FRONTISPIECE. Map of India. The black shading indicates the Himalayan and Palearctic portions to the North and, in India, areas above the dividing line of tropical and sub-tropical India, usually above 2,000 feet. The dotted black line to the North is the political boundary, inclusive of Cashmir and Sikkim. The red lines and lettering indicate the faunal zones of Tropical India as described in the Section on Geographical Distribution below. The dotted lines dividing the West Coast indicate probable sub-regions and correspond to the Palghat and Goa gaps in the Ghauts. Sub-tropical faunal zones are not indicated. . . • ■ ' 1 v ■ /' ll . • ' . . . in ",ti i/ilii'ii.; V'.;: ■qtfjbfvib Yiv< ' in b tbs’- . '.*■ • ■: i • i i‘. >h v bT /- X1..V vi:;p. .*i i ' to m /fei b/tfi ' , ,>n •UujUH ’ ■ < ! '.b. ' :lOti Y'r1: i y ■ , >• : ' - ' :M; ; ' ’• ' ; -V v>-'l , U/> ib\oC:/bi •••/. ; dji -i p:io'4 • ■ ? i i h»d( ‘ -jmh j„ : t 1 1 / "•. ■; : >i J ! i - Ion INDIAN INSECT LIFE A MANUAL OF THE INSECTS OF THE PLAINS (TROPICAL INDIA) BY FT: MAXWELL-LEFROY, M.A., F.E.S., F.Z.S., Entomologist , Imperial Department of Agriculture for India; Author of “ Indian Insect Pests , ” etc Assisted by F. M. HOWLETT, B.A., F.E.S., Second Entomologist, Imperial Department of Agriculture for India [ Published under the Authority of the Government of India] AGRICULTURAL RESEARCH INSTITUTE, PUSA CALCUTTA & SIMLA THACKER, SPINK & CO W. THACKER & CO., 2, Creed Lane, London PRINTED BY THACKER, SPINK AND COMPANY, CALCUTTA. “ Plus je connais les peuples, Plus j* aime les insectes.” ACKNOWLEDGMENTS. The sections on Mallopliaga , Diptera , Cimicidce and A noplura have been prepared by Mr. Howlett, and the Interlude on Insects and Flowers by Mr. I. H. Burkill, Reporter on Economic Products. Illus¬ trations marked I. M.N. are from the stock of drawings accumulated by my predecessors in the Indian Museum, and used in Indian Museum Notes. Those marked F. M. H. have been drawn by Mr. Howlett, who has directed the preparation of those illustrating the sections he has written. Where not otherwise acknowledged, all the plates and illustrations are the work of the Artist staff of this Institute under my or Mr. Howlett’s direction ; it may be pointed out that these artists are wholly Natives of India, trained in Art Schools of this country ; it is needless to emphasise how much the book owes to their beautiful work as also to the enterprise of the publishers, who have done the work of reproducing all the illustrations in this country. I wish to specially express my appreciation of the work of Mr. Slater of the Calcutta Phototype Company in the printing of the Colour Plates, carried out under very trying climatic conditions and for the first time in this country. As regards the text, it is, where not stated to be a quotation, orig¬ inal ; 1 have acknowledged every direct source of information. The book owes something to the work of my staff, since it is based on the Pusa collections to which they have contributed specimens and observ¬ ations. I have acknowledged this where I can. The volume is largely a product of my spare time and scanty holidays ; such a volume has been so much required that I have felt that even an imperfect one was better than none. Six years ago the work of this section commenced and if the book contains imperfections, the critic will recog¬ nise that it is based on collections, observations and reference books that have been accumulated only in that short time ; I shall be glad if those who see omissions or errors will point them out, as it may be that a better volume will be built up on this basis, when the study of Indian Entomology is further advanced. I may also emphasise the fact that where little is said, little is known and the blanks in the book are VI ACKNOWLEDGMENTS. designedly prominent to emphasise the enormous scope there is for work. I trust also that the volume may be a real stepping-stone to better things and may help those who are advancing our knowledge of the insect life of India. Pcsa : ] June , 1909. | H. M. L. CONTENTS Page. Acknowledgments Classification adopted Introduction . . . . . . . . . . 1 Diagnosis . . . . . . . , . . 1 Zoological position . . . . . . . . 2 Instinct and Habit . . . . . . . . 2 Classification . . . . . . . . 10 Number of species . . . . . . . . 14 Nomenclature . , . . . , . . 15 Identification . . . . . . . . . . 15 Entomology in India . . . . . . . . 17 Zoo-geographical Divisions . . . . , . . . 20 Food and Habitat . . . . . . . . 27 Insects and Man . . . . . . . . 35 Aptera . . . . . . . . . . 43 Orthoptera . . . . . . . . . . 47 Where Insects live . . . . . . . . 54 Cosmopolitan Insects . . . . . . . . 62 Deceptive Colouring . . . . . . . . 90 Attraction to light . . „ . . . . . 106 Neuroptera . . . . . . . . . . 108 Gregariousness . , . . . . . . 123 Aquatic Insects . . . . . . . . 131 Relative Duration of Life . . . . . , . . 140 Hymenoptera . . . . . . . . . . 161 Galls . . . . . . . . 167 Size of Insects . . . . . . . . . . 169 Sex . . . . . - . . . . 188 Insects and Flowers . . . . . . . . 222 COLEOPTERA . . . . . . . . . . 234 Myrmecophilous Insects . . . . . . . . 268 Insects as Food .. .. .. .. 276 Lepidoptera . . . . . . . . . . 397 Migration . . . . . . . . . . 419 Emergence from the Cocoon . . . . . . 481 Silk .. .. .. .. ..485 How Insects protect themselves . . . . . . 521 viii contents. Thysanoptera . . . . . . . . . . 542 Diptera . . . . . . . . . . . . 545 Blood-sucking Insects . . . . . . . . 659 Rhynchota . . . . . . . . . . . . 665 Song in Insects . . . . . - . , . . 720 Index of Plants . . . . . . . . . . 765 General Index . . . . . . . . . . 773 SCHEME OF CLASSIFICATION. The following is a complete list of the families into which insects are divided, tabulated under orders. The families in heavy type, thus Forfioulidse should be familiar ; those in ordinary type, thus Campodeidse, are of smaller importance but occur in India : those in italics, thus Smynthuridce, are not yet known to occur in India. APTERA Page. 43 Thysanura. Camped eidu , . 43 Japygidse 44 Maehilid* 44 Lepismidse 45 COLLRMBOLA. Lipuridae 46 Poduridse 46 Smynthuridce . Neelidce. ORTHOPTERA 47 0URSORIA. Forficulidse . . 49 Hemimeridw Blattidee 56 Mantidee 64 Phasmidse 71 Saltatoria. Aoridiidse . . 74 Locustidse . . 91 Gryllidee 97 NEUROPTERA 108 PSEUDONEUROPTERA. Mallophaga . . 110 Ernbiidse 112 Termitidse 115 Psocidee 121 ■ Amphibiotica. PerHdse 124 Page. Odonata 125 Ephemeridae . . 137 Planipennia. Sialidae 143 Panorpidae . . 145 ■Hemerobiidee 146 Trichoptera 157 HYMENOPTERA 161 SESSILI VENTRES 164 Gephidoe Siricidse 164 Tenthredinidee 164 Parasitica 165 Cy rn pi die 166 Proctotrypidse 168 Dryinidse 170 Chalcidee 172 Ichneumonidre 177 Braoonidee 178 Stephaniidse 180 Megalyridce Evaniidse 180 Pelecinidce. Trigonalidse 181 Tubulifera. Chrysidse 182 Aculeata, Fossores. Mutillidse 185 Thynnidse 192 Scoliidse 192 X SCHEME OP CLASSIFICATION. Page. Sapygidce Pompilidae 194 Sphegidse . . . . 199 Diploptera. Eumenidse . . • • 210 Yespidae Masaridee. 213 Anthophila. Colletidae . . 216 Apidae . . 217 Heterogyna. Pormicidae 224 COLEOPTERA 234 Lamellicornia. 241 Passalidae 242 Lucanidae 243 Scarabaeidae 245 Melolonthidae 252 Adephaga. Gicindelidae 259 Carabidae 262 Paussidae 266 Rbysodidae . . Amphizoidce. 272 Pelobiidce. Dytiscidae . . 272 Haliplidae 279 Gyrinidae 280 Polymorpha. 281 Hydrophilidae Platypsyllidce. Leptinidce. 283 Silphidae 286 Scydmaenidae 287 Gnostidce. Pselaphidae . . 287 StaphyliDidae Sphceriidce. 288 Trichopterygidae Hydroscaphidce. 291 Corylophidae 292 Scaphididae . . Synteliidce. 292 Histeridae . . 292 Phalacridae . . , # 294 Nitidulidae . . , , 295 Cossypbodidae • . 297 Page. Colydidae . . . . 298 Lathridiidae . . . . 298 Trogositidae . . 299 Monotomidae . . 300 Cucujidae . . . . 300 Cryptophagidae . . 302 Helotidae . . . . 302 Thorcitidae . . . . 302 Erotylidae . . . . 302 Mycetophagidae . . 303 Coecinellidae . . 303 Endomycliidae . . 309 Mycetceidce. A dimer idee. Dermestidse. . . . 310 Byrrhidae .. .. 311 Cyathoceridce. Georyssidae . . . . 312 Heteroceridae . . . . 312 I Parnidae . . . . 313 Derodontidce. Cioidae . . . . 313 Sphindidce. Bostrichidae . . 313 Ptinidae . . . . 317 Malacodermata. Malacodermidae 319 Cleridae . . . . 325 Lymexylonidae . . 327 Rhagophthalmidae 327 Dascillidae . . . . 327 Rhipiceridae . . . . 327 Sternoxi. Buprestidae. . . . 328 Throscidae . . . . 331 Eucnemidae . . . . 331 Cerophytidce. Elateridse . . . . 332 j Dicronychidae . . 334 Plastoceridoe . Cebrionidae . . . . 334 Heteromera. Tenebrionidae . . 335 Cistelidae . . . . 339 Lagriidae . . . . 340 Othniidae . . . . 340 Aegialitidce. Monommidae . . . . 340 SCHEME OF CLASSIFICATION. XI Page. Nilionidce. Pythid® . . . . 341 Melandryid® . . . . 341 Pyrockroid® . . . . 341 Antkicid® . . . . 342 Oedemeridse . . 342 Mordellid® . . . . 343 Cantharidse. . . . 343 TrictenotomidsB . . 347 Phytophaga. Bmchidee . . . . 349 Ohrysomelidee . . 351 Oerambycidee . . 368 Rhynchophora. Anthribid® . . . . 379 OureulionidsB . . 