// THE CAMBRIDGE NATURAL HISTORY EDITED BY S. F. HARMER, Sc.D., F.R.S., Fellow of King's College, Cambridge; Superintendent of the University Museum of Zoology AND A. E. SHIPLEY, M.A., Fellow of Christ's College, Cambridge University Lecturer on the Morphology of Invertebrates VOLUME VI INSECTS PART II. Hymenoptera continued (Tubulifera and Aculeata), Coleoptera, Strepsiptera, Lepidoptera, Diptera, Aphaniptera, Thysanoptera. Hemiptera, Anoplura. By DAVID SHARP, M.A. (Cantab.), M.B. (Edinb.), F.R.S. iLontion MACMILLAN AND CO, LIMITED NEW YORK: THE MACMILLAN COMPANY 1899 All rights reserved ' ' Men are poor things ; I don't know why the world thinks so much of them." — Mrs. Bee, by L. & M. Wintle. CONTENTS PAGE SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK . . . . vii CHAPTER I HYMENOPTERA PETIOLATA CONTINUED — SERIES 2. TUBULIFERA OR CHRYSI- DIDAE. — SERIES 3. ACTTLEATA — GENERAL — CLASSIFICATION — DIVISION I. ANTHOPHILA OR BEES . . . . . , . 1 CHAPTER II HYMENOPTERA ACULEATA CONTINUED — DIVISION II. DIPLOPTERA OR WASPS — EUMENIDAE, SOLITARY TRUE WASPS — VESPIDAE, SOCIAL WASPS — MASARIDAE 71 CHAPTER III HYMENOPTERA ACULEATA CONTINUED — DIVISION III. FOSSORES OR FOSSORIAL SOLITARY WASPS — FAMILY SCOLIIDAE OR SUBTERRANEAN FOSSORES — FAMILY POMPILIDAE OR RLTNNERS — FAMILY SPHEGIDAE OR PERFECT-STINGERS 90 CHAPTER IV HYMENOPTERA ACULEATA CONTINUED — DIVISION IV. FORMICIDAE OR ' ANTS 131 CHAPTER V COLEOPTERA OR BEETLES — STREPSIPTERA CHAPTER VI LEPIDOPTERA, OR BUTTERFLIES AND MOTHS . 30446 vi CONTENTS CHAPTEK VII PAGE DIPTERA, OR FLIES — APHANIPTERA, OR FLEAS — THYSANOPTERA, OR THRIPS 438 CHAPTER VIII HEMIPTERA, OR BUGS — ANOPLURA 532 NOTES AND CORRIGENDA TO VOLUME VI. AND TO INSECTA OF VOLUME V. . 602 INDEX . 603 SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK Orrlpr auu-uiuei, jjivioiun HYMENOPTERA I Petiolata. (continued from -[ (continued Vol. F). (from Vol. V). Family. HYMENOPTERA (continued) Aculeata (P- 4) 7 " :>. 1). Arcliiapides (p. 21). Obtusilingues (p. 22). ANTHOPHILA I Andrenides (p. 23). (p. 10) \ Denudatae (p. 29). APIDAE (p. 10) Scopulipedes (p. 32). Dasygastres (p. 35). \_ Sociales (p. 53). DlPLOPTERA (p. 71) | EUMENIDAE (p. 72). -j VESPIDAE (p. 78). \ MASARIDAE (p. 88). [ Mutillides (p. 94). Thynnides (p. 961. - Scoliides (p. 97). GrOUP' Sapygides (p. 99). 100). FOSSORES (p. 90) SCOLIIDAE (p. 94) . Rhopalosomides (p POMPILIDAE (p. 101). ( Sphegides (p. 107). Ampulicides (p. 114). Lai-rides (p. 116). Trypoxylonides (p. 118). SPHEGIDAE I Astatides (p. 119). (p. 107) | Bembecides (p. 119). Nyssonides (p. 123). Philanthides (p. 124). Mimesides (p. 127). Crabronides (p. 128). HETEROGYNA (P- 131) FORMICIDAE (p. 131) Camponotides (p. 144). Dolichoderides (p. 157). Myrmicini (p. 159). Attini (p. 165). Myrmicides - Pseudomyrmini (p. 158) (p. 168). Ponerides (p. 170). Dorylides (p. 174M Cryptocerini (p. 169). Ecitonini Amblyoponides (p. 180). (p. 177). via SCHEME OF CLASSIFICATION OrAo-r Sub-Order, Division, T?._,»I_ Sub-Family or der' or Series. mil>' Tribe. C ' PASSALIDAE (p. 192). LUCANIDAE p. 193). Lamelli- 'Coprides (p. 195). cornia (p. 190) SCARABAEIDAE i> V*-,?? / eS,k?\ '" l IQ.I'* l Kutelides (p. 198). Dynastides (p. 199). ^ ^Cetoniides (p. 199). ClCINDELIDAE (p. 201). C Carabides (p. 206). CARABIDAE | Harpalides (p. 206). Adepliaga or Caraboidea • (p. 204) 1 Pseudomorphides (p. 206). I. Mormolycides (p. 206). (p. 200) AMPHIZOIDAE (p. 207). PELOBIIDAE (p. 207). HALIPLIDAE (p. 209). >. DYTISCIDAE (p. 210). f PAUSSIDAE (p. 213). GYRINIDAE (p. 215). HYDROPHILIDAE (p. 216). PLATYPSYLLIDAE (p. 219). LEPTINIDAE (p. 220). SILPHIDAE (p. 221). SCYDMAENIDAE (p. 223). GNOSTIDAE (p. 223). PSELAPHIDAE (p. 223). COLEOPTERA STAPHYLINIDAE (p. 224). (p. 184) SPHAERIIDAE (p. 227). TRICHOPTERYGIDAE (p. 227). HYDROSCAPHIDAE (p. 228). CORYLOPHIDAE (p. 228). SCAPHIPIIDAE (p. 229). SYNTELIIDAE (p. 229). HISTERIDAE (p. 230). PHALACRIDAE (p. 231). NITIDULIDAE (p. 231). Polymorpha TROGOSITIDAE (p. 232). (p. 213) COLYDIIDAE (p. 233). RHYSODIDAE (p. 234). CUCUJIDAE (p. 234). CRYPTOPHAGIDAE (p. 235). HELOTIDAE (p. 23f). THORICTIDAE (p. 236). EROTYLIDAE (p. 236). MYCETOPHAGIDAE (p. 237). COCCINELLIDAE (p. 237). ENDOMYCHIDAE (p. 239). MYCETAEIDAE (p. 239). LATRIDIIDAE (p. 240). ADIMERIDAE (p. 240). DERMESTIDAE (p. 241). BYRRHIDAE (p. 242). CYATHOCERIDAE (p. 243). GEORYSSIDAE (p. 243). HETEROCERIDAE (p. 243). PARNIDAE (p. 243). IDERODONTIDAE (p. 244). (Continued on the next page. ) SCHEME OF CLASSIFICATION IX Sub-Order, Division, i?omii^ Sub-Family or Order- or Series. FamUy- Tribe. 'ClOIDAE (p. 245). SPHIXDIDAE (p. 245). BOSTRICHIDAE (p. 246). PTINIDAE / Ptinides (p. 246). (p. 246) \ Anobiides (p. 246). MALAOOBFR ( Lycides (P- 248)' MALACODER- I DriMes (p> 248)_ •^9481 1 Lampyrides (p. 248). [ Telephorides (p, 248). Polymorpha (continued) MELYRIDAE (p. 252). CLERIDAE (p. 253) LYMEXYLOXIDAE (p. 254). DASCILLIDAE (p. 255). RHIPICERIDAE (p. 256). f Throscides (p. 260). I Eucnemides (p. 260). ELATERIDAE ! Elaterides (p. 260). (p. 256). "i Cebrionides (p. 260). Perothopides (p. 260). 1 Cerophytides (p. 260). BUPRESTIDAE (p. 261). ' TEXEBRIOXIDAE (p. 263). ClSTELIDAE (p. 264). LAGRIIDAE (p. 264). OTHXIIDAE (p. 265). AEGIALITIDAE (p. 265). COLEOPTERA MOXOMMIDAE (p. 265). (continued) Heteromera (p. 262) NlLIOXIDAE (p. 265). MELANDRYIDAE (p. 265). PYTHIDAE (p. 265). PYROCHROIDAE (p. 266). AXTHICIDAE (p. 266). OEDEMERIDAE (p. 266). MORDELLIDAE (p. 267). CAXTHARIDAE (p. 269). ^ TRICTEXOTOMIDAE (p. 275). ( BRUCHLDAE (p. 276) ( Eupoda (p. 280). CHRYSOMEL- I Camptosomes (p. 281). Phytophaga (P- 276) IDAE (p. 278)1 Cyclica (p. 282). 1 Cryptostomes (p. 282). rVRAMRvrmAK f Prionides (p. 287). ( 9SK\ 1 Cerambycides (p. 287). k VP- "»o; ( Lamiides (p. 287). f ANTHRIBIDAE (p. 290). Rhyncho- I CURCULIONIDAE (p. 290). phora(p. 288) | SCOLYTIDAE (p. 294). I BRENTHIDAE (p. 295). / AGLYCYDERIDAE (p. 297). \ PROTKRHINIDAE (p. 298). Order. Famil>'- f ' Danaides (p. 344). Ithomiides (p. 346). Satyrides (p. 347). NYMPHALIDAE I Morphides (p. 348). (p. 343) | Brassolides (p. 349). Acraeides (p. 350). Rhopalocera Heliconiides (p. 351. (p. 341) ' . ISTymphalides (p. 352). ERYCINIDAE / Erycinides (p. 355). (p. 354) t Libytheides (p. 355). LYCAENIDAE (p. 356). PIERIDAE (p. 357). PAPILIONIDAE (p. 359). ^HESPERIIDAE (p. 363. f CASTNIIDAE (p.~ 371). NEOCASTNIIDAE (p. 372). SATUBNIIDAE (p. 372). BRAHMAEIDAE (p. 374). CERATOCAMPIDAE (p. 375). BOMBYCIDAE (p. 375). ElIPTEROTIDAE (p. 376). PEROPHORIDAE (p. 377). SPHINGIDAE (p. 380). COCYTIIDAE (p. 382). NOTODONTIDAE (p. 383). CYMATOPHORIDAE (p. 086). SESIIDAE (p. 386). : TlNAEGERIIDAE (p. 387). SYNTOMIDAE (p. 388). LEPIDOPTERA (p. 304) ZYGAENIDAE (p. 390). HlMANTOPTERIDAE (p. 392). HETEROGYNIDAE (p. 392). PSYCHIDAE (p. 392). COSSIDAE (p. 395). ARBELIDAE (p. 396). CHRYSOPOLOMIDAE (p. 396). Heterocera (p. 366) HEPIALIDAE (p. 396). CALLIDULIDAE (p. 400). DREPANIDAE (p. 400). LlMACODIDAE (p. 401). MEGALOPYGIDAE (p. 404). THYRIDIDAE (p. 404). LASIOCAMPIDAE (p. 405). ENDROMIDAE (p. 406). PTEROTHYSANIDAE (p. 406). LYMANTRIIDAE (p, 406). HYPSIDAE (p. 408). ARCTIIDAE (p: 408). AGARISTIDAE (p. 410). GEOMETRIDAE (p. 411). NOCTUIDAE (p. 414). EPICOPEIIDAE (p. 418). URANIIDAE (p. 419). EPIPI.EMIDAE (p. 420). PYRALIDAE (p. 420). PTEROPHORIDAE (p. 426). . .J j ALUCITIDAE (p. 426). TORTRICIDAE (p. 427). TlNEIDAE (p. 428). ERIOCEPHALIDAE (p. 433). 1 I MlCROPTERYGIDAE (p. 435). SCHEME OF CLASSIFICATION Bub-Order. Division, „ ., Sub-Family or On161- or Series. Family. Tribe ' CECIDOMYIIDAE (p. 458). MYCETOPHILIDAE (p. 462). BLEPHAROCERIDAE (p. 464). CULICIDAE (p. 466). CHIRONOMIDAE (p. 468). Orthorrha- ORPHNEPHILIDAE (p. 470). pha Nemo- PSYCHODIDAE (p. 470). cera DlXIDAE (p. 471). (p. 455) rr, ( Ptychopterinae (p. 472). TlPTJLIDAE 1 LijUbiinae (p;£73). " (Tipulinae (p. 475). BlBIONIDAE (p. 475). SlMTLIIDAE (p. 477). ^RHYPHIDAE (p. 478). " STRATIOMYIDAE (p. 478). LEPTIDAE (p. 479). TABANIDAE (p. 481). ACANTHOMERIDAE (p. 483). THEREVIDAE (p. 484). Orthorrha- SCENOPINIDAE (p. 484). plia Bra NEMESTRINIDAE (p. 484). chycera •< BOMBYLIIDAE (p. 485). ITTSTtrTO A (pp. 455, ACROCERIDAE (p. 489). JIPTEKA (p. 438) 478) LONCHOPTERIDAE (p. 490). MYDAIDAE (p. 491). ASILIDAE (p. 491). APIOCERIDAE (p. 492). EMPIUAE (p. 492). ^ DOLICHOPIDAE (p. 493). Cyclorrha- pha As- chiza (pp. 455, 494) Cyclorrha- plia Belli zophora (pp. 456, 503) Pupipara (pp. 456, 517) f PHORIDAE (p. 494). I PLATYPEZIDAE (p. 496). -| PIPUNCULIDAE (p. 496). CONOPIDAE (p. 497). I SYRPHIDAE (p. 498). 'MdSCIDAE ACALYPTRATAE (p. 503). ANTHOMYIIDAE (p. 506). TACHINIDAE (p. 507). DEXIIUAE (p. 510). SARCOPHAGIDAE (p. 510). MUSCIDAE (p. 511). _OESTRIDAE (p. 514). ( HIPPOBOSCIDAE (p. 518). I BRAULIDAE (p. 520). "I STKEBLIDAE (p. 521). 1. NYCTERIBIIDAE (p. 521). APHANIPTERA (pp. 456, 522) PULICIDAE (p. 522). THYSANO- f Terebrantia (p. 531). PTEEA (p. 526)\ Tubulifera (p. 531). Xll SCHEME OF CLASSIFICATION Order. Sub-Order. HEMIPTERA (p. 532) Heteroptera (pp. 543, 544) Series. Family. ( PEXTATOMIDAE (p. 545). COREIDAE (p. 546). BERYTIDAE (p. 548). LYGAEIDAE (p. 548). PYRRHOCORIDAE (p. 549). TlNGIDAE (p. 549). ARADIDAE (p. 550). HEBRIDAE (p. 551). GYMNOCER- HYDROMETRIDAE (p. 551). ATA (p. -| HENICOCEPHALIDAE (p. 554). 544) PHYMATIDAE (p. 554). REDUVIIDAE (p. 555). AEPOPHILIDAE (p. 559). CERATOCOMBIDAE (p. 559). CIMICIDAE (p. 559). ANTHOCORIDAE (p. 560). POLYCTENIDAE (p. 560). CAPSIDAE (p. 561). ^SALDIDAE (p. 562). f GALGULIDAE (p. 562). c NEPIDAE (p. 563). I NATJCORIDAE (p. 565). 562^ I BELOSTOMII>AE (p. 565). I NOTONECTIDAE (p. 567). I CORIXIDAE (p. 567). Homoptera (pp. 543, 568) Anoplura (p. 599.) TRIMERA 544) DlMERA (] 544) MONOMERA (p. 544). ( ClCADIDAE (p. 568). FULGORIDAE (p. 574). MEMBRACIDAE (p. 576). I CERCOPIDAE (p. 577). [ JASSIDAE (p. 578). f PSYLLIDAE (p. 578). '-! APHIDAE (p. 581). [ ALEURODIDAE (p. 591). -j COCCIDAE (p. 592). -J PEDICULIDAE (p. 599). CHAPTEE I HYMENOPTERA PETIOLATA CONTINUED SERIES 2. TUBULIFERA OR CHRYSIDIDAE SERIES 3. ACULEATA— GENERAL CLASSIFICATION DIVISION I. ANTHOPHILA OR BEES THE First Series — Parasitica — of the Sub-Order Hymenoptera Petiolata was discussed in the previous volume. We now pass to the Second Series. Series 2. Hymenoptera Tubulifera. Trochanters undivided ; the hind-body consisting of from three to Jive visible segments ; the female with an ovipositor, usually retracted, transversely segmented, enveloping a fine, pointed- style. The larvae usually live in the cells of other . Hymenoptera. The Tubulifera form but a small group in comparison with Parasitica and Aculeata, the other two Series of the, Sub-Order. Though of parasitic habits, they do not appear to be closely allied to any of the families of Hymenoptera Parasitica, though M. du .Buysson suggests that they have some affinity with Proctotrypidae ; their morphology and classification have been, however, but little discussed, and have not been the subject of any profound investi- gation. At present it is only necessary to recognise one family, viz. Chrysididae or Ruby-wasps.1 These Insects are usually of glowing, metallic colours, with a very hard, coarsely-sculptured integument. Their antennae are abruptly elbowed, the joints not being numerous, usually about thirteen, and frequently so 1 Systematic monograph, Mocsary, Budapest, 1889. Account of the European Chrysididae, R. du Buysson in Andre, Spec. gen. Hym. vol. vi. 1896. VOL. VI IE B HYMENOPTERA connected that it is not easy to count them. The abdomen is, in the great majority, of very peculiar construction, and allows the Insect to curl it completely under the anterior parts, so as to roll up into a little ball; the dorsal plates are very strongly arched, and seen from beneath form a free edge, while the ventral plates are of less hard consistence, and are connected with the dorsal plates at some distance from the free edge, so that the abdomen appears concave beneath. In the anomalous genus Cleptes the abdomen is, however, similar in form to that of the Aculeate Hymen - optera, and has four or five visible seg- ments, instead of the three or four that are all that can be seen in the normal Chrysididae. The larvae of the Ruby- flies have the same number of segments as other Hymenoptera Petiolata. The difference in this re- spect of the perfect Chrysididae from other Petiolata is due to a greater number of the terminal segments being indrawn so as to form the tube, or telescope-like structure from which the series obtains its name. This tube is shown partially extruded in Fig. 1 ; when fully thrust out it is seen to be segmented, and three or four segments may be distinguished. The ovipositor proper is concealed within this tube ; it appears to be of the nature of an imperfect sting ; there being a very sharply pointed style, and a pair of enveloping sheaths ; the style really consists of a trough-like plate and two fine rods or spiculae. There are no poison glands, except in Cleptes, which form appears to come very near to the Aculeate series. Some of the Chrysi- didae on occasions use the ovipositor as a sting, though it is only capable of inflicting a very minute and almost innocuous wound. Although none of the Ruby-flies attain a large size, they are usually very conspicuous on account of their gaudy or brilliant colours. They are amongst the most restless and rapid of Insects ; FIG. 1. — Chrysis ignita, ?. England. CHRYSIDIDAE they love the hot sunshine, and are difficult of capture. Though not anywhere numerous in species, they are found in most parts of the world. In Britain we have about twenty species. They usually frequent old wood or masonry, in which the nests of Aculeate Hymenoptera exist, or fly rapidly to and fro about the banks of earth where bees nest. Dr. Chapman has observed the habits of some of our British species.1 He noticed Chrysis if/nita flying about the cell of Odynerus parietum, a solitary wasp that provisions its nest with caterpillars ; in this cell the Chrysis deposited an egg, and in less than an hour the wasp had sealed the cell. Two days afterwards this was opened and was found to contain a larva of Chrysis a quarter of an inch long, as well as the Lepidopterous larvae stored up by the wasp, but there was no trace of egg or young of the wasp. Six days after the egg was laid the Chrysis had eaten all the food and was full- grown, having moulted three or four times. Afterwards it formed a, cocoon in which to complete its metamorphosis. It is, however, more usual for the species of Chrysis to live on the larva of the wasp and not on the food ; indeed, it has recently been positively stated that Chrysis never eats the food in the wasp's cell, but there is no ground whatever for rejecting the evidence of so care- ful an observer as Dr. Chapman. According to M. du Buys- son the larva of Chrysis will not eat the lepidopterous larvae, but will die in their midst if the Odynerus larva does not de- velop ; but this observation probably relates only to such species as habitually live on Odynerus itself. The mother-wasp of Chrysis bidentata searches for a cell of Odynerus spinipes that has not been properly closed, and that contains a full-grown larva of that wasp enclosed in its cocoon. Having succeeded in its search the Chrysis deposits several eggs — from six to ten ; for some reason that is not apparent all but one of these eggs fail to pro- duce young ; in two or three days this one hatches, the others shrivelling up. The young Chrysis larva seizes with its mouth a fold of the skin of the helpless larva of the Odynerus, and sucks it without inflicting any visible wound. In about eleven days the Chrysis has changed its skin four times, has consumed all the larva and is full-fed ; it spins its own cocoon inside that of its victim, and remains therein till the following spring, when it changes to a pupa, and in less than three weeks there- 1 Ent. Mag. vi. 1869, p. 153. HYMENOPTERA after emerges a perfect Chrysis of the most brilliant colour, and if it be a female indefatigable in activity. It is remarkable that the larva of Chrysis is so much like that of Odynerus that the two can only be distinguished externally by the colour, the Odynerus being yellow and the Chrysis white ; but this is only one of the many cases in which host and parasite are extremely similar to the eye. Chrysis shanghaiensis has been reared from the cocoons of a Lepidopterous Insect — Monema flavescens, family Limacodidae — and it has been presumed that it eats the larva therein contained. All other Chrysids, so far as known, live at the expense of Hymenoptera (usually, as we have seen, actually consuming their bodies), and it is not impossible that C. shang- haiensis really lives on a Hymenopterous parasite in the cocoon of the Lepidopteron. Parnopes carnea frequents the nests of Bembex rostrata, a solitary wasp that has the unusual habit of bringing from time to time a supply of food to its young larva ; for this purpose it has to open the nest in which its young is enclosed, and the Parnopes takes advantage of this habit by entering the cell and depositing there an egg which produces a larva that devours that of the Bembex. The species of the anomalous genus Cleptes live, it is believed, at the expense of Tenthredinidae, and in all prob- ability oviposit in their cocoons which are placed in the earth. Series 3. Hymenoptera Aculeata. The females (whether workers or true females} provided with a sting: trochanters usually undivided (monotrochous). Usually the antennae of the males with thirteen, of the females with twelve, joints (exceptions in ants numerous). These characters only define this series in a very unsatisfac- tory manner, as no means of distinguishing the " sting " from the homologous structures found in Tubulifera, and in the Procto- trypid division of Hymenoptera Parasitica, have been pointed out. As the structure of the trochanters is subject to numerous exceptions, the classification at present existing is an arbitrary one. It would probably be more satisfactory to separate the Proctotrypidae (or a considerable part thereof) from the Para- sitica, and unite them with the Tubulifera and Aculeata in a great series, characterised by the fact that the ovipositor is ACULEATA 5 withdrawn into the body in a direct manner so as to be entirely internal, whereas in the Parasitica it is not withdrawn in this manner, but remains truly an external organ, though in numerous cases concealed by a process of torsion of the terminal seg- ments. If this were done it might be found possible to divide the great group thus formed into two divisions characterised by the fact that the ovipositor in one retains its function, the egg FIG. 2. — Diagram of upper sur- face of Priocnemis ajfinis ?, Pompilidae. o, ocelli ; Z?1, pronotum ; B2, mesonotum ; /}3, scutellum of mesonotum ; /?4, post- scutellum or middle part of metanotuin ; £5, propo- deum or median segment (see vol. v. p. 491) ; -B", combing hairs, pecten, of front foot : C1, first segment of abdomen, here not forming a pedicel or stalk : IJ1, coxa ; D-, trochanter ; Z>3, femur ; Z)6, calcaria or spurs of hind leg : 1 to 15, nerv- ures of wings, viz. 1, costal ; 2, post -costal ; 3, median ; 4, posterior ; 5, stigma ; 6, marginal ; 7, upper basal ; 8, lower basal ; 9, 9, cubital ; 10, the three sub- marginal ; 11, first recurrent ; 12, second recurrent ; 13, anterior of hind wing ; 14, median ; 15, posterior : I to XI, the cells, viz. I, iipper basal ; II, lower basal ; III, marginal ; IV, V, VI, first, second and third sub-mar- ginal ; VII, first discoidal ; VIII, third discoidal ; IX, second discoidal ; X, first apical ; XI, second apical. passing through it (Proctotrypidae and Tubulifera), while in the other the organ in question serves as a weapon of offence and defence, and does not act as a true ovipositor, the egg escaping at its base. It would, however, be premature to adopt so revolu- tionary a course until the comparative anatomy of the organs concerned shall have received a much greater share of attention ; a detailed scrutiny of Prototrypidae being particularly desired. We have dealt with the external anatomy of Hymenoptera in HYMENOPTERA Vol. V. ; so that here it is only necessary to give a diagram to explain the terms used in the descriptions of the families and sub-families of Aculeata, and to discuss briefly their characteristic structures. The Sting of the bee has been described in detail by Kraepeliii, Sollmann, Carlet 1 and others. It is an extremely perfect me- chanical arrangement. The stirig itself — independent of the sheaths and adjuncts — consists of three elongate pieces, one of them a gouge-like director, the other two pointed and barbed needles ; the director is provided with a bead for each of the needles to run on, these latter having a corresponding groove ; the entrance to the groove is narrower than its subsequent diameter, so that the needles play up and down on the director with facility, but cannot be dragged away from it ; each needle is provided with an arm at the base to which are attached the muscles for its movement. This simple manner of describing the mechanical arrangement is, however, incomplete, inas- much as it includes no account of the means by which the poison is conveyed. This is done by a very com- plex set of modifications of all the parts ; firstly, the director is enlarged at the anterior s part to form a Fin. 3.-Stingofbee. A, One of the needles chamber, through which the separated ; a, the barbed point ; b, piston ; needles play ; the needles are c, arm. B, Transverse section of the i -11 -,1 sting : dd, the two needles ; e, bead for each Provided With a pl'O- guiding the needles ; /, director ; g, jecting piece, which, as the channel of poison. (After Carlet.) , needle moves, plays in the chamber of the director, and forces downwards any liquid that may be therein ; the poison-glands open into the chamber, and the projections on the needles, acting after the manner of a piston, carry the poison before them. The needles are so arranged on 1 Ann. Sci. Nat. (71 ix. 1890, p. 1. B ACULEATA — STING LARVA the director that they enclose between themselves and it a space that forms the channel along which the poison flows, as it is carried forwards by the movement of the pistons attached to the needles. If the needles be thrust into an object quite as far as, or beyond, the point of the director much poison may be introduced into a wound, as the barbs are provided with small orifices placed one above the other, while if this be not the case much of the liquid will flow on the outside of the object. According to Carlet the poison of the bee is formed by the mixture of the secretions of two glands, one of which is acid and the other alkaline ; it is very deadly in its effects on other Insects. We shall see, however, that the Fossorial Hymenoptera, which catch and sting living prey for their young, frequently do not kill but only stupefy it, and Carlet states that in this group the alkaline gland is absent or atrophied, so that the poison con- sists only of the acid ; it is thus, he thinks, deprived of its lethal power. Moreover, in the Fossoria the needles are destitute of barbs, so that the sting does not remain in the wound. Bordas, however, states l that in all the numerous Hymenoptera he has examined, both acid and alkaline glands exist, but exhibit considerable differ- ences of form in the various groups. He gives no explanation of the variety of effects of the poison of different Aculeata. The larvae (for figure of larva of Bombus, see Vol. V. p. 488) are, without known exception, legless grubs, of soft consistence, living entirely under cover, being protected either in cells, or, in the case of social Hymenoptera, in the abodes of the parents. The larvae of Ants and fossorial Hymenoptera have the anterior parts of the body long and narrow and abruptly flexed, so that their heads hang down in a helpless manner. All the larvae of Aculeates, so far as known, are remarkable from the fact that the posterior part of the alimentary canal does not connect with the stomach till the larval instar-is more or less advanced; hence the food amongst which they live cannot be sullied by faecal matter. The pupa is invariably soft, and assumes gradually the colour of the perfect Insect. Almost nothing is known as to the intimate details of the metamorphosis, and very little as to the changes of external form. According to Packard a period inter- venes between the stadium of the full-grown larva and that of the pupa, in which a series of changes he speaks of as semi-pupal 1 C. R. Ac. Paris, cxviii. 1894, p. 873. HYMENOPTERA CHAP. are passed through ; these, however, have not been followed out in the case of any individual, and it is not possible to form any final idea about them, but it seems probable that they are largely changes of external shape, in conformity with the great changes going on in the internal organs. Owing to the fragmentary nature of observations, much obscurity and difference of opinion have existed as to the metamorphosis of Aculeate Hymenoptera. Sir S. Saunders gives the following statement as to the larva of a wasp of the genus Psiliglossa? just before it assumes the pupal form : " The respective segments, which are very distinctly indi- cated, may be defined as follows : — The five anterior, including the head, are compactly welded together, and incapable of separate action in the pseudo-pupa state ; the third, fourth, and fifth bearing a spiracle on either side. The thoracical region termi- nating here, the two anterior segments are assignable to the development of the imago head, as pointed out by Ratzeburg." This inference is not, however, correct. We have seen that in the perfect Insect of Petiolate Hymenoptera the first abdominal segment is fixed to the thorax, and Saunders' statement is in- teresting as showing that this assignment of parts already exists in the larva, but it in no way proves that the head of the imago is formed from the thorax of the larva. It has been stated that the larvae of the Aculeata have a different number of seg- ments according to the sex, but this also is incorrect. The difference that exists in the perfect Insects in this respect is due to the withdrawal of the terminal three segments to the interior in the female, and of two only in the male. The larva consists of fourteen segments, and we find this number distributed in the female perfect Insect as follows : one constitutes the head, four segments the thorax and propodeum, followed by six external seg- ments of the restricted abdomen, and three for the internal structures of the abdomen. This agrees with Forel's statement that in the ants the sting is placed in a chamber formed by three segments. The development of the sting of the common bee has been studied by Dewitz.2 It takes place in the last larval stage. Although nothing of the organ is visible externally in the adult larva, yet if such a larva be placed in spirit, there can be seen within the skin certain small appendages on the ventral surface of the penultimate and antepenultimate abdominal segments 1 Trans, ent. Soc. London, 1873, p. 408. " Zeitschr. wiss. Zool. xxv. 1875, p. 184. AC.ULEATA DEVELOPMENT (Fig. 4, A) placed two on the one, four on the other ; these are the rudiments of the sting. In the course of development the terminal three segments are taken into the body, and the external pair of the appendages of the twelfth body segment (the ninth abdominal) become the sheaths of the sting, and the middle pair become the director; the pair of appendages on the eleventh segment give rise to the needles or spiculae. The sting -rudiments at an earlier stage (Fig. 4, C) are masses of hypodermis connected with tracheae ; there is then but one pair on the twelfth segment, and this pair coalesce to form a single mass ; the rudiments of the pair that form the director are FlG. 4.-DeveioPment of sting of differentiated secondarily from the primary pair of these masses of hypo- dermis. A good deal of discussion has taken place as to whether the component parts of the sting — gonapophyses — are to be considered as modifications of abdominal extremities (i.e. abdominal legs such as exist in Myriapods). Heymons is of opinion that this is not the case, but that the leg-rudiments and gonapophysal rudi- ments are quite distinct.1 The origin of the sting of Hymenoptera (and of the ovipositor of parasitic Hymeuoptera) is very similar to that of the ovipositor of Locusta (Vol. V. p. 315 of this work), but there is much difference in the history of the development of the rudiments. Dewitz has also traced the development of the thoracic appendages in Hymenoptera.'2 Although no legs are visible in the adult larva, they really arise very early in the larval life from masses of hypodermis, and grow in the interior of the body, so that when the larva is adult the legs exist in a segmented though rudimentary condition in the interior of the body. Dewitz's study of the wing-development is less complete. 1 Morph. Jahrb. xxiv. 1896, p. 192. 2 Zeitschr. wiss. Zool. xxx. 1878, p. 78. the bee : A and C, ventral ; B, side view. A, End of abdomen of adult larva : a, b, c, d, the last four segments, c being the eleventh body segment, 11 ; b bearing two pairs, and c one pair, of rudiments. B, Tip of abdomen of adult bee : 9, the ninth, d, the tenth body seg- ment. C, Rudiments in the early condition as seen within the body : c, first pair ; b, the second pair not yet divided into two pairs ; b", c', commence- ment of external growths from the internal projections. (After Dewitz.) 1 0 HYMENOPTERA Four primary divisions of Aculeates are generally recognised, viz. Anthophila (Bees), Diploptera (Wasps), Fossores (Solitary Wasps), Heterogyna (Ants). Though apparently they are natural, it is impossible to define them by characters that are without some exceptions, especially in the case of the males. Ashmead has recently proposed l to divide the Fossores ; thus making five divisions as follows : — Body with more or less of the hairs on it plumose . 1. Anthophila. Hairs of body not plumose. Pronotum not reaching back to tegulae . . 2. Entomophila [ = Fossores part] Pronotum reaching back to tegulae. Petiole (articulating segment of abdomen) simple without scales or nodes. Front wings in repose with a fold making them narrow 3. Diploptera. Front wings not folded . . .4. Fossores [part]. Petiole with a scale or node (an irregular elevation on the upper side) 5. Heterogyna. We shall here follow the usual method of treating all the fossorial wasps as forming a single group, uniting Ashmead's Entomophila and Fossores, as we think their separation is only valid for the purposes of a table ; the Pompilidae placed by the American savant in Fossores being as much allied to Entomo- phila as they are to the other Fossores with which Ashmead associates them. Division I. Anthophila or Apidae — Bees. Some of the hairs of the l>ody plumose ; parts of the mouth elon- gated, sometimes to a great extent, so as to form a protrusible apparatus, usually tubular with a very flexible tip. Basal joint of hind foot elongate. No wingless adult forms ; in some cases societies are formed, and then barren females called workers exist in great numbers, and carry on the industrial operations of the community. Food always derived from the vegetable kingdom, or from other Sees. There are about 150 genera and 1500 species of bees at present known. Some call the division Mellifera instead of Anthophila. The term Apidae is used by some authorities to de- note all the bees, while others limit this term to one of the families 1 Proc. ent. Soc. Washington, iii. 1896, p. 334. ANTHOPHILA BEES I I or sub-divisions. The bees are, as a rule, distinguished from other Hymenoptera by the hairs, by the great development of the mouth parts to form a proboscis (usually, but not correctly, called tongue), and by the modification of the hind-legs ; but these distinctive characters are in some of the species exhibited in so minor a degree of perfection that it is not easy to recognise these primitive forms as Anthophila. A few general remarks on the three points mentioned will enable the student to better appreciate the importance of certain points we shall subsequently deal with. The bees are, as a rule, much more covered with hair than any other of the Hymenoptera. Saunders l states that he has examined the structure of the hairs in all the genera of British Aculeata, and that in none but the Anthophila do branched and plumose hairs occur. The func- tion of this kind of hairs is unknown; Saunders suggests1 that they may be instrumental in the gathering of pollen, but they occur in the parasitic bees as well as in the males, neither of which gather pollen. The variety of the positions they occupy on the body seems to offer but little support to the suggestion. Not all the hairs of the bee's body are plumose, Some are simple, FIG 5.-Hairs of Bees : A, simple hair * from abdomen of Osima; B, spiral as shown in Fig. 5, A, and this is specially the case with the hairs that are placed at the edges of the dilated plates for carrying pollen. In some forms there is an extensive system of simple hairs all over the body, and the " feathers " are distributed between these ; and we do not see any reason for assuming that the feathered are superior to the simple hairs for gathering and carrying pollen. Some bees, e.g. Prosopis, Ceratina, have very little hair on the body, but nevertheless some plumose hairs are always present even though they be very short. 1 Trans, ent. Soc. 1878, p. 169. hair from abdomen of Megachile ; C, plumose hair from thorax of Mega- chile; D, from thorax of Andrena dorsata ; E, from thorax of Prosopis. 12 HYMENOPTERA The hind-legs of bees are very largely used in the industrial occupations of these indefatigable creatures; one of their chief functions in the female being to act as receptacles for carrying pollen to the nest : they exhibit, however, considerable diversity. The parts most modified are the tibia and the first joint of the hind-foot. Pollen is carried by other parts of the body in many bees, and even the hind-leg itself is used in different ways for the purpose : sometimes the outer face of the tibia is highly polished and its margins surrounded by hair, in which case pollen plates are said to exist (Fig. 6, A) ; sometimes the first joint of the tarsus is analogous to the tibia both in structure and function ; in other cases the hind- legs are thick and densely covered with hair that retains the pollen between the separate hairs. In this case the pollen is carried home in a dry state, while, in the species with pollen plates, the pollen is made into a mass of a clay-like consist- ence.1 The legs also assist in arrang- ing the pollen on the other parts of the body. The males do not carry FIG 6— A, Worker of the honey- bee poHen an(l though their llilld-legS (A pis melhfica), with pollen plates * . laden ; B, basal portions of a are also highly modified, yet the middle-leg (trochanter with part of modificationg do not agree with coxa and of lemur) with plumose hairs and grains of pollen ; c, one those of the female, and their func- hair bearing pollen-grains. ^^ ^ in ^ probabilitv gexual The parasitic bees also do not carry pollen, and exhibit another series of structures. The most interesting case in this series of modifications is that found in the genus Apis, where the hind-leg of male, female, and worker are all different (Fig. 25); the limb in the worker being highly modified for industrial purposes. This case has been frequently referred to, in consequence of the difficulty that exists in connection with its heredity, for the 1 The mode of wetting the pollen is not clear. Wolff says it is done by an exu- dation from the tibia; H. Miiller by admixture of nectar from the bee's mouth. The latter view is more probably correct. BEES PROBOSCIS I 3 structure exists in neither of the parents. It is, in fact, a case of a very special adaptation appearing in the majority of the individuals of each generation, though nothing of the sort occurs in either parent. The proboscis of the bee l is a very complex organ, and in its extremely developed forms exhibits a complication of details and a delicacy of structure that elicit the admiration of all who study it. In the lower bees, however, especially in Prosopis, it exists in a comparatively simple form (Fig. 9, B, C), that differs but little from what is seen in some Vespidae or Fossores. The upper lip and the mandibles do not take any part in the formation of the bee's proboscis, which is consequently entirely made up from the lower lip and the maxillae, the former of these two organs ex- hibiting the greatest modifications. The proboscis is situate on the lower part of the head, and in repose is not visible ; a portion, and that by no means an inconsiderable one, of its modifications being for the purpose of its withdrawal and protection when not in use. For this object the under side of the head is provided with a very deep groove, in which the whole organ is, in bees with a short proboscis, withdrawn ; in the Apidae with a long pro- boscis this groove also exists, and the basal part of the proboscis is buried in it during repose, while the other parts of the elon- gate organ are doubled on the basal part, so that they extend backwards under the body, and the front end or tip of the tongue is, when in repose, its most posterior part. For the extrusion of the proboscis there exists a special apparatus that comes into play after the mandibles are unlocked and the labrum lifted. This extensive apparatus cannot be satis- factorily illustrated by a drawing, as the parts composing it are placed in different planes ; but it may be described by saying that the cardo, or basal hinge of the maxilla, changes from an oblique to a vertical position, and thrusts the base of the pro- boscis out of the groove. The maxillae form the outer sheath of the proboscis, the lower lip its medial part (see Figs. 7 and 9) ; the base of the lower lip is attached to the submentum, which rises with the cardo so that labium and maxillae are lifted together ; the co-operation of these two parts is effected by an angular piece called the lorum, in which the base of the submentum rests ; the 1 In studying the proboscis the student will do well to take a Bombus as an example ; its anatomy being more easily deciphered than that of the honey-bee. HYMENOPTERA submentum is articulated with the men turn in such a manner that the two can either be placed in planes at a right angle to one another, or can be brought into one continuous plane, and by this change of plane the basal part of the tongue can also be thrust forwards. There is considerable variety in the lengths of these parts in different genera, and the lor urn varies in shape in accord- ance with the length of the submentum. The lorum is a peculiar piece, and its mechanical adaptations are very remark- able; usually the base of the submentum rests in the angle formed by the junction of the two sides of the lorum, but in Xylo- copa, where the submentum is unusually short, this part reposes FIG. 7. — Side view of basal portions of proboscis of Bombus. a, Epipharyngeal sclerites ; 6, arrow indicating the position of the entrance to pharynx, which is concealed by the epipharyux, c ; d, hypopharyngeal sclerites ; e, vacant space between the scales of the maxillae through which the nectar comes : /, lobe ; /', stipes ; palpiger ; d, scale : f, lobe ; g, palpus ; pharvnx. It is no doubt ^> card°> °f maxilla : i, lorum ; k, submentum ; . I, mentum ; m, labial palp ; n, paraglossa ; tO Slight movements OI the 0, ligula ; p, tip of ligula (with "spoon " at tip membranous parts of the *nd s°me of ^e hairs more magni&ed) ; q, hypopharyngeal sclerites. hypopharynx and of the epipharynx that the further progress of the nectar is due, aided by contraction and expansion of the pharynx, induced by muscles attached to it. It should be recollected that in addition to the movements of the head itself, the hypopharynx is constantly changing its dimensions slightly by the impulses of the fluid of the general body cavity; also that the head changes its position, VOL. vi c 1 8 HYMENOPTERA and that the proboscis is directed downwards as well as forwards. Those who wish to pursue this subject should refer to the works of Breithaupt l and Cheshire. The other external characters of the Bees call for little re- mark. The pronotum is never very large or much prolonged in front, and its hind angles never repose on the tegulae as they do in the wasps,2 but extend backwards below the tegulae. The hind body is never narrowed at the base into an elongate pedicel, as it so frequently is in the Wasps and in the Fossors ; and the pro- podeum (the posterior part of the thorax) is more perpendicular and rarely so largely developed as it is in the Fossors ; this last character will as a rule permit a bee to be recognised at a glance from the fossorial Hymenoptera. Bees, as every one knows, frequent flowers, and it is usually incorrectly said that they extract honey. They really gather nectar, swallow it, so that it goes as far as the crop of their ali- mentary canal, called in English the honey-sac, and is regurgi- tated as honey. Bertrand states that the nectar when gathered is almost entirely pure saccharose, and that when regurgitated it is found to consist of dextrose and levulose : 3 this change appears to be practically the conversion of cane- into grape-sugar. A small quantity of the products of the salivary glands is added, and this probably causes the change alluded to ; so that honey and nectar are by no means synonymous. According to Cheshire the glandular matter is added while the nectar is being sucked, and is passing over the middle parts of the lower lip, so that the nectar may be honey when swallowed by the bee. In addition to gathering nectar the female bees are largely occupied in collecting pollen, which, mixed with honey, is to serve as food for the colony. Many, if not all, bees eat pollen while collecting it. The mode in which they accumulate the pollen, and the mechanism of its conveyance from hair to hair till it reaches the part of the body it must attain in order to be removed for packing in the cells, is not fully understood, but it appears to be accomplished by complex correlative actions of various parts ; the head and the front legs scratch up the pollen, the legs move with great rapidity, and the pollen ultimately reaches its desti- nation. The workers of the genus Apis, and of some other social 1 Breithaupt, Arch. Naturges. lii. Bd. i. 1886, p. 47. 2 See Fig. 26, p. 71. 3 Bull. Mus. Paris, i. 1895, p. 38. BEES HABITS 19 bees, have the basal joint of the hind foot specially adapted to deal with pollen (Fig. 25, 2). We have already mentioned the modifications of the legs used for its conveyance, and need here only add that numerous bees — the Dasygastres — carry the pollen by aid of a special and dense clothing of hairs on the underside of the abdomen. The buzzing of bees (and other Insects) has been for long a subject of controversy : some having maintained that it is parti- ally or wholly due to the vibration of parts connected with the spiracles, while others have found its cause in the vibrations of the wings. According to the observations of Perez and Bellesme,1 two distinct sounds are to be distinguished. One, a deep noise, is due to the vibration of the wings, and is produced whenever a certain rapidity is attained ; the other is an acute sound, and is said to be produced by the vibrations of the walls of the thorax, to which muscles are attached ; this sound is specially evident in Diptera and Hymenoptera, because the integument is of the right consistence for vibration. Both of these observers agree that the spiracles are not concerned in the matter. The young of bees are invariably reared in cells. These (except in the case of the parasitical bees) are constructed by the mothers, or by the transformed females called \vorkers. The solitary bees store the cells with food, and close up each cell after having laid an egg in it, so that in these cases each larva consumes a special store previously provided for it. The social bees do not close the cells in which the larvae are placed, and the workers act as foster-mothers, feeding the young larvae after the same fashion as birds feed their nestling young. The food is a mixture of honey and pollen, the mixing being effected in various ways and proportions according to the species ; the honey seems to be particularly suitable to the digestive organs of the young larvae, and those bees that make closed cells, place on the outside of the mass of food a layer more thickly saturated with honey, and this layer the young grub consumes before attacking the drier parts of the provisions. The active life of the larva is quite short, but after the larva is full-grown it usually passes a more or less prolonged period in a state of quiescence before assuming the pupal form. The pupa shows the limbs and other parts of the perfect Insect in a very distinct manner, and the 1 C.R. Ac. Paris, Ixxxvii. 1878, pp. 378 and 535. 20 HYMENOPTERA CHAP. development of the imago takes place gradually though quickly. Some larvae spin cocoons, others do not. A very large number of bees are parasitic in their habits, laying an egg, or sometimes more than one, in the cell of a work- ing bee of some species other than their own ; in such cases the resulting larvae eat and grow more quickly than the progeny of the host bee, and so cause it to die of starvation. It has been .observed that some of these parasitic larvae, after eating all the store of food, then devour the larva they have robbed. In other cases it is possible that the first care of the parasitic larva, after hatching, is to eat the rival egg. The taxonomy of bees is in a very unsatisfactory state. The earlier Hymenopterists were divided into two schools, one of which proposed to classify the bees according to their habits, while the other adopted an arrangement depending on the length of the parts of the mouth, the development of the palpi, and the form and positions of the organs for carrying pollen. Neither of these arrangements was at all satisfactory, and some ento- mologists endeavoured to combine them, the result being a classification founded partly on habits and partly on certain minor structural characters. This course has also proved unsatis- factory ; this is especially the case with exotic bees, which have been placed in groups that are defined by habits, although very little observation has actually been made on this point. Efforts have recently been made to establish an improved classifi- cation, but as they relate solely to the European bees they are insufficient for general purposes. The more important of the groups that have been recognised are — (1) the Obtusilingues, short-tougued bees, with the tip of the lingua bifid or broad ; (2) Acutilingues, short-tongued bees, with acute tip to the tongue ; these two groups being frequently treated of as forming the Andrenidae. Coming to the Apidae, or the bees with long and folded tongues, there have been distinguished (3) Scopulipedes, bees carrying pollen with their feet, and (4) Dasygastres, those that carry it under the abdomen ; some of the parasitic and other forms have been separated as (5) Denudatae (or Cuculinae) ; the Bombi and the more perfectly social bees forming another group, viz. (6) Sociales. A group Andrenoides, or Panurgides, was also proposed for certain bees considered to belong to the Apidae though exhibiting many points of resem- i BEES — ARCHIAPIDES 2 I blaiice with the Andrenidae. This arrangement is by no means satisfactory, but as the tropical bees have been but little collected, and are only very imperfectly known, it is clear that we cannot hope for a better classification till collections have been very much increased and improved. The arrangement adopted in Dalla Torre's recent valuable catalogue of bees l recognises no less than fourteen primary divisions, but is far from satisfactory. The two genera Prosopis and Sphecodes have been recently formed into a special family, AKCHIAPIDAE, by Friese,2 who, how- ever, admits that the association is not a natural one. The term should be limited to Prosopis and the genera into which it has been, or shortly will be, divided. The primitive nature of the members of this genus is exhibited in all the external characters that are most distinctive of bees; the proboscis (Fig. 9, B, C), is quite short, its ligula being very short, and instead of being pointed having a concave front margin. The body is almost bare, though there is some very short feathered plumage. The hind legs are destitute of modifica- tions for industrial purposes. Owing to these peculiarities it was for long assumed that the Species of FIG. 10. — Prosopis signata. Cam- PrOSOpis must be parasites. This bridge A, Female ; B front of ^ head of female ; C, of male. is, however, known not to be the case so far as many of the species are concerned. They form cells lined with a silken membrane in the stems of brambles and other plants that are suitable, or in burrows in the earth, or in the mortar of walls ; individuals of the same species varying much as to the nidus they select. The food they store in these cells is much more liquid than usual, and has been supposed to be entirely honey, since they have no apparatus for carrying pollen. Mr. E. C. L. Perkins has, however, observed that they swallow both pollen and nectar, brushing the first- named substance to the mouth by aid of the front legs. He 1 Catalogus Hymenopterorum, Leipzig, 10 vols. 1892-96 ; Bees, vol. x. '2 Zool. Jahrb. Syst. iv. 1891, p. 779. This paper is a most valuable summary of what is known as to the habits of European solitary bees, but is less satisfactory from a systematic point of view. 22 IIYMENOPTERA has ascertained that a few of the very numerous Hawaiian species of the genus are really parasitic on their congeners : these parasites are destitute of a peculiar arrangement of hairs on the front legs of the female, the possession of which, by some of the non- parasitic forms, enables the bee to sweep the pollen towards its mouth. These observations show that the structural peculiarities of Prosopis are correlative with the habits of forming a peculiar lining to the cell, and of gathering pollen by the mouth and conveying it by the alimentary canal instead of by external parts of the body. Prosopis is a very widely distributed genus, and very numerous in species. We have ten in Britain ; several of them occur in the grounds of our Museum at Cambridge. The species of the genus Colletes are hairy bees of moderate size, with a good development of hair on the middle and posterior femora for carrying pollen. They have a short, bilobed ligula like that of wasps, and therein differ from the Andrenae, which they much resemble. With Prosopis they form the group Obtusi- lingues of some taxonornists. They have a manner of nesting peculiar to themselves ; they dig cylindrical burrows in the earth, line them with a sort of slime, that dries to a substance like gold-beater's skin, and then by partitions arrange the burrow as six to ten separate cells, each of which is filled with food that is more liquid than usual in bees. Except in regard to the ligula and the nature of the cell-lining, Colletes has but little resemblance to Prosopis; but the term Obtusilingues may be applied to Colletes if Prosopis be separated as Archiapidae. We have six species of Colletes in Britain. Sphecodes is a genus that has been the subject of prolonged difference of opinion. The species are rather small shining bees, with a red, or red and black, abdomen, almost with- out pollen-collecting apparatus, and with a short but pointed ligula. These characters led to the belief that the Insects are parasitic, or, as they are sometimes called, cuckoo-bees. But evidence could not be obtained of the fact, and as they were seen to make burrows it was decided that we have in Sphecodes examples of industrial bees extremely ill endowed for their work. Eecent observations tend, however, to prove that Sphecodes are to a la.rge extent parasitic at the expense of bees of the genera Halictus and Andrena. Breitenbach has taken S. rubicundus out of the brood-cells of Halictus quadricinctus ; and on one of the few BEES ANDRENIDES 2 3 occasions on which this bee has been found in Britain it was in circumstances that left little doubt as to its being a parasite of Andrena nigroaenea. Marchal l has seen S. subquadratus fight with Hcdictus malachurus, and kill it previous to taking possession of its burrows ; and similar observations have been made by Ferton. As the older observations of Smith, Sichel, and Friese leave little doubt that Sphe- codes are sometimes indus- trial bees, it is highly prob- able that we have in this FIG. 11. — Sphecodes gibbus 9. Britain. genus the interesting con- dition of bees that are sometimes parasitic, at other times not ; but so much obscurity still prevails as to the habits of Sphecodes that we should do well to delay accepting the theories that have been already based on this strange state of matters.2 Friese states that in Sphecodes the first traces of collecting apparatus exist ; and, accepting the condition of affairs as being that mentioned above, it is by no means clear whether we have in Sphecodes bees that are abandoning the parasitic habit or com- mencing it ; or, indeed, whether the condition of uncertainty may not be a permanent one. It is difficult to decide as to what forms are species in Sphecodes owing to the great variation. The Hymenopterist Forster considered that 600 specimens sub- mitted to him by Sichel represented no less than 140 species, though Sichel was convinced that nearly the whole of them were one species, S. gibbus. It has recently been found that the male sexual organs afford a satisfactory criterion. The position of Sphecodes in classification is doubtful. The great majority of the species of short-tongued bees found in Britain belong to the genera Andrena and Halictus, and with some others constitute the ANDEENIDES of many writers. Halictus includes our smallest British bees. Their economy escaped the earlier observers, but has recently been to some extent unravelled by Smith, Fabre, Nicolas, Verhoeff, and others, and proves to be 1 Bull. Soc. ent. France, 1894, p. cxv. - Marchal, Rev. Sci. 15th February 1890, and Ferton, t.c. 19th April. 