a href='#Page_73'>73</a></li> - - -<li class="ifrst"><i>Xestobium tessellatum</i>, <a href='#Page_111'>111</a></li> - - -<li class="ifrst">Yellow-fever, <a href='#Page_101'>101</a>-3;</li> -<li class="isub1">localities affected by, American commission on, <a href='#Page_105'>105</a></li> - -<li class="indx">Yellow-fever mosquito, <a href='#Page_101'>101</a>, <a href='#Page_104'>104</a>;</li> -<li class="isub1">metamorphosis of, <a href='#Page_109'>109</a></li> - -<li class="indx">Yersin, <a href='#Page_149'>149</a></li> -</ul> -</div> - - -<p> -AT THE BALLANTYNE PRESS<br /> -PRINTED BY SPOTTISWOODE, BALLANTYNE AND CO. LTD.<br /> -COLCHESTER, LONDON AND ETON<br /> -</p> - - -<div class="footnotes"><h3>FOOTNOTES:</h3> - -<div class="footnote"> - -<p><a id="Footnote_1" href="#FNanchor_1" class="label">[1]</a> <i>The Transformation of Insects</i>, by P. M. Duncan. London: -Cassell, Petter, Galpin and Co., 1882.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_2" href="#FNanchor_2" class="label">[2]</a> From the Portuguese ‘cuspidor.’ Cf. the Latin ‘conspuere.’</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_3" href="#FNanchor_3" class="label">[3]</a> <i>British Medical Journal</i>, 1911, ii. 1531.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_4" href="#FNanchor_4" class="label">[4]</a> <i>The Irish Naturalist</i>, October 1914.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_5" href="#FNanchor_5" class="label">[5]</a> This is a fact I have always tried to conceal from Mrs. -Pankhurst; but, sooner or later, she is bound to find it out.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_6" href="#FNanchor_6" class="label">[6]</a> Owing to the recent restrictions on imported fruit imposed -by the Government the food of these beautiful little insects will -be further diminished. But what does our Government know or -care about insects?</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_7" href="#FNanchor_7" class="label">[7]</a> <i>Compt. Rend. Acad. Paris</i> (1878), lxxxvii, p. 378.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_8" href="#FNanchor_8" class="label">[8]</a> <i>Compt. Rend. Acad. Paris</i> (1878), lxxxvii, p. 535.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_9" href="#FNanchor_9" class="label">[9]</a> <i>Zeit. f. wissensch. Zool.</i> (1891), li, p. 55.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_10" href="#FNanchor_10" class="label">[10]</a> <i>Geschichte der gemeinen Stubenfliege.</i> Nuremberg, 1764.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_11" href="#FNanchor_11" class="label">[11]</a> If you have a beard.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_12" href="#FNanchor_12" class="label">[12]</a> Modern systematists now call the biscuit-‘weevil’ <i>Sitodrepa -panicea</i>.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_13" href="#FNanchor_13" class="label">[13]</a> The figures illustrating this article are taken from <i>The Report -of the Fig-moth in Smyrna</i>, Bul. 104. Bureau of Entomology, -Washington, 1911.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_14" href="#FNanchor_14" class="label">[14]</a> It might be well to repeat the fact that the genus <i>Ephestia</i> -belongs to the family <i>PYRALIDAE</i>, which is by most authorities -included in the <i>Microlepidoptera</i>. The Speaker’s sneer at the entomologists -who work at this group (see his letter in <i>The Times</i> of -February 2, 1916) is hardly worthy of one of the chief trustees of -the British Museum. As a chief trustee, he must have been aware -of the exhibit of the Microlepidoptera, <i>E. kühniella</i>, and its devastating -action on the biscuits supplied to our soldiers by the War Office, -which has for many months occupied a prominent position in the -middle of the central hall of the Natural History Museum at South -Kensington. This exhibit showed how closely the study of the -Microlepidoptera is associated with the food-supply of our soldiers -in many parts of the world.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_15" href="#FNanchor_15" class="label">[15]</a> The modern systematist now calls the black rat <i>Epimys rattus</i>, -and distinguishes two varieties—<i>E. rattus alexandrinus</i> and <i>E. -rattus rattus</i>; the brown rat is now <i>E. norvegicus</i>.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_16" href="#FNanchor_16" class="label">[16]</a> <i>A History of British Quadrupeds</i>, 2nd ed. London, 1874.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_17" href="#FNanchor_17" class="label">[17]</a> London, 1833.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_18" href="#FNanchor_18" class="label">[18]</a> <i>British Zoology.</i> London, 1812.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_19" href="#FNanchor_19" class="label">[19]</a> Ovalle’s ‘History of Chili,’ in <i>Churchill’s Voyages</i>, vol. iii, p. 45.</p> - -</div> - -<div class="footnote"> - -<p><a id="Footnote_20" href="#FNanchor_20" class="label">[20]</a> ‘An Economic Study of Field-mice (Genus <i>Microtus</i>).’ By -Dr. Lantz, in <i>U.S. Dept. of Agric., Biol. 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