380 Brenthid® . . . . 392 Seolytid® . . . . 393 Agly cyder idee. Proterhinidce . Stylopid® . . . . 395 LEPIDOPTERA . . 397 Rhopalgoera . . 401 Nymphalidse . . 404 Memeobiid® . . 415 Pieridse . . . . 416 Papilionidee . . 421 Lyceenidse . . . . 423 Hesperiidse . , 429 Heterocera . . 432 Syntomidae . . 433 Arctiidse . . . . 434 Agaristid® . . 439 Moctuidse . . 440 Pterotliysanid® . . . 458 Lyman true m . . 459 Hypsidas . . 462 Sphingidse . . 464 Oymatopkorid® . . 469 B'upterotidse . . 470 Notodontid® . . 471 Geometrid® . . 473 Saturniidse . . 475 Bombyetdee . . 483 Brahmeid® . . . . 490 Ceratocampidoe. TJraniid® . . . . 490 Psychidae . , . . 491 Heterogynidw . Arbelidee Page. 493 Argymtypidce. R a tar did® # • 494 Oossidae • • 494 Lasiocampid® . . 496 Endromidoe. Chrysopolomidw. Perophoridce . Meg atopy gidw.. Limacodid® 498 Dalceridw . Neocastniid® 501 Castniidoe. Euschemonidce. Microlepidoptera 501 Zyg®nid® 502 Callidulid® 504 Drepanid® . . ^04 Thyridid® 505 Pyralidse • . 505 Orneodid® 526 Pterophoridse 526 Sesiid® 528 Tortricidae 529 Tineidse 531 Protolepidoptera. Hepiaiid® 541 Micropterygidcs . 1 THYSAHOPTERA 542 Terebrantia. Aeolotkripid® 544 Tbripid® 544 Tubulifera. P hi® o t imp id® 544 ! DIPTERA 545 1 Orthorhapha Nemocera 554 Psychodidse 557 CMronomidee 560 OulioidsB 564 ! Dixid® 576 Blepharocerid® 576 Tipulidee ♦ * 578 Ceoidomyiidse 580 Mycetophilid® 583 Bibionid® • * 586 Simuliide© ♦ t 587 Xll SCHEME OF CLASSIFICATION. Orphnephilidae Rhyphidae Orthorhapha Brachycera. Stratiomyidae Leptidae Tabanidae. Cyrtidae Nemestrinidae Bombyliidae Apioceridae Scenopinidae Therevidae Mydaidae Asilidae Empidae Dolichopodidae Pboridae Lonchopteridcz Cyclorhapha Aschiza. Syrphidae Platypezidae Pipunculidae Cyclorhapha Schizophora. Acalyptrate Muscoids Calyptrate Muscoids Oestridae PUPIPARA. Hippoboscidae. Streblidce Nycteribiidae Braulidae SlPHONAPTERA. Pulicidae RHYNCHOTA Heteroptera Gymnocerata PentatomidaB Ooreidae Page, 679 Berytidoe 685 Lygaeidae . . 685 Pyrrhocoridae 690 Tingidae 692 Aradidae 693 Hebridae 693 Hydrometridae 694 Henicocephalidae 696 Phymatidae 696 Saldidae 696 Reduviidae . . 697 Aepophilidce Ceratocombidae 702 Oimicidae . . 702 Anthocoridae 705 Polyctenidae 705 Oapsidae 705 Cryptocerata 709 Pelogonidae . . 709 Nepidae 710 Naucoridae . . 712 Belostomidas 713 Notonectidae 715 Oorixidae . . 716 Homoptera 717 Oicadidae 718 Fulgoridae 722 Membracidae 729 Cercopidae . a 732 Jassidae 734 Phytophthires 740 Psyllidae 742 Aphidae 743 Aleurodidae. . 748 Cocci dee 752 Pediculid^i 762 Page. 589 589 589 591 592 595 596 597 600 600 601 602 602 605 606 608 609 610 612 612 614 617 641 651 654 656 657 657 665 667 667 668 INDIAN INSECT LIFE. INTRODUCTION. The insects are tracheate, hexapodons arthropoda, with a distinct head bearing antennae, with a great degree of complexity in their devel¬ opment during which a series of moults are undergone, culminating in the appearance of functional generative organs and wings ; in the higher forms, the development is sharply divided into three distinct periods, the last of which is marked by the inactivity of the organism as a whole and the complete reorganisation undergone by the tissues ; they are essentially air-breathing animals, living on land, but some have become adapted to living in fresh water. The number of jointed legs separates them clearly from other tracheate Arthropods, just as the metamorpho¬ sis, the possession of wings and the form and the number of segments does. They are regarded as being most closely related to Peripatus of all present forms of life, and undoubtedly represent a great branch of the tree of life whose development equals, if not excels, that of any other branch. In numbers, in species, in all but one form of mentality, the insects are the dominant form of life on the land at the present time, but the limitations put on them are of such a nature that their dominance must remain within bounds and, unless man be removed, cannot be actual and entire. Insects are of all sizes from inch long to over six inches ; their numbers are incalculable, the number of their species being put at about three millions ; their lives are very short, (a week,) up to as long as over ten years, though rarely actually exceeding more than three years, and being in the larger number limited to an active life of less than three months. On the surface of the earth, as in fresh water, they are found wherever nutriment is available, even in the bodies of warm-blooded animals and man ; over the three-fourths of the earth’s surface covered by the sea they are practically non-existent, a very small number of IIL 1 2 INTRODUCTION. species being able to support life near, in or on the sea. Their position in the animal world is shown in the table : — Protozoa. Porifera (Sponges). Ccelenterata (Anemones, etc.). Ctenophora (Jelly-fish, etc.). Echinodermata (Sea-urchins and starfish). Vermes (Worms). POLYZOA. Arthropod a. — Crustacea (Lobsters, etc.) Prototracheata (Peripatus). Myriapoda (Centipedes and millipedes). Insecta (Insects). Arachnida (spiders, mites, scorpions, etc.). Mollusc a (Snails, etc.). Brachiopoda. Chordata. — Hemichordata. Tunicata. Cephalochordata. Craniata. Cyclostomata. Pisces (Fish). Amphibia (Frogs). Reptilia (Snakes, etc.). Aves (Birds). Mammalia (Mammals). Economically, the insects are the most important group of animals next to the Mammals, Birds and Fishes. Their activities affect man daily, either from the nature and extent of their injuries to economically valuable plants, or to domestic animals, or to wild animals, or to stored produce, or from their value in yielding useful products ; or from the part they play in the economy of nature, in fertilising flowers, in scaveng¬ ing and cleansing the earth, in rendering waste matter available as plant food, in preserving the condition of the soil and in furnishing food for birds and fishes. Instinct and Habit. — What is the life of an insect ? In what way can it be compared with our own or with the life, for instance, of any of INSTINCT AND HABIT. 3 the animals familiar to ns ? No answer can be easily given, for the senses, the instincts, the modes of expression of insects are so totally diverse from onr own that there is scarcely any point of contact. In the case of mammals, of birds and to some extent of reptiles, we have in the eyes, in the features and in the movements, a clue to their feelings, to the emotions that sway them, to the motives that guide their actions ; in insects we have none, and the great index of insect feeling, the antenna, has no counterpart in higher animals, and conveys nothing to our un¬ informed brains. We can judge then only from the movements of in¬ sects, from their actions, and this is so extraordinarily meagre a clue that it is not surprising that even the greatest familiarity with the life of an insect inspires no feeling that one has to do with a live organism having feelings and passions, having motives and a will, but suggests that one has before one a beautiful machine, tuned to respond mechanically to certain outside stimuli, to answer to particular influences and to behave in all things as a perfect mechanical structure ; even the highest, the social insects and the fossorial wasps, inspire no other feelings, give one no sense of any relations between the individual insects but those mechanical ones concerned with daily life, and leave one with the conviction that the mentality of the higher animals is wholly absent, that no smallest trace of the emotions, of the will, of the thought processes of ourselves or other mammals, have any part in the lives of insects. Yet there are events in the lives of insects which, for a brief moment, impress us with the conviction that individuality, emotion and feeling may play their part ; and though we see this exceedingly seldom, the few suggestive phenomena may be sufficient to warrant the assump¬ tion that in ways we cannot comprehend, in channels that are beyond our ken, the living active insect is in touch with every other living insect in its environment, by mental and physical processes that make no out¬ ward sign, that may proceed independently of any external sense organ that we can see or study and which possibly pass from mind to mind with no outward physical action or movement ; what occurs when bees swarm, when locusts swarm, when the white ants emerge from the nest, when a stray bee from one nest enters another and is promptly attacked and killed ? Are these wholly due to reflex actions and mechanical instincts, or are they the product of an individual will and mind in each and every insect ; a locust swarm may be the product of a blind impulse 4 INTRODUCTION. sweeping over a host of insects just as a blind impulse ranges through a crowd of human beings by means which are certainly not normal or in daily use ; the emergence of the flying ants suggests a similar blind im¬ pulse, an unreasoned compliance with fixed instincts like the blowing up of a boiler when certain physical conditions are arrived at ; do