24 HYMENOPTERA CHAP. of great interest and variety. Fabre observed H. lineolatus and H. sexcinctus l under circumstances that enabled him to give them continuous attention, whenever requisite, throughout a whole year. These bees are to a certain extent social ; they are gregarious ; each bee works for its own progeny, but there is collaboration between members of a colony, inasmuch as a piece of general work is undertaken from which more families than one derive benefit. This common work is a gallery, that, ramifying in the earth, gives access to various groups of cells, each group the production of a single Halictus ; in this way one entrance and one corridor serve for several distinct dwellings. The work of excavation is carried on at night. The cells are oval, and are covered on the interior with a delicate waterproof varnish ; Fabre considers this to be a product of the salivary glands, like the membrane we noticed when speaking of Colletes. In the south of France both sexes of these species are produced from the nests in September, and then the males are much more numerous than the females ; when the cold weather sets in the males die, but the females continue to live on in the cells underground. In the following spring the females come out and recommence working at the burrows, and also provision the cells for the young ; the new generation, consisting entirely of females, appears in July, and from these there proceeds a parthenogenetic generation, which assumes the perfect form in September, and consists, as we have above remarked, in greater part of males. Perez,2 however, considers that Fabre's observations as to the parthenogenetic generation were incomplete, and that males might have been found a little earlier, and he consequently rejects altogether the occurrence of parthenogenesis in Halictus. Nicolas con- firms Fabre's observations, so far as the interesting point of the work done for common benefit is concerned ; and adds that the common corridor being too narrow to permit of two bees passing, there is a dilatation or vestibule near the entrance that facilitates passage, and also that a sentinel is stationed at this point. Smith's observations on Halictus morio in England lead one to infer that there is but one generation, the appearance of which extends over a very long period. He says, " Early in April the females appeared, and continued in numbers up to the end of 1 C.R. Ac. Paris, Ixxxix. 1879, p. 1079, and Ann. Sci. Nat. (6), ix. 1879, No. 4. 2 Act. Soc. Bordeaux, xlviii. 1895, p. 145. BEES ANDRENIDES June " : then there was an interval, and in the middle of August males began to appear, followed in ten or twelve days by females. Hence it is probable that in different countries the times of appearance and the number of generations of the same species may vary. Verhoeff has described the burrows of Halictus quadricinctus with some detail. The cells, instead of being distributed as usual throughout the length of the burrow one by one, are accumulated into a mass placed in a vault communi- cating with the shaft. This shaft is continued downwards to a depth of 10 cm., and forms a retreat for the bees when engaged in construction. Several advantages are secured by this method, especially better ventilation, and pro- tection from any water that may enter FIG. 12.— Nesting of Halictus quadricinctus. u, Original burrow, with entrance e thereto ; n, retreat or con- tinuation of the burrow ; w, the vaults ; s, the accumula- tion of cells. (After Ver- hoeff, Verh. Ver. Rheinl. xlviii. 1891 ; scale not mentioned.) the shaft. The larvae that are present in the brood-chambers at any one moment differ much in their ages, a fact that throws some doubt on the supposed parthenogenetic generation. No cocoons are formed by these Halictus, the polished interior of the cell being a sufficiently refined resting place for metamorphosis. Verhoeff states that many of the larvae are destroyed by mouldiness ; this indeed, he considers to be the most deadly of the enemies of Aculeate Hymenoptera. The nest of Halictus maculatus has also been briefly described by Verhoeff, and is a very poor construction in comparison with that of H. quadricinctus. The genus Andrena includes a great number of species, Britain possessing about fifty. They may be described in a general manner as Insects much resembling the honey-bee — for which, indeed, they are frequently mistaken — but usually a little smaller in size. Many of the bees we see in spring, in March or April, are of this genus. They live in burrows in the ground, preferring sandy places, but frequently selecting a gravel path as the locality for their operations ; they nearly always live 26 HYMENOPTERA in colonies. Great difficulties attend their study on account of several points in their economy, such as, that the sexes are different, and frequently not found together ; also that there may be two generations of a species in one year, these being more or less different from one another. Another considerable difficulty arises from the fact that these bees are subject to the attacks of the parasite Stylops, by which their form is more or less altered. These Insects feed in the body of the bee in such a way as to affect its nutrition without destroying its life ; hence they offer a means of making experiments that may throw valuable light on obscure physiological questions. Among the effects they produce in the condition of the imago bee we may mention the enfeeble- ment of the sexual distinction, so that a stylopised male bee becomes less different than it usually is from the female, and a stylopised female may be ill developed and less different than usual from the male. The colours and hair are sometimes altered, and distortion of portions of the abdominal region of the bee are very common. Further particulars as to these parasites will be found at the end of our account of Coleoptera (p. 298). We may here remark that these Stylops are not the only parasitic Insects that live in the bodies of Andrenidae without killing their hosts, or even interrupting their metamorphoses. Mr. R. C. L. Perkins recently captured a specimen of Halictus rubicundus,from which he, judging from the appearance of the example, anticipated that a Stylops would emerge ; but instead of this a Dipterous Insect of the family Chloropidae appeared. Dufour in 1 8 3 7 called attention to a remarkable relation existing between Andrena aterrimaamd. a parasitic Dipterous larva. The larva takes up a position in the interior of the bee's body so as to be partly included in one of the great tracheal FIG. 13.— Parasitic Dipterous vesicles at the base of the abdomen ; and larva in connection with th bee then maintains the parasite in its tracheal system of An- drena aterrima. (After position, and at the same time supplies it -|-v f \ with air by causing two tracheae to grow into its body. Dufour states that he demonstrated the continuity of the tracheae of the two organisms, but it is by no means clear that the continuity was initially due to the bee's organisation. BEES ANDRENIDES Dasypoda hirtipes appears to be the most highly endowed of the European Andrenides. The Insects of the genus Dasypoda are very like Andrena, but have only two in place of three submarginal cells (just beneath the stigma) 011 the front wing. The female of D. hirtipes has a very dense and elongate pubes- cence on the posterior legs, and FIG. 14. — D. hirtipes ?. Britain. carries loads of pollen, each about half its own weight, to its nest. The habits of this insect have been described by Hermann Mullen1 It forms burrows in the ground after the fashion of Andrena; this task is accomplished by excavating with the mandibles ; when it has detached a certain quantity of the earth it brings this to the surface by moving backwards, and then dis- tributes the loose soil over a considerable area. It accomplishes this in a most beautiful manner by means of the combined action of all the legs, each pair of these limbs performing its share of the function in a different manner ; the front legs acting with great rapidity — making four movements in a second — push the sand backwards under the body, the bee moving itself at the same time in this direction by means of the middle pair of legs ; simultaneously, but with a much slower movement, the hind legs are stretched and moved outwards, in oar-like fashion, from the body, and thus sweep away the earth and distribute it towards each side. This being done the bee returns quickly into the hole, excavates some more earth, brings it up and distributes it. Each operation of excavation takes a minute or two, the distribution on the surface only about fifteen seconds. The burrow extends to the length of one or two feet, so that a considerable amount of earth has to be brought up ; and when the Insect has covered one part of the circumference of the mouth of the hole with loose earth, it makes another patch, or walk, by the side of the first. The main burrow being completed, the Insect then commences the formation of brood-chambers in connection with it. Three to six such chambers are formed in connection with a burrow ; the lower one is first made and is provisioned by the bee : for this 1 Verh. Ver. Rheinland, xli. 1884, p. 1. 28 HYMENOPTERA CHAP. purpose five or six loads of pollen are brought to the cell, each load being, as we have already remarked, about half the weight of the Insect. This material is then formed into a ball and made damp with honey ; then another load of pollen is brought, is mixed with honey and added as an outer layer to the ball, which is now remodelled and provided on one side with three short feet, after which an egg is placed on the top of the mass ; the bee then sets to work to make a second chamber, and uses the material resulting from the excavation of this to close completely the first chamber. The other chambers are subsequently formed in a similar manner, and then the burrow itself is filled up. While engaged in ascertaining these facts, Mliller also made some observations on the way the bee acts when disturbed in its operations, and his observations on this point show a very similar instinct to that displayed by Chalicodoma, referred to on a subsequent page. If interrupted while storing a chamber the Insect will not attempt to make a fresh one, but will carry its stock of provisions to the nest of some other individual. The result of this proceeding is a struggle between the two bees, from which it is satisfactory to learn that the rightful proprietor always comes out victorious. The egg placed on the pollen-ball in the chamber hatches in a few days, giving birth to a delicate white larva of curved form. This creature embraces the pollen-ball so far as its small size will enable it to do so, and eats the food layer by layer so as to preserve its circular form. The larva when hatched has no anal orifice and voids no excrement, so that its food is not polluted ; a proper moulting apparently does not take place, for though a new delicate skin may be found beneath the old one this latter is not definitely cast off. When the food, which was at first 100 to 140 times larger than the egg or young larva, is all consumed the creature then for the first time voids its refuse. During its growth the larva becomes red and increases in weight from '0025 grains to '26 or '35 grains, but during the subsequent period of excretion it diminishes to '09 or "15 grains, and in the course of doing so becomes a grub without power of movement, and of a white instead of a red colour. After this the larva reposes motionless for many months — in fact, until the next summer, when it throws off the larval skin and appears as a pupa. The larval skin thus cast off contrasts greatly with the previous delicate condi- BEES DENUDATAE 29 tion of the integument, for this last exuvium is thick and rigid. Although it voids no excrement till much later the union of the stomach and hind-intestine is accomplished when the larva is half-grown. A larva, from which Miiller took away a portion of its unconsumed food -store, began directly afterwards to emit excrement. The pupa has greater power of movement than the resting larva; when it has completed its metamorphosis and become a perfect Insect, it, if it be a female, commences almost immediately after its emergence to form burrows by the complex and perfect series of actions we have described. Parasitic Bees (DENUDATAE). — This group of parasitic bees includes fourteen European genera, of which six are British. They form a group taxonomically most unsatisfactory, the members having little in common except the negative characters of the absence of pollen-carrying apparatus. Although there is a great dearth of information as to the life -histories of parasitic bees, yet some highly interesting facts and generalisa- tions about their relations with their hosts have already been obtained. Verhoeff has recently given the following account of the relations between the parasitic bee Stelis minuta and its host Osmia leucomelana : — The Osmia forms cells in blackberry stems, provisions them in the usual manner, and deposits an egg in each. But the Stelis lays an egg in the store of pro- visions before the Osmia does, and thus its egg is placed lower down in the mass of food than that of the legitimate owner, which is in fact at the top. The Stelis larva emerges from the egg somewhat earlier than the Osmia larva does. For a con- siderable time the two larvae so disclosed consume together the stock of provisions, the Osmia at the upper, the Stelis at the lower, end thereof. By the consumption of the provisions the two larvae are brought into proximity, and by this time the Stelis larva, being about twice the size of the Osmia larva, kills and eats it. Verhoeff witnessed the struggle between the two larvae, and states further that the operation of eating the Osmia larva after it has been killed lasts one or two days. He adds that parasitic larvae are less numerous than the host larvae, it being well known that parasitic bees produce fewer offspring than host bees. Verhoeff further states that he has observed similar relations to obtain between the larvae of other parasitic bees and their hosts, but warns us against concluding that the facts are analogous in all cases. 30 HYMENOPTERA CHAP. Fabre has made us acquainted with some points in the history of another species of the same genus, viz. Stelis nasuta, that show a decided departure from the habits of S. minuta. The first-named Insect accomplishes the very difficult task of breaking open the cells of the mason-bee, Chalicodoma muraria, after they have been sealed up, and then, being an Insect of much smaller size than the Chali- codoma, places several eggs in one cell of that bee. Friese informs • us that parasitic bees and their hosts, in a great number of cases, not only have in the perfect state the tongue similarly formed, but also frequent the same species of flower ; thus Colletes daviesanus and its parasite JEpeolus variegatus both specially affect the flowers of Tanacetum vulgare. Some of the parasitic bees have a great resem- blance to their hosts ; Stelis signata, for instance, is said to be so like Anthidium strigatum that for many FLG. 15.— Nomada sex-fasciata ?. years it was considered to be a species of the genus Anthidium. In other cases not the least resemblance exists between the parasites and hosts. Thus the species of Nomada that live at the expense of species of the genus Andrena have no resemblance thereto. Friese further tells us that the Andrena and Nomada are on the most friendly terms. Andrena, as is well known, forms populous colonies in banks, paths, etc., and in these colonies the destroying Nomada flies about unmolested ; indeed, according to Friese, it is treated as a welcome guest. He says he has often seen, and in several localities, Nomada latliburiana and Andrena ovina flying peacefully together. The Nomada would enter a burrow, and if it found the Andrena therein, would come out and try another burrow ; if when a marauding Nomada was in a burrow, and the rightful owner, returning laden with pollen, found on entering its home that an uninvited guest was therein, the Andrena would go out in order to permit the exit of the Nomada, and then would again enter and add the pollen to the store. Strange as this may seem at first sight, it is really not so, for, as we have before had occasion to observe, there is not the slightest reason for believing that host Insects have any idea whatever that the parasites or inquilines are injurious to their PARASITIC BEES DENUDATAE race. Why then should they attack the creatures ? Provided the parasites do not interfere in. any unmannerly way with the hosts and their work, there is no reason why the latter should resent their presence. The wild bee that seals up its cell when it has laid an egg therein, and then leaves it for ever, has no conception of the form of its progeny ; never in the history of the race of the Andrena has a larva seen a perfect insect and survived thereafter, never has a perfect Insect seen a larva. There is no reason what- ever for believing that these Insects have the least conception of their own metamorphosis, and how then should they have any idea of the metamorphosis of the parasite ? If the Andrena found in the pollen the egg of a parasitic Nomada, it could of course easily remove the egg ; but the Andrena has no conception that the presence of the egg ensures the death of its own offspring and though the egg be that of an enemy to its race, why should it resent the fact ? Is it not clear that the race has always maintained itself notwithstanding the enemy ? Nature has brought about that both host and parasite should successfully co-exist ; and each individual of each species lives, not for itself, but for the continuance of the species ; that continuance is pro- vided for by the relative fecundities of host and guest. Why then should the Andrena feel alarm ? If the species of Nomada attack the species of Andrena too much it brings about the de- struction of its own species more certainly than that of the Andrena. Such extremely friendly rela- tions do not, however, exist be- tween all the parasitic bees and r . FIG. 16. — Mdecta luctuosa ?. Britain. their hosts. Friese says that, so far as he has been able to observe, the relations between the two are not in general friendly. He states that marauders of the genera Melecta and Coelioxys seek to get out of the way when they see the pollen-laden host coming home. But he does not appear to have noted any other evidence of mistrust between the two, and it is somewhat doubtful whether this act can properly be interpreted as indicating fear, for bees, as well as other animals, when engaged in work find it annoying to be interfered 32 HYME-NOPTERA CHAP. with ; it is the interest of the parasite to avoid annoyance and to be well-mannered in its approaches. Shuckard, however, says that battles ensue between the parasite Mclecta and its host Anthophora, when the two bees meet in the burrows of the Anthophora.1 We shall have occasion to remark on some of the habits of Dioxys cincta when considering the history of the mason-bee (Chalicodoma), but one very curious point in its economy must here be noticed. The Dioxys, which is a much smaller bee than the Chalicodoma, lays an egg in a cell of the latter, and the resulting larva frequently has more food in the cell than it can consume ; there is, however, another bee, Osmia cyanoxantha, that frequently takes advantage of an unoccupied cell in the nest of the Chalicodoma, and establishes its own offspring therein. The Dioxys, it seems, cannot, or at any rate does not, distinguish whether a cell is occupied by Chalicodoma or by Osmia, and some- times lays its egg in the nest of the Osmia, though this bee is small, and therefore provides very little food for its young. It might be supposed that under these conditions the Dioxys larva would be starved to death ; but this is not so ; it has the power of accommodating its appetite, or its capacity for metamorphosis, to the quantity of food it finds at its disposal, and the egg laid in the Osmia cell actually produces a tiny specimen of Dioxys, only about half the natural size. Both sexes of these dwarf Dioxys are produced, offering another example of the fact that the quantity of food ingested during the lifetime of the larva does not influ- ence the sex of the resulting imago. The highly endowed bees that remain to be considered are by some writers united in a group called Apidae, in distinction from Andrenidae. For the purposes of this work we shall adopt three divisions, Scopulipedes, Dasygastres, Sociales. The group SCOPULIPEDES includes such long-tongued, solitary bees as are not parasitic, and do not belong to the Dasygastres. It is not, however, a natural group, for the carpenter-bees (Xylocopa) are very different from Anthophora. It has recently been merged by Friese with Andrenides into a single group called Podilegidae. Four British genera, Ceratina, Antho- phora, Eucera and Saropoda (including, however, only seven 1 It is impossible for us here to deal with the question of the origin of the para- sitic habit in bees. The reader wishing for information as to this may refer to Prof. Perez's paper, Ad. Soc. Bordeaux, xlvii. 1895. p. 300. i SCOPULIPEDES CARPENTER-BEES 33 species), are referred to the Scopulipedes ; in some forms a con- siderable resemblance to the Bombi is exhibited, indeed the female of one of our species of Anthophora is so very like the worker of Boinbus hortorum var. harrisellus, that it would puzzle any one to distinguish them by a superficial inspection, the colour of the hair on the hind legs being the only obvious differ- ence. Anthophora is one of the most extensive and widely distributed of the genera of bees. Some of the species make burrows in cliffs and form large colonies which are continued for many years in the same locality. Friese has published many details of the industry and metamorphoses of some of the species of this genus ; the most remarkable point he has discovered being that A. personata at Strasburg takes two years to accomplish the life-cycle of one generation. Some of the European species of the genus have been found to be very subject to the attacks of para- sites. An anomalous beetle, Sitai-is, has been found in the nests of A. pilipes ; and this same Anthophora is also parasitised by another beetle, Meloc, as well as by a bee of the genus Mclccta. The genus Xylocopa l contains many of the largest and most powerful of the bees, and is very widely distributed over the earth. In Europe only four or five species have been found, and none of them extend far northwards, X. violacca being the only one that comes so far as Paris. They are usually black or blue- black in colour, of broad, robust build, with shining integuments more or less covered with hair. X. violacea is known as the carpenter-bee from its habit of working in dry wood ; it does not touch living timber, but will form its nest in all sorts of dried wood. It makes a cylindrical hole, and this gives access to three or four parallel galleries in which the broad cells are placed ; the cells are always isolated by a partition ; the bee forms this by cementing together with the products of its salivary glands the fragments of wood it cuts out. Its habits have been described at length by Reaumur, who alludes to it under the name of " abeille perce-bois." This bee hibernates in the imago condition, both sexes reappearing in the spring. Possibly there is more than one generation in the year, as Reaumur states that specimens that were tiny larvae on the 12th of June had by the 2nd of July consumed all their stock of provisions ; they then fasted for a few days, and on the 7th or 8th of July became pupae, and in the first 1 Refer to p. 70 postca, note, as to a recent discovery about Xylocopa. VOL. VI D 34 HYMENOPTERA CHAP. days of August were ready to emerge as perfect Insects. Thus the whole cycle of metamorphoses is passed through in about eight weeks. This species, though very clever in drilling holes, does not hesitate to appropriate old burrows should they be at hand. Fabre observed that it was also quite willing to save itself labour by forming its cells in hollow reeds of sufficient calibre. We have figured the larva and pupa of this species in the previous volume (p. 170). Xylocopa chloroptera in E. India selects a hollow bamboo for its nidus ; it cements together the pieces obtained in clearing FIG. 17. — Xylocopa (Koptorlhosoma), S2). near flavon igrescens, /x (/(>//>$ succeeds in perforating the masonry and depositing therein an egg, so that a Leucospis is reared in the cell instead of a Chalicodoma. i DASYGASTRES — MASON-BEES 37 This Insect has been the object of some of J. H. Fabre's most instructive studies on instinct.1 Although it is impossible for us here to consider in a thorough manner the various points he has discussed, yet some of them are of such interest and im- portance as to demand something more than a passing allusion. We have mentioned that the nest of Clialicodoma is roofed with a layer of solid cement in addition to the first covering with which the bee seals up each cell. When the metamorphoses of the imprisoned larva have been passed through, and the moment for its emergence as a perfect Insect has arrived, the prisoner has to make its way through the solid wall by which it is encom- passed. Usually it finds no difficulty in accomplishing the task of breaking through the roof, so that the powers of its mandibles must be very great. Keaumur has, however, recorded that a nest of this mason-bee was placed under a glass funnel, the orifice of which was covered with gauze, and that the Insects when they emerged from the nest were unable to make their way through the gauze, and consequently perished under the glass cover ; and he concluded that such insects are only able to accomplish the tasks that naturally fall to their lot. By some fresh experiments Fabre, however, has put the facts in a different light. He remarks that when the Insects have, in the ordinary course of emergence, perforated the walls of their dark prison, they find themselves in the daylight, and at liberty to walk away ; when they have made their escape from a nest placed under a glass cover, they, having no knowledge of glass, find themselves in daylight and imprisoned by the glass, which, to their inexperience, does not appear to be an obstacle, and they therefore, he thought, might perhaps exhaust themselves in vain efforts to pass through this invisible obstacle. He therefore took some cocoons contain- ing pupae from a nest, placed each one of them in a tube of reed, and stopped the ends of the reeds with various substances, in one case earth, in another pith, in a third brown paper ; the reeds were then so arranged that the Insects in them were in a natural position ; in due course all the Insects emerged, none of them apparently having found the novel nature of the obstacle a serious impediment. Some complete nests were then taken with their inmates, and to the exterior of one of them a sheet of opaque paper was closely fastened, while to another the same 1 Souvenirs entomologiques. 4 vols. Paris, 1879 to 1891. 38 HYMENOPTERA sort of paper was applied in the form of a dome, leaving thus a considerable space between the true cover of the nest and the covering of paper. From the first nest the Insects made their escape in the usual manner, thus again proving that paper can be easily pierced by them. From the second nest they also liberated themselves, but failed to make their way out through the dome of paper, and perished beneath it ; thus showing that paper added to the natural wall caused them no difficulty, but that paper separated therefrom by a space was an insuperable obstacle. Professor Perez has pointed out that this is no doubt due to the large space offered to the bee, which consequently moves about, and does not concentrate its efforts on a single spot, as it of course is compelled to do when confined in its natural cell. The power of the mason -bee to find its nest again when removed to a distance from it is another point that was tested by Du Hamel and recounted by Ke*aumur. As regards this Fabre has also made some very valuable observations. He marked some specimens of the bee, and under cover removed them to a distance of four kilometres, and then liberated them ; the result proved that the bees easily found their way back again, and indeed were so little discomposed by the removal that they reached their nests laden with pollen as if they had merely been out on an ordinary journey. On one of these occasions lie observed that a C/ialicodoma, on returning, found that another bee had during her absence taken possession of her partially completed cell, arid was unwilling to relinquish it ; whereupon a battle between the two took place. The account of this is specially interesting, because it would appear that the two com- batants did not seek to injure one another, but were merely engaged in testing, as it were, which was the more serious in its claims to the proprietorship of the cell in dispute. The matter ended by the original constructor regaining and retaining posses- sion. Fabre says that in the case of Chalicodoma it is quite a common thing for an uncompleted cell to be thus appropriated by a stranger during the absence of the rightful owner, and that after a scene of the kind described above, the latter of the two claimants always regains possession, thus leading one to suppose that some sense of rightful ownership exists in these bees ; the usurper expressing, as it were, by its actions the idea — Before I i DASYGASTRES — MASON-BEES FINDING THE NEST 39 resign my claims I must require you to go through the exertions that will prove you to be really the lawful owner. Another experiment was made with forty specimens of CJiall- i-nt/uiita i>!i/'<'ii\ Soc, Glasgow, n. s. ii. 1889, p. 194. 68 HYMENOPTERA greatly increased, as the fertilisation of the young new queen is effected during a solitary flight she makes after the colony has settled down. But in a state of nature the colonies do not send off swarms every year or once a year, but increase to an enormous extent, going for years without swarming, and then when their home is really filled up send off, it may be presumed, a number of swarms in one year. Thus the phenomena of bee-life in a wild condition differ considerably from those we see in artifi- cial confinement. And this difference is probably greatly accen- tuated by the action of parasites, the proportions of which to their guests are in a state of nature liable to become very great ; as we have seen to be the case in Itombus. Under these circumstances it is not a matter for surprise when we find that the honey-bee has formed distinct races analogous to those that exist in the case of the domesticated vertebrate animals. The knowledge of these races is, however, at present very little advanced, and is complicated by the fact that only imperfect information exists as to the true species of the genus Apis. There is a bee very like our common honey- bee found in southern Europe called A. ligustica ; this is certainly a variety of A. melli/ica, and the same remark applies to a bee found in Egypt, and called A. fasciata. This gives the honey-bee a very wide distribution, extending possibly over the whole of the palaearctic region : besides this, the species has been introduced into various other parts of the world. According to Karsch the honey-bee shows in Germany several varieties, all of which belong to the northern form, which may be spoken of as the A. domestica of Ray ; the A. ligustica and A. fasciata form as we have said distinct races, and it is a remark- able fact that these races remain distinct even when imported into other climates ; though for how long a period of time this remains true there is very little evidence to show. The northern form, A. domestica, is now found in very widely separated parts of the world, in some of which it is wild ; Smith mentions it as occurring in the West India islands, throughout the North American continent as far south as Mexico, even in Central and Southern Africa, and in Australia and New Zealand. The var. ligustica has been found also at the Cape of Good Hope. The other species known of the genus Apis all belong to the Old World, so that there is very little doubt that A. mellifica is also SOCIALES HONEY-BEE 69 a true native of the eastern hemisphere, and its original home may possibly have been not far from the shores of the eastern portion of the Mediterranean sea. Seven or eight other species of Apis are known, all but one of which occur in Asia, ex- tending as far as Timor and Celebes. The exceptional one, A. adansonii, occurs in tropical Africa and in Madagascar. Gerstaecker thought these species might be reduced to four, but Smith's statement that the males and even the workers show good dis- tinctive characters seems to be correct. Very little is known as to the honey- bees of China and Japan. The queen-bee greatly resembles the worker, but has the hind body more elongated ; she can, however, always be distinguished from the worker by the absence of the beautiful transverse, comb-like series of hairs on the inner side of the first joint of the hind foot, the planta, as it is called by the bee- keeper : she has also no wax plates and differs in important anatomical peculi- arities. The male bee or drone is very different, being of much broader, more robust build, and with very large eyes that quite meet in the middle of the upper part of the head : he also has the hind leg differently shaped. The form of this limb enables the male of A. mellifica FIG. 25. to be distinguished from the correspond- ing sex of allied species of the genus. We are indebted to Home for some particulars as to the habits of A. dorsata, an allied East Indian species. He informs us that these bees greatly disfigure buildings, such as the Taj Mahal at Agra, by attaching their pendent combs to the marble arches, and are so pertinacious that it is almost useless to destroy the nests. This bee is said to be so savage in its disposition that it cannot be domesticated ; it attacks the sparingly clad Hindoos Portions of hind-feet, 1, of male, 2, of worker, 3, of queen, of the honey-bee ; series on the left, outer faces ; on the right, inner faces, a, Tip of tibia : 6, first joint ; c, second joint of tarsus. 70 HYMENOPTERA CHAP, i with great ferocity when they disturb its nest. Notwithstand- ing its inclination and power to defend its societies this Insect appears to be destroyed wholesale. Colonel Eamsay failed to establish hives of it, because the Insects were eaten up by lizards. The crested honey-buzzard carries off large portions of the comb, and devours it on a branch of some tree near by, quite regardless of the stings of the bees; while the fondness of bears for the honey of the " Dingar," as this species is called, is well known. NOTE TO P. 33 : It has just been discovered that a most remarkable symbiosis, with structural modification of the bee, exists between the females of Xylocopa, of the Oriental sub-genus Koptorthosoma, and certain Acarids. A special chamber, with a small orifice for entry, exists in the abdomen of the bee, and in this the Acari are lodged. — See Perkins, Ent. Mag. xx.xv. 1899, p. 37. NOTE TO P. 80 : referring to the habits of social wasps in warm countries. The anticipation we ventured to indulge in is shown to be correct by the recent observations of Von Ihering.1 He states that social wasps in Brazil may be divided into two great groups by their habits, viz. 1. Summer com- munities, lasting for one year, and founded annually by fertilised females that have hibernated — example, Polistes ; 2. Perennial communities, founded by swarms after the fashion of bee colonies — examples, Polybia, Charteryus. 1 Ann. Nat. Hist. (6), xix. 1897, p. 136. NOTE TO VOL. V. PP. 545, 546 : The development of Encyrtns fuscicollis has now been studied by Marchal, who has discovered the existence of embryonic dissociation. The chain of embryos and the epithelial tube in which they are placed, are formed as follows : the Encyrtus deposits an egg in the interior of the egg of the Hyponomeuta. This does not kill the egg of the Lepidopteron, but becomes included in the resulting caterpillar. The arnnion. of the Chalcid egg lengthens, and forms the epithelial tube ; while the cells within it become dissociated in such a way as to give rise to a chain of embryos, instead of a single embryo. — C.R. Ac. Paris, cxxvi. 1898, p. 662, and translation in Ann. Nat. Hist. (7), ii. 1898, p. 28. CHAPTER II HYMENOPTERA ACULEATA CONTINUED DIVISION II. DIPLOPTERA OK WASPS EUMENIDAE, SOLITARY TRUE WASPS VESPIDAE, SOCIAL WASPS MASARIDAE Division II. Diploptera — Wasps. Anterior wings longitudinally plicate in repose; the pronotum extending back, so as to form on each side an angle reposing on the tegula ; the basal seg- ments of the hind body not bearing nodes or scales ; the hind tarsi formed for simple walking. The species either solitary or social in their , , . , ' ... ,, FIG. 26. — Upper aspect of pronotum habits; some existing in three and mesonotum of a wasp, Eume- forms, males, females, and nes coarctata. a, Angle of prono- tum ; b, tegula ; c, base of wing ; Workers. d, mesonotum. THIS division of Hymenoptera includes the true wasps, but not the fossorial wasps. The name applied to it has been suggested by the fact that the front wings become doubled in the long direc- tion when at rest, so as to make them appear narrower than in most other Aculeata (Fig. 27). This character is unimportant in function so far as we know,1 arid it is not quite constant in the division, since some of the Masaridae do not exhibit it. The character reappears outside the Diploptera in the genus Leucospis — a member of the Chalcididae in the parasitic series of Hymen- optera— the species of which greatly resemble wasps in coloration. A better character is that furnished by the well-marked angle, 1 Janet has suggested that the folding is done to keep the delicate hind-margins of the wings from being frayed. HYMENOPTERA formed by the pronotum on the dorsal part (Fig. 26). By a glance at this part a Diplopterous Insect can always be readily distinguished. Three families are at present distinguished in the Diploptera, viz. Eumenidae, Vespidae and Masaridae. We anticipate that Eumenidae and Vespidae will ultimately be found to constitute but one family. Fam. 1. Eumenidae— Solitary True Wasps. Claws of the feet toothed or bifid; middle tibiae ivith only one spur at tip. Social assemblages are not formed, and there is no worker-caste, the duties of nest-construction, etc., briny performed solely by the female. The Eumenidae, or solitary wasps, are very little noticed by the ordinary observer, but they are nevertheless more numerous than the social Vespidae, about 800 species being known. In Britain \vu have sixteen species of the solitary, as against seven of the social wasps. The Eumenidae exhibit a considerable diversity in form and structure ; some of them have the pedicel at the base of the abdomen very elongate, while in others this is so short as to be imperceptible in the ordinary position of the body. A repetition of similar differences of form occurs in the social wasps, so that notwithstanding the FIG. 27. — Eumenes fiavopicta ?. j./v. • •, -, -, ,1 Burma. The wings on the left difference in habits there seems to be in the position of repose, to no satisfactory way of distinguishing show folding. J * ? the members of the two families ex- cept by the structure of the claws and tibial spurs. Fabre has sketched the habits of a species of Eumenes, probably E. pomiformis. This Eumenes constructs with clay a small vase-like earthenware vessel, in the walls of which small stones are embedded (like Fig. 28, B). This it fills with food for the young. The food consists of caterpillars to the number of fourteen or sixteen for each nest. These caterpillars are believed to be stung by the parent-wasp (as is the case in the I DIPLOPTERA WASPS — EUMENIDAE 73 fossorial Hymenoptera), but complete evidence of this does not seem to be extant, and if it be so, the stinging does not completely deprive the caterpillars of the capacity of movement, for they possess the power of using their mandibles and of making strokes, or kicking with the posterior part of the body. It is clear that if the delicate egg of the Eumenes or the deli- cate larva that issues from it were placed in the midst of a mass of this kind, it would probably suffer destruction ; therefore, to prevent this, the egg is not placed among the caterpillars, but is sus- pended from the dome covering the nest by a delicate thread rivalling in fineness the web of the spider, and being above the mass of food it is safe. AVhen the young larva leaves the egg it still makes use of the shell as its habit- ation, and eats its first meals from the vantage-point of this Suspension; although the mass of FIG. 28.— Nidification of solitary wasps: the food grows less by consumption, section **%"&. ™J> A> °f - » nerus remformis ; B, of Eumenes the little larva is Still enabled to arbustorum. a, The suspended egg I -, i , i r> ,1 4.1 of the wasp ; b. the stored cater- reach it by the fact that the egg- pillars> fifa >AM) shell splits up to a sort of ribbon, and thus adds to the length of the suspensory thread, of which it is the terminal portion. Finally the heap of caterpillars shrinks so much that it cannot be reached by the larva even with the aid of the augmented length of the suspensory thread ; by this time, however, the little creature has so much increased in size and strength that it is able to take its place amongst the food without danger of being crushed by the mass, and it afterwards completes its metamorphosis in the usual manner. It is known that other species of Eumenes construct vase- like nests ; E. imguiculata, however, according to an imperfect account given by Ferris, makes with earth a closed nest of irregular shape, containing three cells in one mass. The saliva of these builders has the power of acting as a cement, and of forming with the clay a very impenetrable material. One species, E. coarctata, L. of this genus occurs in Britain. The clay 74 HYMENOPTERA CHAP. nests (Fig. 29) of this Insect are often attached to the twigs of shrubs, while those of the two species previously mentioned are usually placed on objects that offer a large surface for fixing the foundations to, such as walls. According to Goureau the larva of this species forms in one corner of its little abode, separated by a partition, a sort of dust-heap in which it accumulates the various debris re- sulting from the consumption of its stores. Eumenes conica, according to Home, constructs in Hindostan clay-nests with A very delicate walls. This species pro- FIG. 29. — Nest of Eumenes • • •, -,1 , i coardata: A, the nest visions lts uest with ten or twelve green attached to wood ; B, de- caterpillars ; on one occasion this ob- tached, showing the larva. i « n • i , a, the larva ; I, the parti- server took from one cell eight green tion of the cell. (After caterpillars and one black. It is much Andre.) . . ... attacked by parasites owing, it is thought, to the delicacy of the walls of the cells, which are easily pierced ; from one group of five cells two specimens only of the Eumenes were reared. Odynerus, with numerous sub-genera, the names of which are often used as those of distinct genera, includes the larger part of the solitary wasps ; it is very widely distributed over the earth, and is represented by many peculiar species even in the isolated Archipelago of Hawaii ; in Britain we have about fifteen species of the genus. The Odynerus are less accomplished architects than the species of Eumenes, and usually play the more humble parts of adapters and repairers ; they live either in holes in walls, or in posts or other woodwork, or in burrows in the earth, or in stems of plants. Several species of the sub- genus Hoplopus have the remarkable habit of constructing burrows in sandy ground, and forming at their entry a curvate, freely projecting tube placed at right angles to the main bur- row, and formed of the grains of sand brought out by the Insect during excavation and cemented together. The habits of one such species were described by Reaumur, of another by Dufour ; and recently Fabre has added to the accounts of these naturalists some important information drawn from his own. WASPS EUMENIDAE 75 observations on 0. reniformis. This Insect provisions its cell with small caterpillars to the number of twenty or upwards (Fig. 28, A.) The egg is deposited before the nest is stocked with food ; it is suspended in such a manner that the suspensory thread allows the egg to reach well down towards the bottom of the cell. The caterpillars placed as food in the nest are all curled up, each forming a ring approximately adapted to the calibre of the cell. Fabre believes these caterpillars to be partly stupefied by stinging, but the act has not been observed either by himself, Eeaumur, or Bufour. The first caterpillar is eaten by the wasp- larva from its point of suspension ; after this first meal has been made the larva is supposed to undergo a change of skin ; it then FIG. 30. — Odynervs antilope ?. Britain. abandons the assistance of the suspensory thread, taking up a position in the vacant chamber at the end of the cell and draw- ing the caterpillars to itself one by one. This arrangement permits the caterpillars to be consumed in the order in which they were placed in the cell, so that the one that is weakest on account of its longer period of starvation is first devoured. Fabre thinks all the above points are essential to the successful development of this wasp-larva, the suspension protecting the egg and the young larva from destruction by pressure or movement of the caterpillars, while the position of the larva when it leaves the thread and takes its place on the floor of the cell ensures its consuming the food in the order of introduction ; besides this the caterpillars used are of a proper size and of a species the 7 6 HYMENOPTERA CHAP. individuals of which have the habit of rolling themselves up in a ring ; while, as the calibre of the tube is but small, they are unable to straighten themselves and move about, so that their consumption in proper order is assured. Some interesting points in the habits of an allied species, 0. (Pterocheilus) spinipes have been observed by Verhoeff ; the facts as regards the con- struction and provisioning of the cell are almost the same as in 0. reniformis. The species of Odynerus are very subject to the attacks of parasites, and are, it is well known, destroyed to an enormous extent by Chrysididae. Verhoeff says that the wasp in question supplied food much infested by entoparasites ; further, that a fly, Argyromoeba sinuata, takes advantage of the habit of the Odynerus of leaving its nest open during the process of pro- visioning, and deposits also an egg in the nest ; the Odynerus seems, however, to have no power of discovering the fact, or more probably has no knowledge of its meaning, and so concludes the work of closing the cell in the usual way ; the egg of the Argyromoeba hatches, and the maggot produced feeds on the caterpillars the wasp intended for its own offspring. Verhoeff observed that the egg of the wasp-larva is destroyed, but he does not know whether this was done by the mother Argyromoeba or by the larva hatched from her egg. Fabre's observations on allied species of Diptera render it, however, highly probable that the destruction is effected by the young fly-larva and not by the mother-fly. Mr. E. C. L. Perkins once observed several individuals of our British 0. callosus forming their nests in a clay bank, and pro- visioning them with larvae, nearly all of which were parasitised, and that to such an extent as to be evident both to the eye and the touch. In a few days after the wasps' eggs were laid, swarms of the minute parasites emerged and left no food for the Odynerus. Curiously, as it would seem, certain of the parasitised and stored- up larvae attempted (as parasitised larvae not infrequently do), to pupate. From which, as Mr. Perkins remarks, we may infer that (owing to distortion) the act of paralysing by the wasp had been ineffectual. Mr. Perkins has also observed that some of the numerous species of Hawaiian Odynerus make a single mud-cell, very like the pot of an Eumenes, but cylindrical instead of spherical. This little vessel is often placed in a leaf that a spider curls up ; young molluscs of the genus Acliatinella also ii WASPS EUMENIDAE 77 avail themselves of this shelter, so that a curious colony is formed, consisting of the Odynerus in its pot, of masses of the young spiders, and of the little molluscs. Home has recorded that the East Indian 0. punctum is fond of availing itself of holes in door-posts where large screws have been ; after the hole has been filled with provisions, the orifice is covered over level with the surface of the wood so that it eludes human observation. It is nevertheless discovered by an Ichneumon-fly which pierces the covering with its ovipositor and deposits an egg within. The genus Abispa is peculiar to Australia and includes some very fine solitary wasps, having somewhat the appearance of very large Odynerus : these Insects construct a beautiful nest with a projecting funnel-shaped entrance, and of so large a size that it might pass for the habitation of a colony of social wasps ; it appears, however, that this large nest is really formed by a single female. The species of the genus Rhygchium are also of insecticide habits, and appear to prefer the stems of pithy plants as the nidus for the development of the generation that is to follow them. Lichtenstein says that a female of the European R. oculatum forms fifteen to twenty cells in such a situation, and destroys 150 to 200 caterpillars, and he suggests that, as it is easy to encourage these wasps to nest in a suitable spot, we should utilise them to free our gardens from caterpillars, as we do cats to clear the mice from our apartments. The East Indian R. carjiaticum seems to have very similar habits to its European congener, adapting for its use the hollow stems of bamboos. Horne has recorded a case in which a female of this species took possession of a stem in which a bee, Megachile lanata, had already constructed two cells ; it first formed a parti- tion of mud over the spot occupied by the bee, this partition being similar to that which it makes use of for separating the spaces intended for its own young. This species stores caterpillars for the benefit of its larvae, and this is also the case with another Eastern species, R. nitidulum. This latter Insect, however, does not nidificate in the stems of plants, but constructs clay cells similar to those of Eumenes, and fixes them firmly to wood. Rhygchium Irunneum is said by Sir Richard Owen to obliterate hieroglyphic inscriptions in Egypt by its habit of building mud 78 HYMENOPTERA nests amongst them. An individual of this wasp was found by Dr. Birch when unrolling a rnummy — " There being every reason to believe that the Insect had remained in the position in which it was found ever since the last rites were paid to the ancient Egyptian." Fam. 2. Vespidae — Social Wasps. Claws of the feet simple, neither toothed nor bifid, middle tibiae with two spurs at the tip. Insects living in societies, form- ing a common dwelling of a papery or card-like material ; each generation consists of males and females and of workers — imperfect females — that assist the reproductive female by carrying on the industrial occupations. The anterior wing possesses four submarginal cells, as in the Eumenidae. The attention of entomologists has been more directed to the habits and architecture than to the taxonomy of these Insects, so that the external structure of the Insects them- selves has not been so minutely or extensively scrutinised as is desirable ; de Saussure, the most important authority, bases his classification of the Insects themselves on the nature of the nests they form. These habitations consist of an envelope, protecting cells similar in form to the comb of the honey-bee, but there is this important difference between the two, that while the bee forms its comb of wax that it secretes, the wasps make use of paper or card that they form from fragments of vegetable tissue, — more particularly woody fibre — amalgamated by means of cement secreted by glands ; the vegetable fragments are obtained by means of the mandibles, the front legs playing a much less important part in the economy of the Vespidae than they do in that of the bees and fossorial Hymenoptera. In most of the nests of Vespida3 the comb is placed in stages or stories one above the other, and separated by an intervening space, but in many cases there is only one mass of comb. It is the rule that, when the cells of the comb are only partially formed, eggs are deposited in them, and that the larva resulting from the egg is fed and tended by the mother, or by her assistants, the workers ; as the larvae grow, the cells are increased in correspondence with the size of the larva ; the subsequent metamorphosis to pupa and imago taking place in the cells after they have been entirely SOCIAL WASPS VESPIDAE 79 closed. The food supplied is of a varied nature according to the species, being either animal or vegetable, or both. Although the nests of the social wasps are very elaborate con- structions, yet they serve the purposes of the Insects for only a single season. This is certainly the case in our own country. Here each nest is commenced by a single female or queen ; she at first performs unaided all the duties for the inauguration of FIG. 31.— Section of the subterranean uest of the common wasp, Vespa yermanica, in position. (After Janet.) a. One of the chambers of an ant's nest, Lasiustfiici/s, placed above the wasps' nest ; b, root to which the first attachment of the uest was made ; c, secondary attachments ; d, the first-made attach- ment ; e, a flint within the envelopes ot the riest ; /,the chief suspen- sory pillar of the second layer of comb ; g, lateral galleries ; h, one of the secondary pillars of suspension between two layers of comb ; i, the layers of wasp -paper forming the envelope of nest ; j, vacant space round the nest ; k, Hints that fell to the bottom during the work of ex- cavation ; /, numerous larvae of a fly, Pegomyia inanis(1) placed vertically in ground beneath the nest ; ml to m1, the layers of comb, in m- the cells are indicated, in 7ft8 (above the main figure) the arrangement -of the three cells forming the commencement of the new layer of comb, m7, is shown ; it, gallery of access from surface ; o, burrow of a mole ; p, interval of 90 mm. between top of uest and surface ; q, height of tne nest, 163 mm. the colony ; she lays the foundation of the cells, deposits the eggs in them, feeds the young, and thus rears a brood of workers that at once assist her, and for the future relieve her of a con- siderable portion of her former occupations ; the nest is by them added to and increased, till the cold weather of the autumn is at hand ; at this time many males and females are produced ; the cold weather either destroys the inhabitants of the nest, or re- duces their vitality so that it is impossible for them to pursue successfully the avocations necessary for their subsistence, and 80 HYMENOPTERA CHAP. they succumb to adversity. The young females, however, hiber- nate, and each one that lives through the winter is the potential founder of a new nest in the way we have already described. It might be supposed that in tropical countries where no cold season occurs the phenomena would be different, that the colonies would be permanent, and that the nests would be inhabited until they were worn out. De Saussure, however, informs us that this is not the case, but that in the tropics also the colonies die off annually. " The nests are abandoned," he says, " without it being possible to discover the reason, for apparently neither diminution of temperature nor scarcity of food cause them (the Insects) to suffer. One is tempted to suppose that the death of the Insects is the result of a physiological necessity." Nests of Social Wasps. — In Europe wasps' nests disappear very soon after they are deserted. As it would appear from de Saussure's conclusions that in the tropics as well as in the temperate regions the rule is that the colonies endure only a portion of one year, and that a new nest is commenced by a single founder once in twelve months, it is a somewhat remarkable fact that some tropical wasp-nests are much more durable than the lives of the inhabitants require, so that solidly constructed nests are often found hanging to the trees long after they have been deserted, and are sometimes overgrown with moss. Cuming has recorded the fact that he found in South America an old wasp-nest that had been taken possession of by swallows. We do not assign, how- ever, much importance to the views of de Saussure, because we may anticipate that enquiry will reveal much variety in the habits of tropical and sub-tropical wasps. It is known that species exist that store up honey, after the fashion of bees, and von Ihering has recently shown l that in Brazil, species of several genera form new colonies by swarming, after the manner of bees. So that it is possible that certain colonies may remain for a long period in the same nest. Much more variety exists in wasps' nests than would be sup- posed probable ; those formed by some of the tropical species of Vespidae are enveloped in so solid and beautifully constructed an envelope of papier-mache, that they resist with complete success the torrential rains of the tropics ; while some of those found in our own country are made of extremely soft and delicate paper, 1 Zool. Anz. xix. 1896, p. 449. See also note, antca, p. 70. VESPIDAE — WASPS' NESTS 8l which is probably chiefly glandular products. Our British Vespidae number only eight species, all belonging to the one genus Vespa, and yet they exhibit three different modes of nidification. Vespa vulgaris, V. germanica and V. rufa form subterranean nests, while V. arbor ecu, V. sylvestris and V. norvegica suspend their habitations from the branches of trees, bushes, or strong annual plants. Vespa crabro, the hornet, usually adopts an intermediate course, forming its nest above ground, but in a spot where it is protected and concealed. The favourite habitat of this formidable Insect is the interior of an old tree, but the hornet will sometimes avail itself of the protection of a thatched roof. Both it and other arboreal species are said, however, to occasionally make subter- ranean nests. It is ascertained that V. austriaca, the eighth species, is an inquiline. De Saussure,1 the monographer of the social wasps, classifies them according to the architecture of their nests. He estab- lishes three groups: (1) Stelocyttares, in which the layers of comb are not con- nected with the envelope, but are sup- ported by pillars made by the wasps (Fig. 31); (2) Poecilocyttares, an unsatisfac- tory group of which the chief character- istics appear to be that the nest is always covered by an envelope, and the comb is supported by an object such as the branch P T i • i ,, , FIG. 32.— Nest of (?) Polybia of a tree, round, or on, which the envelope 8p_ The envelvope p/rtly is placed (Fig. 32); (3) Phragmocyttares, in which the layers of comb are supported, in part or entirely, by the envelope of the nest, communication being effected by a hole in each layer of the comb (Fig. 33). de Saussure's classification is far from satisfactory. There are many social wasps that construct nests destitute of any proper envelope ; as an example of this, we may mention the species of 1 Monographic des gutpes societies, Geneva, 1853-1858, pp. cc. and 356, plates i.-xxxvii. VOL. VI G cut open ; o, entrance. (After de Saussure.) 82 HYMENOPTERA the abundant genus Polistes ; these Insects make hexagonal cells, of paper -like material, forming an irregular comb, or mass, attached to bushes by a stalk near its centre ; these nests are placed so that the mouths of the open cells look downwards. The species of Ischnogaster (Fig. 34) make layers of comb, con- nected by a pedicel, but without any envelope ; these Insects form a section of Stelocyttares called Gymnodomes. Most of the nests of the Poecilocyttares have only a single layer of comb. The wasps of the genera Synoeca and Polybia, have the habit of spreading a layer of cells on a leaf, or on the bark of a tree, and of covering this with an envelope that is pierced by a single orifice only, but that does not rest on the cells, and so allows circulation of the Insects between the cells and the envelope. This appears to be the arrangement in ;i nest of Synoeca cyanea preserved in the British Museum ; in this construction a large layer of cells is moulded on the branch of a tree, whose contour, for a length of two or three feet, it con- sequently follows ; while outside the mass there is placed a con- tinuous envelope, leaving a considerable distance between it and the cells. It would be impossible in the space at our disposal to give a satisfactory account of all the forms of wasp-nests, and we must therefore refer the student to de Saussure's work, confining ourselves to a brief notice of some specially interesting forms. The habitation of the Brazilian PolyHa (Myrapetra) scutellaris is a very solid, closed structure, covered externally with rough knobs or angular projections. Although of very large size — it may be upwards of two feet in length — it is suspended from a branch, and has but one orifice ; the arrangement of the combs in the interior is that of the Phragmocyttares, they being firmly attached to the outer envelope, and so placed as to form a curved surface, the convexity of which is downwards : the number of wasps in a well-developed nest of this kind must be very great. This species is said to be a honey-gathering wasp. One of the best known of the South American wasps' nests is the construction (Fig. 33) of Charter gus cliartarius ; these nests are so regularly shaped, and formed of papier-mache so compact and solid, as to look like stone : this edifice is attached in a very firm manner to the branch of a tree, and has a single portal of entry beneath ; its interior arrangement is much like that of Myrapetra scutellaris. ii VESPIDAE WASPS' NESTS 83 A very remarkable wasp's nest is preserved in the British Museum of Natural History ; it is considered to he the work of Montezumia dimidiata Sauss. an Eumenid wasp ; it is a large mass of cells encircling the branch of a tree, which therefore pro- jects somewhat after the manner of an axle through the middle : the cells are very numerous, and are quite as regular as those of the most perfect of the combs of bees : the mass is covered with a very thick layer of paper, the nest having somewhat the external appearance of half a cocoa-nut of twice the usual size. Apoica pallida, a South American Insect, forms a nest in a somewhat similar manner to Polistes, but it is covered on its outer aspect by a beautiful paper FIG. 33.— Section of nest of i • ,-1 ,1 LIT Charter a us chart" Skill, SO that the nest looks Somewhat South America, o, Entrance. like a toadstool of large size attached (After de Saussure.) to the branch of a tree. The nests of the Insects of the genus Polybia — which we have already mentioned as located by de Saussure in his unsatis- factory group Poecilocyttares — usually have somewhat the form and size of pears or apples suspended to twigs of trees or bushes ; these little habitations consist of masses of cells, wrapped in wasp-paper, in which there are one or more orifices for ingress and egress. Smith says that the combs in the nest of P. pygmaea are of the most exquisite construction, and that it is by no means an uncommon circumstance to find the outer envelope of the nest ornamented with patches of delicate hexagonal tracery. This nest is about the size of an orange. We have already noticed the variety of nests formed by our British species of the genus Vespa ; in other parts of the world the edifices formed by species of Vespa attain a very large size. V. crabroniformis in China, and V. velutina in India, make nests several feet or even yards in length, inhabited by an enormous number of individuals ; they are apparently constructed of a material like brittle paper, and are arranged much like the nests of our British hornet, V. crabro. Vespa orientalis mixes a considerable quantity of earth with the paper it uses for its 84 HYMENOPTERA constructive efforts. In the British Museum collection there is a nest said to be that of the Japanese hornet, V. japonica. This is completely covered by a paper envelope, and has apparently only a single small orifice for ingress and egress. In the same collection there is a nest from Bahia (believed to be that of a social wasp, though of what species is unknown), the outer wall of which is apparently formed entirely of earth, and is a quarter or half an inch thick : the comb inside appears also to be formed of clay, the whole forming an elaborate construction in pottery. One is tempted to believe it may prove to be the production of a social Eumenid. Habits of Social Wasps. — We have already briefly noticed the way in which a colony of wasps is founded, but some further particulars as to the mode in which the society is increased and developed may be mentioned. The queen-wasp makes at first only a very small group of three or four incomplete cells ; each cell is at first circular, or nearly so, and moreover is of smaller diameter than it will afterwards be. In each of the first three or four incomplete cells an egg is laid, and more cells are commenced ; but as the eggs soon hatch and produce larvae that grow rapidly, the labours of the queen-wasp are chiefly directed to feeding the young. At first she supplies them with saccharine matter, which she pro- cures from flowers or fruits, but soon gives them a stronger diet of insect meat. This is procured by chasing living Insects of various kinds. Some species of wasps prefer particular kinds of Insects, and the hornet is said to be very fond of the honey-bee, but as a rule Diptera are the prey selected. When an Insect has been secured, the hard and innutritions' parts are bitten off, and the succulent parts, more especially the thorax which contains chiefly muscular tissue, are reduced to a pulp by means of the mandibles; this is offered to the larvae, which are said to stretch out their heads to the mother to receive the food, after the manner of nest- ling birds. When a larva is full grown it spins a cocoon in the cell and changes to a pupa. It is said by some entomologists that the queen-wasp closes the cell for the purpose of the larval metamorphosis ; but this is contradicted by others, and is prob- ably erroneous. In about a month, or a little less, from the time of deposition of the egg, the perfect Insect is ready for issue, and almost immediately after leaving its cell it assists in the work that is going on for the development of the society. The ii VESPIDAE SOCIAL WASPS HABITS 85 Insects produced at this early period of the colony are exclusively workers, i.e. imperfect females. They relieve the queen of the task of supplying the larvae with food, and she henceforth remains within the nest, being, it is said, herself fed by her workers ; the society now rapidly increases in numbers, and fresh combs are formed, the upper layer being always the oldest. About the month of August, cells of larger size than those that have previously been constructed are formed, and in these males and perfect females are produced ; in a few weeks after this the colony languishes and becomes extinct. When it is no longer possible for the enfeebled wasps to carry out their tasks of feeding the brood, they drag the larvae out of the cells and destroy them. An uncertain number of queen- wasps seek protected nooks in which to pass the winter, and each of these queens may be the founder' of a nest in the ensuing spring. It should be remarked that de Saussure states that all the intermediate grades between perfect and imperfect females exist, and Marchal's recent observa- tions confirm this. There is in fact no line of demarcation between worker and queen in the wasps as there is in the honey- bee. Von Siebold long since drew attention to the existence of parthenogenesis in certain species of wasps, and it appears prob- able that it is of common occurrence. Our knowledge of the social life of European wasps has recently been much increased by the observations of two French naturalists, P. Marchal and C. Janet. The latter has given an elaborate history of a nest of the hornet, showing the rate and variations of increase in numbers. His observations on this and other species indicate that warmth is of the utmost im- portance to wasps ; the Insects themselves create a consider- able amount of heat, so that the temperature of their abodes is much greater than that of the air. He considers that in Europe an elevated temperature is essential for the development of the individual,1 and that the chief object of the various wrappers of paper with which the Insects surround their nests is to keep up this high temperature. These envelopes give a great deal of trouble to the Insects, for they have to be repeatedly 1 Hence probably the great difference in the abundance of wasps in different years : if a period of cold weather occur during the early stages of formation of a wasp family, operations are suspended and growth delayed ; or death may even put an end to the nascent colony. 86 HYMENOPTERA destroyed and reformed, as the combs they contain increase in size. Marchal's observations 1 relate chiefly to the production of the sexes and worker-forms, in the subterranean species, Vespa germanica and V. rnl>. The layers of comb include cells of two sizes. The upper layers, which are the first formed, consist of small cells only: the lower combs are constructed (at 1'iiris) early in August, and consist of larger cells from which males and large females are reared. The males are, however, reared also in large numbers in the small cells. If the queen be re- moved, the workers become fertile, and produce parthenogenetically many eggs, but all of the male sex. He entertains no doubt that even when the queen is in full vigour the workers produce males if there is an abundant food supply. The social wasps at present known number 500 or 600 species. Polistes is a very extensive genus, and it has also a very wide geographical distribution ; some of the species — and those found in widely-distant parts of the world — are remarkable on account of their excessive variation in colour, and it is worthy of note that the extreme forms have been more than once taken from the same nest. Next to Polistes, Vespa is the most numerous in species, about 150 being known, and it is to this genus that all our British social wasps belong. No Insects are better known in our islands than these wasps, owing to the great numbers of individuals that occur in certain seasons, as well as to their frequently entering our habitations and partaking of our food, and to the terror that is occasioned by their supposed ferocity and desire to sting. This last feature is a complete mistake ; wasps never sting unless they are roused to do so by attacks, or by considerable interference with their work. The only real danger arises from the fact that a wasp may be occa- sionally taken into the mouth with fruit, or may be handled unawares. When they are flying about they are perfectly harmless unless attacked or irritated, and even if they settle on the person no danger of their stinging exists unless move- ment is made. Sichel correctly states that a person may station himself close to a wasp's nest and remain there without any risk at all, provided that he makes no movement ; indeed, it is more than probable that if no movement, or if only gentle 1 CR. Ac. Paris, cxvii. 1893, p. 584 ; op. cit. cxxi. 1895, p. 731 ; Arch. Zool. exper. (3) iv. 1896, pp. 1-100. VESPIDAE — SOCIAL WASPS movement, be made, the wasps are unaware of the presence of an intruder. It is, however, well ascertained that if they are molested at their work, more especially when they are actually engaged in the duties of the nest, they are then extremely vin- dictive, and follow for a considerable distance those who have irritated them. The East Indian V. velutina is specially fierce when aroused, and is said by Home to have followed a party FIG. 34. — Ischnogaster mellyi. Java. A, Female imago (the line at the side shows its length) ; B, nest, C, maxilla ; D, labium ; E, mandible (tip downwards). The nest is probably upside down, although shown here as by de Saussure. through dense jungle for miles, and on some occasions to have stung animals, and even human beings, to death. This vindictiveness is, however, only an exceptional mood due to some interference with the colony. Even the hornet, not- withstanding its threatening appearance, is harmless unless unduly provoked ; its nests and their inhabitants can be kept in domesticity, exhibited to strangers, even moved from place to place, yet the hornets will not take offence if due gentleness be observed. It is said that wasps will rear the progeny of a neigh- bour in circumstances where this assistance is necessary. Hess has related a case in which a queen-hornet had commenced a nest, and was killed by an accident, leaving young brood in the comb 88 HYMENOPTERA CHAP. unprovided for : as a result many of the helpless grubs died, and others were in a state of starvation, when a strange queen-hornet appeared, associated itself with the comb, and, adopting the orphan brood, nourished them and brought them to their full size. "We have already alluded to the fact that, so far as external structure is concerned, there is no great difference between the social and the solitary wasps. Both, too, run through analogous series of forms and colours, and the genus Isclmogaster (Fig. 34) seems to connect the two groups by both its structure and mode of life. The social habits are in many species only inferred, and with greater knowledge will probably prove fallacious as a guide to classification ; indeed we have already said that in the genus Vespa — perhaps the most perfectly social of all the wasps — there is one species that has no worker, and that lives, it is supposed, as a parasite, in the nests of its congeners. For this species, V. austriaca, it has been proposed to create a separate genus, Pseudo- vcspa, on account of this peculiarity of habit, although no structural character has been detected that could distinguish it. De Saussure has stated his conviction that workers do not exist in some of the exotic genera, so that it appears highly probable that with the pro- gress of knowledge the present divi- sion between social and solitary wasps will prove untenable. Eemains of Insects referred to the genera Polistes and Vespa have been found in tertiary strata in various parts of Europe and in North America. FIG. 35. — Masaris vespiformis. A, male B, female. Egypt. (After Schaum.) Fam. 3. Masaridae. Anterior wing with tiuo complete sub-marginal cells. Antennae usually incrassate or clubbed at the extremity. Claws dis- tinctly or obsoletely dentate. This is a group of fifty or sixty species with but few genera, MASARIDAE 89 and most of its components appear to be Insects of the greatest rarity. In their appearance the Insects of this Family differ con- siderably from the other Diploptera, and as the wings are only imperfectly, or not at all, plicate, it must be admitted that the systematic affinities of the group require reconsideration. The pronotal structure is, however, completely that of Diploptera. The typical form of the Family, Masaris vespiformis, though described a hundred years since, is a species of such ex- treme rarity, and its sexes are so different, that entomologists have only recently been able to agree about it. It has been found in Egypt and Algeria. The genera Ceramius, Jugurthia, Quartenia and Coelonites are also members of the Mediterranean fauna, while Paragia is Australian, and Trimeria South American. Several species of the genus Masaris inhabit North America, and Cresson has recently described another Masarid genus from the same country, under the name of Euparagia. The little that is known of their natural history is almost limited to an account given by Giraud of the habits of Ceramius lusitanicus, of which species he found a colony near Brian^on. The Insect makes nests in the earth ; they are entered by means of a chimney - like passage analogous to what is formed by certain Odynerus ; the gallery when completed is about six centimetres long, and at its extremity is an earthen cell in which the larva lives ; this is fed by the mother, who brings to it from time to time a supply of a paste, described as being somewhat like dried honey. The growth FIG. 36. — Cells constructed n. , i i , i • j , , . -, by Coelonites dbbreviatus. ol the larva is believed to be rapid. ^fter Andr(s.) Some fragmentary observations made by Lichtenstein on Coelonites abbreviatus have also been recorded. This species, near Montpellier, constructs earthen cells ; they are not, however, subterranean, but are placed side by side on the dry stems of plants (Fig. 36); these cells are stored with a material similar to that supplied by Ceramius lusitanicus to its young. J; LIBRARY CHAPTER III HYMENOPTERA ACULEATA CONTINUED DIVISION III. FOSSORES OR FOSSORIAL SOLITARY WASPS FAMILY SCOLIIDAE OR SUBTER- RANEAN FOSSORS FAMILY POMPILIDAE OR RUNNERS FAMILY SPHEGIDAE OR PERFECT-STINGERS Division III. Fossores. Aculeate Hymenoptera, in which the abdomen, though very diverse inform, does not bear prominences on the upper aspect of the basal segments ; front wing without longitudinal fold along the middle ; hairs of body not plumose. Only two forms (male and female} of each species. FOSSORIAL Hymenoptera are distinguished from other Aculeates at present only by negative characters, i.e. they are Aculeates. but are not ants, bees or wasps. According to their habits they fall into four, by no means sharply distinguished, groups — (1) those that form no special receptacles for their young, but are either of parasitic or sub-parasitic habits, or take advantage of the abodes of other Insects, holes, etc. ; (2) constructors of cells of clay formed into pottery by the saliva of the Insect, and by drying ; (3) excavators of burrows in the ground ; (4) makers of tunnels in wood or stems of plants. Several species make use of both of the last two methods. The habits are carnivorous; the structures formed are not for the benefit of the makers, but are constructed and stored with food for the next generation. Their remarkable habits attracted some attention even 2000 years or more ago, and were to some extent observed by Aristotle. The great variety in the habits of the species, the extreme industry, skill, and self-denial they display in carrying out their voluntary labours, render them one of the most instructive groups of the animal kingdom. There are no social or gregarious FOSSORIAL SOLITARY WASPS forms, they are true individualists, and their lives and instincts offer many subjects for reflection. Unlike the social Insects they can learn nothing whatever from either example or precept. The skill of each individual is prompted by no imitation. The life is short, the later stages of the individual life are totally different from the earlier : the individuals of one generation only in rare cases see even the commencement of the life of the next ; the progeny, for the benefit of which they labour with FIG. 37. — Sceliphron nigripes ? (Sub-Fam. Sphegides). Amazons, x § unsurpassable skill and industry, being unknown to them. Were such a solicitude displayed by ourselves we should connect it with a high sense of duty, and poets and moralists would vie in its laudation. But having dubbed ourselves the higher animals, we ascribe the eagerness of the solitary wasp to impulse or instinct, and we exterminate their numerous species from the face of the earth for ever, without even seeking to make a prior ac- quaintance with them. Meanwhile our economists and moralists devote their volumes to admiration of the progress of the civilisa- tion that effects this destruction and tolerates this negligence. 92 HYMENOPTERA It should be noted that in the solitary as in the social Insects the males take no part whatever in these industrial occupations, and apparently are even unaware of them. It is remarkable that, notwithstanding this, the sexual differences are in the majority less than is usual in Insects. It is true that the various forms of Scoliidae exhibit sexual distinctions which, in the case of Thynnides and Mutillides are carried to an extreme degree, but these are precisely the forms in which skill and ingenuity are comparatively absent, the habits being rather of the parasitic than of the industrial kind, while the structure is what is usually called degraded (i.e. wingless). The great difference between the habits of the sexes, coupled with the fact that there is little or no difference in their appearance, has given rise to a curious Chinese tradition with regard to these Insects, dating back to Confucius at least.1 The habit of stinging and storing caterpillars in a cell, from which a fly similar to itself afterwards proceeds having been noticed, it was supposed to be the male that performed these operations ; and that when burying the cater- pillars he addressed to them a spell, the burden of which is " mimic me." In obedience the caterpillars produce the wasp, which is called to this day " Jiga," that is in English " mimic me." The idea was probably to the effect that the male, not being able to produce eggs, used charmed caterpillars to continue the species. Summary of the Prey of Fossores. Group of Fossores. Food or Occurrence. Fam. Scoliidae. Sub-Fam. Mutillides . . As parasites on Hymenoptera Aculeata. ,, Thynnides . . (?) Parasites on Lepidopterous pupae. ., Scoliides . . . Larvae of Coleoptera [(?) spiders in the case of Elis 4-notata]. ., Rhopalosomides. Unknown. „ Sapygides . . The provisions stored by bees. Caterpillars (teste Smith). ,, ( Spiders. Earely Orthoptera (Gryllidae and Fam. Pompilidae . . . . < * i^JL •»• v /s i ( Blattidae, teste Bmgham) or Coleoptera. ( Orthoptera (especially Locustidae), larvae Fam. Sphegidae. J of Lepidoptera, Spiders [(?) same species Sub-Fam. Sphegides . . \ (Sceliphron madraspatamim and Sphex V coeruleus), both spiders and caterpillars]. 1 Kumagusu Minakata, in Nature, 1. 1894, p. 30. FOSSORIAL WASPS 93 Group of Fossores. Fain. Spliegiclae. Sub-Fain. Ampulicides . Larrides . Food or Occurrence. Orthoptera (Blattidae only). Orthoptera of various divisions. Aculeate Hymenoptera, in the case of Palarus. [Spiders stolen from nests of Pelopaeus by Larrada.] „ Trypoxylonides . Spiders, caterpillars, Aphidae. „ Astatides . . . Astata boops uses Pentatomid bugs, cockroaches, and even Aculeate Hymenoptera (Oxybelns, teste Smith). „ Bembecides . . Diptera and Cicada. „ Nyssonides . . Diptera, Homoptera (Gorytes mystaceus takes Aphrophora out of its " cuckoo-spit "). ,. Philanthides . . Aculeate Hymenoptera (Philanthus). Hard beetles, viz. Curculionidae, Buprestidae, Chrysomelidae (Cerceris). „ Mimesides . t. Small Homoptera, even Aphidae. Diptera (Tipulidae) in Hawaii. „ Crabronides . . Diptera, Aphidae [? the same species of wasps both of these]. Other small Homoptera. Ants (in the case of Fertonius). Parasitic optera (in the case of Lindenius). Great diversity of opinion exists as to the classification of the Fossores. This arises chiefly from the incomplete state of the collections studied, and from the fact that the larger part of the works published are limited to local faunae. Opinions as to the families vary ; some admitting only three or four, others upwards of twenty. After consideration of the various views, the writer thinks it best to admit at present only three families, which speaking broadly, correspond with habits, viz. (1) Scoliidae, subterranean stingers ; (2) Pompilidae, runners ; (3) Sphegidae, stingers above ground. 1. Scoliidae. Pronotum and tegulae in contact. Abdomen with the plane of the ventral surface interrupted by a chink between the first and second segments. Numerous wingless forms. 2. Pompilidae. Pronotum and tegulae in contact. Abdomen with the plane of the ventral surface not interrupted by a chink. Legs very long. No wingless forms. 3. Sphegidae. Pronotum and tegulae not in contact. No wingless forms. We shall treat as sub-families those divisions of Scoliidae and Sphegidae considered by many as families. 94 HYMENOPTERA Fam. 1. Scoliidae. The members of this family, so far as is known, display less perfect instincts than the Sphegidae and Pompilidae, and do not construct cells or form burrows. Information as to the habits is almost confined to European forms. We adopt five sub-families. Sub-Fam. 1. Mutillides. — The sides of the pronotum reach tin, tegulae : the female is destitute of icings and ocelli, frequently having the parts of the thorax so closely soldered that the divisions between them are obliterated: the male* «/•<• winged, furnished with ocelli, and having the thoracic divisions distinct ; intermediate tibiae with two apical spurs. Front wing with two or three sub-marginal cells. The larvae live parasitically at the 'expense of other Hymenoptera Aculeata. The Mutillides have some resemblance to ants, though, as they are usually covered with hair, and there is never any node at the base of the abdomen, they are readily distinguished from the Formicidae. The great difference between the sexes is their most striking character. Their system of coloration is often very remarkable, the velvet-like pubescence clothing their bodies being variegated with patches of sharply contrasted vivid colour ; in other cases the contrast of colour is due to bare, ivory-like spaces. They have the faculty of stridulating, the position and nature of the organ for the purpose being the same as in ants. Very little exact information exists as to the habits and life- histories of the species. Christ and Drewseu, forty or fifty years ago, recorded that M. europaea lives in the nests of bees of the genus Bombus, and Hoffer has since made some observations on the natural history of the same species in South East Europe, where this Mutilla is found in the nests of ten or eleven species of Bombus, being most abundant in those of B. agrorum, and B. variabilis ; occasionally more individuals of Mutilla than of bees may be found in a nest. He supposes that the egg of the Mutilla is placed in the young larva of the Bombus, and hatches in about three days ; the larva feeds inside the bee-larva, and when growth is completed a cocoon is spun in the interior of the pupa -case of the bee. When the perfect Insects emerge, the males leave the nest very speedily, but the females remain for some time feeding on the bees' honey. Females are usually produced in greater numbers than males. This account leaves SCOLIIDAE— MUTILLIDES 95 much to be desired. From the observations of Badoszkowsky it is clear that other species of Mutillides are by 110 means confined to the nests of Boiribus but live at the expense of Aculeate Hymenoptera of various groups. This naturalist asserts that the basal abdominal segment of the parasite resembles in form that of the species on which it preys. The apterous condition of the females of Mutillides and Thynnides is very anomalous in the Fossors ; this sex being in the other families distinguished for activity and intelligence. The difference between the sexes is also highly remarkable. The males differ from the females by the possession of wings and by the structural characters we have mentioned, and also in a most striking Fid. 38. — Mutilla stridula. Europe. A, Male ; B, female. manner in both colour and form ; Burmeister, indeed, says that in South America — the metropolis of Mutillides — there is not a single' species in which the males and females are alike in appearance ; this difference becomes in some cases so extreme that the two sexes of one species have been described as Insects of different families. Upwards of one thousand species are assigned to the genus Mutilla, which is distributed over the larger part of the world ; there is so much difference in these species as to the nervuration of the wings in the males, that several genera would be formed for them were it not that no corresponding distinctions can be detected in the females. Three or four species of Mutilla are . described as being apterous in the male as well as in the female sex ; they are very rare, and little is known about them. Only three species of Mutillides occur in Britain, and they are but rarely seen, except by those who are acquainted with their 96 HYMENOPTERA habits. The African and East Indian genus, Apterogyna, includes some extremely peculiar Hymenoptera ; the males have the wing nervuration very much reduced, and the females are very ant-like owing to the deep constriction behind the first abdominal ring. Sub-Fam. 2. Thynnides. — Males and females very different in form ; the male winged, the front wing with three, or only two, sub-marginal cells ; the female wingless and with the thorax divided into three sub-equal parts. The Thynnides are by some entomologists not separated from theMutillides; but the distinction in the structure of the thorax of the females is very striking. In the Thynnides the nervuration of the wing appears always to extend to the outer margin, and in the Muti Hides not to do so. This family is represented in Britain by a single very rare Insect, Methoca ichneumonides : to the unskilled observer the female would appear to be without doubt an ant. This Insect is by some considered as the type of a family distinct from the Thynnides proper. Thynuides are numerous in Australia. Very little is really known as to their habits, though it has been stated that they are parasitic on Lepidoptera, Bakewell having obtained specimens from sub- terranean cocoons of that Order. Those who are interested in differences between the sexes of one species should examine the extraordinary examples of that phenomenon presented by the Thynnides ; the dissimilarity throughout the group — which is now of considerable extent — being so extreme that no ento- mologist would from simple inspection believe the two sexes to have any connection ; but the fact that they are so con- nected has been demonstrated beyond doubt. In very few FIG. 39. — MetJioca ichneumonides. Britain. A, Male ; B, female. SCOLIIDAE THYNNIDES SCOLIIDES 97 cases, however, have the sexes been matched, so that at present males are no doubt standing in the lists of Hymenoptera as one species and their females as other species. Sub-Fam. 3. Scoliides. — Pronotum reaching back to the tegulae ; legs stout ; intermediate tibiae with one apical spur ; both sexes winged; the nervures not extending to the posterior (i.e. distal) margin. This group includes some of the largest and most powerful of the Aculeate Hymenoptera. Its members are usually hairy Insects with thick legs, the colour being black, more or less variegated with bands or spots of red or yellow ; the hind body is elongate, has only a very short pedi- cel, and in the male is usually termin- ated by three project- ing spines. The pro- notum is of variable dimensions, but its front angles are always co- adapted with the points of insertion of the front wings. The nervuration of the front wings is confined to the basal part, the extensive apical or outer area possessing no nervures. There is frequently a great difference in the size of the two sexes of the same species, the female being very much larger than the other sex. The larvae, so far as is known, devour those of Lamellicorn Coleoptera. Fabre has investigated the habits of some of the species of Scoliides found in France, and has informed us that their means of subsistence consists of larvae of the larger Lamellicorn beetles, Cetonia, Oryctes, Anoxia, and Euchlora ; these beetles belong to very different divisions of the Lamellicornia, but they have in common the fact that their larvae are of subterranean habits, living in the earth or in accumulations of debris in which there is a large proportion of vegetable matter or roots. The female Scolia penetrates into the ground in order to find the Lamellicorn larvae necessary as food for its progeny. Scolia bifasciata VOL. VI H FIG. 40. — Scolia haemorohoidolis 9. Europe. 