the ants have councils and decide when the nest shall be moved to a new locality, or is it simply the common impulse of the community, simultaneously born of the same reaction to certain physical conditions ? So wide apart are our senses from those of insects, so divergent are our means of expression, and the mechanism of our bodies, that no answer can be given to these questions ; we cannot establish any connection with the individuality of insects, we can get no common basis of thought, no pos¬ sible means whereby even to 4 4 tame ’ ’ them or to get even so little response to our efforts as a tame bird will give. To us, the closest study of large numbers of the same species reveals no individuality, nothing but a mechanical sameness in a large number ; perhaps this is because we cannot get near enough ; to the ordinary man, sheep are sheep and while differing in small points are alike ; to the shepherd they are as individual as human beings and have a similar mental individuality ; I have never seen that this was the case with insects, and none that have been kept in activity, fed, cared for and most closely observed, have shown more than very small traces of individual mentality or even responded to advances. (That this is not the view every author takes is evident from the writings of naturalists who state that butterflies in particular become tame and welcome their captor’s visits ; but these cases are not sufficiently numerous or well authenticated to be valid.) It is not unreasonable to consider that, in freedom and living under natural surroundings, nearly every insect is solitary ; an individual insect appears to take no notice of any other, save such as it may prey on or parasitise ; it goes about its business of food-getting and the like, it makes no smallest sign that it is aware of the existence of any other insect, and so far as can be judged from its actions, is leading an abso¬ lutely and wholly solitary life ; there are exceptions, of course, but very few ; the social insects are apparent exceptions, but even there it is extremely doubtful how far individuals are not isolated ; they work to¬ gether it is true, but in a manner that suggests two machines under the same controlling conditions, not two sentient reasoning organisms acting INSTINCT AND HABIT. 5 in agreement due to any mental process. The same is true of termites, of locusts, of all the social insects which exhibit such wonderful phenomena. The Pyrrhocorid Iphita limbata is gregarious and lives in colonies on the bark of trees ; is there any communication, any individuality, any mental process other than a blind reaction to some outside stimulus, under which all alike find that a particular spot is perhaps the warmest or the best suited for some such reason ? There are other exceptions which are perhaps more valuable ; the courtship of butterflies is a beautiful thing, suggesting two perfectly happy beings enjoying to the full the delights of each other’s company and the perfect happiness of the crowning moment of life; there is no doubt of their being aware of each other’s presence, but the cold thought creeps in that it is after all a mechanical process, born of peculiar instincts, with nothing more c ‘ living ’ ’ than the reaction of two parts of an engine. The dances of flies and other small flying insects suggests mentality, social insects thoroughly enjoy¬ ing each other’s company and the extraordinary pleasure that huifran beings find in concerted movement ; it is possible that we can compare insects with ourselves in this respect, but the balance -of evidence is certainly against it ; one comes inevitably to the feeling that insects are a supreme expression of living matter adapted and co-ordinated to physical conditons, responding perfectly to mechanical stimuli, without mind or mental processes as we know them and as we can see them in birds and mammals ; they are the highest expression of life as evolved by natural processes, perfect machines without emotions. No thinking man questions the existence in higher mammals of mind-processes akin to our own if far lower, of some slight evidences of that higher mentality we call the soul, and which we hold to be the essential life, for which the objective life and the material body is but a case. No one would credit an insect with such forms of mentality, and the most sympathetic student of insect life has not advocated such a point of view. An insect is a living machine, responding to definite physical stimuli, with well- defined and very complex instincts, which are mechanical forms of mental action and take their origin in outward conditions. Were they possessed of higher forms of mentality, such as reason, judgment, voli¬ tion and the like, no one can say what might be the course of the world’s history ; a combination of the red ants (( Ecophylla smaragdina) could probably drive human beings out of India and render the continent 6 INTRODUCTION. uninhabitable to any form of life inimical to them ; an organised cam¬ paign of the common black ant ( Camponotus compressus) could effect a great deal and human methods of warfare would require to be revo¬ lutionised to deal with it. In practice we can consider insects as consisting of organisms whose actions will be definite responses to stimuli, whose movements and acti¬ vities will, under the same circumstances, be the same ; given the same conditions, all the individuals of a species will behave alike with only very minute variations which we have great difficulty in seeing. If we find that one of a species has a certain definite life history we are safe in concluding that under the same circumstances all of that species will have the same life history and that with a given departure from normal circumstances all will behave alike ; when we have worked out the life history and habits of one of a species, we can confidently assert that all will have that life history, with only small variations due to changed conditions ; a leaf- eating caterpillar that feeds on maize leaf in Behar, might quite well feed on juari leaf in Gujarat where maize is not grown, but it would not, for instance, become a borer in the Punjab and a pre¬ daceous caterpillar in Madras. We may, therefore, treat a species as an individual, and not expect to find different habits in different indivi¬ duals of the same species. At the same time we must allow for the variation consequent on changed conditions ; the limit of adaptation to changed conditions is a very variable one ; as an example, many cater¬ pillars have but a very few foodplants and cannot live on others ; a few have many, and the Gram Caterpillar ( Chloridea obsoleta) feeds on the seeds of gram, the heads of opium poppy, the heads of bajra or sunflower and a variety of other plants ; in the United States it is the boll worm feeding on the seed of cotton and accordingly has slightly different habits ; in this there is a certain amount of variation in habits due to changed foodplants. Such cases are frequent, but the variety of habits lies with¬ in perfectly clear and definite limits, varying slightly from species to species. On the above reasoning, a species is definable not only on structural characters but also on its habits and mode of life ; if we look on a species as composed of individuals reacting mechanically to stimuli, with a limited play of adaptation to changing conditions, habits and mode of life are as much specific characters as is structure ; if our struc¬ tural distinctions are sound, they will be in agreement with habits and INSTINCT AND HABIT. 7 life history, and the one aspect is as important as the other. Our know¬ ledge of structure is far greater than our familiarity with the habits of insects, but the latter will increase. It is all important for the student to grasp clearly from the beginning that a “ species” is a distinct indivi¬ dual as much in habits, mode of life and all details of its life as in its colour, form, or any structural detail on which it is declared to be a distinct species. We are here far more concerned with the living insect as a living reality than with the dead shell on which its place in the insect world is determined and on which it is described and named ; the characters of the living insect, its method of flight, its walk, its feeding habits, its expressive antennal movements, all the details of its daily life are of as great value as its structure and are of far greater importance to us in these pages ; a realisation of this fact and an understanding of what a species really is, must come to every student sooner or later if he is to become anything more than a systematist and a classifier of insects on purely structural details; the individuality of a species is as much discernable in the field as in the museum and takes in every detail of the insects life. For that reason, we have considered this abstruse point at some length and we would emphasize the point of view given, though it may seem at first sight an incorrect one. Variations in