98 HYMENOPTERA CHAP. attacks the larvae of several species of Cetonia, and S. (Colpa) interrupta chooses the larvae of the chafers Anoxia villosa and A. matutinalis. The mother Scolia enters the ground in August or September, and having found a suitable larva stings it and deposits an egg on the ventral surface of the prey ; the paralysed larva is left where it was found, no attempt being made to place it in a special receptacle. The egg is placed on the ventral surface, well behind the feet, under a mass of matter in the alimentary canal. Shortly after being hatched the young- destroyer penetrates with its head the skin of the victim, and in this position commences to feed ; it is necessary that it should obtain its food without killing the Cetonia larva, for it cannot prosper on decaying food, so that if the Cetonia larva die the Scolia larva likewise perishes ; the latter, accordingly, does not withdraw its head from the interior of the victim, but remains always in the same position, as it grows larger extending its head forwards into the front part of the interior of its victim ; the internal organs of the latter are consumed in a systematic order so as to delay bringing about its death till the last moment, and thus all the interior of the Cetonia larva is appropriated till nothing remains but an empty skin. By a series of experiments, Fabre showed how essential it is that this apparently revolting operation should be carried on with all details strictly en regie. If the head of the Scolia larva be taken out from the victim and applied to another part of the body of the Cetonia, the result is that it cannot eat ; even if it be replaced in the original situa- tion, after being taken away, it frequently happens that the Cetonia larva dies, its death involving also that of the destroyer. It is necessary, too, that the victim should be paralysed, for if an intact Cetonia larva be taken and bound down in such a position that it cannot move, and if a small orifice in its skin be made in the proper spot and a young Scolia larva be placed on it, the little parasite will avail itself of the opportunity and commence to feed on the larva provided for it, but the latter will speedily die, and the Scolia necessarily perishes with it. Thus both the paralysis of the victim and the special mode of eating are essential to the life of the Scolia. The operation of stinging the larva so as to produce the necessary paralysis, or rather insensibility, is a difficult one, and requires great skill and patience. The Cetonia larva is of large size, and must be pierced in one particular spot ; in SCOLIIDAE SCOLIIDES SAPYGIDES 99 in order to reach this the Scolia mounts on its victim, and is frequently dislodged by its struggles; sooner or later, however, the proper position is obtained by the wasp, and the larva is then stung in the exact spot necessary to allow the sting (and the poison introduced by it) to reach the most important of the nervous ganglia that control the movements of the body, this spot being, in the case of the Cetonia, the line of demarcation between the pro- and meso-thorax, on the middle line of the ventral surface of the body. The Scolia gives but one sting to the victim, and this it will not administer until it can do so exactly in the proper place. This practice of devouring the victim slowly, without killing it till all is eaten, is very widely spread in the Hymenoptera, and it is satisfactory to find that we may infer from Fabre's observations that it is not so horrible as it would at first appear; for it is probable that the stinging prevents decomposition of the victim, not by reason, as some have supposed, of the poison injected by the wasp having an antiseptic effect, but rather by means of destroying sensibility, so that the creature does not die from the pain, as it is believed it did in certain cases where Fabre induced the young Scolia larva to feed on a victim that had not been stung. We may here remark that very little exact information exists as to the operation of stinging. Fabre attaches great importance to the sting being inflicted on a nerve -ganglion. Whether a sting that did not reach this part might not have a sufficient effect appears, how- ever, doubtful.1 A remarkable form of Scoliides, with wings of smaller size than usual and deeply divided, has been described by Saunders under the name Pseudomeria graeca. Still more remarkable is Komarovia victoriosa found in Central Asia ; in this Insect the male retains the appearance of a slender, pallid Scolia, but the female differs totally in form, and has the peculiar wings so re- duced in size as to be useless for flight. Sub-Fam. 4. Sapygides. — Closely allied to the Scoliides, but pos- sessing slender legs and antennae ; also the first abdominal segment is less disconnected from the second, so that the outline 1 As this work is passing through the press we receive a book by Mr. and Mrs. Peckham on The Instincts and Habits of the Solitary Wasps, Madison, 1898. They are of opinion that, in the case of some species, it does not matter much whether the victim is or is not killed by the stinging. IOO HYMENOPTERA CHAP. FIG. 41. — Sapyga 5-punctata 9 Britaiu. is less interrupted ; the eyes are deeply emarginate ; the hind body is not spinose at the apex. The economy of Sapyga, the only genus, has been the subject of difference of opinion. The views of Latreille and others that these species are parasitic upon bees is confirmed by the observations of Fabre, from which it appears that S. 5-punctata lives in the burrows of species of the bee-genus Osmia, consuming the store of provisions, consisting of honey-paste, that the bee has laid up for its young. Ac- cording to the same distinguished observer, the Sapyga larva exhibits hypermetamorphosis (i.e. two consecutive forms), and in its young state destroys the egg of the bee ; but his observations on this point are incomplete and need repetition. We have two species of Sapyga in Britain ; they differ in colour, and the sexes of S. 5-punctata also differ in this respect ; the abdomen, spotted with white in both sexes,, is in the female variegate with red. Smith found our British Sapyga 5- punctata carrying cater- pillars. Sub-Fam. 5. Rhopalo- somides. — Antennae elongate, spinigerous ; ocelli very prominent ; tarsi of peculiar structure, their claws bifid. FIG. 42. — Rhopalosmna poeyi. A, female imago ; B, front of head. Cuba. (After Westwood.) This sub-family has recently been proposed by Ashmead * for 1 P. ent. Soc. Washington, iii. 1896, p. 303. in FOSSORES 10 1 an extremely rare American Insect that had previously been placed by Cresson among parasitic Hymenoptera. Westwood classed Ehopalosoma among Diploptera, saying of it " animal quoad affinitates excrucians." We reproduce Westwood's figure, but not being acquainted with the Insect we can express no opinion as to whether it is allied to the Scoliidae or to the Sphegidae. The habits are, we believe, quite unknown. Fam. 2. Pompilidae. Pronotum at the sides reaching the tegulae ; hind body never definitely pedicellate, though the first segment is sometimes elongate and conical ; hind legs long ; eyes elliptic in form,, not emarginate. The Pompilidae are perhaps the most extensive and important of the groups of Fossores, and are distributed over all the lands of the globe, with the exception of some islands and of the inclement arctic regions. The sting of the Pompilidae, unlike that of most of the Fossores, inflicts a burning and painful wound; the creatures sometimes attain a length of two or three inches, and a sting from one of these giants may have serious results. Although there is considerable variety in the external form of the members of the group, the characters given above will enable a Pompilid to be recognised with approximate certainty. The elongation of the hind legs includes all the parts, so that while the femur extends nearly as far back as the extremity of the body — in dried examples at any rate — the tibiae and the long tarsi extend far beyond it ; thus these Insects have great powers of running ; they are indeed remarkable for extreme activity and vivacity. They may frequently be seen running rapidly on the surface of the ground, with quivering wings and vibrating antennae, and are probably then employed in the search for prey, or some other of the operations connected with providing a store of food for their young. Spiders appear to be their special, if not their only, prey. Several authors have recorded details as to the various ways in which the prey is attacked. Fabre has observed the habits of several species, and we select his account of the modus operandi of species of the genera Pompilus and Calicurgus, in their attacks on poisonous spiders that inhabit holes in the ground or in walls. The wasp goes to the mouth of the spider's burrow, and the latter then dashes to the entry, apparently IO2 HYMENOPTERA enraged at the audacity of its persecutor. The Calicurgus will not actually enter a burrow when there is a spider in it, because if it did so the spider would speedily dispose of the aggressor by the aid of its poisonous fangs. The Calicurgus, therefore, has recourse to strategy with the object of getting the spider out of its nest ; the wasp seizes its redoubtable foe by one foot and pulls ; probably it fails to extract the spider, and in that case rapidly passes to another burrow to repeat its tactics ; sooner or later a spider is in some moment of inatten- tion or incapacity dragged from its stronghold, and, being then comparatively helpless, feels itself at a disadvantage and offers but a feeble resistance to the wasp, which now pounces on its body and immediately in- flicts a sting between the fangs of the foe, and thus at once paralyses these dangerous weapons ; thereafter it stings the body of the spider near to the junction of the abdomen and cephalothorax, and so produces complete inactivity. Having secured its prey, the wasp then seeks a suitable hole in which to deposit it ; probably an empty burrow of a spider is selected for the purpose, and it may be at a height of several feet in a wall ; the Hymenopteron, walking backwards, drags its heavy prey up the wall to bring it to the den. When this is accom- plished an egg is deposited on the spider, and the wasp goes in search of a fragment or two of mortar, with which the mouth of the burrow is finally blocked. Fabre's accounts refer to the habits of several species, and give a good insight into some points of the instincts of both the spider and the wasp. It seems that a sense of superiority is produced in one or other of the foes, accord- ing as it feels itself in suitable conditions ; so that though a spider out of its burrow and on the ground is speedily vanquished by the Pompilid, yet if the two be confined together in a vase, both are FIG. 43. — Calicurgus hyalinatus ?. Britain. POMPILIDAE 103 shy and inclined to adopt defensive or even evasive tactics, the result probably being that the wasp will be killed by the spider during the night, that being the period in which the attacking powers of the spider are more usually brought into play. It seems to be the habit of some Poinpilus to procure a victim before they have secured a place for its reception ; and Fabre took advantage of this fact, and made very interesting observations on some points of the instinct of these wasps. Having found a Pompilus that, after having caught a spider and paralysed it, was engaged in making a retreat for its reception, he abstracted the booty, which was deposited at the top of a small tuft of vegetation near to where the Pompilus was at work. In this case the burrow in course of preparation was subterranean, and was formed by the Pompilus itself, which therefore could not, while it was engaged underground, see what took place near it. It is the habit of the wasp to leave its work of excavation from time to time, and to visit the prey as if to assure itself of the safety of this object, and to enjoy the satisfaction of touching it with the mouth and palping it. Desirous of testing the wasp's memory of locality, Fabre took the opportunity, while the Insect was working at the formation of its burrow, of remoA'ing, as we have said, the booty from the place where it had been deposited, and putting it in another spot some half-yard off. In a short time the Pompilus suspended work and went straight to the spot where it had deposited its property, and finding this absent, entered on a series of marches, counter-marches, and circles round the spot where it had left the prey, as if quite sure that this was really the place where the desired object ought to be. At last convinced that the paralysed prey was no longer where it had been placed, the Pompilus made investigations at a greater distance and soon discovered the spider. Fabre recounts that its movements then appeared to indicate astonishment at the change of position that it thus ascertained to have occurred. The wasp, however, soon satisfied itself that this was really the very object it was seeking, and seizing the spider by the leg slightly altered its position by placing it on the summit of a small tuft of vegetation ; this latter proceeding being apparently always carried out by this species of Pompilus. Then it returned to its excavation, and Fabre again removed the spider to a third spot ; the wasp when it next rested from its work made its Way 1 04 HYMENOPTERA CHAP. immediately to the second spot, where it had last left the spider, thus showing that it possessed an accurate memory for locality ; the wasp was very much surprised at the absence of the valued prize and persisted in seeking it in the immediate vicinity with- out once returning to the place where it had been first located. Fabre repeated this manoeuvre five times, and the Pompilus invariably returned at once to the spot where it had last left its prey. The acute memory for localities displayed by this Insect seems to be more or less general throughout the Aculeate Hymenoptera, and is of very great importance to them. The power of finding the object appears to depend on sight, for when Fabre, after removing the spider to a fresh spot, made a slight depression in the ground, placed the spider in it and covered it over with a leaf, the wasp did not find it. At the same time, the Insect's sight must be a very different sense from our own, for the wasp, when seeking its lost booty, frequently passed within a couple of inches of it without perceiving it, though it was not concealed. Belt gives an example of the habits of the Mexican Pompilus polistoides. He noticed it, when hunting for spiders, make a dart at a web in the centre of which a spider was stationed ; by this movement the creature was frightened and fell to the ground, where it was seized by the wasp and stung. The Pompilus then dragged its prisoner up a tree and afterwards flew off with it, the burden being probably too heavy for conveyance to the nest without the vantage of an elevation to start from. Several modifications adopted by Pompilidae in their mode of stinging their spider-victims have been recorded by Ferton ; these we cannot allude to in detail, but will nevertheless mention that one species stings the body of its spider-prey at random, and that in other cases it would appear that the paralysis of the spider is evanescent. In short, there are various degrees of perfection in the details of the art of stinging. The most remarkable of the forms of Pompilidae are the numerous species of Pepsis, a genus peculiar to America, whence upwards of 200 species are already known.1 Some of them attain a length of two inches or more, and are able to conquer the largest spiders ; even the formidable My gale avicularis succumbs to their agility and skill. Some of these Pepsis have beautifully coloured wings ; according to Cameron, this may be 1 Monograph by Lucas, Berlin ent. Zeitschr. xxxix. 1894. POMPILIDAE 105 due to scales. P. formosus, Say, is called in Texas the tarantula- killer ; according to Buckley, its mode of attack on the huge spider is different from that made use of by its European ally. When it discovers a tarantula it flies " in circles in the air, around its victim. The spider, as if knowing its fate, stands up and makes a show of fighting, but the resistance is very feeble and of no avail. The spider's foe soon discovers a favourable moment and darts upon the tarantula, whom it wounds with its sting, and again commences flying in circles." The natural retreat of this huge spider, Mygale lientzii, is in holes in the ground, and this account does not inform us whether the spider allows itself to be overcome when in its nest, or is only attacked when out of its retreat. The genus Mygnimia includes a very large number of species, and has a wider geographical distribution than Pepsis, being found in the tropical regions of both the Old and New Worlds, some of them rivalling in size and ferocity the larger specimens of the genus Pepsis. In the Insects of this genus there is usually a more or less distinct small space of more pallid colour on the middle of each front wing. Parapompilus is a curious genus consisting of Insects of a great variety of peculiar coloration, and having the wings short, so as to be of little use for flight. P. gravesii is an inhabitant of Chili. Agenia carbonaria and A. hyalipennis are small and feeble Insects inhabiting the south of Europe. A. carbonaria extends to the south of England. They construct, as nests for their offspring, small earthenware vessels, differing in form according to the species, those of A. hyalipennis being vase-like in shape, while those of A. carbonaria are contracted near the mouth, something after the fashion of a wide-mouthed bottle. The Insect is able by some means — Fabre thinks by the use of saliva — to varnish the interior of the vessel so that it will not absorb water ; the outside of the cells is, however, not so protected, and speedily crumbles away when exposed to the action of water ; hence the vessel is placed in a protected situation, such as in a tree-stump, or a hole in a wall, or even in an empty snail-shell under a heap of stones. The cells are stored with spiders that have been paralysed by stinging and that serve as food for the larva of the Agenia. The larva of A. carbonaria has been described, and some particulars as to its habits have been given by Verhoeff. 1 06 HYMENOPTERA It has been stated that this wasp does not paralyse its prey by stinging, but substitutes a process of biting to prevent the spider from hurting the larva that is to feed on it ; and Verhoeff 's observations seem to show that the legs of the spider are broken by some proceeding of the kind. The Agenia larva is of peculiar shape, the head not being inflexed, wrhile the pleurae of each segment, from the second onwards, are prominent, so as to give the outline of the body a scalloped appearance. This larva is much infested by an Ichneumon that devours, it appears, not only the larva itself, but also the spider that was destined to be food for the larva. Verhoeff seems to have found some evidence that Pompilus sericeus may also be a parasite on the Agenia. The construction of earthenware cells, instead of the burrows usual in Pompilidae, by the species of this genus is one of the cases alluded to in our introductory remarks as to allied Fossores exhibiting different habits. Mr. Pride has recently sent us from Brazil similar earthen vessels constructed by some Pompilid. The habits of Pompilids of the genus Ceropales are analogous to those of the parasitic bees. Perez has recently given us information as to a very curious form of parasitism in this genus ; he says that when a Pompilus has obtained a spider as provision for its young, it is pursued by a Ceropales, which lays an egg on the spider, thus as it were substituting in advance its own young for that of the Pompilus. Information as to the subsequent course of events in this case is not at present forthcoming. In another case a Ceropales was observed to oviposit on the spider, not while this is being carried in, but subsequently by entering the nest for the purpose ; a habit quite similar to that of some parasitic bees. Ferton has recently made the unexpected discovery that some Pompilus act as robbers ; one individual taking away by force the spider that another has captured and is carrying off. Lichtenstein described a Pompilid larva, that he afterwards ascertained to be Calicurgus hyalinatus, as possessing the extra- ordinary habit of feeding as an external parasite fixed to the dorsal surface of a spider ; thus repeating, it would appear, the habits of some of the Ichnemonidae, though the perfect Insect (Fig. 143) does not differ in structure from its congeners. Emery has given an account of some Pompilids that do not bury their prey, but after stinging it and depositing an egg, simply leave the spider on the spot. Hi FOSSORES SPHEGIDAE — SPHEGIDES IO/ Buller has described the habits of a Pompilid in New Zealand ; his account is interesting because it shows a remarkable similarity in the proceedings of this antipodean wasp to those of its con- geners on our own side of the world. The species is not scientifically named, but it appears that it is known in New- Zealand as " the Mason-bee." It forms a nest of yellow clay consisting apparently of about eight cells, each of which is filled with one or more spiders in a paralysed condition. The figure given of the larva of this Insect by Buller shows it to possess a peculiarly formed head. It is pleasing to find that Pompilidae do not make use of cruel methods when others will serve their purpose. We are informed that a large Australian Pompilid — Priocnemis bicolor — may find a Cicada sucking sap from a hole it has pierced in a tree. The Priocnemis has not the art of making the puncture necessary to procure sap, so the wasp seizes the Cicada, and shakes it till it leaves its hold and flies away, when the Priocnemis takes its place and sips the sap. It is added that the wasp never hurts the Cicada. Fam. 3. Sphegidae. Pronotum free from the tegulae ; ivhen the stigmatic lobes extend as far back as the wing-insertion, they are placed below it and separated by a space from it. This large assemblage of Fossores is the one about which the greatest difference of opinion prevails. It is based entirely on the prothoracic characters mentioned above, and cannot be looked on as natural. We shall, however, follow Kohl1 in treating for the present as only one family the divisions considered by many as distinct families. They are ten in number. Sub-Fam. 1. Sphegides. — Hind body with a slender pedicel of variable length ; two spurs on the middle tibia. The pro- podeum usually horizontally elongate? This group includes a great number of species, about 200 of which are referred to the genus Sphex. 1 "Die Gattungen der Sphegiden," Ann. Hofmus. Wien. xi. 1896, pp. 233-596. Seven plates. 2 We will take this opportunity of correcting an error in the explanation of Fig. 333 of the preceding volume, showing the propodeum, etc. of Sphex chrysis. f points to a division of the mesonotum, not of the metanotum, as there stated. 108 HYMENOPTERA CHAP. The habits of one species of this genus have been fully de- scribed by Fabre ; he assigns to the species the name of S. flavi- pennis, but Kohl considers that it is more probably S. maxillosus. This Insect forms its nests, in the South of France, in the ground, excavating a main shaft with which are connected cells intended for the reception of the provisions for the young. The entrance to the burrow is formed by piercing a hole in the side of a very slight elevation of the soil. Thus the entrance to the construc- tion consists of a horizontal gallery, playing the part of a vesti- bule, and this is used by the Sphex as a place of retreat and shelter for itself; at the end of the vestibule, which may be two or three inches long, the excavation takes an abrupt turn down- wards, extending in this manner another two or three inches, and terminating in an oval cell the larger diameter of which is situate in a horizontal plane. When this first cell has been com- pleted, stored with food, and an egg laid in it, the entrance to it is blocked up, and another similar cell is formed on one side ; a third and sometimes a fourth are afterwards made and pro- visioned, then the Insect commences anew, and a fresh tunnel is formed ; ten such constructions being the number usually prepared by each wasp. The Insect works with extreme energy, and as the period of its constructive activity endures only about a month, it can give but two or three days to the construction and pro- visioning of each of its ten subterranean works. The provisions, according to Fabre, consist of a large species of field-cricket, of which three or four individuals are placed in each cell. Kohl states, however, that in Eastern Europe an Insect that he considers to be the same species as Fabre's Sphex, makes use of locusts as provisions, and he thinks that the habit may vary according to the locality or to the species of Orthoptera that may be available in the neighbourhood. However that may be, it is clear from Fabre's account that this part of the Sphex's duties do not give rise to much difficulty. The cricket, having been caught, is paralysed so that it may not by its movements destroy the young larva for whose benefit it is destined. The Sphex then carries it to the burrow to store it in one of the cells ; before entering the cell the Insect is in the habit of depositing its prey on the ground, then of turning round, entering the burrow backwards, seizing as it does so the cricket by the antennae, and so dragging it into the cell, itself going back- in SPHEGIDAE SPHEGIDES 1 09 wards. The habit of depositing its prey on the ground enabled Fabre to observe the process of stinging ; this he did by himself capturing a cricket, and when the wasp had momentarily quitted its prey, substituting the sound cricket for the paralysed one. The Sphex, on finding this new and lively victim, proceeds at once to sting it, and pounces on the cricket, which, after a brief struggle, is overcome by the wasp ; this holds it supine, and then administers three stings, one in the neck, one in the joint between the pro- and meso-thorax, and a third at the base of the abdomen, these three spots corresponding with the situation of the three chief nervous centres governing the movements of the body. The cricket is thus completely paralysed, without, however, being- killed. Fabre proved that an Insect so treated would survive for several weeks, though deprived of all power of movement. Three or four crickets are placed by the wasp in each cell, 100 individuals or upwards being thus destroyed by a single wasp. Although the sting has such an immediate and powerful effect on the cricket, it occasions but a slight and evanescent pain to a human being ; the sting is not barbed, as it is in many bees and true wasps, and appears to be rarely used by the Insect for any other purpose than that of paralysing its victims. The egg is laid by the Sphex on the ventral surface of the victim between the second and third pairs of legs. In three or four days the young larva makes its appearance in the form of a feeble little worm, as transparent as crystal ; this larva does not change its place, but there, where it was hatched, pierces the skin of the cricket with its tiny head, and thus begins the process of feed- ing ; it does not leave the spot where it first commenced to feed, but gradually enters by the orifice it has made, into the interior of the cricket. This is completely emptied in the course of six or seven days, nothing but its integument remaining ; the wasp-larva has by this time attained a length of about 12 milli- metres, and makes its exit through the orifice it entered by, chang- ing its skin as it does so. Another cricket is then attacked and rapidly consumed, the whole stock being devoured in ten or twelve days from the commencement of the feeding operations ; the con- sumption of the later-eaten crickets is not performed in so delicate a manner as is the eating of the first victim. When full-grown, the process of forming a cocoon commences : this is a very ela- borate operation, for the encasement consists of three layers, in IIO HYMENOPTERA addition to the rough silk that serves as a sort of scaffolding on the exterior : the internal coat is polished and is of a dark colour, owing to its being coloured with a matter from the alimentary canal : the other layers of the cocoon are white or pale yellow. Fabre considers that the outer layers of the cocoon are formed by matter from the silk-glands, while the interior dark coat is furnished by the alimentary canal and applied by the mouth of the larva : the object of this varnish is believed to be the exclu- sion of moisture from the interior of the cocoon, the subterranean tunnels being insufficient for keeping their contents dry through- out the long months of winter. During the whole of the pro- cess of devouring the four crickets, nothing is ejected from the alimentary canal of the larva, but after the cocoon is formed the larva ejects in it, once for all, the surplus contents of the intestine. Nine months are passed by the Insect in the cocoon, the pupal state being assumed only towards the close of this period. The pupa is at first quite colourless, but gradually assumes the black and red colour characteristic of the perfect wasp. Fabre exposed some specimens of the pupa to the light in glass tubes, and found that they went through the pupal meta- morphosis in just the same manner as the pupae that remained in the darkness natural to them during this stage of their existence. Spliex coeruleus is frequently stated to have the habit of pro- visioning its nests with both Orthoptera and Spiders ; but Kohl considers with reason that this record is, as regards spiders, a mistake, arising probably from a confusion with some other Insect of similar appearance, such as Pelopaeus (Sceliphron) coeruleus. S. coeruleus is no doubt the same as S. (Chloriori) lobatus, which Eothney observed in East India, provisioning its nests with Orthoptera. He discovered a nest in process of con- struction, and during the absence of the mother-wasp abstracted from the burrow a large field-cricket that she had placed in it; he then deposited the Orthopteron near the cell ; the parent Spliex on returning to work entered the tunnel and found the provision placed therein had disappeared ; she came out in a state of excitement, looked for the missing cricket, soon discovered it, submitted it to the process of malaxation or kneading, and again placed it in the nest, after having cleared it from some ants that had commenced to infest it. She then disappeared, and Eothney repeated the experiment ; in due course the same series in SPHEGIDAE SPHEGIDES I I I of operations was performed, and were repeated many times, the Spliex evidently acting in each case as if either the cricket had disappeared owing to its being incompletely stunned, or to its having been stolen by ants. Finally, the observer placed the cricket at a greater distance from the nest, when it recovered from the ill-treatment it had received sufficiently to make its escape. The points of interest in this account are the fact that the cricket was only temporarily paralysed, and that the wasp was quite able to cope with the two special difficulties that must frequently occur to the species in its usual round of occupations. The genus Ammophila is of wide distribution, and its species make vertical tunnels in the ground. The habits of some of the species found in France have been described by Fabre. The Insect does not inhabit the burrow while it is in process of formation, but quits it ; and some of the species temporarily close the entry to the incomplete nest with a stone. The tunnel is a simple shaft with a single cell at its termination ; this is stored with caterpillars, the different species of Ammo- pkila selecting different grubs for the purpose. A. hirsuta hiber- nates in the perfect state, and carries on its work in the spring ; it chooses a single larva of considerable size belonging to one of the nocturnal Lepidoptera, and this it paralyses by a series of about nine stings, of which one is implanted in each segment from the first thoracic ring backwards ; it forms the burrow only after the food to be placed therein has been obtained. The caterpillar used is subterranean in habit, and the Ammophila detects the larva by some sense, the nature of which appears at present quite uncertain. A. holosericea chooses smaller larvae of the family Geometridae, and uses only one or two stingings to paralyse each larva ; several caterpillars are used to provision a single cell, and they are often selected of different colours. Marchal has also published an important account of the proceedings of A. cijfinis ; he confirms Fabre's observations, and even adds to their interest by suggesting that the Ammophila administers special stings for the purpose of paralysing the mandibles of the caterpillar and depriving it of any power of afterwards injuring the larva that will feed on it. He thinks the mokher-Ammophila herself profits by appropriating an exuda- tion from the victim. Some species of Sphegides have the curious habit of choosing 112 HYMENOPTERA CHAP. the interiors of human habitations as the spots most suitable for the formation of their own domestic establishments. Fabre has given a charming account of the habits of Pelopaeus (Sceliphron) spirifex, a species that inhabits the South of Europe, and that forms its nests in the cottages of the peasants. The spot usually selected is a nook in the broad, open fireplace, out of reach of the flames, though not of the smoke ; here the Pelopaeus forms a nest of earth, consisting of ten to fifty cells, the material being mud or clay brought in little balls by the aid of the Insect's mandibles ; about twenty visits are required in order to complete one cell, so that for the construction of a large nest of fifty cells, about one thousand visits must be made by the Insect. It flies in and out of the house apparently not at all incommoded by the human habitants, or by the fact that the peasant's potage may be simmering on the fire quite close to where the fearless little creature is carrying on its architectural operations. The cells are stored with spiders, of which the wasp has to bring a plentiful supply, so that its operations extend over a considerable period. The prey is captured by the Pelopaeus whilst on the wing, and carried off at once, being probably stung by the wasp during the process of transit ; apparently it is killed by the operation, not merely paralysed. Only small spiders are taken by this species, and the larva of the Pelopaeus consumes them in a short time, one by one, before the process of decomposition sets in ; the egg, too, is laid on the first spider introduced, and this is of course at the bottom of the cell, so that the spiders are eaten by the wasp's larva in the order in which they were brought to the cell. The cell is sealed up when full, the number of spiders placed in it being on the average about eight. The larva completes its task of consuming the store in about ten days, and then forms a cocoon for its metamorphosis. • Two or three generations are produced in a single year, the autumnal one passing eight or nine months in the clay cells, which are lodged in a nook of the peasant's hearth, and exposed to the smoke of his fire during all the months of winter. Pelopaeus (Sceliphron) is a genus including many species ; l several of them are known 1 Pelopaeus disappears from the new catalogue of Hymenoptera as the name of a valid genus ; its species being assigned to Sceliphron and various other genera. AVe have endeavoured, as regards this name, to reconcile the nomenclature of previous authors with that used in the new catalogue by placing the generic name adopted in the latter in brackets. in SPHEGIDAE SPHEGIDES PELOPAEUS I I 3 to be specially attached to the habitations of human, beings. Eoth has given an account of the habits of P. (Sceliphron} laetus in Australia ; he says that in some parts it is very difficult to keep these wasps out of the houses ; the nest is formed of mud, and constructed on the furniture or in any part of a room that suits the fancy of the Insect. This it must be admitted is, according to human ideas, liable to the charge of being very capricious. Roth timed a wasp building its nest, and found that it brought a fresh load of mud every two or three minutes. If the wasp be allowed to complete the nest undisturbed, she does so by adding to the exterior diagonal streaks of mud, so giving to the nest the look of a small piece of the bark of a common acacia. The construction consists of from ten to twenty cells, and when completed is provisioned with spiders for the use of the young. This wasp is much pestered by parasites, some of which prevent the development of the larvae by consuming the spiders intended by the mother- wasp for its young. A fly, of the Order Diptera, is said to follow the wasp when carrying a spider, and to deposit also an egg on the food ; as the Dipterous larvae have more rapid powers of assimilation, the Pelopaeus larvae are starved to death ; and their mildewed remains may be found in the cell, after their enemies have become fully developed and have flown away. Another parasite is said to eat the wasp-larva, and attains this end by introducing an egg through the mud wall and the cocoon of the wasp — a habit that seems to indicate a Leucospicl parasite. Tcichytes australis, a wasp of the sub-family Larrides also dis- possesses this Pelopaeus in a manner we shall subsequently describe. This fragment of natural history from Australia has a special interest, for we find repeated there similar complex biological relations to those existing in the case of the European congeners. P. (Sceliphrori) madraspatanus is common in the north-west provinces of Hindostan, and is called the " mud-dauber " by the European residents. According to Home it constructs its cells in the oddest places, but chiefly about the inhabited apartments in houses. It is perfectly fearless when engaged in building : the cells are four to six in number, and are usually provisioned with spiders to the number of about twenty. On one occasion it was observed that green caterpillars were stored instead of VOL. VI I HYMENOPTERA spiders. The species is said to be protected by a peculiar odour as well as by its sting ; it is also stated that it disguises its edifice when completed by making it look like a dab of mud, and on one occasion " rays of mud were observed round the nest, even more exactly imitating a lump of mud thrown with some force." P. (Scdiphron) bilineatus, formerly thought to be a variety of P. madraspatanus, builds its nests in hedges and trees. Sub-Fam. 2. Ampulicides. — Prothorax long and narrow, forming a neck in front ; clypeus beak-like ; four submarginal cells, the outer one being complete ; metathorax elongate, the pos- terior part of the metasternum deeply divided to allow a perfect inflection of the abdomen. This is one of the smallest of the divisions of the Sphegidae, but has a very wide distribution, being represented in both the Eastern and Western Hemispheres. It is allied to the Sphegides, but differs by the prolongation of the neck and of the head, and by the articulation between the petiole and thorax being placed on the under surface of the body ; the wing- nervures are said to be of inferior importance owing to their frequently differing in indi- viduals of the same species. These Insects appear to be rare in individuals, as well as few in species, and but little has been recorded as to their habits ; but it is known that they live on cockroaches. Per- kins has given a brief sketch of the habits of Ampulex sibi- rica that is of great interest, but requires confirmation. He says that this Insect, in West Africa, enters apartments where cockroaches abound, and attack- ing one, that may probably be FIG. 44.— Ampulex compressa. Male. four times its Own S1Z6, SUC- East India. i • «. i • > • ceeds, alter a struggle, in sting- ing it ; the cockroach instantly becomes quiet and submissive, and suffers itself to be led away and placed in confinement in some in SPHEGIDAE AMPULICIDES I I 5 spot such as a keyhole, and in one case was apparently pre- vented from afterwards escaping, by the wasp carrying some heavy nails into the keyhole. The larva of the Ampulex may be presumed to live on the Blattid, as it is added that dead bodies of the cockroaches are frequently found with the empty cocoon protruding from them. This account, if correct, points to some features in the habits of this Insect that are unique. A remark made by Kothney in reference to the habits of A. (Bhi- nopsis) ruficornis seems to indicate some similar instinct on the part of that species ; he says, " I also saw two or three of these wasps collar a peculiar cockroach by the antennae and lead it off into a crack in the bark, but as the cockroach reappeared smiling each time, I don't know what was up." The same observer records that this species associates with Sima rufonigrd, an ant it greatly re- sembles in appearance, as well as with a spider that is also of similar appearance (Fig. 72). Schurr has given a brief account of the proceedings of Ampulex compressa, and his statements also tend to confirm the correctness of Perkins' report. The habits of a species of Ampulex were partially known to Eeaumur, who described them on the authority of M. Cossigni. The species is believed to be A. compressa, which occurs not only in East India, but also in the island of Bourbon, the locality where M. Cossigni made his observation : his account is, like the others, a mere sketch of certain points observed, the most important of which is that when Ampulex cannot introduce the cockroach into a hole that it has selected as suitable, it bites off some portions of the body in order to reduce the poor Insect to the necessary extent. From these fragmentary observations it would appear that the sting of the Ampulex has not so powerful a paralysing effect as that of most other Fossores ; and that the Ampulex does not form any nest, but takes advantage of suitable holes and crevices to store the victim in ; also that it displays consider- able ingenuity in the selection of materials with which to block up the cavity in which it has placed the partially incapacitated creature. The genus Dolichurus is by some entomologists considered the type of a sub-family allied to the AnipuHcides ; it long consisted of a small and rare European Insect, but some exotic species have recently been added to it. It will probably prove not II 6 HYMENOPTERA CHAP. sufficiently distinct from Ampulicides, although the pronotum is much shorter, but Handlirsch has recently observed that the European species attacks Blattidae as do the normal Ampulicides ; and Ferton has recorded that D. haemorrhous lives at the expense of Loboptera decipiens, the wasp depositing its egg on the left intermediate femur of the prey. This is placed in a solitary cell, and is entirely consumed by the larva, life being preserved till within a few hours of the end of the repast, which occupies altogether eight days. Sub-Fam. 3. Larrides. — Hind lody not pedicellate, or with only a short pedicel ; one spur on the middle tibia ; labrum inconspicuous. Marginal cell of the front wings appendi- culale,1 or mandibles excised externally, or loth. This group is by some writers called Tachytides instead of Larrides, as owing to a change of nomenclature Tachytes may now be considered its principal genus. It is in connection with this and the neighbouring sub -families of Sphegidae that some of the greatest taxonomical difficulties exist. We include in Larrides the " Miscophus group " of Kohl. The species of the genus Tachytes seem to have habits very similar to those of the genus Sphex ; they form shafts in the earth and provision them with Orthoptera ; like the Sphex and other Fossores, they have the habit, when they fly to their tunnel with a victim, of depositing it for a short time on the ground close to the mouth of the burrow while they turn round and enter backwards; and, after doing this they again seize their prey and drag it into the burrow. Fabre availed himself of an opportunity to remove the prey while the Hymenopteron was entering the hole alone ; as a result it had to come out again to seek the object ; this it soon found, and carried to the hole, relinquishing it again as usual while it turned round ; Fabre repeated the operation several times, and always with the same result ; the wasp, though it might have kept hold of the victim while it turned, and thus have saved itself from losing the precious object, never did so. 1 When a second cell is more or less perfectly marked out, the cell with which it is connected is said to be appendiculate. The nervures frequently extend beyond the complete cells towards the outer margin, forming "incomplete" cells; only complete cells are counted, except when "incomplete" is mentioned. in SPHEGIDAE— LARRIDES I I/ One species of Tachytes in the south of France selects as its prey Orthoptera of the family Mantidae, Insects of a highly ferocious disposition, and provided with most powerful front legs, capable of cutting in two by a single act the body of an aggressor like the Tachytes; the latter is, however, by no means dismayed by the arms of its future victim, but hover- ing above the latter for some time, as if to confuse it, and causing it repeatedly to turn its very mobile head, the FIG. 45.— Tachytes pectinipes 9. Tachytes at last pounces down and instantaneously stings the Mantis in the nerve centre between the formidable arms, which at once are reduced to in- capacity ; subsequently the Tachytes paralyses each of the other pairs of legs, and then carries off its victim. La i" HI ii/Killicnta chooses mole -crickets as the viand for its young, and Tachygphex panzeri selects grasshoppers of the family Acridiidae. Larra pompiliformis ( = Tachytes niger, Fabre) some- times associates itself with Sphex flavipcnnis (? S. maxillosus, according to Kohl), forming its burrow amidst the works of a colony of that species, and making use, like the Sphex, of crickets for provender. This led Fabre to believe that the Larra stole its prey from the Sphex, but he has since withdrawn this indict- ment, and declares that the Larra obtains its crickets by the more honourable, if not more humane, process of catching and stinging them itself. Smith has informed us, on the faith of his own observation, that L. pompiliformis uses both Lepidopterous larvae and grasshoppers for its stores. T. (Larrada} australis, according to Whittell, plays the part of a burglar, breaking open the cells of Pelopaeus (Sceliphron) laetus after they have been completed and stored with spiders ; it then takes possession of the cell, and curiously enough the Pelopaeus permits this, although the cell contains its egg and the store of food that is intended for the use of its own young. To us this seems very strange, but it is probable that the Pelopaeus has no idea of the consequences of the intruder's operations ; I I 8 HYMENOPTERA it being one of the strange facts of nature that these highly endowed creatures never even see the offspring for whose welfare they labour with such extraordinary ingenuity and perseverance. Neither can we suppose that they have a conception of it derived from a knowledge of their own individual history ; for their very complete metamorphosis is scarcely reconcilable with any such recollection on their part. It may possibly therefore be the case that, having no idea whatever of the offspring, they are equally destitute of any conception that it will be destroyed by the operations of the Larrada. However this may be, Whittell informs us that both wasps skirmish about for a little as if each were mistrustful and somewhat afraid of the other ; this ends by the Pelopaeus withdrawing its opposition and by the Larrada taking possession of the cell, which it then proceeds to divide into two, using for the purpose of the partition portions of the material of the nest itself; possibly it is only a contraction of the size of the cell, not a true division, that is effected ; however this may be, after it is accomplished the Larrada deposits its own egg in the cell, having, it is believed by Whittell, previously destroyed that of the Pelopaeus. Judging from what occurs in other species it is, however, more probable that the destruction of the egg or young of the Pelopaeus is carried out by the larva of the Larrada and not by the parent-wasp. From a remark made by Maindron as to the proceedings of Larrada modesta, in Ternate, it seems probable that its habits may prove to be similar to those of L. australis, for it frequents the nests of Pelopaeus after they have been completed. Sub-Fam. 4. Trypoxylonides. — Differ from Larrides by the inner margin of the eyes being concave, and the marginal cell not appendiculate. (In Trypoxylon there is only one distinct submarginal and one distinct discoidal cell, a second of each being indicated faintly.} The nervuration of Trypoxylon is very peculiar, and differs from that of the widely-distributed genus Pison, though according to Kohl's views the two may be correctly associated to form this sub-family. The species of Trypoxylon are apparently rather fond of human propinquity, and build clay- or mud-nests in or near houses. T. albitarse has this habit, and is well known in Southern Brazil under the name of " Marimbouda da casa " SPHEGIDAE ASTATIDES BEMBECIDE 119 this Insect, like Pelopaeus, stores its nest with spiders, and Peckholt has remarked that however great may be the number of spiders placed by the mother- wasp in a cell, they are all consumed by the larva, none ever being found in the cell after the perfect Insect escapes therefrom. The European T. figulus forms a nest either in bramble-stems or in sandy soil or walls ; it makes use of spiders as provisions. Sub-Fam. 5. Astatides. — Eyes very large in the male, meeting broadly on the vertex ; two spurs on the middle tibia. "We have two species of the genus Astata in Britain : one of them — A. loops — is known to form burrows in the ground, each of which contains only a single cell ; this, it appears, is usually provisioned with bugs of the genus Pentaloma, Insects re- markable for their strong and offensive odour. St. Fargeau records that this species also makes use of a small cockroach for forming the food - store : thus exhibiting an unique catholicity in the toleration of the disagreeable ; almost the only point of connection be- tween bugs and cockroaches being their disagreeable char- FlG" 46 -Astata bo°^ male' Britaln' acter. According to Smith, Oxybelus, another genus of Fossores, is also used. Authorities are far from agreement as to the validity and relations of the sub-family Astatides. It consists only of the widely-distributed genus Astata, with which the North American Diploplectron (with one species) is doubtfully associated. Sub - Fam. 6. Bembecides. — Labrum frequently elongate ; wing - nervures extending very near to the outer margin ; marginal cell of front wing not appendiculate ; mandibles not emarginate externally ; hind body stout, not pedicellate. The elongation of the labrum, though one of the most trust- worthy of the characters of the Bembecides, cannot be altogether I2O HYMENOPTERA relied on owing to the variation it presents both in this and the allied sub-families. The Bembecides carry their prey to their young tucked underneath their own bodies and hugged to the breast ; they affect loose, sandy soils for nidification ; make use, in the great majority of the cases where the habits are known, of Diptera for provisions, and give these dead to the young ; making repeated visits to supply fresh food to the progeny, which notwithstanding this fact, are distributed in isolated burrows. One of the most interesting of Fabre's studies of the instincts of Hymenoptera is devoted to Bembex rostrata. The Bembecides have the habit of forming their nests in the ground in wide expanses of sand, and of cover- ing them up, they leave them so that there appears to be absolutely nothing by which the exact position of the nest can be traced ; nevertheless the Bembex flies direct to it with- out any hesitation. How neces- sary it is to these Insects to possess this faculty of finding their nests will be understood when we recall that the Bembex does not provision its nest once and for all, but supplies the young at first with only insufficient food, and has therefore to return at daily, or other intervals, with a fresh store of provisions. The burrow is made in the sand by means of the fore-legs ; these work with such rapidity and skill that a constant stream of sand flows out behind the Insect while it is engaged in the act of excavation. The nest or cell in which the larva is to live, is formed by this process of digging ; but no fastening together of the material occurs, nor does any expedient seem to be resorted to, other than that of making a way through the sand by clearing out all the pieces of stick or stone that might diminish facility of access. The cell being formed, the Bembex leaves the spot in search of prey, and when it has secured a victim in the shape of a two- winged fly, it returns therewith to the burrow, and the booty is placed therein, an egg being deposited on it. The wasp then leaves the burrow, disguising, however, the spot where it is situate, and flies away ; to proceed possibly with the formation FIJ. 47. — Bembex rostrata J. Europe. in SPHEGIDAE BEMBECIDES 121 of other burrows.1 In the course of twenty -four hours the egg hatches, and the larva in two or three days completely devours the stock provided for it. The mother - wasp then returns with another fly — this time probably a larger one — penetrates rapidly to the bottom of the burrow, and again re- treats, leaving the second stock of provisions for the benefit of the greedy larva. These visits of supply are repeated with increased frequency, as the appetite of the larva for the benefit of which they are made increases with its growth. During the fourteen or fifteen days that form this portion of the life-cycle, the single larva is supplied with no less than fifty to eighty flies for food. To furnish this quantum, numerous visits are made to each burrow, and as the mother Bembex has several burrows — though how many does not appear to be known — her industry at this time must be very great. All the while, too, a great danger has to be avoided, for there is an enemy that sees in the booty brought by the Bembex to its young, a rich store for its own progeny. This enemy is a feeble, two-winged fly of the family Tachinidae and the genus Miltogramma ; it hangs about the neighbourhood of the nests, and sooner or later finds its opportunity of descending on the prey the Bembex is carrying, choosing for its purpose a moment when the Bembex makes a brief delay just at the mouth of the burrow ; then down comes the Miltogramma and lays one, two, or three eggs on some portion of the booty that may be projecting from beneath the body of the wasp. This latter carries in the food for its own young, but thus introduces to the latter the source of its destruction, for the Miltogramma larvae eat up the supply of food intended for the Bembex larvae, and if there be not enough of this provender they satisfy their voracity by eating the Bembex larva itself. It is a remarkable fact that notwithstanding the presence of these strange larvae in the nest the mother Bembex continues to bring food at proper intervals, and, what is stranger still, makes no effort to rid the nest of the intruders : returning to the burrow with a supply of food she finds therein not only her legitimate offspring, a single tenant, but several others, strangers, it may be to the number of twelve ; . although she would have no difficulty in freeing the nest from this band of little brigands, she makes no attempt to do so, but continues to bring the 1 See on this point the note on p. 130. 