habits between two members of a species are so small that what we find out of a single individual, applies to every individual of that species with due allow¬ ance for variable conditions ; a very large part of our work lies in deter¬ mining how far different conditions modify the habits of an insect and the limits of this variation are becoming clearly established; if, therefore, the habits of an insect are observed in Peshawar, we know that the individuals of that species will have in the main the same habits at Madras, that we can predict the variations likely to be found, and that if we knew enough we could absolutely say how far they would differ. We may touch very lightly upon one more point ; whence come the instincts and beautiful habits of our present-day insects ? According to the accepted theories of evolution, insects, like other animals, are descended from more primitive forms of life which existed in earlier geologic periods; if we imagine the primitive types of insects being evolved and multiplying, and supposing them to feed on the abundant decaying vegetable matter, we shall get a great development of simpler forms scattered over large areas of land, and living in a diversity of physi- 8 INTRODUCTION. cal conditions ; remembering their less specialised and complex structure, we can see that the influence of altered conditions might produce great variations in structure, in habits, in life history ; the pressure of com¬ petition would arise, supposing there were fewer checks ; (what checks there may have been is doubtful but both parasitic and predaceous insects, as well probably as insectivorous birds arose later and these are now the main checks) ; some, from feeding on decaying vegetable matter, might come to feed on decaying animal matter, with a consequent change of habits, of structure, of senses, possibly of life history ; others might find growing plants provided an ample supply of food and their descendants gradually get modified to suit these circumstances ; in time we can imagine some becoming predaceous, the descendants perhaps of insects that fed on dead insects ; we can still see the stages between land and aquatic insects, and it requires little imagination to picture the necessary gradations from an insect feeding on decaying leaves by a riverside, to one that entered the river water and found its food there. Given a plastic structure capable of modification, granted grow¬ ing competition and a free unoccupied field, one can readily see how, in earlier ages, the various groups may have arisen ; with the alter¬ ing conditions of successive geologic periods, with the evolution of higher plants and animals, with alterations of climate and natural con¬ ditions, one can realise how the diversity of forms of insect life would be evolved. That this has occurred with other forms of life one can read ; that the steps cannot be traced so clearly in insects is due to the imperfection of the geological record, insects being small, soft and not so fitted for preservation as are bones or shells. Granting that in previous ages this occurred, and seeing the present dominance of insect life on the earth and in fresh water, it is easy to see that the competition might be so severe that more and more complex structures, instincts and habits might be evolved leading steadily away from plasticity to more and more fixed and unalterable types ; the more primitive and simple insect feeding on decaying leaves, having simple biting mouth- parts, laying eggs in the ground, requiring no special colouring or pro¬ tective devices disappeared ; predaceous insects require more complex trophi ; quick flight necessitates better wings and a more consolidated thorax ; protection from birds implies protective attitudes, colouring or form, and may require possibly the nocturnal habit, which implies INSTINCT AND HABIT. 9 better sense organs ; all crystallises down to a specialised form with fixed instincts. So too, for instance, with parasitic insects, the new habits imply new structure, the petiolate body and the ovipositor are developed to lay the eggs, and with the necessity for flying by day comes warning colouring and unpleasant taste or odorous glands, since birds are developed also and are taking to eating insects. Consider a Sphegid catching live insects, paralysing them, laying them up for its young ; imagine the development of such forms, the gradual acquirement of more and more perfect structures, and with them of more and more fixed instincts till we have the perfect insect, with intensely modified life history, with fixed and complex structure and with nearly all plasticity and power of change gone. This is the point I wish to make ; we are now at a stage in the earth’s history when competition has produced an amazingly complex number of forms of insect life, which adapted themselves to every condition of life but that in saltwater, which have, by the im¬ provement of more and more perfect forms, become increasingly complex, specialised and fixed ; variation, except in each special direction, makes for destruction ; from the increasing competition plasticity is gone, the forms are fixed and unalterable, and what may once have been forms of active mentality implying some choice, some volition, are now fixed instincts, crystallised reflex and, possibly, voluntary actions. It is true that all are not equally complex or special¬ ised, but I believe it to be true that almost all, simple or complex, are fixed, are no longer alterable except so minutely and so slowly that we can no longer see it. It is questionable whether there is any form with which we could people a part of the earth, say an island, that was abso¬ lutely devoid now of insect life, and in which we could see this process of differentiation and specialisation take place, but could we find such a form, could we give it the same free field and let it multiply and increase, we should get a similar differentiation and an ultimate specialisation of equally fixed forms. The student may read this for himself at greater length in text¬ books of palaeontology, geology and evolution ; he must realise it if he is to grasp the meaning and origin of the forms and habits of insects ; and in no other group is it so marked as in insects ; when we consider the abundance of forms of life in the insect world, their absolutely 10 INTRODUCTION. universal occurrence on land and in fresh water , the extraordinary variety in habits, food and ways of life, as compared with any other group or with all groups together, we can see that in no other class in the animal world is competition so keen, are instincts and habits so fixed, is the whole of life for each species so unalterable and delicate. Insects have lived, have dominated the earth, have become what we see them by carrying to an extreme the principle of adaptation to circumstances, of making the most of natural conditions ; man has become what he is, because he has carried to an extreme the principle of adapting natural conditions to himself while only adapting himself to them to a limited extent ; the two classes dominate the land, and when man cannot alter the conditions to make life permanently bearable, insects can adapt themselves and do. But in the process man has developed one form of mentality implied in the terms free-will, choice, volition, while insects have become perfect mechanical structures reacting in a definite way to natural forces and stimuli, their lives ruled by fixed and most perfect “ instincts.” It is not my intention to give the impression that instincts are absolutely fixed but only that they are fixed as compared with the plasti¬ city of earlier insects and as compared, say, with man. There is a certain latitude still, more in some groups than in others, but even in them not much and in the most specialised probably very little. I imagine that such simple forms as Machilis are fixed in their simple habits as compared with a Sphegid fixed in complex habits, but to both there is a certain small latitude within which they can still alter. The instincts of a polyphagous caterpillar such as Chloridea obsoleta are pro¬ bably much less fixed and specialised than are the instincts of the caterpillar of Scirpophaga aurif.ua , for instance, and in each case possibly their degree of specialisation, low or high, makes for success, success being purely the ability to get food and lay eggs freely. Some are- successful because they are fixed in delicate mechanical instincts, notably the insect- stinging wasps ; others are successful because they can adapt themselves still to a limited variation of circumstances, such as food, temperature, etc., and they are still to some extent plastic. But it is a very limited plasticity, little akin to the plasticity of the earlier forms from wdiich our present insect life has arisen. Classification.— When insects were first studied in some detail, CLASSIFICATION. 