122 HYMENOPTERA CHAP. supplies. In doing so she is fulfilling her duty ; what matters it that she is nourishing the enemies of her race ? Both race and enemies have existed for long, perhaps for untold periods of time, why then should she disturb herself, or deviate from her accustomed range of duties ? Some of us will see in such pro- ceedings only gross stupidity, while others may look on them as sublime toleration. The peculiar habits of Bembex rostrata are evidently closely connected with the fact that it actually kills, instead of merely paralysing, its prey ; hence the frequent visits of supply are neces- sary that the larvae may have fresh, not putrefying, food; it may also be because of this that the burrow is made in a place of loose sand, so that rapid ingress may be possible to the Bembex itself, while the contents of the burrow are at the same time protected from the inroads of other creatures by the burrow being filled up with the light sand. Fabre informs us that the Bembex larva constructs a very remarkable cocoon in connection with the peculiar nature of the soil. The unprotected creature has to pass a long period in its cocoon, and the sandy, shifting soil renders it necessary that the protecting case shall be solid and capable of keeping its contents dry and sound. The larva,, how- ever, appears to have but a scanty supply of silk available for the purpose of constructing the cocoon, and therefore adopts the device of selecting grains of sand, and using the silk as a sort of cement to connect them together. For a full account of the ingenious way in which this difficult task is accomplished the reader should refer to the pages of Fabre himself. Bembe- cides appear to be specially fond of members of the Tabanidae (or Gad-fly family) as provender for their young. These flies infest mammals for the purpose of feasting on the blood they can draw by their bites, and the Bembecides do not hesitate to capture them while engaged in gratifying their blood-thirsty pro- pensities. In North America a large species of Bembecid some- times accompanies horsemen, and catches the flies that come to attack the horses ; and Bates relates that on the Amazons a Bembecid as large as a hornet swooped down and captured one of the large blood-sucking Motuca flies that had settled on his neck. This naturalist has given an account of some of the Bembecides of the Amazons Valley, showing that the habits there are similar to those of their European congeners. in SPHEGIDAE - NYSSONIDES 123 Spliecius speciosus is a member of the Stizinae, a group recog- nised by some as a distinct sub-family. It makes use, in North America, of Insects of the genus Cicada as food for its young. Burrows in the ground are made by the parent Insect ; the egg is deposited on the Cicada, and the duration of the feeding-time of the larva is believed to be not more than a week ; the pupa is contained in a silken cocoon, with which much earth is incor- porated. Eiley states that dry earth is essential to the well- being of this Insect, as the Cicada become mouldy if the earth is at all damp. As the Cicada is about twice as heavy as the Sphecius itself, this latter, \vhen about to take the captured burden to the nest, adopts the plan of climbing with it to the top of a tree, or some similar point of vantage, so that during its flight it has to descend with its heavy burden instead of having to rise with it, as would be necessary if the start were made from the ground. Sub-Fam. 7. Nyssonides. — Labrum short; mandibles entire on the outer edge; hind body usually not pedicellate; wing icith the marginal cell not appendiculate. This group has been but little studied, and there is not much knowledge as to the habits of the species. It is admitted to be impossible to define it accurately. It is by some entomologists considered to include Mellinus, in which the abdomen is pedi- cellate (Fig. 48), while others treat that genus as forming a distinct sub-family, Mellinides. Kohl leaves Mellinus unclassified. Gerstaecker has called attention to the fact that many of the Insects in this group have the trochanters of the hind and middle legs divided : the division is, as a rule, not so complete as it usually is in Hymenoptera Parasitica ; but it is even more marked in some of these Nyssonides than it is in certain of the parasitic groups. arvensis is one of our commonest British Fossores, and we are indebted to the late F. Smith for the following account of its habits : " It preys upon flies, and may be commonly observed resorting to the droppings of cows in search of its prey; it is one of the most wary and talented of all its fraternity ; were it at once to attempt, by a sudden leap, to dart upon its victim, ten to one it would fail to secure it ; no, it does no such thing, it wanders about in a sort of innocent, unconcerned way, amongst 124 HYMENOPTERA the deluded flies, until a safe opportunity presents itself, when its prey is taken without any chance of failure ; such is its ordinary mode of proceeding. At Bournemouth the flies are more active, more difficult to capture, or have they unmasked the treacherous Mcllinus ? and is it found necessary to adopt some fresh contrivance in order to accomplish its ends ? if so, it is FIG. 48. — MeUinus arvensis ?. Britain. j n • • j T not deficient m devices. 1 noticed once or twice, what I took to be a dead specimen of Mellinus, lying on patches of cow-dung ; but 011 attempting to pick them up off they flew ; I at once suspected the crea- ture, and had not long to wait before my suspicions were confirmed. Another, apparently dead fellow, was observed ; and there, neither moving head or foot, the treacherous creature lay, until a fine specimen of a Bluebottle ventured within its grasp, when, active as any puss, the Mellinus started into life, and pounced upon its victim." Lucas states that 'in the north of France Mellinus sabulosus provisions its nest with Diptera, which it searches for on the flowers of Umbelliferae, and then carries to its nest. This is a burrow in the earth, and when it is reached the Hymenopteron deposits its Insect burden for a moment on the ground while it turns round in order to enter the burrow backwards. The same writer states that two varieties of this Insect live together — or rather in the same colonies — and make use of different species of Diptera, even of different genera, as food for their young. These Diptera are stung before being placed in the nest. The stinging does not kill the Insect, however, for Lucas was able to keep one specimen alive for six weeks after it had passed this trying ordeal. Sub-Fam. 8. Philanthides. — Labrum small ; anterior wings with three complete submarginal cells ; hind body constricted at the base but not so as to form a slender pedicel. This sub-family contains Insects resembling wasps or Cra- bronides in appearance, and is, as regards the pronotal structure, SPHEGIDAE PHILANTHIDES 125 intermediate between the two great divisions of the Fossores, for the pronotal lobe extends nearly or quite as far back as the tegulae, and in Philanthus the two come into almost actual contiguity. The species of the genus Cerceris are numerous in Europe, and several of them are known to make burrows in the ground, and store them with beetles for the benefit of the future larvae. The beetles chosen differ in family according to the species of Cerceris ; but it appears from the observations of Fabre and Dufour that one kind of Cerceris never in its selection goes out of the limits of a particular family of beetles, but, curiously enough, will take Insects most dissimilar in form and colour provided they belong to the proper family. This choice, so wide in one direction and so limited in another, seems to point to the existence of some sense, FIG. 49. — Philanthus triangulum o - i-2 0 '51 sL° u Name of Ants. ^1 3 £•- • Ifl^ S o"o-- _g |J 1 l^1 p £ il-s ||§ 2 C 1 o c| 0 a 0 & JJ 1 Si My r mica, Polyrhachis, \ etc. . . ./ Camponotus, Atta,\ Phcidologeton, etc. . J "*" "*" "*" Pheidole, subg. Colo-\ bopsis . . .) "*" "*" T Eciton hamatum,\ E. quadriglume, j- + + + + + E. foreli, etc. . . ) Cryptocerus disco- \ cephalus, etc. . J + + + + Strongylognathus -1- 4- -I- Carebara and Solen- ^ opsis (except S. r + + + geminata) . . j Solenopsis geminata . + + + + r + Formica rufa . + + •j excep- [tionally Ponera punctatissima + + + + Ponera ergatandria . ? + + + Cardiocondyla emeryi + + + + C. ivroughtonii and \ -f. G. stambulojfi . . j "*" Formicoxenus niti- ) dulus . . . J + + Tomognathus . + + + Odontomachus hae- \ matodes . . . ] + * •j excep- [tionally Polyergus . + + + Dorylus, Anomma, ) , Eciton part. . . I Aenictus . 4 + Leptogenys, Dia-} , camma . . .J {4_ Myrmecocystus mel- ~\ and . liger, M. mexicanusj + honey- pots Ponera eduardi . + + } eyes -! eyes (^ large (_ obsolete Ancrgates . + + In addition to tlie above there are apparently cases of females with post-meta- m orphic growtli in Dorylides, but these have not yet been the subject of investiga- tion. 142 HYMENOPTERA Much has been written about the mode in which the variety of forms of a single species of ant is produced. As to this there exists but little actual observation or experiment, and the subject has been much complicated by the anxiety of the writers to display the facts in a manner that will support some general theory. Dewitz was of opinion that workers and queens of ants were produced from different kinds of eggs. This view finds but little support among recent writers. Hart in recording the results of his observations on the parasol ant (of the genus Attci) — one of the species in which polymorphism is greatest — says : that these observations prove that " ants can manufacture at will, male, female, soldier, worker or nurse," but he has not determined the method of production, and he doubts it being " the character of the food." There is, however, a considerable body of evidence suggesting that the quality or quantity of the food, or both combined, are important factors in the treatment by which the differences are produced. The fact that the social Insects in which the phenomena of caste or polymorphism occur, though belonging to very diverse groups, all feed their young, is of itself very suggestive. When we add to this the fact that in ants, where the phenomena of polymorphism reach their highest complexity, the food is elaborated in their own organs by the feeders that administer it, it appears probable that the means of producing the diversity may be found herein. Wasmann has pointed out that the ants'-nest beetle, Lomechusa, takes much food from the ants, and itself destroys their young, and that in nests where Lomechusa is abundant a large percentage of erga- togynous forms of the ants are produced. He attributes this to the fact that the destruction of the larvae of the ant by the beetle brings into play the instinct of the ants, which seek to atone for the destruction by endeavouring to produce an increased number of fertile forms ; many ergatogynous individuals being' the result. This may or may not be the case, but it is clear that the ants' instinct cannot operate without some material means, and his observation adds to the probability that this means is the food supply, modified either qualitatively or quantitatively. The existence of these polymorphic forms led Herbert Spencer to argue that the form of an animal is not absolutely 1 Mature li. 1894, p. 125. iv ANTS 143 determined by those " Anlagen " or rudiments that Weismann and his school consider to be all important in determining the nature or form of the individual, for if this were the case, how can it be, he asked, that one egg may produce either a worker, nurse, soldier or female ant ? To this Wasmann (who continued the discussion) replied by postulating the existence of double, triple or numerous rudiments in each egg, the treatment the egg receives merely determining which of these rudiments shall undergo de- velopment.1 Forel seems to have adopted this explanation as being the most simple. The probability of Weismann's hypothesis being correct is much diminished by the fact that the limit between the castes is by no means absolute. In many species intermediate forms are common, and even in those in which the castes are believed to be quite distinct, intermediate forms occur as very rare excep- tions.2 Emery accounts 3 for the polymorphism, without the assistance of the Weismannian hypothetical compound rudiments, by another set of assumptions ; viz. that the phenomenon has been gradually acquired by numerous species, and that we see it in various stages of development ; also that variation in nutrition does not affect all the parts of the body equally, but may be such as to carry on the development of certain portions of the organisation while that of other parts is arrested. Speaking broadly we may accept this view as consistent with what we know to be the case in other Insects, and with the phenomena of post-embryonic development in the class. But it must be ad- mitted that our knowledge is at present quite inadequate to justify the formulation of any final conclusions. The geological record of Formicidae is not quite what we should have expected. They are amongst the earliest Hymen- optera ; remains referred to the family have been found in the Lias of Switzerland and in the English Purbecks. In Tertiary times Formicidae appear to have been about the most abundant of all Insects. At Florissant they occur in thousands and form in individuals about one-fourth of all the Insects found there. They have also been met with numerously in the European Tertiaries, and Mayr studied no less than 1500 specimens found 1 Biol. Ccntralbl. xv. 1895, p. 640. 2 Prof. Forel has favoured the writer by informing him of several cases of these rare intermediate forms he has himself detected. 3 Biol. Centralbl. xiv. 1894, p. 53. 144 HYMENOPTERA CHAP. in amber. Formicides and Myrmicides are more abundant than Ponerides, but this latter group has the larger proportion of extinct genera ; conditions but little dissimilar to those existing at present. Classification of Ants. — Ants are considered by many ento- mologists to form a series called Heterogyna. They can, however, be scarcely considered as more than a single family, Formicidae, so that the serial name is superfluous. Their nearest approach to other Aculeates is apparently made, by Atnblyopone,, to certain Mutillides (e.g. Apterogyna} and to the Thynuides, two divisions of Scoliidae. Emery considers Dory- lides rather than Amblyoponides to be the most primitive form of ants, but we are disposed to consider Forel's view to the effect we have above mentioned as more probably correct. The point is, however, very doubtful. The condition of the peduncle is in both the sub-families we have mentioned very imperfect compared with that of other ants. Both these sub-families are of very small extent and very imperfectly known. We shall also follow Forel in adopting six sub-families, Camponotides, Dolicho- derides, Myrmicides, Ponerides, Dorylides, and Amblyoponides. Emery rejects the Amblyoponides as being merely a division of the Ponerides. This latter group displays the widest relations of all the sub-families, and may be looked on as a sort of central form. The Camponotides and Dolichoderides are closely allied, and represent the highest differentiation of the families in one direction. The Myrmicides are also highly differentiated, but are not allied to the Camponotides and Dolichoderides.1 Sub-Fam. 1. Camponotides. — Hind body furnished with but one constriction, so that only a single scale or node exists on the pedicel. Poison-sac forming a cushion of convolutions, on which is situate the modified sting, which forms merely an ejaculatonj orifice for the poison. The members of this very extensive division of ants can be readily distinguished from all others, except the Dolichoderides, by the absence of a true sting, and by the peculiar form of the hind body ; this possesses only a single scale at the base, and has no 1 Forel's latest views on this subject will be found in the Ann. Soc. ent. Belgique xxxvii. 1893, p. 161 ; the very valuable paper by Emery, in Zool. Jahrl. Syst. viii. 1896, p. 760. iv ANTS CAMPONOTIDES 145 constriction at all on the oval, convex and compact mass of the abdomen behind this. The cloacal orifice is circular, not, as in other ants, transverse. These characters are accompanied by a difference in habits. The Camponotides, though they do not sting, produce poison in large quantity, and eject it to some dis- tance. Hence, if two specimens are confined in a tube they are apt to kill one another by the random discharges they make. Janet suggests that in order to neutralise the effect of this very acid poison, they may have some means of using, when they are in their natural abodes, the alkaline contents of a second gland with which they are provided. We shall mention the characters by which the Camponotides are distinguished from the small sub-family Dolichoderides when we deal with the latter. The sub -family includes 800 or more species. Camponotus itself is one of the most numerous in species of all the genera of Formicidae, and is distributed over most parts of the earth. We have no species of it in Britain, but in the south of Europe the Camponotus become very conspicuous, and may be seen almost everywhere stalking about, after the fashion of our British wood- ant, Formica rufa, which in general appearance Camponotus much resembles. Until recently, the manner in which fresh nests of ants were founded was unknown. In established nests the queen-ant is fed and tended by the workers, and the care of the helpless larvae and pupae also devolves entirely on the workers, so that the queens are relieved of all functions except that of producing eggs. It seemed therefore impossible that a fresh nest could be estab- lished by a single female ant unless she were assisted by workers. The mode in which nests are founded has, however, been recently demonstrated by the observations of Lubbock, M'Cook, Adlerz, and more particularly by those of Blochmann, who was successful in observing the formation of new nests by Camponotus ligni- perdus at Heidelberg. He found under stones in the spring many examples of females, either solitary or accompanied only by a few eggs, larvae or pupae. Further, he was successful in getting isolated females to commence nesting in confinement, and observed that the ant that afterwards becomes the queen, at first carries out by herself all the duties of the nest : beginning by making a small burrow, she lays some eggs, and when these hatch, feeds and tends the larvae and pupae ; the first specimens of these VOL. VI L 146 HYMENOPTERA latter that become perfect Insects are workers of all sizes, and at once undertake the duties of tending the young and feeding the mother, who, being thus freed from the duties of nursing and of providing food while she is herself tended and fed, becomes a true queen-ant. Thus it seems established that in the case of this species the division of labour found in the complex community, does not at first exist, but is correlative with increasing numbers of the society. Further observations as to the growth of one of these nascent communities, and the times and conditions under which the various forms of individuals composing a complete society first appear, would be of considerable interest. An American species of the same genus, C. pennsylvaniciis, the carpenter-ant, establishes its nests in the stumps of trees. Leidy observed that solitary females constructed for themselves cells in the wood and closed the entrances, and that each one in its solitary confinement reared a small brood of larvae. The first young produced in this case are said to be of the dwarf caste, and it was thought by the observer that the ant remained not only without assistance but also without food during a period of some weeks, and this although she was herself giving food to the larvae she was rearing. Adlerz states that the females or young queens take no food while engaged in doing their early work, and that the large quantity of fat-body they possess enables them to undergo several months of hunger. In order to feed the young larvae they use their own eggs or even the younger larvae. It is to the small quantity of food rather than to its nature that he attributes the small size of the first brood of perfect workers. M. Janet : has recently designed an ingenious and simple apparatus for keeping ants in captivity. In one of these he placed a solitary female of Lasius alienus, unaccompanied by any workers or other assistants, and he found at the end of 9 8 days that she was taking care of a progeny consisting of 50 eggs, 2 larvae, 5 pupae in cocoons, 5 without cocoons. On the 102nd day workers began to emerge from the cocoons.2 From these observations it is evident that the queen-ant, when she begins her nest, lives under conditions extremely different from those of the royal state she afterwards reaches. 1 Ann. Sod. ent. France, 1893, p. 467. 2 Ann. Soc. ent. France, 1893, Bull. p. cclxiv. iv ANTS — CAMPONOTIDES 147 In many kinds of ants the full-grown individuals are known to feed not only the larvae by disgorging food from their own mouths into those of the little grubs, but also to feed one another. This has been repeatedly observed, and Forel made the fact the subject of experiment in the case of Camponotus ligniperdus. He took some specimens and shut them up without food for several days, and thereafter supplied some of them with honey, stained with Prussian blue ; being very hungry, they fed so greedily on this that in a few hours their hind bodies were dis- tended to three times their previous size. He then took one of these gorged individuals and placed it amongst those that had not been fed. The replete ant was at once explored by the touches of the other ants and surrounded, and food was begged from it. It responded to the demands by feeding copiously a small specimen from its mouth : when this little one had received a good supply, it in turn communicated some thereof to other specimens, while the original well-fed one also supplied others, and thus the food was speedily distributed. This habit of receiv- ing and giving food is of the greatest importance in the life- history of ants, and appears to be the basis of some of the associations that, as we shall subsequently see, are formed with ants by numerous other Insects. Oecophylla smaragdina, a common ant in Eastern Asia, forms shelters on the leaves of trees by curling the edges of leaves and joining them together. In doing this it makes use of an expedient that would not be believed had it not been testified by several competent and independent witnesses. The perfect ant has no material with which to fasten together the edges it curls ; its larva, how- ever, possesses glands that secrete a supply of material for it to form a cocoon with, and the ants utilise the larvae to effect their FIG. QO.— Oecophylla smaragdina. Worker purpose. Several of them combine to hold the foliage in the desired position, and while they do so, other ants come up, each one of which carries a larva in its jaws, applies the mouth of the larva to the parts where the cement is required, and makes it disgorge the sticky 148 HYMENOPTERA material. Our figure is taken from a specimen (for which we are indebted to Mr. E. E. Green) that was captured in the act of bearing a larva. Formica rufa, the Red-ant, Wood-ant, or Hill-ant, is in this country one of the best-known members of the Formicidae. It frequents woods, especially such as are composed, in whole or part, of conifers, where it forms large mounds of small sticks, straws, portions of leaves, and similar material. Although at first sight such a nest may appear to be a chaotic agglomeration, yet examination reveals that it is arranged so as to leave many spaces, and is penetrated by galleries ramifying throughout its structure. These mound-nests attain a considerable size when the operations of the industrious creatures are not interfered with, or their work destroyed, as it too often is, by ignorant or mischievous persons. They may reach a height of three feet or near it, and a diameter of twice that extent. The galleries by which the heaps are penetrated lead down to the earth below. From the mounds extend in various directions paths constantly traversed by the indefatigable ants. M'Cook observed such paths in the Trossachs ; they proceed towards the objects aimed at in lines so straight that he considers they must be the result of some sense of direction possessed by the ants ; as it is impossible to suppose they could perceive by the sense of sight the distant objects towards which the paths were directed : these objects in the case M'Cook describes were oak-trees up which the ants ascended in search of Aphides. M'Cook further observed that one of the oak-trees was reached by individuals from another nest, and that each of the two parties was limited to its own side of the tree, sentinels being placed on the limits to prevent the trespassing of an intruder ; he also noticed that the ants saw an object when the distance became reduced to about an inch and a half from them. This species is considered to be wanting in individual courage ; but when acting in combination of vast numbers it does so with intelligence and success. It does not make slaves, but it has been observed by Bignell and others that it sometimes recruits its numbers by kidnapping individuals from other colonies of its own species. Its nests are inhabited by forty or fifty species of guests of various kinds, but chiefly Insects. Another ant, Myrmica laevinodis, sometimes lives with it in perfect harmony, and Formicoxenus iv CAMPONOTIDES— SLAVE-MAKING ANTS 149 nilidulus lives only with F. rufa. Amongst the most peculiar of its dependants we may mention large beetles of the genera Cetonia and Clythra, which in their larval state live in the hills of the wood-ant. It is probable that they subsist on some of the vegetable matter of which the mounds are formed. Adlerz has given some attention to the division of labour amongst the different forms of the workers of ants, and says that in F. rufa it is only the bigger workers that carry building and other materials, the smaller individuals being specially occupied in the discovery of honey-dew and other Aphid products. In Camponotus it would appear, on the other hand, that the big individuals leave the heavy work to be performed by their smaller fellows. The wood-ant and its near allies have been, and indeed still are, a source of great difficulty to systematists on account of the variation that occurs in the same species, and because this differs according to locality. Our European F. rufa. has been supposed to inhabit North America, and the interesting accounts pub- lished by M'Cook of the mound-making ant of the Alleghanies were considered to refer to it. This Insect, however, is not F. rufa, as was supposed by M'Cook, but F. exsectoides, Forel. It forms colonies of enormous extent, and including an almost in- credible number of individuals. In one district of about fifty acres there was an Ant City containing no less than 1700 of these large ant-hills, each one teeming with life. It was found by transferring ants from one hill to another that no hostility whatever existed between the denizens of different hills ; the specimens placed on a strange hill entered it without the least hesitation. Its habits differ in some particulars from those of its European congener ; the North American Insect does not close the formicary at night, and the inquilines found in its nest are very different from those that live with F. rufa in Europe. Whether the typical wood -ant occurs in North America is doubtful, but there are races there that doubtless belong to the species. F. sanguined is very similar in appearance to its commoner congener F. rufa, and is the only slave-making ant we possess in Britain. This species constructs its galleries in banks, and is of very courageous character, carrying out its military operations with much tactical ability. It is perfectly able to live without the assistance of slaves, and very frequently does so ; indeed it ISO HYMENOPTERA has been asserted that it is in our own islands (where, however, it is comparatively rare) less of a slave-owner than it is in Southern Europe, but this conclusion is very doubtful. It ap- pears when fighting to be rather desirous of conquering its opponents by inspiring terror and making them aware of its superiority than by killing them ; having gained a victory it will carry oft' the pupae from the nest it has conquered to its own abode, and the ants of the stranger-species that develop from these pupae serve the conquerors faithfully, and relieve them of much of their domestic duties. The species that F. sanguined utilises in this way in England are F. fusca, F. cunicularia, and possibly Lasius flavus. Huber and Forel have given graphic accounts of the expeditions of this soldier-ant. In the mixed colonies of F. sanguined and F. fusca the slaves do most of the house-work, and are more skilful at it than their masters. Adlerz says that one of the slaves will accomplish twice as much work of excavation in the same time as the slave-owner ; these latter being lazy and fond of enjoyment, while the slaves are very industrious. Polyergus rufescens, an European ant allied to Formica, is renowned since the time of Huber (1810) as the slave-making or Amazon ant. This creature is absolutely dependent on its auxiliaries for its existence, and will starve, it is said, in the midst of food unless its servitors are there to feed it. Wasmann, however, states that Polyergus does possess the power of feeding itself to a certain extent. Be this as it may, the qualities of this ant as warrior are superb. When an indi- vidual is fighting alone its audacity is splendid, and it will yield to no superi- ority of numbers ; when the creatures are acting as part of an army the individual boldness gives place to courage of a more suitable sort, the ants then exhibiting the FIG. 61.— Head of Polyergus act of retreating or making flank move- rufcscens. (After Andre. ) ° ments when necessary. 11 a Jrolyergus that is acting as a member of a troop finds itself isolated, and in danger of being overpowered, it has then no hesitation in seeking safety even by flight. This species is provided witli mandibles of a peculiar nature ; they are not armed with teeth, iv CAMPONOTIDES SLAVE-MAKING ANTS 151 but are pointed and curved ; they are therefore used after the manner of poignards, and when the ant attacks a foe it seizes the head between the points of these curved mandibles, and driv- ing them with great force into the brain instantly paralyses the victim. Mandibles of this shape are evidently unfitted for the purposes of general work, they can neither cut, crush, nor saw, and it is not impossible that in their peculiar shape is to be found the origin of the peculiar life of Polyergus : we find similar mandi- bles reappearing amongst the aberrant Dorylides, and attaining a maximum of development in the ferocious Eciton ; they also occur, or something like them, in a few aberrant Myrmicides ; and in the male sex of many other ants, which sex exercises no industrial arts, this sort of mandible is present. The ants that Polyergus usually attacks in order to procure slaves are Formicafusca and F.fusca, race auricularia ; after it has routed a colony of one of these species, P. rufcscens pillages the nest and carries off pupae and some of the larger larvae to its own abode. When the captives thus deported assume the imago state, they are said to commence working just as if they were in their own houses among their brothers and sisters, and they tend their captors as faithfully as if these were their own relatives : possibly they do not recognise that they are in unnatural conditions, and may be quite as happy as if they had never been enslaved. The servitors are by no means deficient in courage, and if the place of their enforced abode should be attacked by other ant-enemies they defend it bravely. The fact that P. rufescens does not feed its larvae has been considered evidence of moral degeneration, but it is quite possible that the Insect may be unable to do so on account of some deficiency in the mouth- parts, or other similar cause. The larvae of ants are fed by nutriment regurgi- tated from the crop of a worker (or female), and applied to the excessively minute mouth of the helpless grub : for so delicate a process to be successfully accomplished, it is evident that a highly elaborated and specialised arrangement of the mouth- parts must exist, and it is by no means improbable that the capacity of feeding its young in true ant-fashion is absent in Polyergus for purely mechanical reasons. M'Cook states that the North American ant, Polyergus lucidus, which some entomologists consider to be merely a variety of 152 the European species, makes slaves of Formica scliaufussi, itself does no work, and partakes of food only when fed by its servi- tors. He did not, however, actually witness the process of feed- ing. When a migration takes place the servitors deport both the males and females of P. lucidus. M'Cook adds that the servitors appear to be really mistresses of the situation, though they avail themselves of their power only by working for the advantage of the other species. The honey-ant of the United States and Mexico has been in- vestigated by M'Cook and others ; the chief peculiarity of the species is that certain individuals are charged with a sort of honey till they become enormously distended, and in fact serve as leather bottles for the storage of the fluid. The species Myrmecocystus hortideorum and M. melliger, are mode- rate-sized Insects of subterranean habits, the entrance to the nest of M. hortideorum being placed in a small raised mound. The honey is the product of a small gall found on oak leaves, and is obtained by TiG.62.—Myrmecocystusmexi- the worker-ants during nocturnal expedi- canus Honey -pot ant, tiong from which they return much dis- dorsal view. ' tended ; they feed such workers left at home as may be hungry, and then apparently communicate the remainder of the sweet stuff they have brought back to already partly charged " honey-bearers " left in the nest. The details of the process have not bgen observed, but the result is that the abdomens of the bearers become dis- tended to an enormous extent (Figs. 62, 63), and the creatures move but little, and remain suspended to the roof of a special chamber. It is considered by M'Cook that these living honey-tubs preserve the food till a time when it is required for the purposes of feeding the com- munity. The distension is pro- duced entirely by the overcharging of the honey-crop, the other contents of the abdomen being FIG. 63. — Myrmecocystus mexicamis. Lateral view. iv ANTS — CAMPONOTIDES I 5 3 forced by the distention to the posterior part of the body. Lubbock has since described an Australian ant, Melophorus iii flat us, having a similar peculiar habit, but belonging to the allied tribe Plagiolepisii. Quite recently a South African honey- tub ant belonging to the distinct genus Plagiolepis (Ptrimeni For.) has been discovered, affording a proof that an extremely specialised habit may arise independently of relation between the Insects, and in very different parts of the world. Species of the genus Lasius are amongst the most abundant of the ant-tribe in Britain. They are remarkable for their con- structive powers. L. niger, the common little black garden-ant, forms extensive subterranean galleries, and is extremely successful in the cultivation of various forms of Aphidae, from the products of which the species derives a large part of its subsistence. The ants even transport the Aphidae to suitable situations, and thus increase their stock of this sugary kind of cattle, and are said to take the eggs into their own dwellings in the autumn so that these minute and fragile objects may be kept safe from the storms and rigours of winter. These little creatures are brave, but when attacked by other ants they defend themselves chiefly by staying in their extensive subterranean galleries, and blocking up and securing these against their assailants. L. fuliginosus, another of our British species, has very different habits, preferring old trees and stumps for its habitation ; in the hollows of these it forms dwellings of a sort of card ; this it makes from the mixture of the secretions of its salivary glands with comminuted fragments of wood, after the fashion of wasps. It is a moderate-sized ant, much large1' than the little L. niger, and is of a black colour and remarkably shining ; it gives off a very strong but by no means disagreeable odour, and may be seen on the hollow trees it frequents, stalking about in large numbers in a slow and aimless manner that contrasts strikingly with the active, bustling movements of so many of its congeners. When this species finds suitable trees near one another, a colony is established in each ; the number of individuals thus associated becomes very large, and as the different colonies keep up inter- communication, this habit is very useful for purposes of defence. Forel relates that he once brought a very large number of Formica pralensis and liberated them at the base of a tree in which was a nest of L. fuliginosus ; these latter, finding them- 154 HYMENOPTERA CHAP. t selves thus assaulted and besieged, communicated in some way, information of the fact to the neighbouring colonies, and Ford soon saw large columns of the black creatures issuing from the trees near by and coming with their measured paces to the assistance of their confreres, so that the invaders were soon dis- comfited and destroyed. Although the European and North American representatives of the sub-family Camponotides live together in assemblies comprising as a rule a great number of individuals, and although the separate nests or formicaries which have their origin from the natural increase of a single original nest keep up by some means a connection between the members, and so form a colony of nests whose inhabitants live together on amicable terms, yet there is no definite information as to how long such association lasts, as to what is the nature of the ties that connect the members of the different nests, nor as to the means by which the colonies become dissociated. It is known that individual nests last a long time. Charles Darwin has mentioned in a letter to Forel that an old man of eighty told him he had noticed one very large nest of Formica rufa in the same place ever since he was a boy. But what period they usually endure is not known, and all these points probably vary greatly according to the species concerned. It has been well ascertained that when some ants find their nests, for some unknown reason, to be unsuit- able the inhabitants leave their abodes, carrying with them their young and immature forms, and being accompanied or followed by the various parasites or commensals that are living with them. AYusmann and other entomologists have observed that the ants carry bodily some of their favourite beetle-companions, as well as members of their own species, Forel observed that after a nest of Formica pralensis had been separated into two nests placed at a considerable distance from one another so as to have no intercommunication, the members yet recognised one another as parts of the same family after the lapse of more than a month ; but another observation showed that after some years of separation they were no longer so recognised. Although it is now well ascertained that ants are able to distinguish the individuals belonging to their own nests and colonies from those that, though of their own species, are not so related to them, yet it is not known by what means the recogni- tion is effected ; there is, however, some reason to suppose that it ANTS CAMPONOTIDES 155 is by something of the nature of odour. One observer has noticed that if an ant fall into water it is on emerging at first treated as if it were a stranger by its own friends ; but other naturalists have found this not to be the case in other species. Contact with corrosive sublimate deprives ants for a time of this power of recognising friends, and under its influence they attack one another in the most ferocious mariner. The nests and colonies of the species of Camponotides we have considered are all constructed by societies comprising a great number of indi- viduals ; there are, however, in the tropics numerous species that form their nests on foliage, and some of these contain only a few individuals. The leaf -nests (Fig. 64) of certain species of Poly- rhachis are said to be formed of a paper-like material, and to con- tain each a female and about 8 or 10 worker ants. Forel 1 has ex- , FIG. 64. — Nest of Polyrhachis sp. (After Smith.) ainined nests of several Indian species, and finds they differ from those of other ants in consisting of a single cavity, lined with silk like that of a spider. These nests are further said to be constructed so as to render them either inconspicuous or like other objects on the leaves ; P. c/'f/entea covers its small dwelling with little bits of vegetable matter, and a nest of P. rastella was placed between two leaves in such a manner as to be entirely hidden. All the species of the genus do not, however, share these habits, P. mayri making a card-nest, like Dolichoderus and some other ants. The species of the genus Polyrhachis are numerous in the tropics of the Old World. Forbes noticed that a species of this genus, that makes its paper-like nest on the underside of bamboo-leaves produces a noise 1 Forel, J. Bombay Soe. viii. 1893, p. 36. iS6 HYMENOPTERA by striking the leaf with its head in a series of spasmodic taps. The same observer has recorded a still more interesting fact in the case of another species of this genus — a large brown ant — found in Sumatra. The individuals were " spread over a space, perhaps a couple of yards in diameter, on the stem, leaves, and branches of a great tree which had fallen, and not within sight of each other ; yet the tapping was set up at the same moment, con- tinued exactly the same space of time, and stopped at the same in- stant ; after the lapse of a few seconds all recommenced at the same instant. The interval was always of about the same duration, though I did not time it ; each ant did not, however, beat synchronously with every other in the congeries nearest to me ; there were independent tappings, so that a sort of tune was played, each congeries dotting out its own music, yet the beginnings and endings of the musical parties were strictly synchronous." Mr. Peal has also recorded that an ant — the name is not mentioned, but it may be presumed to be an Assamese species — makes a concerted noise loud enough to be heard by a human being at twenty or thirty feet distance, the sound being produced by each ant scraping the horny apex of the abdomen three times in rapid succession on the dry, crisp leaves of which the nest is usually composed. These records suggest that these foliage-ants keep up a connection between the members of different nests somewhat after the same fashion as do so many of the terrestrial Camponotides. Although the species of Camponotides have no special organ for the production of sound in the position in which one is found in Myrmicides and Ponerides, yet it is probable that they are able to produce a sound by rubbing together other parts of the abdomen. FIG. 65. — Polyrhachis pandurus, worker. Singapore. ANTS 157 Sub-Fam. 2. Dolichoderides. — Hind body furnished with but one constriction so that only a single scale or node is formed ; Sling rudimentary ; the poison-sac without cushion. The Dolichoderides are similar to Camponotides in appearance, and are distinguished chiefly by the structure of the sting and the poison apparatus. To this we may add that Forel also considers the gizzard to be different in the two sub-families, there being no visible calyx in the Dolichoderides, while this part is largely developed in the Camponotides. This is one of the least extensive of the sub-families of ants, not more than 150 species being yet discovered. Comparatively little is known of the natural history of its members, only a very small number of species of Dolichoderides being found in Europe. The best known of these (and the only British Dolichoderid) is Tapi- noma erraticum, a little ant of about the size of Lasius niger, and somewhat similar in appearance, but very different in its habits. T. erraticum does not cultivate or appreciate Aphides, but is chiefly carnivorous in its tastes. Our knowledge of it is due to Forel, who has noticed that it is very fond of attending the fights between other ants. Here it plays the part of an interested spectator, and watching its opportunity drags off the dead body of one of the combatants in order to use it as food. Although desti- tute of all power of stinging, this Insect has a very useful means of defence FlG- 66.— Zfcpinowza emtti- , , , . , ... . , . cum, worker. Britain. m the anal glands with which it is Upper side and profile. provided ; these secrete a fluid having a strong characteristic odour, and possessing apparently very noxious qualities when applied to other ants. The Tapi- noma has no power of ejecting the fluid to a distance, but is very skilful in placing this odorous matter on the body of an opponent by touching the latter with the tip of the abdomen ; on this being done its adversary is usually discomfited. This I 5 8 HYMENOPTERA Insect is subterranean in its habits, and is said to change its abode very frequently. T. erraticum occurs somewhat rarely in Britain. Forel has also noted the habits of Liometopum micro- cephalum, another small European species of Dolichoderides. It is a tree-ant, and by preference adopts, and adapts for its use, the burrows made by wood-boring beetles. It forms extremely populous colonies which may extend over several large trees, the inhabitants keeping up intercommunication by means of numerous workers. No less than twelve mighty oaks were found to be thus united into a colony of this ant in one of the Bulgarian forests. The species is very warlike, and compensates for the extreme minute- ness of its individuals by the skilful and rapid rushes made by combined numbers on their ant-foes of larger size. Fritz Miiller has given a brief account, under the name of the Imbauba ant, of a Brazilian arboreal ant, that forms small nests in the interior of plants. The species referred to is no doubt an Azteca, and either A. instabilis, or A. mulleri. The nests are founded by fertilised females which may frequently be found in the cells on young Cecropia plants. Each internode, he says, has on the outside, near its upper part, a small pit where the wall is much thinner, and in this the female makes a hole by which she enters. Soon afterwards the hole is completely closed by a. luxuriant excrescence from its margins, and it remains thus closed until about a dozen workers have developed from the eggs of the female, when the hole is opened anew from within by the workers. It is said that many of the larvae of these ants are devoured by the grubs of a parasite of the family Chalcididae. This Insect is thought to protect the plant from the attacks of leaf-cutting ants of the genus Atta. We may here briefly remark that much has been written about the benefits conferred on plants by the protection given to them in various ways by ants : but there is reason to suppose that a critical view of the subject will not support the idea of the association being of supreme importance to the trees.1 Sub-Fam. 2. Myrmicides. — Pedicel of abdomen formed of two well-marked nodes (knot-like segments'). Sting present (absent in the Cryptocerini and Attini}. (It should be noted that the 1 See von Ihering, Berlin, ent. Zeitschr. xxxix. 1894, p. 364 ; and Forel, Ann. Soc. ent. Selgique, xl. 1896, p. 170. ANTS MYRMTCIDES 159 workers of the genera Eciton and Aenictus of the sub-family Dorylides have, like the Myrmicides, two nodes in the pedicel.} This sub-family consists of about 1000 species, and includes a great variety of forms, but, as they are most of them of small size, they are less known than the Camponotides, and much less attention has been paid to their habits and intelligence. Forel, until re- cently, adopted four groups : Myrmicini, Attini, Pseudomyrmini and Cryptocerini ; but he is now disposed to increase this number to eight.1 They are distinguished by differences in the clypeus, and in the form of the head ; but it must be noted that the characters by which the groups ,-, • * Fits. O/. — Pheidologeton • labo- are defined are not in all cases fully riosus, large and small applicable to the males. The Crypto- cerini are in external structure the most highly modified of Hymenoptera, if not of all the tribes of Insecta. i. The MYRMICINI proper are defined by Forel as having the antennae inserted near the middle, a little behind the front, of the head, which has carinae on the inner sides, but none on the outer sides, of the insertions of the antennae ; the clypeus ex- tends between the antennae. Certain genera of small European ants of the group Myrmicini display some most anomalous phenomena. This is especially the case in Formicoxenus, Aner gates and Tomognathus. The facts known have, how- ever, been most of them only recently dis- covered, and some obscurity still exists as to many of even the more important points FIG. 68.- Formicoxenus iri these extraordinary life-histories. nitidulus, male. (After If, nas long |)een known that the little Formicoxenus nitidulus lives as a guest in the nests of Formica rufa, the wood -ant ; and another similar ant, Stenamma westwoodi, which shares the same life, 1 Ann. Soc. cnt. Bdgique, xxxvii. 1893, p. 163. i6o HYMENOPTERA was declared by Nylander and Smith to be its male; it was however shown some years ago by Andre that this is a mistake, and that S. westivoodi is really the male of another ant that had till then been called Asemorhoptrum lippulum. This correc- tion left the workers and females of Formicoxenus nitidulus destitute of a male, but Adlerz has recently discovered that the male of this species is wingless and similar to the worker, the female being a winged Insect as usual. It is very curious that the characters by which the male is distinguished from the worker should vary in this species ; but according to Adlerz this is the case, individuals intermediate in several points between the males and workers having been discovered. This pheno- menon of quite wingless males in species where the female is winged is most exceptional, and is extremely rare in Insects ; but it occurs, as we shall see, in one or two other Myrmicides. Charles Darwin made the very reasonable suggestion that winged males may be developed occasion- ally as an exceptional phenomenon, and it is very probable that this may be the case, though it has not yet been demonstrated. Formi- coxenus nitidulus occurs in England in the nests of Formica rufa and of F. congerens, but we are not aware that the male has ever been FIG. 69. — Anergates atratulus. Europe. A. male, with found in this country, part of liind leg broken off ; B, female, with wings : C, mi A . female, after casting the wings and becoming a queen. e genus -Sinergates IS allied to Formicoxenus, and occurs in Central Europe, but has not been found in Britain ; the female, as in Formicoxenus, is winged and the male wingless, but there is no worker-caste ; the male is a rather helpless creature, and incapable of leaving the nest. The species lives in company with Tetramorium caespitum, a little ant very like Myrmica, and not uncommon in South-East England. The female Anergates is at iv MYRMICIDES ANERGATES l6l first an active little creature with wings, but after these are lost the body of the Insect becomes extremely distended as shown in Fig. 69, C; the creature is in this state entirely helpless, and as there are no workers, the Anergates is completely dependent, for the existence of itself and its larvae, on the friendly offices of the Tetramorium that lives with it. The mode of the association of these two Insects is at present both unparalleled and inexplic- able, for only workers of the Tetramorium are found in company with the i i L • worker. Tangier. specimens, and took what is scarcely a different view, viz. that they are not females but an intermediate form ; and he also expressed the opinion that " the true female may not exist." The male of Anochetus is not known. The female of A. mayri, a Neotropical species, has rudimentary wings. Sub-fam. 5. Dorylides. — Clypeus extremely small, the antennae inserted very near the front margin of the head. Hind ~body usually elongate and subcylindrical, with an imperfect pedicel formed by the constriction of the hick of the first segment, ~but occasionally there are two nodes in the workers. Distinctions between the two sexes, and between the workers and sexed forms, enormous, the queens truly wingless. The females and workers usually blind, or at any rate destitute of facetted eyes. (In Ecitonini the antennae are not inserted quite at the front of the head, and there are two nodes in the pedicel.} DORYLIDES WANDERING ANTS 175 AVe have reserved to the end of the ants the consideration of the two groups Dorylides and Amblyoponides, recent investigations having rendered it somewhat doubtful whether they can be maintained as distinct from Ponerides. The chief character of the Dorylides is that the males are much less ant-like in form than they are in the other groups, and that the distinction between the females and workers are enormous. The little that is known as to the males and females of this group suggests the view that these sexes may offer sufficient reason for keep- ing the Dorylides as a group distinct from the other ants ; but it must be admitted that it is very difficult to find satisfactory characters to distinguish the workers of the Dorylides in some cases from the Ponerides, in others (Eciton} from the Myrmicides.1 The Dorylides are of great interest, for they exhibit the remark- able phenomenon of a nomadic social life, accompanied by im- perfect sight in the wanderers. The sub-family includes two apparently distinct groups : (1) the Ecitonini, peculiar to the New World, and having a close relationship with the Myrmicides ; and (2) the Dorylini existing chiefly in the eastern hemisphere, and related closely by its workers to the Ponerides and Ambly- oponides. (i.) The ECITONINI consist of the species of the genus Eciton, the wandering ants of America, and of Labi- das, which there is now good reason for believing to con- sist of the males of Eciton. The female is still uncertain. The Eciton are nomad ants having no fixed abode, but wandering from place to place in search of prey, and forming temporary resting-places. The 1 For a valuable revision of Dorylus and its allies see Emery, Zool. Jahrb. Syst. viii. 1895, pp. 685, etc. We, however, doubt the wisdom of extending the sub- family so as to include Cerapachys, Parasyscia, etc. FIG. 78. — Various forms of worker of Eciton hamatum. Guatemala. HYMENOPTERA species are rather numerous, and the habits of several have been described by Bates, who, however, was not acquainted with some of the most peculiar features in their biology, these having been since revealed by Belt and W. Miiller. These ants are predaceous in their habits, and some of the species travel in vast hordes ; they occasionally enter houses and clear them of much of the vermin with which they may be infested. They have no facetted eyes, some of the forms being quite blind, while others have a pair of peculiar lenses in the position normally occupied by the compound eyes. Usually there are two castes of the workers, and in some species these are very different from one another, the mandibles being in the larger form very elongate, cylindrical and unfit for industrial purposes, while the individuals of the smaller caste have the outer jaws shorter, with their edges apposed and coadapted : in other species individuals with mandibles differentiated from the normal form do not exist. The nomad habits of these ants were described by Bates, but the detection of their temporary resting- places was reserved for Belt, who found that, after their plundering raids, they retired to a place of concealment, and there clustered together in a compact mass like a swarm of bees. Belt says : " They make their temporary habitations in hollow trees and sometimes underneath large fallen trunks that offer suitable hollows. A nest that I came across in the latter situation was open at one side. The ants were clustered together in a dense mass, like a great swarm of bees, hanging from the roof, but reaching to the ground below. Their innumerable long legs looked like brown threads binding together the mass, which must have been at least a cubic yard in bulk, and contained hundreds of thousands of individuals, although many columns were outside, some bringing in the pupae of ants, others the legs and dissected bodies of various Insects. I was surprised to see in this living nest tubular passages leading down to the centre of the mass, kept open, just as if it had been formed of inorganic materials. Down these holes the ants who were bringing in booty passed with their prey. I thrust a long stick down to the centre of the cluster and brought out clinging to it many ants holding larvae and pupae." Turning now to the Labidus question : many American species of this genus have long been known, though all of them iv DORYLIDES WANDERING ANTS I 77 by the male sex only. The discoveries (to be subsequently alluded to) made in the Old World as to the relations between the driver ants and Dorylus raised a suspicion that Labidus might be the male of Eciton, the distinctions in the two cases being very analogous : this conjecture has been almost proved to be correct by the recent observations of Hetschko and W. Mtiller. The latter, who observed the temporary nests of Eciton hamatum, confirms Belt's statements as to the ants hanging together in clumps, like swarms of bees ; he also states that the change from one temporary abode to another takes place at night, though, as is well known, the hunting forays of this ant are carried on in the daytime. The periods of migration appear to be determined by the time at which all the larvae have assumed the pupal state, this at any rate being the time chosen in the case observed by Miiller. This naturalist bagged a part of one of the nests by the aid of ether, and found the larger portion to consist of pupae ; there were also some larvae and eggs ; a specimen of Labidus (L. burchelli) was also found on friendly terms with the Eciton- workers ; and myrmecophilous Coleoptera were discovered. The pupae are enclosed in cocoons. Persistent search failed to reveal any female, but the examination was made under great difficulties. Miiller also states that the earliest pupated larvae yield soldiers, the latest the smallest forms of workers. From observations made by Forel on a pupa, it seems probable that a wingless form of male may be found to exist. If there- fore, as appears practically certain, Labidus is the winged male of Eciton, it is probable also that males of more or less worker-like form exist, as is now known to be the case in some other Formicidae. We may here notice a peculiar apterous female ant recently described by Andre under the name of Pseudodicthadia incerta. He thought this might prove to be the female of Eciton- Labidus ; but his description and figure are imperfect, and do not greatly support his idea of a connection between Eciton and Pseudodic thadia. ii. The group DOKYLINI includes the genus Dorylus, which was founded many years ago for Insects very like Labidus. As in the case of the American Insect named, males only were known ; two or three allied genera, consisting exclusively of individuals of the sex mentioned, were subsequently described. In the VOL. VI X 178 HYMENOPTERA regions inhabited by these males numerous species of blind ants are known, but only in the worker form, and were, or still are, referred to genera called Typldopone and Anomma. No- thing that could be considered to be a female pertaining to any of these Insects was dis- covered until Gerstaecker de- scribed under the generic name Dicthadia an extraordinary apterous female ant found in Java, and it was suspected that it might be the long- expected female of the male Dorylus and of the worker Ty2)ldopone or Anomma. This remained for many years with- out confirmation, but in 1880 Trimen announced the dis- FIG. 79.— Dorylus helvolus. Africa. A, male; C0very ill South Africa of an B, female (Dicthadia) ; C, worker major (Typhiopone) ; D, worker minor. (After enormous apterous temale ant, Emer>'-) allied to Dicthadia; it had been disinterred from a nest of small red ants believed (wrongly) to be Anomma. As Dorylus had been previously found in con- nection with allied worker ants it has since then been clear that notwithstanding the enormous differences existing between these three forms they may all pertain to one (or to closely allied) species. From this summary the student should understand that he will find in myrmecological literature many references to two or three genera that really belong to one species. The workers of the Dorylini at present known are without exception quite blind, and are believed to be all of predaceous habits ; it is thought by some that they have no fixed abodes, but, like the Ecitonini, frequently change their residence, and it has been suggested that in doing so they make use of the nests of other ants as temporary abodes ; all these points are, however, still unsettled, and as there are several genera it is not unlikely that considerable variety will be found to prevail. The driver ants of Africa, belonging to the genus Anomma, are in some iv DORYLIDES DRIVER ANTS 179 respects similar to Eciton in habits, as they enter human habita- tions and cause nearly everything else to quit ; it is probable that they are also exclusively carnivorous. Savage detected the nests of A. arcens, but the account he has given of them is too vague to permit one to decide whether the assemblages he saw were of a nomad kind. The workers of this species vary greatly in size, and Emery has recently stated that he believes all the supposed species of the genus to be merely varieties of A. burmeisteri. The female of the driver FIG. 80.— Body of male of Dorylus sp. Delagoa Bay. •mf«! i« ssHll nnifp a' Pron°tum ; b, c, divisions of mesonotum ; d, metanotum ; e, propodeum ; /, first abdominal seg- UllkllOWn. A Dorylus ment ; g, h, points of insertion of anterior and pos- has been ascertained terior wings. to be the male of Typhlopone. The male Dorylus (Figs. 79, A, and 80) is of great interest, for the propodeum is in a more primi- tive form than it is in any other petiolate Hymenopteron known to us, while at the same time the pronotum and mesonotum are very highly developed. The genus Typhlatta Sm. has been recently identified by Wroughton and Forel as the worker-condition of which Aenictus is the winged male. The genus Alaopone will probably be found to have some species of Dorylus as its male. The females of the Dorylides are amongst the rarest of Insects, and are also amongst the greatest of natural curiosities. Although worker auts and female ants are merely forms of one sex — the female — yet in this sub-family of ants they have become so totally different from one another in size, form, structure, and habits that it is difficult to persuade oneself they can possibly issue from similar eggs. In the Insect world there are but few cases in which males differ from females so greatly as the workers of Dorylides do from the females, the phenomena finding their only parallel in the soldiers and females of Termites ; the mode in which this difference is introduced into the life of the individuals of one sex is unknown. The largest of all the Dorylides are the African Insects of the genus Rliogmus. Only the male is known. I 80 HYMENOPTERA The specimens of female Dorylides that have been detected may, after fifty or sixty years of research, be still counted on the fingers. As the greatest confusion exists in entomological literature owing to the forms of a single species having been described as two or three genera, the following summary of the principal names of genera of Dorylides may be useful : — Eciton = the workers, Ldbidus = male : ? unknown. Pseudodicthadia : female only known, possibly that of Eciton. Cheliomyrmex : workers and soldiers only known. Aenictus = the male, Typhlatta = worker : unknown. Ehogmus : male ; female unknown. (According to Emery the worker is very small and like Alaopone.} Anomma : only worker known ; male probably a Dorylus. Dorylus = male ; Dicthadia = : Alaopone and Typhlopone = workers. Sub-Fam. 6. Amblyoponides. — Abdomen destitute of distinct pedicel ; the articulation between the first and second segments behind the true petiole being broad. We follow Forel in separating Amblyopone and a few allies from the Ponerides, because the abdominal pedicel is more imperfect than in any other ants. It is, indeed, very difficult to frame a definition that will include the Amblyoponides among ants, and at the same time sepa- rate Formicidae and Scoliidae. Forel con- siders the Amblyoponides to approach closely to certain divisions of the Scoliidae (Thynnides, e.g.}. Little is known of these Insects, though they are widely distri- buted. Amblyopone is found in Australia and New Zealand ; the allied genus FIG. 81--^2ne' worker- Stigmatomma has a wide distribution, occurring even in Europe. The social life is believed to be imperfect, and the habits subterranean and sedentary. The males and females are winged ; the latter much resemble the workers, which are nearly blind, and have a con- siderable general resemblance to Anomma in Dorylides. Association of Ants with other kinds of Insects. — We have already alluded to the fact that a few species of ants are iv INSECTS INHABITING ANTS'-NESTS l8l used by other species as attendants, and that the two kinds then live together quite amicably ; and we have also seen that a few ants live in association with other species on terms that are not yet understood. One little ant, Formicoxenus nitidulus, lives only in the large nests of Formica rufa; these ants tolerate the little Formicoxenus, which so far as is known does them neither good nor harm. There are also a considerable number of species of small ants that are in the habit of choosing the neigh- bourhood of larger species for their dwelling-places ; in some cases the nests are constructed actually within a portion of the edifice of the more powerful species, and the rule then appears to be that these neighbours do not molest one another. Not- withstanding the militant lives that many of them lead, ants cannot be considered as of generally ferocious disposition. But the most remarkable point in connection with their toleration consists in the fact that the nests of many species are inhabited by quite a colony of foreign Insects of various Orders ; many of these, being found nowhere else, are spoken of as ants'- nest or Myrmecophilous Insects.1 The relations of ants with other Insects are of the most varied and complex character ; some of their guests live with them on terms of the most intimate association, being indeed absolutely dependent for their existence on the good offices of their hosts ; others of the ants'-nest Insects are enemies, while others are neutral or indifferent to the ants. We have already mentioned that the guests migrate in company with their hosts. Many species of ants derive a considerable portion of their sustenance from the sweet substances excreted by Aphidae. Ants may constantly be seen occupied with clusters of Aphidae, and it is said that the ingenious little creatures defend from enemies the manufacturers of the sweet-stuff they are so fond of, even going so far as to form barricades and covered places for the isolation and protection of this peculiar kind of cattle ; a few ants keep some of the root -feeding Aphidae in their nests. Coccidae and other Homoptera, which also excrete much matter of a sugary nature, are likewise consorted with by ants ; as are also the larvae of some butterflies of the family Lycaenidae ; these latter being believed to furnish to the ants some substance 1 A Catalogue of Myrmecophilous and Termitophilous Arthropods was pub- lished by Wasmann, Berlin 1894. 1 82 HYMENOPTERA of a nutritious kind. The Insects we have spoken of are, how- ever, rather of the nature of ant-cattle, and the fondness of the ants for them is not very remarkable. The relations of the ants to the peculiar species of Insects that live only in or around their nests are much more extraordinary. The greater number of these guests belong to the Order Coleoptera, and of these there are many hundreds — probably many thousands — of species that depend on ants for their existence. The family Pselaphidae furnishes a large number of ants'-nest beetles, and it appears probable that most of them excrete some sugary substance of which the ants are fond. Many of these Pselaphidae are of the most fantastic shapes, more especi- ally the members of the sub- family Clavigerides. But the . , FIG. 82. — The beetle, Atemeles, soliciting niOSt CUriOUS OI all the ant S- f00d from an ant. (After Wasmann.) nest beetles are the Paussidae, a family exclusively dependent on ants, and having the curious faculty, when disturbed, of bombarding — that is, of discharging a small quantity of vapour or liquid in a state of minute subdivision accompanied by a detonation. Many species of Staphylinidae are peculiar to ant's-nests, and most of them are indifferent or inimical to their hosts, but some of them, such as Atemeles (Fig. 82) and Lomechusa, are doubtless producers of sweet stuff that is liked by the ants. The ants feed some of their special favourites amongst these guests in the same manner as they feed one another, viz. by opening the mouth, causing a drop of liquid to appear on the lip, and remaining passive while the guest partakes of the proffered bonne louche. This way of giving food to other individuals is a most remarkable feature in the character of ants ; it is not the same system that they adopt in feeding the larvae, for they then make a series of actual movements, and force the nutriment into the mouths of the grubs. Besides the Insects we have mentioned there are also Orthoptera, Hemiptera, Poduridae and Thysanura, Acari, and small Isopod crustaceans that live exclusively in company with ants. We have mentioned that a few Hymenopterous and Dipterous parasites have been detected living at the expense of ants ; it is probable that closer observation of the ant larvae and pupae in their nests iv INSECTS INHABITING ANTS'-NESTS 183 will disclose a greater number of the parasites of this latter class. Much attention has been given to the relations between ants and their guests by Wasmann.1 He arranges them in four categories ; 1, " Symphily " for the true guests, which are fed and tended by the ants, the guests often affording some substance the ants delight in ; 2, " Metochy," the class of tolerated guests, being so far as is known not disagreeable to the hosts ; 3, " Synecthry," including those Insects, etc., to which the ants are hostile, but which nevertheless maintain themselves in the midst of their foes ; 4, Parasites, dwelling in the bodies of the adult, or of the young ants. Many of these ants'-nest Insects present a more or less perfect resemblance to the ants in one or more points, such as sculpture, colour, size, or form. To these resemblances Wasrnami attaches great importance. We should, too, notice that some of the inquilines ~ have become acquainted with the movements and habits of the ants, and stroke them (as the ants do one another) to induce them to disgorge food in the manner we have alluded to. According to Janet, ants of the genus Lasius are infested by Acari of the genus Antennophorus. The ants carry the mites, which assume positions so as not to cause greater inconvenience than is inevitable. Moreover, the ants give food to the mites when requested, and behave in a most obliging way to them, though there is not any reason for supposing that in this case the ants derive any benefit from the Symphily. The relations between ants and plants have been of late years much discussed. We have already briefly alluded to the subject when speaking of the Pseudomyrmini. We will here only remark that ants frequent plants not only for the purpose of securing the sweet stuff excreted by the Aphidae that live on them, but also for the sake of getting the sweet products the plants themselves afford. Mr. Aitken, speaking of ants in India, says : " I have come to the conclusion that one of the most important sources of food-supply which ants have is the sacchariferous glands to be found at the bases of so many leaves." It is supposed that the ants are on the whole beneficial to the plants that thus afford them supply ; and this fact is considered by many to afford an adequate explanation of the existence of these interesting relations. 1 For a summary of this subject see Wasmann, Congr. internal. Zool. iii. 1896, pp. 411-440. '2 For explanation of this term see vol. v. p. 524. CHAPTER V COLEOPTERA OR BEETLES Order V. Coleoptera. Apparently wingless Insects when at rest, but really with four wings ; the elytra, or anterior pair, shell-like, reposing on the back of the body and fitted together accurately along the middle by a straight suture ; the posterior pair membranous, folded together under the elytra. Mouth ivitli mandibles ; lower lip not divided along the middle. Meta- morphosis great and very abrupt ; the larva being a grub or maggot, which changes to a pupa (usually soft) in which the external structure of the perfect Insect is conspicuous. COLEOPTERA — or Beetles — are chiefly distinguished from other Insects by the solidity of their external integument, and by the peculiar nature of the first pair of their alar organs, which do not serve as instruments of flight, but as shells for protecting the upper face of the after-body, which, unlike the other parts, remains as a rule soft and membranous. These modifications of structure, though apparently slight, must be really extremely advantageous, for beetles are the predominant Order of Insects in the existing epoch. They depart from most other Insects in being less aerial in their habits ; therefore, notwithstanding their enormous numbers, they do not meet the eye so frequently as flies, bees, or butter- flies. The parts of the hard outer skeleton are beautifully fitted together, and as their modifications are easily appreciated they offer as fascinating a subject for study as do the skeletons of Vertebrata. The habits of beetles are so extremely varied that it is but little exaggeration to say that Coleoptera are to be found everywhere, when looked for. The number of species at present known is probably about 150,000. Of these some- where about 3300 have been found in Britain. The structure CHAP. V COLEOPTERA BEETLES I85 of the hard parts of the skeleton is of importance, as the classi- fication of this enormous number of species is entirely based thereon ; it will be readily understood from the accompanying diagram (Fig. 83). The general proportions of the chief parts of the body call for a few remarks. The prothorax is remarkably free, and is therefore capable of a much greater amount of move- ment independent of the after-body than it is in other Insects. The mesothorax is, on the other hand, much reduced ; its chief function in the higher forms is to support the elytra, and to FIG. 83. — Under-surface of a beetle, Harpalus caliginosus ; legs and antenna of one side, and some parts of the mouth removed. A, an- tenna ; B, mandible ; C, labrum ; D, ligula ; E, paraglossa ; F, labial palp ; G, inner lobe of maxilla ; H, outer lobe (palpiform) of maxilla ; I, maxillary palp ; K, mentum ; L, gena ; M, gula ; N, buccal fissure ; V, plates of ven- tral segments. 1, Prosternum ; 2, prosternal episternum ; 3, pro- sternal epimeron ; 4, anterior and middle coxal cavities ; 5, inflexed side of pronotum ; 6, mesosternum ; 7, mesosternal episternum ; 8, mesosternal epimerou ; 9, meta- sternum ; 10, posterior division of metasternum or ante-coxal piece ; 11, metasternal episternum ; 12, metasternal epimeron ; 13, epi- pleuron or inflexed margin of ely- tron ; 14, ventral or ambulatory setae ; 15, trochanter ; 16, pos- terior coxa ; 17, femur ; 18, tibia ; 19, tarsus. (Modified from Le- conte and Horn.) help to keep them together by means of its scutellum. The metathorax, on the contrary, is largely developed, except in the rather numerous forms that are entirely deprived of powers of night. The composition of the abdomen has been a subject of great difference of opinion. Its upper surface is usually entirely covered by the elytra ; the parts visible on the lower surface are called ventral segments, and are usually five in number. Although these five plates may constitute all that is superficially visible of the abdomen, yet if the elytra are taken off it is found that a larger number of segments — usually seven or eight — are visible on the dorsum. This seeming discrepancy of number between the 1 86 COLEOPTERA CHAP. dorsal and ventral plates is due to two facts ; 1, that the hind coxae have a great and complex development, so that they conceal the true base of the venter, which, moreover, remains membranous to a greater or less extent, and thus allows much mobility, and at the same time a very accurate coadaptation between the hard parts of the venter and the metasternum l ; 2, that the terminal segments are withdrawn into the interior of the body, and are correspondingly much modified, the modifica- tion being greater in the case of the ventral than in that of the dorsal plates. The anatomy of the parts of the abdomen that are not externally visible has not been adequately studied by coleopterists, but Verhoeff has inaugurated a careful study of the comparative anatomy of the terminal segments 2 ; unfor- tunately, however, he has not so thoroughly studied the modifi- cations at the base, and as it is not clear that these are so uniform as he has taken for granted, it is possible that his num- bering of the segments may have to be in some cases modified. The retracted plates or segments are so intimately connected with the internal copulatory organs that it is no easy matter to interpret them. For the nomenclature of these parts we must refer the student to Verhoeff's later works. He considers the abdomen as composed of ten segments, the dorsal plates being demonstrable, while the tenth ventral plate is usually absent. The anal orifice is placed immediately beneath the tenth dorsal plate, and above the genital orifice, which lies behind and above the ninth ventral plate. Peytoureau admits a diversity in both the number of segments and the position of the orifice. These studies in comparative anatomy are surrounded with difficulties, and no morphological conclusions based on them can be con- sidered as final until they have been confirmed by observation of the development of the parts. The elytra — or wing-cases — frequently have a remarkable sculpture, the use of which is unknown. According to Hofbauer there are between the outer and inner layers, glands secreting a 1 An interesting exception occurs in the Malacodermidae, where this coadaptation is wanting, or is imperfect ; they are frequently considered to be the most primitive of existing beetles. 2 In a series of memoirs in various German periodicals during the last five or six years (see especially Deutsche ent. Zcit. 1893 and 1894, also subsequent years of Arch. Naturges.}. It should be noticed that in the course of his studies Verhoeff has modified some of his earlier views. v BEETLES 187 fluid that reaches the surface through small pores. Hicks sup- posed that he detected nerve cells. Meinert is of opinion that the elytra correspond to the tegulre of Hymenoptera rather than to the wings of other Insects, but the little evidence that exists is not favourable to this view. The two elytra are usually, in repose, very perfectly fitted together by a complete coadaptation along the middle of the body, so that it is difficult to separate them ; this line of junction is called the suture. There are forms in which the coadaptation is quite imperfect (Malacodermidae) and some in which it does not exist at all (Meloe}. The wings proper of beetles correspond to the posterior pair in other Insects, and are much more irregular in nervuration than those of most other In- sects, correlative, it is supposed, with the folding they are subjected to in order to get them beneath the wing-cases. There are large numbers of species, genera, and groups of genera, all the members of which have the wings so much reduced in size as to be quite useless for purposes of flight. These forms are called apterous, though they are not really so, for the elytra (which are really the anterior wings) are present, and even the posterior wings are not truly absent in these cases, though they are sometimes so extremely rudimentary as to elude all but the most careful observation. The number of forms in which the elytra are absent is extremely small ; this condition occurs only in the female sex ; it is usually confined to cases in which the female is larva-like in form ; but in the extraordinary Mediterranean Lamellicorn genus, Pachypus, the females are destitute of wings and elytra, though the anterior parts of the body are normally formed : these individuals live underground and rarely or never emerge. When the wings are absent the elytra are frequently soldered ; that is to say, united together along the suture by some sort of secondary exudation ; this union occurs in every degree of firmness, and appears to be variable in the individuals of one species ; probably in accordance with the age of the individual. In most beetles the elytra are not only themselves closely con- nected, but are also very accurately coadapted with the sides of the body, except at the tip. Sometimes a coadaptation occurs between the tips of the elytra and the body, but not at the tip of the latter. In such cases one or more dorsal plates are left ex- posed : the last of such exposed dorsal plates is termed pygidium ; a similar plate anterior to the pygidium is called propygidium. I 88 COLEOPTERA Larvae. — Owing to the difficulty of rearing Coleoptera, less is perhaps known of their life-histories than of those of other Insects. They exhibit, however, extreme diversity correlative with the great specialisation of so many beetles to particular kinds of life. Most beetles must have exactly the right condi- tions to live in. The larvae of many forms are known. They .are composed of a head, three thoracic segments (usually very distinct), and a number of abdominal segments varying from eight to ten. Coleopterous larvae are usually described as having nine abdominal segments ; and it is but rarely that ten can be readily detected ; they are, however, visible in various forms, as is the case in the form figured (Fig. 84). A great many of them possess a peculiar pseudopod at the underside of the body near or at the extremity ; it can in many cases be entirely retracted into the body, and is generally described as being the pro- truded termination of the ali- mentary canal. Inspection of a series of larvae shows that it represents a body segment : it is FIG. 84. —Larva of a beetle, Family sometimes armed with hooks. Cerambycidae (? Aromia moschata). ml • f -,-, ,r • -i The first spiracle is placed just at the Three pairs of small thoracic legs hind margin of the large prothoracic are often present, but are very segment. (From La Massane. ) P. mi often completely absent. Inese thoracic legs may be present in the young larva, but not in the older (Bruchus). The usual number of spiracles is nine pairs, one prothoracic, eight abdominal ; but this is subject to many exceptions, and mesothoracic and metathoracic stigmata are occa- sionally found. The figures we give in the following pages will enable the student to form some idea of the variety of form exhibited by beetle larvae. Pupation usually takes place in a cavity in the earth, or near the feeding-place, but a great many species form a cocoon, composed either of fragments of earth or of wood, and slightly cemented together. A few suspend themselves by the tail after the manner of butterfly caterpillars (Cassididae, Coccinellidae). The pupae are usually extremely soft, their appendages not being fastened to the body. But some pupae (Staphylinides) are truly obtected, having a hard shell and the rudimentary appendages fastened by exudation to the body, like Lepi- dopterous pupae, and others (Coccinellidae) are intermediate v BEETLES 1 89 between this state and the normal soft pupa, The pupal state lasts but a short time, from one to three weeks being the usual period. The perfect Insect is at first soft and almost colourless, and it is often some days before it attains its complete coloration and hardness. Classification. — Owing to the hardness of the skeleton, beetles shrivel but little after death, so that the form and relations of the various sclerites can usually be detected with ease. These sclerites seem to be remarkably constant (except in the case of sexual distinctions) within the limits of each species, and are very useful for the formation of genera and grotips of genera ; but they vary so much outside the limits mentioned that it is very difficult to make use of them for defining the larger groups. Hence it is not easy to frame accurate definitions of the families, and still less so to arrange these families in more com- prehensive series. The natural difficulty has been much increased by the habit coleopterists have of framing their definitions on what is visible without the aid of dissection. Nevertheless considerable progress has been made. We are obliged at present to adopt upwards of eighty families ; and we are able to dis- tinguish on positive characters five series ; this leaves a large number of forms still unclassified, and these we have here associated as a sixth series, which we have called Coleoptera Poly- morpha. This series corresponds with the two series called in books Clavicornia and Serricornia. As it is admitted to be impossible to define these two series, we think it much better to act accordingly, and to establish for the present a great group that can only be characterised by the fact that its members do not belong to any of the other five series. No doubt a larger knowledge of development, coupled with the advance of com- parative anatomy, will ultimately bring about a better state of affairs. The Strepsiptera, with one family Stylopidae, are only provisionally included among the Coleoptera. These six series are fairly equal as regards extent. Though the Polymorpha includes the larger number of forms, yet a large part of them belong to' four great families (Staphylinidae, Buprestidae, Elat- eridae, Malacodermidae), which are easily recognisable, so that the number of unmanageable forms is not really great. Indeed, an acquaintance with the external anatomy of two or three dozen species, selected as typical, would enable a student to classify 1 90 COLEOPTERA with tolerable certainty the vast majority of species that he would subsequently meet with. Series 1. Lamellicornia. — Antennae with the terminal joints leaf-like (or broader than the others, if not actually leaf-like), and capable of separation and of accurate apposition. Tarsi five-jointed. Series 2. Adephaya — (Caraboidea of some authors). — Antennae never lamelli- form, thin at the end ; all the tarsi five-jointed, with the fourth joint quite distinct. Maxillae highly developed, with the outer lobe slender and divided into two segments so as to be palpiform. Abdomen with six (or more) ventral segments visible. Series 3. Polymorpha. — Antennae frequently with either a club, i.e. the distal joints broader [Clavicorn series of authors], or the joints from the third onwards more or less saw-like, the serrations being on the inner face [Serricorn series of authors]; but these and all the other characters, including the number of joints in the feet, very variable. Series 4. Heteromera. — Front and middle tarsi five-jointed, hind tarsi four- jointed. Other characters very variable. Series 5. Phytophaga. — Tarsi four-jointed [apparently], but with a small addi- tional joint at the base of the fourth joint : sole usually densely pubescent [sometimes the feet are bare beneath or bristly, and occasionally the small joint at the base of the fourth joint is more distinct]. Series 6. Khynchophora. — Head prolonged in front to form a beak ; gula indistinguishable. [Palpi usually not evident,] Tarsi four-jointed [apparently], but with a very minute additional joint at the extreme base of the fourth joint. Strepsiptera (see p. 298). The first and second series, with much of the third, form the Pentamera, the fifth and sixth the Tetramera [or Pseudotetra- mera *]. The term Isomera was applied by Leconte and Horn to a combination of series 1, 2, 3, and 5. Series I. Lamellicornia. Tarsi Jive-jointed ; antennae with the terminal joints (usually th ree, sometimes more), broader on one side, so as to form a peculiar club, the leaves of which are movable, and in repose are more or less perfectly coadapted so as to have the appearance of being but one piece. This series includes three families, Passalidae, Lucanidae, and Scarabaeidae ; the latter includes an enormous majority of the species, and in them the structure of the antennae characteristic of the series is well developed ; but in the other two families 1 We consider this term inferior to Tetramera for nomenclatorial purposes. LAMELLICORNS the form of the antennae is not so widely different from that of other Coleoptera. The larvae live on decaying vegetable matter, roots or dung. They have legs, three pairs of and are thick clumsy grubs with curved bodies, the last two segments being of larger size than usual. Many of them possess organs of stridulation, and the structure of their spiracles is very peculiar, each one being more or less completely sur- rounded by a chitin- ous plate. The spiracles usually form a system entirely closed, except at the moment when the skin is shed and the tracheal exuviae are detached. Meinert l considers these spiracles to be organs of hearing. The life of the larvae is passed underground or in the decaying wood on which the Insect feeds. Most of the members of this series are remarkable on account of the great concentration of the nerve-centres. This is extreme in Rhizotrogus, where there are only two great ganglia, viz. the supra-oesophageal and a great ganglion situate in the thorax, and consisting of the conjoined infra-oesophageal, thoracic, and abdominal ganglia. According to Brandt2 there are several distinct forms of concentration in the series : the Lucanidae only participate in it to the extent that the perfect Insects exhibit fewer ganglia than the larvae ; the latter possess two cephalic, three thoracic, and eight abdominal ganglia, while the perfect Insect has the abdominal ganglia reduced in number to six, and 1 Danske Selsk. Skr. (6), viii. No. 1, 1895. 2 Horae Soc. ent. Ross. xiv. 1879, p. 15. FIG. 85. — Antennae of Lamellicorns. 1, Helens ruptus ; 2, Lucanus cerrus N , i • •• FIG. 95. — Cnemidotus caesus. England. A, Imago ; B), there are no spiracles, B Iarva5 highly magnified. ( After Schiodte.) and air is obtained by means of a trachea traversing each of the long filaments. The Insects of these two genera are so similar in the imaginal instar that it is well worthy of note that their larvae should be distin- guished by such important characters. Haliplidae is a small family consisting of three genera, having about 100 species; VOL. VI P 2IO COLEOPTERA it is very widely distributed. We have 13 species in Britain, all the genera being represented. Fam. 9. Dytiscidae (Water-beetles). — Antennae bare; hind legs formed for swimming, not capable of ordinary walking : meta- sternum without a transverse line across it ; behind closely united with the extremely large coxae. Outer lobe of maxilla forming a two-jointed palpus. The Dytiscidae, or true water-beetles, are of interest because — unlike the aquatic Neuroptera — they exist in water in both the larval and imaginal instars ; nevertheless there is reason for sup- posing that they are modified terrestrial Insects : these reasons are (1) that in their general organisation they are similar to the Carabidae, and they drown more quickly than the majority of land beetles do ; (2) though the larvae are very different from the larvae of terrestrial beetles, yet the ima- ginal instars are much less profoundly changed, and are capable of existing perfectly well on land, and of taking prolonged nights through the air ; (3) the pupa is, so far as known, always terrestrial. The larvae and iinagos are perfectly at home in the water, except that they must come to the surface to get air. Some of them are capable, however, when quiescent, of living for hours together beneath the water, but there appears to be great diversity in this respect.1 The hind pair of legs is the chief means of locomotion. These swimming- legs (Fig. 9V) are deserving of admiration on account of their mechanical perfection ; this, however, is exhibited in various 1 See J. Linn. Soc. Zool. xiii. 1876, p. 161. FIG. 96. — Cybister roeseli ( = laterimarginalis De G.) Europe. A, Larva (after Schiodte) ; B, e scarcely evident: antennae short, of less than eleven joints, not filiform, but consisting of 1 For classification and monograph of the family, see Regimbart, Ann. Soc. ent. France, 1882, 1883, and 1886. For a catalogue, Severin, Ann. Soc. ent. Bclgiquc, xxxiii. 1889. v POLYMORPHA HYDROPHILIDAE 2 I / three parts, a basal part of one or two elongate joints, an inter- mediate part of two or more small joints, and an apical part of larger (or at any rate broader} joints, which are pubescent, the others being bare. Outer lobe of maxillae usually complex, but not at all palpiform, maxillary palpi often very long ; the parts of the labium much concealed behind the mentum, the labial palpi very 'ir'nldy separated. Hind coxae extending the width of the body, short, the lamina interior small in comparison with the lamina exterior. Abdomen of Jive visible segments. The Hydro- philidae are an extensive family of beetles, unattractive in colours and appearance, and much neglected by collectors. A large part of the family live in water, though most of them have only feeble powers of aquatic locomotion, and the beetles appear chiefly to devote their attention to economising the stock of air each individual carries about. The best known forms of the family are the species of Hydrophilus. They are, however, very exceptional in many respects, and are far more active and pre- daceous than most of the other forms. Much has been written about Hydrophilus piceus, one of the largest of British beetles. This Insect breathes in a most peculiar manner : the spiracles are placed near bands of delicate pubescence, forming tracts that extend the whole length of the body, and in this particular species cover most of the under surface of the body ; these velvety tracts retain a coating of air even when the Insect is submerged and moves quickly through the water. It would appear rather difficult to invent a mechanism to supply these tracts with fresh air without the Insect leaving the water ; but nevertheless such a mechanism is provided by the antennae of the beetle, the terminal joints of which form a pubescent scoop, made by some longer hairs into a funnel sufficiently large to convey a bubble of air. The Insect therefore rises to the sur- face, and by means of the antennae, which it exposes to the air, obtains a supply with which it surrounds a large part of its body ; for, according to Miall, it carries a supply on its back, under the elytra, as well as 011 its ventral surface. From the writer's own observations, made many years ago, he inclines to the opinion that the way in which the Hydrophilus uses the antennae to obtain air varies somewhat according to circumstances. Many of the members of the sub-family Hydrophilides con- struct egg-cocoons. In the case of Hydrophilus piceus, the boat- 218 COLEOPTERA like structure is provided with a little mast, which is supposed by some to be for the purpose of securing air for the eggs. Helo- chares and Spercheus (Fig. 100) carry the cocoon of eggs attached to their own bodies. Philydrus constructs, one after the other, a number of these egg-bags, each containing about fifteen eggs, and fixes each bag to the leaf of some aquatic plant ; the larvae as a rule hatch speedily, so that the advantage of the bag is somewhat problematic. The larvae of the aquatic division of the family have been to a certain extent studied by Schiodte and others ; those of the Sphaeridiides — the terrestrial group of the family — are but little known. All the larvae seem to be predaceous and carnivorous, even when the imago is of vegetable -feeding habits ; and Dumeril in Hydrous caraboides the canal undergoes a great B FIG. 100. — Spercheus emar- states that gvnattu -, • i -I emarqinatus. (After ing. In Britain we have nearly ninety schiodte). species. Some taxonomists treat the family as a series with the name Palpicornia. The series Phil- hydrida of older authors included these Insects and the Parnidae and Heteroceridae. Fam. 13. Platypsyllidae. — This consists of a single species. It will be readily recognised from Fig. 102, attention being given to the peculiar antennae, and to the fact that the mentum is tri- lobed behind. This curious species has been found only on the beaver. It was first found by Eitsema on American beavers (Castor canadensis) in the Zoological Gardens at Amsterdam, but it has since been found on wild beavers in the Rhone in France : in America it appears to be commonly distributed on these animals from Alaska to Texas. . It is very remarkable that a wingless parasite of this kind should be found in both hemi- spheres. The Insect was considered by Westwood to be a separate Order called Achreioptera, but there can be 110 doubt that it is a beetle. It is also admitted that it shows some points of resem- blance with Mallophaga, the habits of which are similar. Its Coleopterous nature is confirmed by the larva, which has been described by both Horn and Riley.1 Little is known as to the fund and life-history. Horn states that the eggs are placed on 1 Horn, Tr. Amcr. ent. Soc. xv. 1888, p. 23 ; Riley, Insect Life, i. 1889, p. 300. 22O COLEOPTERA the skin of the beaver amongst the densest hair ; the larvae move with a sinuous motion, like those of Staphylinidae. It has been FIG. 102. — Platypsyllus castor is. A, Upper side ; B, lower side, with legs of one side removed ; C, antenna. (After Westwood.) suggested that the Insect feeds on an Acarid, Schizocarpus mingaudi ; others have supposed that it eats scales of epithelium or hairs of the beaver. Fam. 14. Leptinidae. — Antennae rather long, eleven-jointed, without club, but a little thicker at the extremity. Eyes absent or imperfect. Tarsi five-jointed. Elytra quite covering abdomen. Mentum with the posterior angles spinously prolonged. A family of only two genera and two species. Their natural history is obscure, but is apparently of an anomalous nature ; the inference that may be drawn from the little that is known being that they are parasitic on mammals. There is little or nothing in their structure to indicate this, except the condition of blindness ; and FIG. 103. — Leptinus testaceus. ,•-, ,-. , -. T 1-^1 Britain. until recently the Insects were classified amongst Silphidae. Leptinus testaceus (Fig. 103) is a British Insect, and besides occurring in Europe is well known in North America. In Europe it has been found v POLYMORPHA LEPTINIDAE SILPHIDAE 221 in curious places, including the nests of mice and bumble-bees. In America, it has been found 011 the mice themselves by Dr. Ryder, and by Riley in the nests of a common field-mouse, together with its larva, which, however, has not been described. The allied genus Leptinillus is said by Riley to live on the beaver, in company with Platypsyllus.1 It has been suggested that the natural home of the Leptinus is the bee's nest, and that perhaps the beetle merely makes use of the mouse as a means of getting from one nest of a bumble-bee to another. Fam. 15. Silphidae. — The mentum is usually a transverse plate, having in front a membranous hypoglottis, which bears the exposed labial palpi, and immediately behind them the so-called bilobed ligula. The anterior coxae are conical and contiguous : prothoracic epimera and episterna not distinct. Visible abdomi- nal segments usually Jive, but sometimes only four, or as many as seven. Tarsi frequently Jive-jointed, but often with one joint less. Elytra usually covering the body and free at the tips, but occasion- ally shorter than the body, and even truncate behind so as to expose from one to four of the dorsal plates ; but there are at least three dorsal plates in a membranous condition at the base of the abdomen. These beetles are extremely diverse in size and form, some being very minute, others upwards of an inch long, and there is also considerable range of structure. In this family are included the bury ing-beetles (Necrophorus), so well known from their habit of making excavations under the corpses of small Vertebrates, so as to bury them. Besides these and Silpha, the roving carrion - beetles, the family includes many other very different forms, amongst them being the larger part of the cave-beetles of Europe and North America. These belong mostly to the genera Bathyscia in Europe, and Adelops in North America ; but of late years quite a crowd of these eyeless cave-beetles of the group Leptoderini have been discovered, so that the European catalogue now includes about 20 genera and 150 species. The species of the genus Catopomorphus are found in the nests of ants of the genus Aphaenogaster in the Mediterranean region. Scarcely anything is known as to the lives of either the cave- Silphidae or the myrmecophilous forms. The larvae of several of the larger forms of Silphidae are well known, but very little has been ascertained as to the smaller forms. 1 Insect Life, i. 1889, pp. 200 aiid 306. 222 COLEOPTERA Those of the burying-beetles have spiny plates on the back of the body, and do not resemble the other known forms of the family. The rule is that the three thoracic segments are well developed, and that ten abdominal segments are also distinct ; the ninth abdominal segment bears a pair of cerci, which are sometimes elongate. Often the dorsal plates are harder and better developed than is usual in Coleopterous larvae. This is especially the case with some that are en- dowed with great powers of locomotion, such as X. obscura (Fig. 104). The food of the larvae is as a rule decomposing animal or vegetable matter, but some are predaceous, and attack living objects. The larger Silplia larvae live, like the Necro- phorus, on decomposing animal matter, but run FIG. 104.— A, Larva of SUpha obscura. Europe, about to seek it ; hence (After Schiodte). B, PtomapMa lacrymosa, many Specimens of Some Australia. ot these large larvae may sometimes be found amongst the bones of a very small dead bird. We have found the larva and imago of 8. thoracica in birds' nests containing dead nestlings. S. atrata and S. laevigata make war on snails. S. lapponica enters the houses in Lapland and ravages the stores of animal provisions. S. opaca departs in a very decided manner from the habits of its congeners, as it attacks beetroot and other similar crops in the growing state ; it is sometimes the cause of serious loss to the growers of beet. The larvae of the group Anisotomides are believed to be chiefly subterranean in habits ; that of A. cinnamomca feeds on the truffle, and the beetle is known as the truffle-beetle. The number of species of Silphidae known must be at present nearer 900 than 800. Of these an unusually large proportion be- long to the European and North American regions; Silphidae being apparently far from numerous in the tropics. Bather more than 100 species are natives of Britain. The family reappears in con- siderable force in New Zealand, and is probably well represented v SCYDMAENIDAE — GNOSTIDAE PSELAPHIDAE 223 in South Australia and Tasmania. The most remarkable form known is perhaps the Australian genus Ptomaphila (Fig. 104, B). The classification of the family is due to Dr. Horn.1 The only change of importance that has since been suggested is the removal of Sphaerites from this family to Synteliidae. Anisotomidae and Clambidae have been considered distinct families, but are now included in Silphidae. Fam. 16. Scydmaenidae. — Minute Insects allied to Silphidae, but with the hind coxae separated, and the facets of the eyes coarser ; the tarsi are Jive-jointed ; the number of visible abdominal segments is six. These small beetles are widely spread over the earth's surface, and about 700 species are now known, of which we have about a score in Britain ; many live in ants' nests, but probably usually rather as intruders than as guests that have friendly relations with their hosts. Nothing is known as to their life-histories, but the food of the imago, so far as is known, consists of Acari. Afastigu* is a very aberrant form, found in moss and dead leaves in Southern Europe. By means of Brathinus the family is brought very near to Silphidae ; Casey, however, considers Brathinus to belong to Staphylinidae rather than to Scydmaenidae. The South European Leptomastax is remarkable on account of the slender, long, sickle- shaped mandibles. The Oriental genus Clidicus is the largest and most remarkable form of the family ; it has a very slender neck to its broad head, and is more than a quarter of an inch long. Fam. 17. Gnostidae. — Minute Insects with three-jointed antennae, Jive-jointed tarsi, and three apparent ventral segments, the first of which, however, is elongate, and consists of three united plates. Elytra entirely covering the after-body. The family con- sists of two species which have been found in the nests of ants, of the genus Cremastogaster, in Brazil.2 Fam. 18. Pselaphidae. Very small Insects ; the elytra much abbreviated, usually leaving as much as half the abdomen uncovered ; the maxillary palpi usually greatly developed, and of a variety of remarkable forms ; the segments of the abdomen not more than seven in number, with little or no power of movement. Tarsi with not more than three joints. These small Coleoptera mostly live in the nests of ants, and present a great diversity of extraordinary 1 Tr. Amer. ent. Soc. viii. 1880, pp. 219-321. 