11 the complexity of the increasing number of recorded species led to a system of grouping, say, the beetles under one title, the moths and butter¬ flies under another, and so on, the insects most obviously similar being put into one group chiefly as a matter of convenience. As the subject grew, the morphological characters of the collected insects were utilised to an increasing extent, and the more the number of known insects increased, the more minute and detailed was this classification. When the evolution theory was accepted, it was evident that every scrap of available information would be required to give data on which to make a natural grouping of insects ; what was the origin of insects ? from what had they developed ? how far had different insects remained for a long period in the same condition, and how far was the evolution either continuing still or had it been continuous up to the recent past ? These were the questions to be answered, and the answer is embodied in the present-day system of classification which is believed to be so far natural that it conforms, as far as possible, to the actual developments of insects during the earth’s history and does represent actual relation¬ ships. On these terms all the members of one group are more closely interrelated than each one is to any other insect not in that group. In making this classification, there are practically three main sources of evidence: (1) the morphology of the insect in all its stages ; (2) the processes of embryological and post-embryological development ; (3) the evidence of fossil and extinct insects. In the beginning, the first alone was utilised, and it is still the main source of information; at first superficial characters were used, then more detailed ones such as the structure of the trophi, finally the fuller evidence afforded by all parts of all stages is being utilised, though this is by no means near completion. The second has been utilised, but not to a great extent. The third has been utilised as far as it is available, but the geological record is scanty, and what there is, is very imperfectly available as yet. There is a great bulk of literature on this question, and it is impossible to more closely enter into the subject here. How little is really known can be gauged from the great changes made in the classi¬ fication of Ileterocera, for instance, as well as from the fact that ento¬ mologists have arrived at no definite conclusions which are generally accepted. The most diverse views prevail, and there is no standard classi¬ fication that is or can be universally employed even if it be admittedly 12 INTRODUCTION not academically accurate, but sufficiently so for practical purposes. As knowledge grows, as groups are revised, new views are expressed, new systems adopted. This would matter little if there were, for instance, agreement as to one unit, say the family, if it could be decided that Coleoptera. for instance, are a homogeneous group of say 80 families ; unfortunately this is impossible at present. Actually, insects are prima¬ rily divided or have been divided into primary divisions called orders. Thus Coleoptera are a distinct enough order ; when we go below this, we should have a definite number of sub- orders, each containing a definite number of families ; the sub-family is the next division containing a number of genera. Unfortunately superfamilies, legions, cohorts, tribes, etc., have been used, and it is rare to find all authorities on an order or sub- order using the same classification. In this volume, we propose to follow the Fauna of India, in using the terms order, sub-order, family, sub-family, division, genus, species, but as classification is not our main object, we can largely simplify the system actually used in the Fauna. Entomologists have adopted the family as the unit of classification trying to group insects first into divisions which must have had a common ancestor ; on this basis we get nearly 300 families, each of which represents a fairly homogeneous assemblage, derived from one branch of the tree ; the difficulty is greater when we try to group these families to find the main limbs of our tree or to find how many separate limbs we should have, derived each from some lower form of life ; for instance, Lepidoptera area very homogeneous order, the families derived from one branch ; Orthoptera on the other hand are by no means uniform, and so far as can be seen, the order instead of coming from one branch may really come from three ; none the less, in the absence of sufficient data to find really how many branches there are, the order Orthoptera as here adopted is a very convenient one. Our nine orders are constituted then with a regard both to truth and con¬ venience and a student should think in terms of families, grouping these families into aggregates which we may call sub-orders and orders. In practice we have to utilise a conventional system that embodies as much truth as possible and which is reasonable for working purposes. Of the nine orders we adopt here, seven are generally accepted by entomologists, but there is great divergence of views over the Neurop - CLASSIFICATION, 13 tera. With regard to this, the following tables show the terms used by other authors : — Orders. Sub-orders. Families. Smith’s orders. Wood worth’s orders. 'Mallophaga. ( Embiidge.* Mallophaga.* 1 Pseudoneuroptera Termitidas Isoptera > Corrodentia. ( Psocidae ... Corrodentia.* \ j i ( Perlidas Plecoptera.* Neuroptera > Amphibiotica .. Odonata Odonata. Odonata. *1 [ Epheneridae . Ephemerida ... Ephemerida. 1 | Sialidge Platyptera* Planipennia : Panorpidge ... Mecoptera.* i f Hemerobiidse Neuroptera.* * Neuroptera. .Trichoptera Phryganeidas Trichoptera.* We believe the most logical and workable system of insect classi¬ fication to be the following : — 1. Aptera. 2. Forficulld/r. 3. BLATTIDiE. 4. Orthoptera (5 families). 5. TERMITIDiE. 6. Mallophaga. 7. Pseudoneuroptera. (Embiidae, Psocidee). 8. Neuroptera Amphibiotica. 9. Neuroptera Planipennia. 10. Trichoptera. 11. Hymenoptera? Phytophaga. (Sessiliventres). 12. „ Parasitica. 13. „ Tubulifera. 14. „ Aculeata. 15. COLEOPTERA. 16. Lepidoptera. 17. Diptera, Orthorhapha. 18. „ Cyclorhapha. 19. Siphonaptera. 20. Rbynchota, Heteroptera, 14 INTRODUCTION. 21. Rhynchota, Homoptera, 22. Phytophthires. 23. Anopleura. 24. Thysanoptera. It is, however, impossible to express accurately the relationship of insects by adopting any one sub-division of equal value throughout, and the student may be warned against getting to attach too much importance to any classification systems except as working conven¬ tions which have as much regard to truth as circumstances will allow. What systems of classification we adopt is, in the present state of confusion, immaterial ; the Fauna covers only parts of four orders and we can there adopt the system in use ; beyond that we must unfortu¬ nately anticipate the “ Fauna.” The system adopted is the following; it is as near to Sharp’s insects as possible, and we have contrasted it with the system in use in America as a guide to the student who wishes to refer also to American literature. W e may remark that classification is not an end in itself but is the means to an end ; with so vast and com¬ plex a subject, it is imperative that we should be able to classify, to fix the position of an insect with regard to its fellows, simply for ease of working. Our main object being the observation of living insects as they affect man, classificaton in this case becomes necessary to enable us to record and collate our observations ; for this reason we aim at a simple system, on which we can arrange our collections, file our notes and, by working with one system, follow each other’s work at once with¬ out having to readjust our ideas or bother more than is necessary with the way our things are arranged. The insects in one collection are arranged exactly as they are in another ; a worker from a distance can take up work in Pusa without mastering a fresh system, and whether our classification be correct or not, it is, and must be, the standard and will be, we hope, with small modifications, the standard in India for many years. Number of Species. — Blanford in 1881 published a numerical enumeration of the known Fauna of India (J. A. S. B., p. 263). He in¬ cludes Beluchistan, Kashmir, the Himalayas, Nepal, Sikkim, Bhutan, Assam, British Burma? Tennasserim, Ceylon, Andamans, Nicobars, NOMENCLATURE. 15 which is practically the area now covered by the “Fauna of British We reproduce his figures : — Orthoptera 350 (?) 1,700 Neuroptera 350 400 Hymenoptera 850 3,600 Coleoptera 4,780 6,000 Lepidoptera 4,620 10,000 Diptera 500 (?) 1,000 Rhynchota 650 3,000 Total 12,100 29,700 giving also an enumeration of our own based on the available figures. Thus the Fauna of India and Hampson’s later papers enumerate about 8,000 moths, there are about 1,500 butterflies, and we estimate 500 Tineids, etc. Mr. Distant has already enumerated 2,500 Rhynchota, and we anticipate 400 more with 100 Coccidse. Nomenclature. Could we divide all known insects into, say, 300 families of roughly 1,000 species each, and group these systematically, our nomenclature would be a simple matter. As we have explained above, the general object is to make families the basis of classification ; but we have in this volume to steer a middle course between the really accurate classification of the pure svstematist, which changes as knowledge grows, and the practical point of view of those for whom we write ; we cannot keep remodelling our arrange¬ ment and nomenclature. Odonata, for instance, may be a sub-order composed of say seven families ; for us and for all field entomologists it is practically a family. Whenever possible, family names end in — idee, sub-family names in — inw , and the names of tribes or sub-divisions of families in — ini ; the student must, however, remember that sub-family names frequently end in —ides ; and tribes in — ines. It is to be regretted that no uniform system can be introduced, and that were we to rigidly adhere to some system in this volume, the student would be puzzled when reading foreign text-books or literature. Identification of Specimens. — Insects are known by names, nomi¬ nally of Latin or Greek form, given to them by the entomologist 16 INTRODUCTION. who first describes them. That is, every distinct species of insect that ha*s been described or accurately figured is designated by the specific name assigned to it by its first describer. The problem then is, with living or preserved insects on one side, and the mass of descriptions or figures on the other, to correlate the two. Only working entomologists ever realise the immense labour in¬ volved in this work, except in the case of the fauna of a locality such as England where the insects have been studied very closely, where there are ample books, and reference collections. Where one has either a description of every species of insect of a country or a good reference collection, identification is a matter of so much comparison, but where as in India, the only handbooks contain descriptions only of part of the known insects, or where there are no handbooks at all, only scattered descriptions, and where there are no reference collections and access to the National Collections at the British Museum is impossible, the actual identification of an insect is not an easy matter and is not, as a rule, even possible in India. The question must remain so until there are complete handbooks such as the Fauna of India, which are kept up-to-date, and also complete reference collections of Indian insects, accurately named ; progress to these is being slowly made, but very slowly indeed. Actually if an insect belonging to one of the families described in the Fauna of India is sent in for identification, it is examined, referred to some division of its family, worked out with the generic key in the volume and compared with the descriptions in the volume ; if it exactly agrees with the description of a particular species, it is believed to be that species and is, if possible, compared with a specimen that has been identified by a specialist in that family. If it agrees with no species in the volume, it may be either a species described since the volume was prepared, or a species known from another country but not from India, or a new species ; to determine this requires an expert knowledge of the family, a complete literature of the family and a reference collection. On the other hand, if a beetle, for instance, is sent in, it is examined, referred to its family, and compared with any accurately named speci¬ mens of its kind which are available ; if it agrees with none of them it must be sent to a specialist in that family who has the literature, the reference collection, and, after years of work on that particular family, ENTOMOLOGY IN INDIA. 17 the requisite special knowledge. If proper attention was devoted to entomology in England, all specimens could be sent to the National Collection at the British Musuem and there compared ; at present this is not possible, and we are largely dependent on the kindness of workers in Europe and the United States. It can be seen that the accurate identification of an insect is no easy matter in every case ; in many cases it means months of waiting, and even years, as there are no workers for a large number of groups. As an accurate identification is necessary before publishing matter about any insect, this question is one of great importance ; a large number of insects have been accurately identified and can be seen in the Pusa Collections ; every assistance will be given in identifying insects, but the reader must realise what it means and be prepared to do the only thing he can to help, namely, to always send enough good specimens to allow of some being sent on to Europe, if the species is one that cannot be named from the Pusa Collection. This matter is discussed here because requests are constantly received for the name of an insect of which perhaps one mangled specimen is sent, and surprise is expressed because the identification is not immediately forthcoming. (See also Indian Insect Pests, page 57.) Entomology in India.— -This volume has been compiled primarily for the use of students of entomology in India and for those interested in the subject. A few words as to the present state of the subject in India will not be out of place. Entomology, as a subject, occupies the whole time of one section of the Agricultural Research Institute, Pusa, and in this Institute alone there are three Entomologists with English University qualifications, and a staff of trained native workers. In connection with this Institute, there are a limited number of entomological assistants employed by the Agricultural Departments of each province for purely agricultural work and simple teaching. Whilst the ultimate object of work at Pusa is mainly agricultural and directed to useful practical ends, the work must rest on a scientific basis, and the collection, study, and classi¬ fication of all insects of the agricultural areas of India is a necessary part of the activities of the staff. It is open to any worker in India to visit Pusa or to write there for advice or assistance, which will be freely given. 2 IIL 18 INTRODUCTION. Our aim is to be in touch with every worker in India and to invite co¬ operation and mutual help. Elementary and advanced teaching in entomology is also given at Pusa and at no other place in India at the present time. For many years, the Indian Museum, Calcutta, was the centre of entomological work, where a special staff was devoted to this subject, including the economic aspect. At the present time, the economic work has been transferred to Pusa, and systematic entomology takes its place as one branch of the systematic zoology which forms the work of one section of the Musuem. Collections of insects are preserved there, are constantly added to and are sent to specialists to Europe, just as the Pusa collections are. There is a large exhibit collection open to the public and the reference collections, while not open to the public, are generally available to work¬ ers in entomology. Forest entomology is solely dealt with in the Forest Research Institute, Dehra Dun, by the Imperial Forest Zoologist and his staff, and all enquiries regarding insects injurious to forests are referred there. The study of insects injurious to tea is the work of the Entomologist to the Indian Tea Association stationed at Hilika, Assam. Apart from minor and inconsiderable collections in Provincial Museums, the only other public collections exist at the rooms of the Bombay Natural History Society ; members of this society refer specimens to the Committee who, if the Society5 s collection and library cannot furnish the required information, refer them to either of the above Indian Institutions or to Entomologists in Europe. Excepting private wmrkers who own private collections, there are no other centres of entomological activity in this country. Publications dealing with entomology in its different aspects are issued as follows : The Imperial Agricultural Department issues, from Pusa, the “ Agricultural Journal of India, ?? in which are contained articles and notes relating solely to those insects injurious to crops or to those of economic value. Other and similar work is issued in bulletins ; the. more scientific or lengthy work is issued in memoirs and purely popular and useful information as leaflets. ENTOMOLOGY IN INDIA. 