2 AVestwood, Tr. ent. Soc. London (N.S.) iii. 1855, p. 90; Wasmann, Krit. Verzeichniss Myrmekoph, Arthropod. 1894, p. 121. 224 COLEOPTERA shapes, and very peculiar structures of the antennae and maxillary palpi. Owing to the consolidation of some of its segments, the abdomen frequently appears to have less than the usual number. In the curious sub-family Clavigerides, the antennae may have the joints reduced to two or even, to all appearance, to one ; the tarsi suffer a similar reduction. There are about 2500 species of Pselaphidae known ; many of them have never been found outside the ants' nests ; very little, however, is known as to their natural history. It is certain that some of them excrete, from little tufts of peculiar pubescence, a substance that the ants are fond of. The secretory patches are found 011 very different parts of the body and appendages. Claviger testaceus is fed by the ants in the same way as these social Insects feed one another ; the Claviger has also been seen to eat the larvae of the ants. They ride about on the backs of the ants when so inclined. The family is allied to Staphylinidae, but is easily distinguished by the rigid abdomen. Only one larva — that of Chennium bituber- culatum — is known. It appears to be very similar to the larvae of Staphylinidae. The best account of classification and structure is that given by M. Achille Eaffray,1 who has himself discovered and described a large part of the known species. Fam. 19. Staphylinidae. — Elytra very short, leaving always some of the abdominal segments exposed, and covering usually only two of the segments. Abdomen usually elongate, with ten dorsal, and seven or eight ventral segments ; of the latter six or seven are usually exposed ; the dorsal plates as hard as the ventral, except sometimes in the case of the first tivo segments ; the segments very mobile, so that the abdomen can be curled upwards. The number of tarsal joints very variable, often Jive, but frequently as few as three, and not always the same on all the feet. Staphylinidae (formerly called Brachelytra or Microptera) is one of the most extensive of even the great families of Coleoptera ; notwithstanding their diversity, they may in nearly all cases be recognised by the more than usually mobile and uncovered abdomen, combined with the fact that the parts of the mouth are of the kind we have mentioned in Silphidae. The present state of the classification of this family has been recently discussed by Ganglbauer.2 At present 1 Rev. ent. franc, ix. 1890. Die Kdfer von MMeleuropa : II. Familienreihe, Staphylinoidea. Vienna, 1895 and 1899. POLYMORPHA^-STAPIIYLINIDAE about 9000 species are known, some of which are minute, while scarcely any attain a size of more than an inch in length, our common British black cock-tail, or " devil's coach-horse beetle," Ocypus olens, being amongst the largest. Though the elytra are short, the wings in many forms are as large as those of the majority of beetles ; indeed many Staphylinidae are more apt at taking flight than is usual with Coleoptera ; the wings when not in use are packed away under the short elytra, being transversely folded, and otherwise crumpled, in a com- plicated but orderly manner. It is thought that the power of curling up the abdomen is connected with the packing away of the wings after flight ; but this is not the case : for though the Insect sometimes experiences a difficulty in fold- ing the wings under the elytra after they have been expanded, yet it overcomes this difficulty by slight movements of the base of the abdomen, rather than by touching the wings with the tip. What the value of this exceptional condition of short elytra and corneous dorsal abdominal segments to the FIG. 105. — Staphylinidae. A, Larva of Phi- present lonthusnitidus. Britain. ( After Schiddte.) B, Ocypus olens, Britain ; C, tip of abdo- men, of O. olens with stink-vessels-. Insect may be is at quite mysterious. The habits of the members of the family are very varied ; many run with great activity ; the food is very often small Insects, living or dead; a great many are found in fungi of various kinds, and perhaps eat them. It is in this family that we meet with some of the most remarkable cases of symbiosis, i.e. lives of two kinds of creatures mutually accommodated with good will. The relations between the Staphylinidae of the genera Atemeles and Lomechusa, and certain ants, in the habitations of which they dwell, are very interesting. The beetles are never found out of the ants' nests, or at any rate not very far from them. The most friendly relations exist between them and the ants : they have patches of yellow hairs, and these VOL. vi Q 226 COLEOPTERA apparently secrete some substance with a flavour agreeable to the ants, which lick the beetles from time to time. On the other hand, the ants feed the beetles ; this they do by regurgitating food, at the request of the beetle, on to their lower lip, from which it is then taken by the beetle (Fig. 82). The beetles in many of their movements exactly resemble the ants, and their mode of requesting food, by stroking the ants in certain ways, is quite ant-like. So reciprocal is the friendship that if an ant is in want of food, the Lomechusa will in its turn disgorge for the benefit of its host. The young of the beetles are reared in the nests by the ants, who attend to them as carefully as they do to their own young. The beetles have a great fondness for the ants, and prefer to sit amongst a crowd thereof; they are fond of the ants' larvae as food, and indeed eat them to a very large extent, even when their own young are receiving food from the ants. The larva of Lomechusa, as described by Wasmann (to whom we are indebted for most of our knowledge of this subject),1 when not fully grown, is very similar to the larvae of the ants ; although it possesses legs it scarcely uses them : its development takes place with extraordinary rapidity, two days, at most, being occupied in the egg, and the larva completing its growth in fourteen days. Wasmaun seems to be of opinion that the ants scarcely distinguish between the beetle- larvae and their own young ; one unfortunate result for the beetle follows from this, viz. that in the pupal state the treatment that is suitable for the ant -larvae does not agree with the beetle- larvae : the ants are in the habit of digging up their own kind and lifting them out and cleaning them during their meta- morphosis ; they also do this with the beetle-larvae, with fatal results ; so that only those that have the good fortune to be forgotten by the ants complete their development. Thus from thirty Lomecliusa larvae Wasmann obtained a single imago, and from fifty Atemeles larvae not even one. Many other Staphylinidae are exclusively attached to ants' nests, but most of them are either robbers, at warfare with the ants — as is the case with many species of Myrmedonia that lurk about the outskirts of the nests — or are merely tolerated by the ants, not receiving any direct support from them. The most 1 Verglcichende Stttdien iiber Ameisengciste, Nijhoff, 1890 ; and T-ijdschr. ent. xxxiii. 1890, pp. 93, etc. ; Biol. Centralbl. xv. 1895, p. 632. STAPHYLINIDAE SPHAERIIDAE TRICHOPTERYGIDAE 227 remarkable Staphylinidae yet discovered are some viviparous species, forming the genera Corotoca and Spirachtha, that have very swollen abdomens, and live in the nests of Termites in Brazil : l very little is, however, known about them. A very large and powerful Staphylinid, Velleius dilatatus, lives only in the nests of hornets and wasps. It has been supposed to be a defender of the Hymenoptera, but the recent observations of Janet and Wasmann make it clear that this is not the case : the Velleius has the power of making itself disagreeable to the hornets by some odour, and they do not seriously attack it. The Velleius finds its nutriment in larvae or pupae of the wasps that have fallen from their cells, or in other organic refuse. The larvae of Staphylinidae are very similar to those of Carabidae, but their legs are less perfect, and are terminated only by a single claw ; there is no dis- tinct labrum. The pupae of some are obtected, i.e. covered by a secondary exu- dation that glues all the appendages together, and forms a hard coat, as in Lepidoptera. "We have about 800 species of Staphyliuidae inBritain,and it is prob- able that the family will prove one of the most extensive of the Order. It is prob- able that one hundred thousand species or even more are at present in existence. Fam. 20. Sphaeriidae. — Very minute. Antennae eleven-jointed, clubbed. Tarsi three-jointed. Abdomen with only three visible ventral segments. This family includes only three or four species of In- sects about nX of an inch long. They are FlG- iW.—Trichopteryx fasti- • j 11 • cularis. Britain. A, Out- M TV convex, and may be found walking iine of perfect Insect; B, on mud. S. acaroides occurs in our fens. part °J uPPe.r surface ; C, larva from side : D, from Mr. Matthews considers that they are above ; E, pupa ; F, wing ; most nearly allied to Hydrophilidae.2 G' natural size of imas°' Fam. 21. Trichopterygidae. — Extremely minute: antennae 1 Schibdte, Ann. Sci. Nat. Zool. (4) v. 1857, p. 169. 2 JBioL Ccnti: Amcr. Col. ii. pt. i. 1888, p. 156. 228 COLEOPTERA clavicorn (basal and apical joint* thicker llt-nn middle joints} ; tarsi three-jointed; elytra sometimes covering abdomen, in other cases leaving a variable number of segments exposed ; wings fringed. This family comprises the smallest Insects ; Nanosella fungi being only T^JJ of an inch long, while the largest Trichopterygid is only -^g of an inch. The small size is not accompanied by any degeneration of structure, the minute, almost invisible forms, having as much anatomical complexity as the largest Insects. Very little is known as to the natural history. Probably these Insects exist in all parts of the world, for we have about eighty species in England, and Trichopterygidae are apparently numerous in the tropics.1 Fam. 22. Hydroscaphidae. — Extremely minute aquatic Insert*, with elongate abdomen. Antennae eight -jointed. The other characters are much the same as those we have mentioned for Trichopterygidae. The family is not likely to come before the student, as only three or four species from Southern Europe and North America are known.'"' Fam. 23. Corylophidae. — Minute beetles. Tarsi four-jointed, but appearing only three -jointed, owing to the hind joint being concealed by the emarginate (or notched} second joint. Six free ventral segments. Maxillae with only one lobe. Antennae of peculiar form. There are about 200 species of these little Insects, but the family is apparently repre- sented all over the world, and will probably prove to be much more extensive. The peculiar larva of Orthoperus brunnipes was found abundantly by Ferris in thatch in France. Mr. Matthews proposes to separate the genus Aphanoceplt- alus as a distinct family, Pseudocory- FIO. 107.— A, Larva of Orthoperus lophidae.3 In Corylophidae the brunnipes (after Ferris); B.O.ato- • f • , .., , , . marius, perfect Insect. Britain. wmgs are fringed With long hairs, as is the case in so many small Insects : the species of Aphanocephalus are rather larger Insects, and the wings are not fringed ; the tarsi are only three-jointed. 1 Monograph, Trichopterygia illustrata, by A. Matthews, London, 1872. 2 For further information refer to Matthews, An Essay on Hydroscapha, London, 1876, 20 pp. 1 pi. 3 Ann. Nat. Hist. (5) xix. 1887, p. 115. POLYMORPRA SCAPHIDIIDAE — SVNTELIIDAE 229 Fam. 24. Scaphidiidae. — Front coxae small, conical; protlwrax rrrt/ rlowly applied to the after-body ; hind coxae transverse, widely separated: abdomen with six or seven visible ventral plates; antennae at the i\i:ti'nnity with about Jive joints that become gradually broader. Tarsi five-jointed. This family consists of a few beetles that live in fungi, and run with extreme rapidity ; they are all small, and usually rare in collections. Some of the exotic forms are remarkable for the ex- treme tenuity and fragility of the long antennae, which bear fine hairs. The number of described species does not at present reach 200, but the family is very widely distributed. We have three or four species in Britain. All we know of the larvae is a description of that of Scapkisoma aqaricinum by Perris;1 it is T ,., , „ ,. . , FIG. 108. — Scaphisomaagari- like the larva ot Staphylmidae, there are cinum. Britain. A nine abdominal segments in addition to a Lar.va (?fter Perns) ; B perfect Insect. very short, broad pseudopod, and very short cerci. This larva feeds on agarics ; it goes through its development in about three weeks ; unlike the adult it is not very active. Fam. 25. Synteliidae. — Antennae clavicorn, with very large dub : labium, with hypoglottis and the parts beyond it, exposed. Front coxae transverse. Abdomen with Jive visible ventral 'segments, and eight or nine dorsal, the basal four of which are semi-corneous. This family includes only five species ; its clas- sification has given rise to much difference of opinion. We have, after consideration of all its characters, established it as a distinct family ~ allied to Silphidae. The perfect Insects live on the sap running from trees : but nothing else is known of their natural history. Like so many others of the very small families of aberrant Cole- optera, it has a very wide distribution ; TIG. iQ9.—synteiia west- Syntdia, being found in Eastern Asia and woodi. Mexico. (From Mexico, while the sub-family Sphaeritides Bwl. Cents. Amer.) . . . occurs, as a single species, 111 Europe and ISTorth America. The earlier instars are unknown. 1 Larves de CoUopttres, 1878, p. 11, pi. i. - Biol. Ccntr. Amer. Col. ii. pt. i. p. 438. 230 COLEOPTERA CHAP. Fam. 26. Histeridae. — Very compact beetles, with very hard integument, short, bent antennae, with a very compact club : no hypoglottis. Elytra closely applied to body, but straight behind, leaving two segments exposed. Abdomen with Jive visible ventral segments; with seven dorsal segments, all hard. Front coxae strongly transverse, hind coxae ividely separated. The extremely compact form, and hard integument, combined with the peculiar antennae — consisting of a long basal joint, six or seven small joints, and then a very solid club of three joints covered with minute pubescence — render these Insects unmistakable. The colour is usually shining black, but there are numerous depar- tures from this. The way in which these Insects are put together so as to leave no chink in their hard exterior armour when in repose, is very remark- able. The mouth - parts are rather highly developed, and the family is entitled to a high rank ; it consists at present of about 2000 species ; l in Britain we have about 40. The larvae are without ocelli or labrum, FIG. \io.-piatysoma depressum. Europe, but have well-developed mandi- A, Larva (after Schiodte) : B, perfect , -, •, , , . 3 insect, bles, the second arid third thoracic segments being short, the ninth segment of the abdomen terminal, with two distinctly jointed cerci.'^ Histeridae are common in dung, in carcases, decay- ing fungi, etc., and some live under bark — these being, jn the case of the genus Hololepta, very flat. Some are small cylinders, elaborately constructed, for entering the burrows of Insects in wood (Trypanaeus) ; a certain number are peculiar to ants' nests. Formerly it was supposed that the Insects were nourished on the decaying substances, but it is now believed, with good reason, that they are eminently predaceous, in both larval and imaginal 1 The family was monographed by the Abbe de Marseul in Ann. Soc. ent. France, 1853-1862, but great additions have been made since then. 2 For characters of larvae of various genera, see Ferris, Larrcs, etc. p. 24. v HISTERIDAE rHALACRIDAE NITIDULIDAE 23! instars, and devour the larvae of Diptera, etc. The relations of the ants'-nest forms to the ants is not made out, but it is highly probable that they eat the ants' larvae, and furnish the ants with some dainty relish. A few species live in company with Termites. Fam. 27. Phalacridae. — Body very compact ; elytra entirely cover i nit if ; apical joints of antennae rather broad'1/1, usually long ; front coxae globular ; posterior coxae contiguous ; abdomen with Jive risible ventral segments; tarsi five- jointed, fourth joint usually small and obscure. This family consists entirely of small Insects : the tarsal structure is very aberrant, and is also diverse, so that the student may without careful observation FIG. ill. — Olibrus Mcolor. pass the Insects over as having only four- Heegerj ; j^piSnsect" jointed tarsi ; their structure, so far as the front two pairs are concerned, being very nearly that of many Phytophaga. The larvae live in the heads of flowers, especially of the flowers of Compositae. Having bored their way down the stems, they pupate in earthen cocoons. Heeger l says that he has observed in favourable seasons six generations ; but the larvae die readily in unfavourable seasons, and are destroyed in vast numbers when the meadows are mowed. Seven years ago very little was known as to the family, and the list of their species scarcely amounted to 100, but now probably 300 are described. They occur in all parts of the world ; we have fourteen in Britain. Fam. 28. Nitidulidae. — Antennae with a three-jointed club ; all the coxae separated, and eaclt with an external prolongation ; tarsi Jive-jointed, the fourth joint smaller than any of the others ; abdomen with five visible jrfates. These Insects are numerous, about 1600 species being at present known ; in many of them the elytra nearly or quite cover the hind body, but in many others they are more or less abbreviated ; in this case the Insects may be distinguished from Staphylinidae by the form of their antennae, and the smaller number of visible ventral seg- ments. The habits are very varied, a great many are found on flowers, others are attracted by the sap of trees ; some live in carcases. We have about 9 0 species in Britain : several forms of 1 SS. Ak. Wien. xxiv. 1857, p. 330. 232 COLEOPTERA the genera Meligethes and Epuraea are among the most abundant of our beetles. Most of what is known as to the larvae is due to Ferris ; several have been found living in flowers ; that of Pria haunts the flower of Solanum dulcamara at the junction of the stamens with the corolla ; the larva of Meligethes aeneus sometimes occasions much loss by prevent- ing the formation of seed in cultivated Cruciferae, such as Rape. These floricolous larvae grow with great rapidity, and then leave the flowers to pupate in the ground. The larva of Nitidula lives in carcases, though it is not very different from that . of Pria. The larva of Soronia lives in FIG. 112.— Pria duicamame. fermenting sap, and has four hooks curv- Britain. A, Larva (after incr upwards at the extremity of the body. Ferris) ; B, perfect Insect. ° . n , J , . » Ihe curious genus Cybocep/iaius consists of some very small, extremely convex Insects that live in flowers in Southern Europe ; they have only four joints to the tarsi. The perfect Insects of the group Ipides are remarkable from having a stridulating organ on the front of the head. The classi- fication of the well-known genus Rhizophagus has given rise to much discussion ; although now usually placed in Nitidulidae, we think it undoubtedly belongs to Cucujidae. Fam. 29. Trogositidae. — Differs from Nitidulidae in the struc- ture of the tarsi ; these appear to befour- jointed, with the third joint similar in size and form to the preceding ; they are, hoivcver, really Jive-jointed, an ex- tremely short "basal joint being present. Hind coxae contiguous. The club of each antenna is bilaterally asymmetric, and the sensitive surface is confined to certain parts of the joints. There are some 400 or 500 species of Trogositidae, but nearly all of them are exotic. The larvae (Fig. 113, A), are predaceous, destroying other i -. -. .. . larvae 111 large numbers, and it is pro- bable that the images do the same. The larva of Tenelroides (better known as Trogosita} mauritanica is found in corn and flour, and is said to have sometimes been very B 113. — Temnochila coerulea. Europe. A, Larva (after Ferris) ; B, perfect Insect. v POLYMORPHA — TROGOSITIDAE — COLYDIIDAE 233 injurious by eating the embryo of the corn, but it is ascertained that it also devours certain other larvae that live on the corn. This beetle has been carried about by commerce, and is now nearly cosmopolitan. Our three British species of Trogositidae repre- sent the three chief divisions of the family, viz. Nemosomides, Temnochilides, Peltides ; they are very dissimilar in form, the Peltides being oval, with retracted head. It is doubtful whether the members of the latter group are carnivorous in any of their stages ; it is more probable that they live on the fungi they frequent. Peltidae stand as a distinct family in many .works.1 Fam. 30. Colydiidae. — Antennae with a terminal club, tarsi four -jointed, none of the joints broad; front and middle coxae small, globose, embedded ; kind coxae transverse, either contiguous or separated; Jive visible ventral segments, several of which have no movement. This is a family of interest, owing to the great diver- sity of form, to the extraordinary sculpture and clothing exhibited by many of its members, and to the fact that most of its members are attached to the primitive forests, and disappear entirely when these are destroyed. We have fifteen species in Britain, but about half of them are of the greatest rarity. There are about 600 species known at present; Xew Zealand has produced the greatest variety of forms ; the forests of Tenerifie are rich in the genus 7'ni-- phius. The sedentary lives of many of these beetles are very remarkable ; the creatures concealing themselves in the crannies of fungus-covered wood, and scarcely ever leaving their retreats, so that it is the rarest circumstance to find them at any distance from their homes. Langelandia anophtJialma lives entirely FIG. 114.— Bitoma crenata. underground and is quite blind, the Britain. A, Larva (after Qptic lobeg bei, absent. Some Coly- Perns) ; B, perfect Insect. f. diidae are more active, and enter the burrows of wood-boring Insects to destroy the larvae (Colydiuni). Few of the larvae are known ; but all appear to have the body terminated by peculiar hard corneous processes, as is the case with a great variety of Coleopterous larvae that live in wood.2 1 Catalogue of Trogositidae, by Leveilli-. in A tin. Soc. cnt. France, 1888, p. 429. 2 For classification, see Sharp, Biol. Ccntr. Amcr. Col. ii. pt. i. 1894, p. 443. 234 COLEOPTERA Fam. 31. Rhysodidae. — Tarsi four -jointed ; mouth-parts at i- creel by the large mentum ; front tibiae notched on the inner r\ This family consists only of a few species, but is found nearly all over the world in the warm and temperate regions. In many of their characters they resemble the Adephaga, but are very different in appearance and in the mouth. The larvae are not known. Some authorities think these Insects should be placed in the series Adephaga,1 but it is more probable that they will prove to be amongst the numerous aberrant forms of Coleop- tera that approach the various large natural series, without really belonging to them. The three families, Colydiidae, Cucu- jidae, and Ehysodidae, exhibit relations not only with other families of the Coleoptera Polymorpha, but also with most of the great series ; Adephaga, Rhynchophora, Phytophaga, and Hetero- mera, being each closely approached. Fam. 32. Cucujidae.— Tarsi Jive- or four-jointed, the first joint often short : antennae sometimes clubbed, but more often quite thin at the tip ; front and middle coxae deeply embedded, globular, but with an angular prolongation externally ; abdomen ' with five visible ventral segments, all movable. This family and the Cryptophagidae are amongst the most difficult families to define ; indeed it is in this portion of the Clavicorns that an extended and Iitl? ffTff VJSSfc/T thorough study is most urgently 5 ^ \MlL iflStSfrv required. The Cucujidae include a great diversity of forms ; they are mostly found under the bark of trees, and many of them are very Hat. c Many of the larvae are also very FIG. us.— Brontes pianat vs. Britain, flat, but Perris says there is great insect"! A and Rafter Ferris!)6' '* diversity in their structure: they are probably chiefly carnivorous. There are about 400 species described ; we have nearly a score in Britain. The family Cupesidae of certain taxonomists must be at present associated with Cucujidae, though the first joint of the tarsus is elongate. 1 See Ganglbauer, Kaf. Mitteleuropas, i. p. 530, as well as Leconte and Horn Classification, etc., p. 130. POLYMORPHA CRYPTOPHAGIDAE HELOTIDAE 235 Fam. 33. Cryptophagidae. — Front and middle coxae very small and deeply embedded; antennae with enlarged terminal joints ; tarsi Jive-jointed, the posterior sometimes in the male only four- jointed ; abdomen with Jive visible ventral segments, capable of movement, the first much longer than any of the others. A small family composed of obscure forms of minute size, which apparently have mould-eating habits, though very little is known on this point, and several of . _, the genera (Anther ophagus, Telmatophi- \ ^ lus) are found chiefly on growing plants, -=> especially in flowers. Although the ^a imago of Anther ophagns lives in flowers, yet the larva has only been found in the nests of bumble-bees ; there is FIG. UQ.—Cryptojtiagus denta- reason for believing that the imago makes use of the bee to transport it from the flowers it haunts to the nests in which it is to breed ; * this it does by catching hold of the bee witli its mandibles when the bee visits the flower in which the beetle is concealed. It is strange the beetle should adopt such a mode of getting to its future home, for it has ample wings. "We must presume that its senses and instinct permit it to recognise the bee, but do not suffice to enable it to find the bee's nest. Some of the larvae of the genus Cryptophagus are found abundantly in the nests of various wasps, where they are probably useful as scavengers, others occur in the nests of social caterpillars, and they are sometimes common in loose straw ; this being the habitat in which Ferris found the one we figure. Fam. 34. Helotidae. — Front and middle coxal cavities round, with scarcely any angular prolongation externally ; all the coxae widely separated ; '-Jive visible ventral segments, all mobile. The Insects of this family are closely allied to Trogositidae and Nitidulidae, and have the tarsal structure of the former family ; but the Helotidae are different in appearance from any members of either of these two families, and are readily distinguished by the coxal character. They are frequently classified with the Erotylidae, from which they differ by the differently shaped feet, especially by the diminished basal joint. 1 Penis, Larves, etc., p. 75. 236 COLEOPTERA There is but one genus, and for a long time only two or three species were known, and were great rarities in collections ; in the last few years the number has been raised to nearly forty.1 They are remarkable beetles with oblong form, and a somewhat metallic Tipper surface, which is much sculptured, and possesses four yellow, smooth spots on the elytra. According to Mr. George Lewis they are found feeding at the running sap of trees, but the larvae are not known. Helotidae are peculiar to the Indo-Malayaii region (including Japan) with one species in Eastern Africa. Fam. 35. Thorictidae. — Tarsi Jive-jointed, none of the joints In-u/nl ; front coxae small, rather prominent, but not at all trans- verse ; jive visible ventral plates, all mobile ; metasternum very short ; antennae short, with a solid club. This little family, con- sisting of the genus Thorictus, appears to be a distinct one, though the structure has only been very imperfectly studied. It is peculiar to the Mediterranean region, where the species live in ants' nests. They appear to be on terms of great intimacy with the ants ; a favourite position of the beetle is on the scape of the antenna of an ant ; here it hooks itself on firmly, and is carried about by the ant. Like so many other ants'-nest beetles, Thorictidae possess tufts of golden hair, which secrete some substance, the flavour of which is appreciated by the ants ; these tufts in Thorictidae are situated either at the hind angles of the pronotum, or on the under surface of the body on each side of the breast ; Wasmann thinks that when the beetles are riding about, as above described, the ants have then an opportunity of getting at the patches on the under surface. L__J= r^'^^^ Fam' ^' Erotylidae. — Tarsi fivc- 4, 4~ /1|!; : W\ jointed, but with the fourth usually very small, the first three more or less broad and pubescent beneath. Antennae strongly clubbed. Front and middle coxal aceta- bula round, without angular prolongation FIG. in.—Trito-ina Upustulata. externally ; five visible ventral segments. Erotylidae. Britain. A, Larva This is now a large and important family (after Ferris) ; B, perfect Insect, „ . . in/\/-k • i i. •* • i • a oi about 1800 species, but it is chiefly exotic and tropical, its members haunting the fungoid growths 1 Ritsema, Catalogue of Helota, Xotes Leyden Mus. xiii. 1891, p. 223, and xv. 1893, p. 160. v EROTYLIDAE MYCETOPHAGIDAE COCCINELLIDAE 237 in forests. We have only six species in Britain, and the whole of Europe has only about two dozen, most of them insignificant (and in the case of the Dacnides aberrant, approaching the Cryptophagidae very closely). The sub-family Languriides (quite wanting in Europe) consists of more elongate Insects, with front acetabula open behind ; they have different habits from Eroty- lides proper ; some are known to live as larvae in the stems of herbaceous plants. They possess a highly developed stridulating organ on the front of the head. The Clavicorn Polymorpha are very closely connected with the Phytophaga by Languriides. Fam. 37. Mycetophagidae. — Tarsi four-jointed, slender, the f /'a //t feet of the male only three-jointed; coxae oval, not deeply embedded; abdomen with Jive ventral seg- ments, all movable. A small family, of in- terest chiefly because of the anomaly in the feet of the two sexes, for which it is im- possible to assign any reason. The species are small, uninteresting Insects that live chiefly, on Cryptogams of various kinds, especially in connection with timber : the . larvae being also found there. There are FIG n8._Litar^ WM. about a dozen species in Britain, and ciatus. Mycetophagidae. scarcely 100 are described from all the ^££Bfi5 world. The Diphyllides, placed by Leconte and Horn in this family, seem to go better in Cryptophagidae. Fam. 38. Coccinellidae (Lady -birds}. — Tarsi apparently three- jointed ; the first two joints pubescent beneath ; the third joint consisting really of two joints, the small true third joint being inserted near the base of the second joint, the upper surface of which is grooved to receive it. Head much, concealed by the tlmrn.'i. Antennae feebly clubbed. The lady-birds number fully 2000 species. The structure of their feet distinguishes them from nearly all other Coleoptera except Endomychidae, which are much less rotund in form, and have larger antennae. One genus of Endomychids — Panomoea — bears, however, a singular resemblance to lady-birds, both in form and style of coloration. Several species of Coccinellidae are remarkable on account of the numerous variations in colour they present. Coccinellidae frequently multiply to an enormous extent, and are of great value, as they destroy wholesale the plant -lice, scale - Insects, 238 COLEOPTERA and Acari that are so injurious to cultivated plants. They also eat various other soft-bodied Insects that attack plants. As they are excessively voracious, and are themselves singularly free from enemies and multiply with great rapidity, all these features of their economy render them of inestimable value to the agriculturist and horticulturist. The species of the sub-family Epilachmdes feed on plants, and one or two are occasionally in- jurious. The body-fluid of Coccinellidae has an unpleasant odour and taste. Many lady-birds have the power of exuding, when disturbed, small quantities of a yellow fluid. Lutz has shown that this is not a special secretion, but an exudation of the fluid of the body that takes place through a small orifice at the tip of the tibia, from pressure caused by contraction of the body and limb.1 The larvae are much more active than beetle-larvae usually are, and many of them are very conspicuous when running about on plants to hunt their prey. They usually cast their skins three times, and sometimes concomitantly change a good deal in colour and form ; the larval life does not usually exceed four or five weeks ; at the end of which time the larva suspends itself by the posterior extremity, which is glued by a secretion to some object ; the larval skin is pushed back to the anal extremity, disclosing the pupa ; this differs in several respects from the usual pupa of beetles ; it is harder, and is coloured, frequently conspicuously spotted, and dehisces to allow the escape of the beetle, so that the metamorphosis is altogether more like that of Lepidoptera than that of Coleoptera. There is much variety in the larvae ; some of them bear large, complexly-spined, projections ; those of the group Scymnites have small depressions on the surface, from which it has been ascertained that waxy secre- tions exude ; but in Scymnus minimus no such excretions are formed. Certain species, when pupating, do not shuffle the skin to the extremity of the body, but retain it as a covering for the pupa. The larvae that feed on plants are much less active than the predaceous forms. We are well supplied with Coccinellidae in Britain, forty species being known here. The systematic position of Coccinellidae amongst the Coleoptera has been for long a moot point. Formerly they were associated with various other beetles having three-jointed, or apparently three-jointed, feet, as a series with the name Trimera, or 1 Zool. Anz. xviii. 1895, p. 244. v COCCINELLIDAE - ENDOMYCHIDAE - MYCETAEIDAE 239 Fseudotrimera. But they are generally placed in the Clavicorn series, near Endoinychidae. Verhoeff has recently made con- siderable morphological studies on the male genital organs of Coleoptera, and as the result, he concludes that Coccinellidae differ radically from all other Coleoptera as regards these structures, and he therefore treats them as a distinct series or sub-order, termed Siphonophora. The genus Lithophilus has been considered doubtfully a member of Coccinellidae, as the tarsi possess only in a slight degree the shape characteristic of the family : Verhoeff finds that they are truly Coccinellidae, forming a distinct division, Lithophilini; and our little species of Cocci J /////, which have somewhat the same appearance as Lithophilini, he treats as another separate group, Coccidulini. Fam. 39. Endomychidae.1 — Tarsi apparently three-jointed, the first tivo joints broad, the terminal joint elongate ; at th e base of the terminal joint there is, however, a very small joint, so that the tarsi are pseudotetramerous ; antennae rather large, with a lanjc club ; labium not at all retracted behind the mentum ; front and middle coxae globose ; abdomen with Jive movable ventral segments, and a sixth more or less visible at the tip. This family includes a considerable diversity of elegant Insects that frequent fungoid growths on wood. It comprises at present fully 500 species, but nearly the whole of them are exotic, and inhabit the tropical forests. We have only two British species, both of which are now rarities, but apparently were much commoner at the beginning of the century. The larvae are broader than is usual in Coleoptera ; very few, however, are known. Fam. 40. Mycetaeidae. — Tarsi four- jointed, the first two joints not very different from the third, usually slender ; abdomen with five visible ventral segments, which are movable ; front and middle coxae globular. The little Insects composing this family are FIG ii9-J/yce^« J Britain. A, Larva by many placed as a division of Endomy- (after Blisson) ; B, per- chidae, and Verhoeff is of opinion that the fect lusect group is an altogether artificial one ; but we think, with Duval, it makes matters simpler to separate them. There are only 1 Gerstaecker, Monoyrojrftii'tli-,- Endomychiden, Leipzig, 858, 1433 pp. Since this work was published, the species known have been multiplied two or three times. 240 COLEOPTERA some forty or fifty species, found chiefly in Europe and North America. We have three in Britain ; one of these, Mycetaea hirta is very common, and may be found in abundance in cellars in the heart of London, as well as elsewhere ; it is said to have injured the corks of wine-bottles, and to have caused leakage of the wine, but we think that it perhaps only increases some previous deficiency in the corkage, for its natural food is fungoid matters. The larva is remarkable on account of the clubbed hairs at the sides of the body. Fam. 41. Latridiidae. — Tarsi three-jointed; anterior coxal cavities round, not prolonged externally ; abdomen with Jive visible and mobile ventral segments. Very small Insects, species of which are numerous in most parts of the world, the individuals being sometimes very abundant. The larvae (Fig. 120, A) are said by Ferris to have the mandibles replaced by fleshy appendages. The pupa of Latridius is remarkable, on account of the numerous long hairs with heads instead of points ; the larva of Corticar'm is very like that of Latridius, but some of the hairs are replaced by obconical projections. The sub-family Monotomides is by many treated as a distinct family ; they have the elytra truncate behind, exposing the pygidium, and the coxae are very small and very deeply embedded. Most of the Latridiidae are believed to live on fungoid matters ; species of Monotoma live in ants' nests, but probably have no relations with the ants. A few species of Latridiides proper also main- tain a similar life ; Coluocera formicaria is said to be fond of the stores laid up by Aphaenogaster structor in its nests. About 700 species are now known; scarcely any of the individuals are more than one-tenth of an inch long. We FIG. 120. — Latridius minutus. have about 40 species in Britain. The Xorth American genus Stephostethus has the prosternum constructed behind the coxae, somewhat in the same manner as it is in the Rhynchophorous series of Coleoptera. Fam. 42. Adimeridae. — Tarsi appearing only two-jointed, a broad basal joint and an elongate claw-bearing joint, but between the two there are two very small joints. This family consists only of the American genus Adimerus ; nothing is known of POLYMORPHA — DERMESTIDAE 24I the life -history of these small Insects, interest, as this structure of the foot is not found in any other beetles. Fam. 43. Dermestidae. — Tarsi fire-jointed ; antennae usually short, with the club frequently very large in proposition, and with the under side of the thorax bearing a hollow for its reception, front coxae rather long, oblique : hind coxa, formed to receive the femur when in repose. A family of 300 or 400 species of The are of some small or moderate-sized beetles : the FlG- ^ — Adimmu «*»«*. Adi- meridae. A, the Insect ; B, one foot more enlarged. Mexico. From m°L Centr- Amer- CoL "• ?*• l surface, usually covered with fine hair, forming a pattern, or with scales. Byturus, the position of which has long been disputed, has now been placed in this family ; it has a more imperfectly formed prosternum, and the third and fourth joints of the tarsi are prolonged as membranous lobes beneath ; the hind coxae leave the femora quite free. Dermestidae in the larval state nearly all live on dried animal matter, and are sometimes very destructive ; some of them totally destroy zoological collections. They are very remarkable on account of the complex clothing of hairs they bear ; they have good powers of locomotion, and many of them have a peculiar gait, running for a short distance, then stopping and vibrating some of their hairs with extreme rapidity. They exhibit great variety of form. Many of them are capable of supporting life for long periods on little or no food, and in such cases moult an increased number of times : pupation takes place in the larval skin. Anthrenus fasciatus has been reared in large numbers on a diet of dried horse-hair in FIG. 122.— Tiresias serra. furniture. The young larva of this species Larva. New Forest. observed by the writer did not possess the remarkable, complex arrangement of hairs that appeared when it was further grown. The most curious of Dermestid Jarvae is that of Tiresias serra, which lives amongst cobwebs in VOL. VI R 242 COLEOPTERA old wood, and probably feeds on the remains of Insects therein, perhaps not disdaining the cobwebs themselves. Attention has been frequently called to the hairs of the larvae of these Insects, but they have never been adequately discussed, and their function is quite unknown. Fam. 44. Byrrhidae (Pill-beetles). — Oval or round, convex beetles; tarsi Jive-jointed, front coxae not exserted, transverse ; hind coxa shielding the retracted femur. The whole of the appendages capable of a complete apposition to the body. Although a small family of only 200 or 300 species, Byrrhidae are so hetero- geneous that no characteristic definition that will apply to all the sub-families can be framed. Very little is known as to their life -histories. Byrrhus pilula is one of our commonest beetles, and may be found crawling on. paths in early spring even in towns ; it moves very slowly, and when' disturbed, at once contracts the limbs so completely that it looks like an inanimate object. The larva is cylindrical, soft ; the prothoracic and last two abdominal segments are larger than the others, the last bearing two pseudopods ; its habits are unknown, and no good figure exists of it. The chief groups of Byrrhidae are Nosodendrides, Byrrhides (including Amphicyrtides), Limnichides, and Chelonariides. The first consists of species frequenting the exuding sap of trees ; they have an unusually large mentum, abruptly clubbed antennae, and the head cannot be .retracted and concealed. The genus Nosodendron seems to be distributed over a large part of the world. The Byrrhides have the antennae gradually thicker towards the tip, the mentum small, and the head and thorax so formed that the former can be perfectly retracted. The species are rather numerous, and are found in the northern and anti- podeal regions, being nearly completely absent from the tropics. The Limnichides are minute Insects living in very moist places ; they have small delicate antennae, which are imperfectly clubbed. The group is very widely distributed. The Chelonariides are a very peculiar form of Coleoptera : oval Insects of small size with the prothorax so formed that the head can be withdrawn under (rather than into) it, and then abruptly inflexed, so that the face then forms part of the under surface : the antennae have the basal three joints thicker than the others ; these being not in the least clubbed, but having the POLYMORPHA 243 joints so delicately connected that the organs are rarely un- mutilated. The modifications of the head and prothorax are quite unlike those of other Byrrhidae, and if the Chelonariides do not form a distinct family, they should be associated with Dascillidae. Nothing is known as to the earlier stages. They are chiefly tropical Insects, though one species is found in North America. Fam. 45. Cyathoceridae — Minute Insects of broad form; parts of the mouth concealed ; antennae four-jointed ; tarsi not divided into joints ; prosternum small. The only species of this aberrant family, Cyathocerus horni, has been found in Central America. Nothing is known as to its life-history. Fam. 46. Georyssidae. — Antennae short, clubbed ; tarsi four- jointed; prosternum very small; front coxae exserted, but not contiguous. There are about two dozen species of these small beetles known. Our British Georyssus pygmaeus lives in extremely wet places, and covers itself with a coating of mud or fine sand so that it can only be detected when in movement. Nothing further is known as to its life-history or habits. Members of the genus have been detected in widely- separated parts of the globe. Fam. 47. Heteroceridae. — Labrum and mandibles projecting forwards; antennae short, the terminal seven joints broad and short, forming a sort of broad serrate club ; legs armed with stout spines ; tarsi four-jointed. The Heteroceridae are small beetles covered with very dense but minute pubescence ; they live in burrows among mud or sand in wet places, and are found in many parts of the world. They possess a stridulating organ in the form of a slightly elevated curved line on each side of the base of the abdomen, rubbed by the posterior femur. The larvae live in the .same places as the beetles ; they have well-developed thoracic legs, the mandibles are porrect, the three thoracic segments rather large, and the body behind these becomes gradually narrower ; they are believed to eat the mud amongst which they burrow. We have seven British species of Hetero- ceridae. Fam. 48. Parnidae. — Prostermim distinct in front of the coxae, usually elongate, behind forming a process received into a dejinite cavity on the mesosternum ; head retractile, the mouth protected by the prosternum. Tarsi Jive -jointed, terminal joint long. 244 COLEOPTERA CHAP. Although the characters of these Insects are not very different from those of Byrrhidae, of Dascillidae, and even of certain Elateridae, there is practically but little difficulty in distinguish- ing Parnidae. They are of aquatic habits, though many, in the perfect state, frequently desert the waters. There are about 300 or 400 species known, but the family is doubtless more extensive, as these small beetles attract but little notice. There are two groups: — 1. Parnides, in which the front coxae have a con- siderable transverse extension, the antennae are frequently short and of peculiar structure, and the body is usually clothed with a peculiar, dense pubescence. 2. Elmides, with round front coxae, a bare, or feebly pubescent body, and simple antennae. Parnus is a genus commonly met with in "Europe, and is less aquatic in habits than its congeners ; it is said to enter the water carrying with it a coating of air attached to its pubescence. Its larvae are not well known; they live in damp earth near streams, and are said to much resemble the larvae of Elateridae. Potamophilus acuminatus has a very interesting larva, described by Dufour ; it lives on decaying wood in the Adour. It is remarkable from the ocelli being arranged so as to form an almost true eye on each side of the head ; there are eight pairs of abdominal spiracles, and also a pair on the mesothorax, though there are none on the pro- or meta-thorax ; each of the stigmata has four elongate sacs between it and the main tracheal tube ; the body is terminated by a process from which there can be protruded bunches of filamentous branchiae. The larvae of Macrony/i //-s quadrituberculatus is somewhat similar, though the features of its external structure are less remarkable. The Elmides live attached to stones in streams ; the larva is rather broad, fringed at the sides of the body, and bears behind three elegant sets of fine filamentous branchiae. The North American genus Psephenus is placed in Parnidae, though instead of five, the male has seven, the female six, visible ventral segments ; the larva is elliptical, with dilated margins to the body. Friederich, has given,1 without mentioning any names, a detailed account of Brazilian Parnid larvae, that may perhaps be allied to Psephenus. Fam. 49. Derodontidae. — Tarsi Jive-jointed, slender, fourth joint rather small; front coxae prominent and transversely pro- 1 Stettin, ent. Zeit. xlii. 1881, pp. 104-112. POLYMORPHA — DERODONTIDAE CIOIDAE 245 FIG. 123. — Derodontiis macu- latus. North America. longed ; middle coxae small ; abdomen with Jive visible segments, (dl mobile, the first not elongated. One of the smallest and least known of the families of Coleoptera ; it consists of four or five species of small Insects of the genera Derodontiis and J'dtasticta, found in Xorth America, Europe, and Japan. The distinction of the family from Cleridae is by no means cer- tain ; our European Laricobius apparently possessing characters but little different. Nothing is known as to the life-histories. Fam. 50. Cioidae. — Small or minute beetles; antennae short, terminal joints thicker; tarsi short, four-jointed ; anterior n ml middle coxae small, oval, deeply em- bedded; abdomen with five ventral seg- ments, all mobile. The position of these obscure little Insects seems to be near Colydiidae and Crypto- phagidae, though they are usually placed near Bostrichidae. So far as known, they all live in fungi, or in wood penetrated by fungoid growths. The cylindrical larvae live also in similar matter ; they usually have the body terminated behind by one or two hooks curved upwards ; that of Cis melliei (Fig. 124) has, instead of these hooks, a curious chitinous tube. About 300 species of the family are now known ; a score, or so, occurring in Britain. The Hawaiian Islands have a remarkably rich and varied fauna of Cioidae. Fam. 51. Sphindidae. — This family of half a dozen species of rare and small Insects, differs from Cioidae by the tarsi being five-jointed at any rate on the front and middle feet, opinions differing as to whether the number of joints of the hind tarsi is four or five. These Insects live in fungi growing in wood, e.g. Ecticularia hortensis, that are at first pulpy and Kic. 124. — Cis melliei. Martin- ique. A, Perfect Insect ; B, pupa ; C, larva ; D, terminal portion of body of larva. (After Coquerel.) 