19 The Imperial Forest Research Institute publishes information relative to Forest Entomology in “ Forest Records and Memoirs/’ and some has appeared in the pages of the “ Indian Forester.” “ The Bulletins of the Tea Association ” contain the bulk of the work on insects injurious to tea, supplementary to the volume on Diseases and Pests of the Tea Plant by Watt and Mann. The Indian Museum, in “ Indian Museum Records ” and “ Memoirs of the Indian Museum,” issues articles mainly on systematic entomology but also bionomic work. The “ Journal of the Bombay Natural History Society ” is the recog¬ nised medium for most purely systematic work and for some bionomic work ; the papers in this Journal are of extreme value and must be consulted. We have referred below to the more important papers. The Journal of the Asiatic Society of Bengal contain also papers on general entomology and on systematic work. This exhausts the present publications dealing with the various aspects of this subject in India ; occasional papers on systematic entomology appear in the proceedings of learned Societies in England, Europe, the United States. A summary of these is contained in the Annual Report of the Board of Scientific Advice in India, as is a summary of all entomological work and publications in India. It is necessary to mention one further publication no longer in exist¬ ence. For over fifteen years, “ Indian Museum Notes” was issued from the Indian Museum, Calcutta, and contained papers, notes, etc., dealing with economic and systematic entomology. We have made constant reference to it below and practically all information contained in it, dealing with the insects of the plains, is abstracted or referred to here, or is amplified in Indian Insect Pests. The best feature of this publica¬ tion was its beautiful photogravure plates ; the originals of many of these are here reproduced as text figures. Sets of this publication are still available at Pusa, and complete sets can be consulted in most official or public libraries in India. With the exception of the Bombay and Asiatic Societies, the above publications are issued by Government and copies of most of them are available to serious workers. All can be seen also in most public libraries, and the published work in entomology is generally available. It is impossible to refer here to other literature ; the reader will see 20 INTRODUCTION. below from how many sources we have drawn the published informa¬ tion of past years and these scattered papers are often very difficult to see. The best entomological libraries known to me in India are that of the Indian Museum, Calcutta, and of the Pusa Research Institute. Of books dealing only with Indian Entomology, the Fauna of India is the only systematic one of real value now. It covers Aculeate Hymen- optera (2 vols.), a small part of Coleoptera (2 vols.), nearly the whole of Lepidoptera (6 vols.), Rhynchota to the end of Jassidse (4 vols.). Progress with this is being steadily made and the student should ascer¬ tain what volumes have since been issued. They are the standard guides to the systematic entomology of India, Burmah and Ceylon and are essential in the arrangement and identification of species. West¬ wood’s Cabinet of Oriental Entomology is with Donovan’s “ Insects of India,” remarkable chiefly for beautiful plates in colour of many striking Indian insects, mainly butterflies, moths, large beetles and Fulgorids. It is the only book of its kind but is of little value at the present day except (in the words of Westwood), “that, by finding its way to the table of the Indian drawing room, it may gain additional converts to the study of a science full of curiosity and awaken an interest in the objects of pursuit, thus supplying an engaging occupation to our Indian friends.” A very short introduction to entomology is given in ‘ ‘ Indian Insect Pests,” which also treats of insects injurious to agriculture. It is the only general book on pure entomology relating solely to India published recently (1906), and contains short instructions regarding necessary apparatus, methods, etc. We assume every reader to have as much general knowledge as is included in the first part of that volume and in the second appendix. Zoo-Geographical Divisions.— British India is not a distinct zoo- geographical area, and it is necessary to define very carefully the faunal zone that is dealt with in this volume. The “ Fauna of India’ ’ series deals with the Fauna of the Indian Empire and Ceylon, i.e., Himalaya, Hindustan, Assam, Burmah, Ceylon, regardless of faunal zones, and we endeavour here to indicate the zoo-geographical status of this region. In the first place, we wish to make clear that a fundamental point is elevation ; starting from the plains of North India at an elevation of, 200»GE0GRAPHICAL DIVISIONS. 21 say, 1,600 feet and going steadily up the Himalayas to say. 10,000 feet, one passes from, through and into three distinct life-zones, which we may call tropical, subtropical and temperate ; the tropical extends to 2,000 feet elevation ; it is marked by one period yearly of intense dry heat or a limited season of moist weather ; the subtropical covers 2,000 feet to between 5,000 and 6,000 feet and is marked by a greater humidity, a more even and less intense temperature, a less limited period of rainfall ; the temperate extends above about 6,000 feet. To accurately define the limits of the subtropical zone would require much elaborate detail ; it commences for instance at an elevation of about 500 feet at the foot of the Eastern Himalayas, at about 2,000 feet at the foot of the Western Himalayas ; in the Milgiris it commences at about 2,500 feet on the Mysore plateau side but runs down to well under 1,000 feet on the Western Ghaut side ; a large part of the Deccan above 1,000 feet is tropical; the Western Ghauts from 600 to 2,000 feet and over are subtropical, and in this case the dry tropical area (as at Poona and Nasik) is at a greater elevation than the moist subtropical belt. The zone is of course not definable merely on elevation ; it is the moister more agreeable climate produced by the abun¬ dant rainfall falling on the slopes of moderate elevation which run up from the level plains to the Himalayas or to the various ranges of hills ; it is a zone of varied vegetation, often forest or dense jungle ; it is the zone in which tea, coffee, rubber, and similar crops are grown, and it is, in India, a belt along the hills, running up the valleys, as well as more or less isolated patches on the hill ranges of Central India, the Deccan and South India. The student can get some idea of it from the 2,000 feet elevation line on Eliott’s meteorological atlas of India. The fauna of the subtropical zone is far more varied than that of the tropical zone or of the temperate zone and is quite distinct. There are some prominent features of the tropical and subtropical faunae which may be very briefly discussed here. We omit any discus¬ sion of the temperate fauna as, except in South India, it is certainly not “ Indian ” but is holarctic or Indo-Chinese. The subtropical fauna is far more varied than the tropical ; the number of species that can find food and can support existence in the extremely varied vegetation and moist equable climate of the former is far greater than those that can endure the intense dry heat and more limited vegetation of the latter. 22 INTRODUCTION. In addition to this, which is true of nearly every family of insects, there are families which are confined to the subtropical region, or which im¬ mensely predominate there as compared with these families in the plains, and there are also families which occur far more abundantly in the tropical plains. The Phasmidce , Siricidce , Tenthredinidce , Sialidce, Panorpidce, Passalidce, Lucanidce, Simuliidce, Aradidce , Phymatidce, Sesiidce , Zygcenidce are practically confined to the moist forested lower hill slopes ; the Rhopalocera are characteristic of the subtropical region, especially the Nymphalidce and Papilionidce ; the Cicadidce, Tipulidce , Mycetophilidce, Locustidce , Dynast idee. Cetoniidce , Erotylidce , Endomychidce , Boslrichidce, Scolytidce are found abundantly in the subtropical, rarely in the tropical areas ; Chrysomelidce, Buprestidce, Capsidce. Syrphidce occur in both but in immense profusion only in the former ; Limacodidce and Pliryganeidoe stand out conspicuously in the same way. On the other hand, the Acridiidce, Carabidce , Dytiscidce , Hydrophilidce, Gyrinidce, Tenebrionidce, Myrmeleonince , Ascalaphince , Scaraboeidce are far more abundant in the plains, though occurring also in the lower hills. Allow¬ ing for the fundamental excess of species in the subtropical region owing to its varied flora, the other large families are more proportionately represented in both areas. We would suggest also that the varied sur¬ face fauna of the plains is less marked a feature of the subtropical region, possibly because the surface soil offers protection from heat not required in the hills and because the usually dense perpetual vegetation of the hills produces a fauna centering more round the bushes and low vegetation (see below u Where Insects Live ” under Forficulidce). This fundamental distinction is of the very greatest importance, and unless it is fully realised and clearly kept in mind, any conception of the faunal zones must be imperfect. W e sharply mark off the fauna of the plains of India (usually below 2,000 feet) from that of the forested slopes of the hills and from that of the upper hills ; and, in this volume, we deal only with the tropical zone except where the number of species occurring in India is stated when we mean British India exclusive of the temperate upper Himalayas. India is placed by Beddard (Zoogeography 1895) in the Oriental Region as the “ Indian ” subregion ; Ceylon is distinct as a subregion and is taken to include part of South India. The Himalayas, inclusive of Kashmir, Nepal, Sikkim, Bhutan, are not part of the Indian subregion ZOO-GEOGRAPHICAL DIVISIONS* 23 at all, being holarctic, and we take the dividing line to be at about 6,000 feet. The extreme North-West of India is also not strictly “ Indian 55 but is holarctic. Burmah, we exclude, as being Malayan and Indo- Chinese, and the hills of Assam are strictly Indo-Chinese in part. “ In¬ dia ?? proper then does not include these areas at all and it must be clear¬ ly borne in mind that in these pages we do not use India in the sense that the “ Fauna of India 55 does : the term “ British India ” is used throughout this volume for the political India covered by the Fauna ; the term “ India ?? includes tropical and subtropical India, i.e.t up to about 6,000 feet ; “ subtropical India ” denotes the moist forested slopes of the hills usually between 2,000 and 6,000 feet ; “ tropical India ” or “ the plains ” means the great stretches of India lying between sea-level and about 2,000 feet, usually not forested and extending from Tinnevelly in the South to Bawai Pindi in the North, from the border of Sind and Baluchistan in the West to the Assam and Surma valleys in the East. It is the insects of this area that are discussed in these pages and for one insect in this area there are at least five in “ subtropical India. ” The frontispiece illustrates the divisions of tropical India according to fauna so far as we are able to tentatively delimit them ; the faunal zones of subtropical India are not indicated. In considering this question fully, the factors to be considered are (1) the physical features of the country ; (2) the geological formation composing it ; (3) its climate ; and (4) its flora. The first three probably affect insects in much the same way as they affect plants, and we may take the flora as the basis of our divisions ; Sir J. D. Hooker, in his sketch of the flora of British India, divides the whole area into nine provinces as follows (1) Eastern Himalayas.— Sikkim to Mishmi mountains in Upper Assam. (2) Western Himalayas — -Kumaun to Chitral. (3) Indus Plain.— Punjab, Sind, Kajputana, west of the Araval- li range and the Jumna river, Cutch and Gujarat (to the Tapti). (4) Gangetie Plain.— From the Aravalli Hills and the Jumna river to Bengal, the Sundarbans, the plains of Assam, the low country of Orissa north of the Mahanadi. 24 INTRODUCTION. There are three distinct sub-provinces ; the dry upper area, the United Provinces and Behar ; the lower humid area, the Assam plain, Lower Bengal and Orissa ; and the Sundarbans. (5) Malabar. — The Western Ghauts from the Tapti river to Cape Comorin ; the Konkan, Kanara, Malabar, Cochin, Travancore, Laccadive Islands. This is better termed the West Coast. (6) The Deccan. — The high plateau lying between the Eastern and Western Ghauts, south of the Gangetic and Indus plains ; the Coromandel Coast on the East Coast from the Mahanadi to Cape Comorin is included as a sub¬ province. (7) Ceylon and the Maidive Islands. (8) Burmah. (9) The Malay Peninsula. With the last three, as with the first two, we have no concern here. If on the basis of the above divisions we omit subtropical forest hill areas, and we take into account the influences on the fauna of these neighbouring areas, we shall get divisions as follows : — - (1) The Indus Plain. (2) Desert India. (3) Central India, West. (4) Gangetic Plain, West, (5) Gangetic Plain, East. (6) Sundarbans. (7) Central India, East. (8) Deccan. (9) West Coast. (10) Coromandel Coast. 1. The Indus Plain has a fauna containing many holarctic forms. The winter is cold, the hot weather is dry and intense and these two sea¬ sons are well marked. 2. Desert India is similar, but with a peculiar fauna and flora, owing to the arid conditions. ZOO- GEOGRAPHICAL DIVISIONS. 25 3. Central India , West. — An area of greater rainfall, a more definite period of humidity and less alternation of day and night temperature. 4. Gangetic Plain, West. — Well marked winter with moderate cold and rain, dry hot weather and moist rainy weather. Immigrants from the Himalayas for the cold weather. 5. Gangetic Plain, East. — No well-marked dry hot weather, the humidity higher in the cold weather and hot weather. Immigrants from the Himalayas and other hills for the cold weather and insect activity more general in the hot weather ; there is a marked Malayan element. (A feature of this area is the flooding that occurs over large stretches of land; the influence this exerts on the fauna may be a very marked one.) 6. Sundarbans. — Doubtfully distinct. Little alternation of temperature or humidity. Peculiar flora. Strong Malayan element. 7. Central India, East. — Well-marked dry hot weather when insect activity is suspended, followed by a prolonged moist warm period. Fewer insects hibernate than in the regions North and West. 8. Deccan. — Well-marked seasons, the dry hot weather following a marked cold weather, when hibernation sets in. 9. West Coast. — The fauna is influenced by the neighbouring sub¬ tropical region of permanent forests and high humidity which produce a very large fauna equalled only by the lower slopes of the hills in Assam and the Eastern Himalayas. No hibernation in the plains below ghauts. Many Ceylonese forms. 10. Coromandel Coast. — Less well marked seasons to the Deccan, and a smaller flora to the West Coast. A large proportion of Ceylonese forms. We may roughly indicate the separate faunal zones into which we would divide British India as a whole exclusive of Burmah and Ceylon: — 1. Indus Plain. — Tropical. 2. Himalaya, West.— Western Himalayas above 6,000 feet, inclu¬ ding Kashmir, Nepal and Kumaon. Holarctic. 3. Sub-Himalaya, West. — -Lower slopes of Western Himalayas 2,000 to 6,000 feet. Subtropical forest fauna. 4. Desert India. — Tropical. 5. Central India , West. — -Tropical. 26 INTRODUCTION. 6. Central India , West, Hills. — -Subtropical. 7. Gangetic Plain, West. — Tropical. 8. Gangetic Plain, East. — Tropical. 9. Sub-Himalaya, East. — Lower slopes of Eastern Himalayas 700 to 5,000 feet. Subtropical. 10. Himalaya, East. — -Eastern Himalayas above 5,000 feet. Sikkim to Mishmi Mountains. Holarctic. 11. Assamia. — Hills of Assam and Assam- Bur mah border, in¬ clusive of Khasi hills, above 6,000 feet. Indo-Chinese. 12. Sub- Assamia. — Lower slopes of Assam hills, 500 to 5,000 feet. Subtropical with strong Malayan affinities. 13. Sundarbans. — Tropical. 14. Central India, East, Hills above 500 to 800 feet. Subtropical. 15. Central India, East, Plains. — Tropical. 16. Deccan. — Tropical. 17. West Coast, Plains . — Tropical. 18. Western Ghauts. — Hills up to 6,000 feet. Subtropical. This is probably divisible into three ; (a) Surat to Londa-Goa gap ; (b) Goa gap to Palghat gap with the Nilgiris, Coorg, Mysore Hills ; (c) South of Palghat gap, including Travancore, Pulneys, etc. 19. South India Hills. — Hills of West Coast and South India above 6,000 feet. The fauna of this zone is not sufficiently known, as apart from the fauna below 6,000 feet, for this division to be more than a doubtful one. 20. Coromandel Coast. — Tropical. 21. Eastern Ghauts. — Subtropical. Classing these zones under elevation and climate we get : — Temperate. Subtropical. Tropical. Himalaya, West Sub-Himalaya, West Indus Plain. Desert India. Central India, West, Hills Central India, West. ,, East Sub-Himalaya, East Gangetic Plain, West. Assamia Sub Assamia „ ,, East. Sundarbans. Central India East, Hills ... Central India, East. Western Ghauts Deccan. West Coast. South India Hills Eastern Ghauts Coromandel Coast. FOOD AND HABITAT* 27 ( H.OL ARCTIC*) Himalaya West. Baluchistan. Afghanistan. (Scheme of In¬ dian Region.) (Indo-Chinese.) Assamia. Himalaya, East. Burmah Hills. Indus Plain. Desert India. Central India, West, Gangetic Plain, West. -Cent ml India, East- West Coast. Western Ghauts. South India Hills./ Coromandel Coast. Eastern Ghauts. Ceylon. Sub-Himalaya, East. Sub-Assamia. Gangetic Plain, East. Sundarbans. Burmah Plains." Malayia. (Singhalese.) (Malayan.) Food and Habitat. Insects live in a great diversity of ways, but it is possible to roughly classify these into groups ; this classification is of considerable value to the student in placing his insect ; for instance, a tree- boring insect will be a member of' one of a small number of families, and it will often assist in placing an insect to look up the families which have a particular habit i,et> it is useful to classify insects according to food and habitat, as well as by structure and genealogy. For this purpose we tabulate below the principal families that live in distinct ways, using food and habitat together as the basis of our classification. c I.— LAND INSECTS.