246 COLEOPTERA afterwards become powder. The larvae of both of our British genera, Sphindus and Aspidiphorus, have been described by Ferris, who considers them allied to the fungivorous Silphidae and Lutridiidae. The systematic position of these Insects has been the subject of doubt since the days of Latreille. Fam. 52. Bostrichidae (Apatidae of some authors). — Tarsi Jive-jointed, but the first joint very short and imperfectly separated from the second; front coxae prominent, con- tiguous, very little extended transversely ; Jive visible ventral segments. The Bostrichidae attack dry wood, and sometimes in such large numbers that timber is entirely destroyed "by them ; most of them make cylindrical burrows into the wood. The larvae have the posterior part of the body incurved, and resemble the wood- boring larvae of Anobiidae rather than the predaceous larvae of Cleridae. We follow Leconte and Horn in placing Lyctides as a division of Bostrichidae ; although differing very much in appear- anc6' the have siniilar habits and larvae- no. 125,-Apate. capucina. Europe. A, Larva (after The typical Bostrichides are remarkable sect ' ' PCr f°r their variety of sculpture and for the shapes of the posterior part of the body ; this part is more or less conspicuously truncate, and furnished with small prominences. Dinapate wrightii, found in the stems of a species of Yucca in the Mojave desert of California, attains a length of nearly two inches ; its larva is extremely similar to that of A. capucina. Some of the forms (Plionapate] stridulate in a manner peculiar to themselves, by rubbing the front leg against some projections at the hind angle of the prothorax. l']>- wards of 200 species of the family are known. In Britain we have only four small and aberrant forms. Fam. 53. Ptinidae. — Tarsi Jive-jointed, Jirst joint not reduced in size, often longer than second ; front and middle coxae small, not transversely extended, the former slightly prominent ; Jive visible ventral segments ; prosternum very short. Here are in- cluded two sub - families, Ptinides and Anobiides ; they are considered as distinct families by many authors, but in the POLYMORPHA — PTINIDAE 247 FIG. 126.— "Biscuit-weevil." Anobimn paniceum. present imperfect state of knowledge l it is not necessary to treat them separately. Ptinidae are sometimes very destructive to dried animal matter, and attack specimens in museums ; Anobiides bore into wood, and apparently emerge as perfect Insects only for a very brief period; Anobium (Sito- drepct) paniceum is, however, by no means restricted in its tastes ; it must possess extraordinary powers of digestion, as we have known it to pass several consecu- tive generations on a diet of opium ; it has also been reported to thrive on tablets of dried compressed meat ; in India it is said to disintegrate books ; a more usual food of the Insect is, how- ever, hard biscuits ; weevilly biscuits are known to every sailor, and the so-called " weevil " is usually the larva of A. paniceum (Fig. 127, B). In the case of this Insect we have not detected more than one spiracle (situate on the first thoracic segment) ; the other known larvae of Anobiides are said to possess eight abdominal spiracles. The skeleton in some FIG. 127. — Early stages of Anobium paniceum. A, Eggs, variable in form ; B, larva ; C, pupa ; D, asymmetrical processes terminat- ing body of pupa. [This larva is pro- bably the " book- worm " of librar- ians]. of this sub-family is extremely modified, so as to allow the Insects to pack themselves up in repose ; the head is folded in over the chest, and a cavity existing on the breast is thus closed by the head ; in this cavity the antennae and the prominent mouth-parts are received and protected ; the legs shut together 1 It is probable that we do not know more than the fiftieth part of the existing species, most of which lead lives that render them very difficult to find. 248 COLEOPTERA in an equally perfect manner, so that no roughness or chink remains, and the creature looks like a little hard seed. Anobium striatum is a common Insect in houses, and makes little round holes in furniture, which is then said to be " worm-eaten." A. (Xestobiwni) tessellatum, a much larger Insect, has proved very destructive to beams in churches, libraries, etc. These species are the "death-watches" or "greater death-watches " that have been associated with the most ridiculous superstitions (as we have mentioned in Volume V., when speaking of the lesser death- watches, or Psocidae). The ticking of these Insects is really connected with sex, and is made by striking the head rapidly against the wood on which the Insect is standing. FIG. i2S.-Ectrephes\ingi. . The very anomalous genus Ectrephes West Australia. (After (Fig. 128) is found ill ailts' nests ill Australia. Westwood placed it in Pti- iiidae. Wasmann has recently treated it as a distinct family, Ectrephidae, associating it with Polyplocotes and Diplocotes, and treating them as allied to Scydmaenidae. Fam. 54. Malacodermidae. — Seven (or even eight} visible ven- tral segments, the basal one not co-adapted inform with the coxae ; tarsi five-jointed. Integument softer than usual, the parts of the body not accurately co-adapted. This important family includes a variety of forms : viz. Lycides, Drilides, Lampyrides, Telepho- rides ; though they are very different in appearance, classifiers have not yet agreed on separating them as families. Of these the Lampyrides, or glow-worms, are of special interest, as most of their members give off a phosphorescent light when alive ; in many of them the female is apterous and like a larva, and then the light it gives is usually conspicuous, frequently much more so than that of its mate ; in other cases the males are the most brilliant. The exact importance of these characters in the crea- tures' lives is not yet clear, but it appears probable that in the first class of cases the light of the female serves as an 'attraction to the male, while in the second class the very brilliant lights of the male serve as an amusement, or as an incitement to rivalry amongst the individuals of this sex. The well-known fire-flies MALACODERMIDAE FIRE-FLIES GLOW-WORMS 249 {Luciola} of Southern Europe are an example of the latter con- dition. They are gregarious, and on calm, warm nights crowds of them may be seen moving and sparkling in a charm- ing manner. These individuals are all, or nearly all, males ; so rare indeed is the female that few entomologists have even noticed it. The writer once assisted in a large gathering of Luciola italica in the Val Anzasca, which consisted of many hundreds of specimens ; all of those he caught, either on the wing or displaying their lights on the bushes, wrere males, but he found a solitary female on the ground. This sex possesses ordinary, small eyes instead of the large, convex organs of the male, and its antennae and legs are much more feeble, so that though provided with elytra and wings it is altogether a more imper- fect creature. Emery has given an account of his observations ,iii(l experiments on this Insect, but they do not give any clear idea as to the exact function of the light.1 In our British glow- worm the female is entirely apter- ous hence the name glow-worm FI°- l29.—Phengodes hier&nymi. Cor- doba, South America. (After Haase.) -but the male has elytra and A. Male ; B, female, i, i, Positions ample wings, and frequently flies of luminous spots ;/«, spiracles. About at night into lighted apartments. Although so little has been ascertained as to the light of Lampy- ridae, there are two facts that justify us in supposing that it is in some way of importance to the species. These are: (1) that in a great many species the eyes have a magnificent and unusual develop- ment ; (2) that the habits of the creatures are in nearly all cases nocturnal. It is true that the little Phosphacnus hemipterus is said to be diurnal in habits, but it is altogether an exceptional form, being destitute of wings in both sexes, and possessed of only very feeble light-giving powers, and we have, moreover, very little real knowledge as to its natural history ; it is said 1 Bull. cut. ital. 1886, p. 406, and Ent. Zcit. Stettin, : xliii. 1887, pp. -201-206. Emery does not mention the name of the species, but we presume it to be the common Italian fire-fly, Luciola it< 250 COLEOPTERA CHAP. that the female is of the utmost rarity, though the male is not uncommon. The nature of the luminosity of Lampyris has given rise to many contradictory statements ; the light looks somewhat like that given off by phosphorus, and is frequently spoken of as phosphorescence ; but luminescence is a better term. The egg, larva, pupa, and male are luminous as well as the female (at any rate in L. noctiluca) ; the luminescence is, however, most marked in the female imago, in which it is concentrated near the extremity of the abdomen ; here there are two strata of cells, and many fine capillary tracheae are scattered through the luminous substance. Wielowiejski concludes that the light- producing power is inherent in the cells of the luminous organ, and is produced by the slow oxidation of a substance formed under the influence of the nervous system. The cells are considered to be essentially similar to those of the fat-body.1 The luminescence of Lampyridae is very intermittent, that is to say, it is subject to rapid diminutions and increases of its brilliancy ; various reasons have been assigned for this, but all are guesses, and all that can be said is that the changes are possibly due to diminution or increase of the air-supply in the luminous organ, but of the way in which this is controlled there seems to be 110 evidence. Considerable difference of opinion has existed as to the luminescence of the eggs of Lampyris. If it exist in the matter contained in the egg, it is evident that it is independent of the existence of tracheae or of a nervous system. Newport and others believed that the light given by the egg- depended merely on matter on its exterior. The observations of Dubois 2 show, however, that it exists in the matter in the egg ; he has even found it in the interior of eggs that had been deposited unfertilised. From time to time, since the commencement of the nineteenth century, there have appeared imperfect accounts of extraordinary light-giving larvae found in South America, of various sizes, but attaining in some cases a length, it is said, of three inches ; they are reported as giving a strong red light from the two extremities of the body, and a green light from numerous points along the 1 Zeitschr. iviss. Zool. xxxvii. 1882, p. 354 ; also Emery, op. cit. xl. 1884r p. 338. For another theory as to the luminescence, see p. 259. 2 Bull. Soc. Zool. France, xii. 1887, p. 137, posted. v POLYMORPHA — GLOW-WORMS 2 5 I sides of the body, and hence are called, it is said, in Paraguay the railway-beetle. We may refer the reader to Haase's paper 1 on the subject of these " larvae," as we can here only say that it appears probable that most of these creatures may prove to be adult females of the extraordinary group Phengodini, in which it would appear that the imago of the female sex is in a more larva - like state than it is in any other Insects. The males, however, are well- developed beetles ; unlike the males of Lampyrides, in general they have not peculiar eyes, but 011 the other hand they possess antennae which are amongst the most highly developed known, the joints being furnished on each side with a long appendage densely covered with pubescence of a remarkable character. There is no reason to doubt that Haase was correct in treating the Insect we figure (Fig. 129, B) as a perfect Insect ; he is, indeed, corroborated by Eiley.2 The distinctions between the larva and female imago are that the latter has two claws on the feet instead of one, a greater number of joints in the antennae, and less imperfect eyes ; the female is in fact a larva, making a slightly greater change at the last ecdysis, than at those previous. It is much to be regretted that we have so very small a know- ledge of these most interesting Insects. Malacodermidae are probably the most imperfect or primitive of all beetles, and it is a point of some interest to find that in one of them the phenomena of metamorphosis are reduced in one sex to a minimum, while in the other they are — presumably at least — normal in character. Ximierous larvae of most extraordinary, though diverse, shapes, bearing long processes at the sides of the body, and having a head capable of complete withdrawal into a slender cavity of the thorax, have long been known in several parts of the world, and Dr. "\Villey recently found in New Britain a species having these body-processes articulated. Though they are doubtless larvae of Lampyrides, none of them have ever been reared or exactly identified. A very remarkable Ceylonese Insect, Dioptoma adatnsi I'ascoe, is placed in Lampyrides, but can scarcely belong there, as apparently it has but five or six visible ventral segments ; this Insect has twro pairs of eyes, a large pair, with coarse facets on 1 Deutsche ent. Zeitschr. xxxii. 1888, pp. 145-167. - Ent. Mag. xxiv. 1887, p. 148. 252 COLEOPTERA the under side of the head, arid a moderate-sized pair with fine facets on the upper side. Nothing is known as to the habits of this curiosity, not even whether it is luminous in one or both sexes. It is believed that the perfect instar of Lampyrides takes no food at all. The larvae were formerly supposed to be vegetarian, but it appears probable that nearly all are carnivorous, the chief food being Mollusca either living or dead. The larvae are active, and in many species look almost as much like perfect Insects as do the imagos. The other divisions of Malacodermidae — Lycides, Drilides, Telephorides — also have predaceous, carnivorous larvae. All these groups are extensive. Though much neglected by collectors and naturalists, some 1500 species of the family Malacodermidae have been detected. We have about 50 in Britain, and many of them are amongst the most widely distributed and abundant of our native Insects. Thus, however near they may be to the primitive condition of Coleoptera, it is highly probable that they will continue to exist alongside of the primitive Cockroaches and Aptera, long after the more highly endowed forms of Insect-life have been extinguished wholesale by the operations of mankind on the face of the earth. Fam. 55. Melyridae (or Malachiidae). — Six visible and move- able ventral abdominal segments; the basal part more or less distinctly co-adapted ivith the coxae. These Insects are extremely numerous, but have been very little studied. In many works they are classified with Malacodermidae, but were correctly separated by Leconte and Horn, and this view is also taken by Dr. Verhoeff, the latest investigator. The smaller num- ber of visible ventral segments appears to be due to a change at the base correlative with an adaptation between the base of FIG. iBQ.—Maiachius aeneus. Britain, the abdomen and the hind A, Larva (after Ferris) : B, female m, , imago. coxae. Ihe characters are singu- larly parallel with those of Silphidae ; but in Melyridae the antennae are filiform or serrate, v POLYMORPHA MELYRIDAE CLERIDAE 253 iiot clavate. The habits in the two families are different, as the Melyridae are frequenters of flowers. Many of the Melyridae have the integument soft, but in the forms placed at the end of the family — e.g. Zygia — they are much firmer. Thus these Insects establish a transition from the Malacodermidae to ordi- nary Coleoptera. Although the images are believed to consume some products of the flo\vers they frequent, yet very little is really known, and it is not improbable that they are to some extent carnivorous. This is the case with the larvae that are known (Fig. 130, larva of Malachius aeneus}. These are said by Ferris to bear a great resemblance to those of the genus Telephorus, belonging to the Malacodermidae. Fam. 56. Cleridae. — I'arsi Jive-jointed ; l>ut the basal joint of the posterior very indistinct, usually very small above, and closely united with the second by an oblique splice; the apices of joints two to four usually prolonged as membranous flaps ; anterior coxae prominent, usually contiguous, rather large, but their cavities not 2>rolonged externally; labial palpi usually with large hatchet- shaped terminal joint ; ventral segments five or six, very mobile. The Cleridae are very varied in form and colours ; the antennae are usually more or less clubbed at the tip, and not at all serrate, but in Cylidrus and a few others they are not clubbed, and in Cylidrus have seven flattened joints. The student should be very cautious in deciding as to the number of joints in the feet in this family, as the small basal joint is often scarcely dis- tinguishable, owing to the obliteration of its suture with the second joint. The little Alpine Laricobius has the anterior coxal cavities prolonged externally, and the coxae receive the femora to some extent, so that it connects Cleridae and Derodontidae. The Cleridae are predaceous, and their larvae are very active ; they are specially fond of wood-boring Insects ; that of Tillus elon- gatus (Fig. 131) enters the burrows of Ptilinus pectinicornis in search of the larva. The members of the group Corynetides frequent animal matter, carcases, bones, etc., and, it is said, feed thereon, but Perris's recent investigations 1 make it probable that the larvae really eat the innumerable Dipterous larvae found in such refuse ; it is also said that the larvae of Cleridae spin cocoons for their metamorphosis ; but Ferris has also shown that the larvae of Necrobia ruficollis really use the puparia formed 1 Larves des Coleopteres, 1878, p. 208. 254 COLEOPTERA by Diptera. Some of the species of Necrolia have been spread by commercial intercourse, and N. rufipes appears to be now one of the most cosmopolitan of Insects. The beautifully coloured Corynetes coeruleus is often found in our houses, and is useful, as it destroys the death-watches (Anobium) that are sometimes very injurious. Trichodes apiarius, a very lively -coloured red and blue beetle, destroys the larvae of the honey-bee, arid Lampert has reared Trichodes alvearius from the nests of Chalicodoma muraria, a mason-bee ; he re- cords that one of its larvae, after being full grown, remained twenty - two months quiescent and then transformed to a pupa. Still more remarkable is a ca^e of fasting of the larva of Tri- chodes ammios recorded by FIG- ^V^TVw77?"* fTf"' Mayet;1 this Insect, in its (New Forest). A, Head ; B, front leg ; » C, termination of the body, more mag- immature form, destroys Aci'i- mfied- dium maroccanum ; a larva sent from Algeria to M. Mayet refused such food as was offered to it for a period of two and a half years, and then accepted mutton and beef as food ; after being fed for about a year and a half thereon, it died. Some Cleridae bear a great resemblance to Insects of other families, and it appears probable that they resemble in one or more points the Insects on which they feed. The species are now very numerous, about 1000 being known, but they are rare in collections ; in Britain we have only nine species, and some of them are now scarcely ever met with. Fam. 57. Lymexylonidae. — Elongate beetles, with soft integu- ments, front and middle coxae exserted, longitudinal in position; tarsi slender, Jive-jointed ; antennae short, serrate, but rather broad. Although there are only twenty or thirty species of this family, they occur in most parts of the world, and are remarkable on account of their habit of drilling cylindrical holes in hard wood, after the manner of Anobiidae. The larva of Lymexylon navale was formerly very injurious to timber used for constructing ships, but of late years its ravages appear to have been of little importance. The genus Atractocerus consists of a few species of very abnormal 1 Ann, Soe. cut, France, 1894, p. 7. v POLYMORPHA DASCILLIDAE 255 Coleoptera, the body being elongate and vermiform, the elytra reduced to small, functionless appendages, while the wings are ample, not folded, but traversed by strong longitudinal nervures, and with only one or two transverse nervures. Owing to the destruction of our forests the two British Lymexylonidae — L. navale and Hylecoetus dermestoides — are now very rarely met with. Fam. 58. Dascillidae. — Small or moderate-sized beetles, with rather flimsy integuments, antennae either serrate, filiform, or even made flagellate Ity long appen- dages ; front coxae elongate, greatly cxserted ; abdomen with Jive mobile rentral segments ; tarsi Jive-jointed. This is one of the most neglected and least known of all the families of Coleoptera, and one of the most difficult to classify ; though always placed amongst the Serricornia, it is more nearly allied to Parnidae and Byrrhidae, that are placed in Clavicornia, than it is to any of the FlG 132> __ nydrocypho Ordinary families of Serricornia. It Britain. A, Larva (after Tournier) ; is probable that careful study will show that it is not natural as at present constituted, and that the old families, Dascillidae and Cyphonidae, now comprised in it, will have to be separated. Only about 400 species are at present known; but as nearly 100 of these have been detected in New Zealand, and 17 in Britain, doubtless the numbers in other parts of the world will prove very considerable, these Insects having been neglected on account of their unattractive exterior, and fragile structure. The few larvae known are of three or four kinds. That of DasciHus cervinus is subterranean, and is believed to live on roots ; in form it is somewhat like a Lamelli- corn larva, but is straight, and has a large head. Those of the ( Vphonides are aquatic, and are remarkable for possessing antennae consisting of a great many joints (Fig. 132, A). Tournier describes the larva of Helodes as possessing abdominal but not thoracic spiracles, and as breathing by coming to the surface of the water and carrying down a bubble of air adhering to the posterior part of the body; the larva of Hydrocyphon (Fig. 132, A) 256 COLEOPTERA possesses several finger-like pouches that can be exstulpated at the end of the body. It is probable that these larvae are carni- vorous. The imago of this Insect abounds on the bushes along the banks of some of the rapid waters of Scotland ; according to Tournier, when alarmed, it enters the water and goes beneath it for shelter. The third form of larva belongs to the genus Euci- netus, it lives on fungoid matter on wood, and has ordinary antennae of only four joints.1 It is very doubtful whether Eucinetus is related to other Dascyllidae ; some authorities indeed place it in Silphidae. Fam. 59. Rhipiceridae. — Tarsi Jive -jointed, furnished with a robust onychium (a straight chitinous process bearing hairs} behveen the claws; antennae of the male bearing long processes, and sometimes consisting of a large number of joints. Man- dibles robust, strongly curved, and almost calliper -like in form. This small family of less than 100 species is widely distributed, though confined to the warmer regions of the earth, a single species occur- ring in the extreme south of Eastern Europe. Very little is known as to the natural history. The larva of Calli- rhipis dejeani (Fig. 133, A) is described by Schiodte as hard, cylindrical in form, and peculi- FIG. 133.— A, Larva of Qaliirhipis dejeani. arl7 truncate behind, so that (after Schiodte) ; B, Rhipicera mystaciwt there appear to be Ollly eight male, Australia ; C, under side of its hind , , . , foot. abdominal segments, the ninth segment being so short as to look like an operculum at the extremity of the body. It lives in wood. Fam. 60. Elateridae (Click-beetles'). — Antennae more or less' serrate along the inner margin, frequently pectinate, rarely filiform. Front coxae small, spherical. Thorax usually with 1 Perris, Ann. Soc. ent. France (2) ix. 1851, p. 48. CLICK-BEETLES 257 . — AtJwus rhui/ibeus. New Forest. A, Larva ; B, female imago. hind angles more or less prolonged backwards ; with a prosternal process that can be received in, and usually can move in, a mesosternal cavity. Hind coxa with a plate, above which the femur can be received. Visible ventral segments usually Jive, only the terminal one being mobile. Tarsi Jive-jointed. This large family of Coleoptera comprises about 7000 species. Most of them are readily known by their peculiar shape, and by their faculty of resting on the back, stretching themselves out flat, and then suddenly going off witli a click, and thus jerking themselves into the air. Some, however, do not possess this faculty, and certain of these are extremely difficult to recognise from a defi- nition of the family. According to Bertkau1 our British Lacon murinus is provided near the tip of the upper side of the ab- domen with a pair of eversible glands, comparable with those that are better known in Lepi- dopterous larvae. He states that this Insect does not try to escape by leaping, but shams death and " stinks away " its enemy. The glands, it would appear, become exhausted after the operation has been repeated many times. The extent of the leap executed by click-beetles differs greatly ; in some species it is very slight, and only just sufficient to turn the Insect right side up when it has been placed on its back. In some cases the Insects go through the clicking movements with little or no appreciable result in the way of consequent propulsion. Although it is difficult to look on this clicking power as of very great value to the Elateridae, yet their organisation is profoundly modified so as to permit its accomplishment. The junction of the prothorax with the after-body involves a large number of pieces which are all more or less changed, so that the joint is endowed with greater mobility than usual ; while in the position of repose, on the other hand, the two parts are firmly locked together. The thoracic stigma is of a highly remarkable nature, and the extensive 1 Arch. Naturgesclt. xlviii. 1, 1882, p. 371. VOL. VI S 258 COLEOPTERA membrane in which it is placed appears to be elastic. Although the mechanics of the act of leaping are still obscure, yet certain points are clear ; the prosternal process possesses a projection, or notch, on its upper surface near the tip ; as a preliminary to leaping, this projection catches against the edge of the meso- sternal cavity, and as long as this position is maintained the Insect is quiescent ; suddenly, however, the projection slips over the catch, and the prosternal process is driven with force and rapidity into the mesosternal cavity pressing against the front wall thereof, and so giving rise to the leap. Several larvae are well known ; indeed the " wire-\vorms " that are sometimes so abundant in cultivated places are larvae of Elateridae. In this instar the form is usually elongate and nearly cylindrical ; the thoracic segments differ but little from the others except that they bear rather short legs ; the skin is rather hard, and usually bears punctuation or sculpture ; the body frequently terminates in a very hard process, of irregular shape and bearing peculiar sculpture on its upper surface, while beneath it the prominent anal orifice is placed : this is sometimes furnished with hooks, the function of which has not yet been observed. The majority of these larvae live in decaying wood, but some are found in the earth ; as a rule the growth is extremely slow, and the life of the larva may extend over two or more years. Some obscurity has prevailed as to their food ; it is now considered to be chiefly flesh, though some species probably attack decaying roots ; and it is understood that wire- worms destroy the living roots, or underground stems, of the crops they damage. Various kinds of My riapods (see Vol. V. p. 2 9 ) are often called "wire-worm," but they may be recognised by possessing more than six legs. The larvae of the genus Cardiophorus are very different, being remarkably elongate without the peculiar terminal structure, but apparently composed of twenty-three segments. The genus Pyrophorus includes some of the most remarkable of light-giving Insects. There are upwards of 100 species, exhibiting much diversity as to the luminous organs ; some are not luminous at all ; but all are peculiar to the New World, with the exception that there may possibly be luminous species, allied to the American forms, in the Fiji Islands and the Xew Hebrides. In the tropics of America the Pyrophorus, or Cucujos, form one of the most remarkable of the natural phenomena. v ELATERTDAE FIRE-FLIES 259 The earliest European travellers in the New World were so im- pressed by these Insects that descriptions of their wondrous display occupy a prominent position in the accounts of writers like Oviedo, whose works are nearly 400 years old. Only one of the species has, however, been investigated. P. noctilucus is one of the most abundant and largest of the Pyrophorus, and possesses on each side of the thorax a round polished space from which light is given forth ; these are the organs called eyes by the older writers. Besides these two eye-like lamps the Insect possesses a third source of light situate at the base of the ventral surface of the abdomen ; there is no trace of this latter lamp when the Insect is in repose ; but when on the wing the abdomen is bent away from the breast, and then this source of light is exposed ; hence, when Hying, this central luminous body can be alternately displayed and concealed by means of slight movements of the abdomen. The young larva of P. noctilucus is luminous, having a light- giving centre at the junction of the head and thorax ; the older larva has also numerous luminous points along the sides of the body near the spiracles. It is remarkable that there should be three successive seats of luminescence in the life of the same individual. The eggs too are said to be luminous. The light given off by these Insects is extremely pleasing, and is used by the natives on nocturnal excursions, and by the women for orna- ment. The structure of the light-organs is essentially similar to that of the Lampyridae. The light is said to be the most economical known ; all the energy that is used being converted into light, without any waste by the formation of heat or chemical rays. The subject has been investigated by Dubois,1 who comes, however, to conclusions as to the physiology of the luminous processes different from those that have been reached by Wielowiejski and others in their investigations on Glow- worms. He considers that the light is produced by the reactions of two special substances, luciferase and luciferine. Luciferase is of the nature of an enzyme, and exists only in the luminous organs, in the form, it is supposed, of extremely minute granules. Luciferine exists in the blood ; and the light is actually evoked by the entry of blood into the luminous organ. We have given to this family the extension assigned to it by 1 " Les Elaterides lumineux," Bull. Soc. Zool. France, xi. 1886; also Lemons de Physiologic gene-rale, Paris, 1898, and C.R. Ac. Sci. cxxiii. 1896, p. 653. 26o COLEOPTERA Schiodte. Leconte and Horn also adopt this view, except that they treat Throscides as a distinct family. By most authors Eucnemides, Throscides, and Cebrionides are all considered dis- tinct families, but at present it is almost impossible to separate them on satisfactory lines. The following table from Leconte and Horn exhibits the characters of the divisions so far as the imago is concerned : — Posterior coxae laminate ; trochanters small Labruni concealed ; antennae somewhat distant from the eyes, their insertion narrowing the front . . . EUCNEMIDKS. Labruni visible, free ; antennae arising near the eyes under the frontal margin ...... ELATERIDES. Labrum transverse, connate with the front. Ventral segments six ; claws simple ; tibial spurs well developed. CEBRIOXIDES. Ventral segments five ; claws serrate ; tibial spurs moderate. PEROTHOPIDES. Posterior coxae not laminate ; trochanters of middle and posterior legs very long ....... CEROPHYTIDES. Throscides are considered to be distinguished by the mesosternum being impressed on each side in front for the accommodation of the posterior face of the front coxae. The genus Throscus has the antennae clavate. The classification of the Elaterides and these forms is a matter of the greatest difficulty, and, if the larvae are also considered, becomes even more complex. Cebrionid larvae are different from those of any of the other divisions, and possess laminate, not calliper-like, man- dibles. The larvae of Eucnemides (Fig. 135) are very little known, but are highly remarkable, inasmuch as it is very difficult to find any mouth-opening side ; B, under side : s s, in some of them, and they have 110 legs. head101more enlarged'- D,' ^ne °^ler ^ visions pOSSCSS Very few Species under side of terminal seg- compared with Elaterides. In Britain inent : a, anus. , . . we have about sixty species ot Elate- rides, four of Throscides and three of Eucnemides ; Cerophytum was probably a native many years ago. Neither Perothopides FIG. 135. POLYMORPHA BUPRESTIDAE 26l nor Cebrionides are represented in our fauna ; the former of these two groups consists only of four or five North American species, and the Cerophytides are scarcely more numerous. Fam. 61. Buprestidae. — Antennae serrate, never elongate; prothorax fitting closely to the after-body, with a process received into a cavity of the mesosternum so as to permit of no movements of nutation. Five visible ventral segments, the first usually elongate, closely united with the second, the others mobile. Tarsi Jive-jointed, the first four joints usually with membranous pads beneath. This family is also of large extent, about 5000 species being known. Many of them are remarkable for the magnificence of their colour, which is usually metallic, and often of the greatest brilliancy ; hence their wing-cases are used by our own species for adorn- ment. The elytra of the eastern kinds of the genus Sternocera are of a very brilliant green colour, and are used extensively as embroidery for the dresses of ladies : the bronze elytra of Buprestis (Euchroma) giyantea were used by the native chieftains in South America as leg -ornaments, a large number being strung so as to form a circlet. The integument of the Buprestidae is very thick and hard, so as to increase the resemblance to 11, 0,1 11 FIG. 136.— A, Larva of Euchroma metal. 1 lie dorsal plates OI the abdO- goliath (after Schiodte) ; B, imago men are usually soft and colourless in beetles, but in Buprestidae they are often extremely brilliant. The metallic colour in these Insects is not due to pigment, but to the nature of the surface. Buprestidae appear to enjoy the hottest sunshine, and are found only where there is much summer heat. Australia and Madagascar are very rich in species and in remarkable forms of the family, while in Britain we possess only ten species, all of which are of small size, and nearly all are excessively rare. The family is remarkably rich in fossil forms; no less than 28 percent of the Mesozoic beetles found by Heer in Switzerland are referred to Buprestidae. The larvae (Fig. 136, A) find nourishment in living vegetable matter, the rule being that they form galleries in or under the of Mdanophila Europe. decostiijma. 262 COLEOPTERA bark of trees and bushes, or in roots thereof; some inhabit the steins of herbaceous plants and one or two of the smaller forms have been discovered to live in the parenchyma of leaves. A few are said to inhabit dead wood, and in Australia species of Ethon dwell in galls on various plants. Buprestid larvae are of very remarkable shape, the small head being almost entirely withdrawn into the very broad thorax, while the abdomen is slender.1 A few, how- ever, depart from this shape, and have the thoracic region but little or not at all broader than the other parts. The larvae of Julodis — a genus that inhabits desert or arid regions — are covered with hair ; they have a great development of the mandibles ; it is believed that they are of subterranean habits, and that the mandibles are used for burrowing in the earth. Only the newly hatched larva is, however, known. Series IV. Heteromera. Tarsi of the front and middle legs with five, those of the hind legs with four, joints. This series consists of some 14,000 or 15,000 species. Twelve or more families are recognised in it, but the majority of the species are placed in the one great family, Tenebrionidae. The number of visible ventral segments is nearly always five. Several of the families of the series are of doubtful validity ; indeed beyond that of Tenebrionidae the taxonomy of this series is scarcely more than a convention. The larvae may be con- sidered as belonging to three classes ; one in which the body is cylindrical and smooth and the integument harder than usual in larvae ; a second in which it is softer, and frequently possesses more or less distinct pseudopods, in addition to the six thoracic legs; and a third group in which hypermetamorphosis prevails, the young larvae being the creatures long known as Triungulins, and living temporarily on the bodies of other Insects, so that they were formerly supposed to be parasites. 1 It seems impossible to understand the morphology of the anterior segments by mere inspection ; the anterior spiracle being seated on the segment behind flu- broad thorax. Considerable difference of opinion has prevailed as to what is head, what thorax ; the aid of embryology is necessary to settle the point. The larva described by Westwood (Mod. Clussif. i. 1839, p. 229), and figured as probably Buprestis attenuata, is doubtless a Passalid. HETEROMERA 263 Fam. 62. Tenebrionidae. — Front coxae short, not projecting from the cavities, enclosed l>rhi/i' body is peculiarly shaped in conformity with the curious habit of using the excrement as a covering. The larva is less elon- gate than usual, and has the anus placed on the upper surface, and formed so that the excrement when voided is pushed forward on to the Insect ; here it is retained by means of a slimy matter, and a thick coat entirely covering the creature, is ultimately formed. The larva of Lema melanopa is not uncommon about Cambridge, where it feeds on the leaves of growing corn. It is a remarkable fact that even in one genus the species have some of them this habit, but others not. The species of Crioceris living on lilies — C, merdigera, e.g. — are noted for possessing it; while C. asparagi does not pro- tect itself in this way, but emits fluid from its mouth when dis- turbed. This larva is a serious nuisance in some localities to the cultivators of asparagus. The eggs are deposited on the stems of the plant — as shown in our figure — sometimes in great num- bers. The perfect Insects of many of the Criocerides possess a stridu- lating organ. Two contiguous areas at the base of the last dorsal segment, where they can be rubbed by the tips of the elytra, are slightly elevated and bear very close and fine straight lines. ii. The CAMPTOSOMES, as we have already noticed, are distin- guished by a peculiar structure of the abdomen. This character appears to be connected with a very remarkable habit, viz. the formation of a case to envelop the egg. The tip of the abdomen is somewhat curved downwards, and, in the female, bears a hollow near the extremity ; when an egg is extruded the female holds it in this hollow by means of the hind legs, and •envelops it with a covering said to be excrementitious. When the larva hatches, it remains within this case, and subse- B FIG. 143. — Crioceris asparwjl. A, Eggs in position on stem of asparagus ; B, one egg much enlarged ; C, young larva. Cambridge. 282 COLEOPTERA quently enlarges it by additions from its own body. The beautiful Insects of the genus Cryptoceplialus, which is fairly well represented in Britain, belong to this division. The exotic group Megalopodes is incorrectly placed in Camptosomes ; the side pieces of the prothorax meet in it behind the middle coxae, as they do in Rhynchophora. The species of Megalopodes stridulate by means of an area on the base of the meso-scutellum rubbed by a ridge inside the pronotum, as in the Cerambycidse. iii. The division CYCLICA includes the great majority of Chryo- melidae ; we have not less than 170 species in Britain. The larvae live, like those of Lepidoptera, at the expense of foliage, and the species frequently multiply to such an extent as to be injurious. Some of them are destroyed in great numbers by Hymenopterous parasites, the Braconid genus Perilitus being one of the best known of these ; in some cases the parasite deposits its eggs in either the larva or perfect Insect of the beetle, and the metamorphoses of the parasites in the latter case are some- times, if not usually, completed, the larvae emerging from the living beetles for pupation. iv. The CRYPTOSTOMES, though comparatively few in number of species, include some very remarkable beetles. There are two groups, Hispides and Cassidides. The former are almost peculiar to the tropics and are not represented by any species in the British fauna. The head in this group is not concealed ; but in the Cassidides the margins of the upper surface are more or less expanded, so that the head is usually completely hidden by the expansion of the pronotum. Both the groups are characterised by the antennae being inserted very near together, and by the short claw-joint of the feet. Hispa is one of the most extensive of the numerous genera of Hispides, and is remarkable from the imago being covered on the surface with long, sharp spines. But little is known as to the metamorphosis, beyond the fact already alluded to, that the larvae of several species mine the interior of leaves. The larva of Hispa testacea, according to Ferris,1 makes use of the leaves of Cistus salvifolius in Southern Europe ; it is broad and flat, and possessed of six short legs. The eggs are not deposited by the parents inside the leaves, but are probably attached to various parts of the plant. After hatching, the young larva enters a leaf, and feeds on the parenchyma without rupturing 1 Ann. Soc. Lifyc, x. 1855, p. 260. PHYTOPHAGA CHRYSOMELIDAE 283 the epidermis ; but when it has consumed about three-fourths of the soft interior of the leaf it ruptures the epidermis of the upper surface, and seeks another leaf ; this found, it places itself on the midrib, tears the upper epidermis, arid lodges itself in the leaf. In the case of this second leaf it attacks the parenchyma in the neighbourhood of the petiole, and so forms an irregular tube which has an open mouth, the point of entry. In this tube it undergoes its metamorphosis. Each larva, it is said, always makes use of two leaves, and of two opposed leaves. A know- ledge of the habits of some of the larger of the exotic Hispides would be of much interest. FIG 144. — Pupa of Cassidid beetle (? Aspidomorpha sp.). A, With appendage ex- tended ; B, with the appendage re- posing on the back. New Britain. The Cassidides, in addition to the curious marginal expansion of their upper surface, have the power of withdrawing the head into the thorax, and hence they are often called shield or tortoise- beetles. They exhibit considerable variety in form and colour, and some of them display a peculiar metallic reflection of great delicacy and beauty ; this disappears entirely after death, but it may be restored by thoroughly moistening the dead Insect. The colour, therefore, probably depends on the presence of water in the integument. The larvae of Cassidides are notorious on account of their habit of covering their bodies with dried excrement, for which purpose they are provided with a forked 284 COLEOPTERA CHAP. process at the posterior extremity ; this serves to place the pro- tecting matter in a proper position and to retain it there. The excrement assumes in various species forms so peculiar that triey cannot be considered merely incidental. In several species this covering-matter is like lichen. This is the case with DolicJiotoma palmar um, the larva of which has, in place of the usual fork, a more complex appendage on the back for the purpose of prepar- ing and retaining its peculiar costume. The pupae, too, some- times retain the larval skin. An extremely remarkable pupa of a Cassidid — possibly of the genus Aspidomorpha — was recently found by Dr. Arthur Willey in New Britain (Fig. 144). The back of the pupa is covered with a complex appendage, so that the creature has no resemblance to an Insect ; this appendage is perhaps capable of being moved, or even extended (Fig. 144, A), during life. Whether it may be formed by the retention of portions of the moulted skins of the larva we cannot say with certainty. The most remarkable of the Cassidid coverings yet discovered are those formed by certain small beetles of the tropical Ameri- can genus Porpliyraspis. P. tristis is apparently a common Insect at Bahia, where it lives on a cocoa-palm. The larva is short and broad, and completely covers itself with a very dense coat of fibres, each many times the length of the body, and elaborately curved so as to form a round nest under which the larva lives. On examination it is found that these long threads are all attached to the anal extremity of the Insect, and there seems no alternative to believing that each thread is formed by small pieces of fibre that have passed through the alimentary canal, and are subsequently stuck together, end to end. The process of forming these long fibres, each one from scores of pieces of excrement, and giving them the appropriate curve, is truly remark- able. The fibres nearest to the body of the larva are abruptly curled so as to fit exactly, FIU. 145. — Nest of intes- and make an even surface ; but the outside Se/^fch " <*>«» stand out in a somewhat bushy of Porphyraspis tristis fashion. The construction is much like that of a tiny bird's nest. Senor Lacerda informed the writer that the larva makes a nest as soon as it is hatched. Another Porphyraspis — P. palmarum — has been recorded as PHYTOPHAGA CERAMBYCIDAE forming similar nests on a species of Thrinax in St. Domingo. Candeze says l that when it has completed its growth the larva ejects on to the leaf a quantity of semi-liquid matter, and this, on drying, sticks the nest to the leaf, so that the metamorphosis is effected under shelter. Fam. 79. Cerambycidae (Longicorns). — Form usually ollong, not much curved in outline at the sides; surface very frequently ren- dered dull l)y a very minute hairiness, which often forms a pattern ; antennae usually long, and their insertion much embraced by the eyes. This great family of beetles includes some 12,000 or 13,000 known species. The elegance and variety of their forms and the charm of their colours have caused them to attract much attention, so that it is probable that a larger proportion of the existing species have been obtained than is the case in any other of the great families of Coleoptera. Still it is not likely that one-half of the living forms are known. It is not possible at present to point out any one character of importance to distinguish Cerambycidae from Chrysomelidae, though the members of the two families have, as a rule, but little resemblance in external appearance. Most of them live on, or in, wood, though many are nourished in the stems of her- baceous plants. The larvae live a life of con- cealment, and are soft, whitish grubs with powerful mandibles, and usually with a comparatively small head, which is not much exserted from the thorax. Most of them are without legs, but a good many have three pairs of small legs, and there are numerous cases in which the surface of the body is furnished above or below with swellings believed to act as pseudopods (Fig. 84), and help the larvae to move about in their galleries ; but this is probably not the sole function of these organs, as their surface is varied in character, and often not of a kind that appears specially adapted to assist in locomotion. There is a slight general resemblance between the larvae of Ceram- bycidae and those of Buprestidae, and when the thorax of a Longicorn larva is unusually broad, e.g. Astynomus, this similarity is very pronounced. 1 Mem. Soc. LUye, xvi. 1861, p. 387. -Saperda popul- nea. Britain. 286 COLEOPTERA The modes of life of Cerambycid larvae exhibit considerable variety, and much perfection of instinct is displayed by the larvae, as well as by the mother beetles. The larvae of Saperda populnea are common in certain woods in the South of England in the stems of aspen ; they consume only a small quantity of the interior of the stem, and are probably nourished by an afflux of sap to the spot where they are situated. Elapliidion villosum is called the oak-pruner in North America. The parent beetle lays an egg near the axilla of a leaf-stalk or small stem, and the young larva enters this and feeds on the tender material ; as it grows it enters a larger limb, and makes an incision within this in such a manner that the wood falls to the ground with the larva within it, the dead wood serving subsequently as pabulum and as a shelter, within which the metamorphosis is completed. The species of the American genus Oncideres are called girdle rs, because the parent beetle, after laying an egg in a small branch, girdles this round with a deep incision, so that the portion containing the larva sooner or later falls to the ground. The growth of a Longicorn larva frequently takes more than a year, and under certain circumstances it may be enormously prolonged. Monohammus confusus has been known to issue from wooden furniture in a dwelling-house when the furniture was fifteen years old. Individuals of another Longicorn have issued from the wood of a table, twenty and even twenty-eight years after the felling of the tree from which the furniture was made. Sereno Watson has related a case from which it appears probable that the life of a Longicorn beetle extended over at least forty-five years.1 It is generally assumed that the prolongation of life in these cases is due to the beetle resting quiescent for long after it has completed the metamorphosis. Kecent knowledge, however, renders it more probable that it is the larval life that is pro- longed; the larva continuing to feed, but gaining little or no nutriment from the dry wood in these unnatural conditions. Mr. C. 0. Waterhouse had for some years a Longicorn larva under observation, feeding in this way in the wood of a boot-tree ; 2 the burrows in the wood contained a great deal of minute dust indicating that the larva passed much matter through the ali- mentary canal, probably with little result in the way of nutriment. 1 Packard, 5th Rep. U.S. Ent. Comm. 1890, p. 689. 2 Not a growing tree, but the instrument used for stretching boots. v HYTOPHAGA CERAMBYCIDAE 287 There are numerous Longicorns that bear a great resemblance in form and colour to Insects to which they are not related. Haensch a has noticed that species of the genus Odontocera resemble various Hymenoptera, one species being called 0. braconoides ; he also observed that these Hymenoptera - like Longicorns, instead of withdrawing their underwiiigs under the elytra as beetles generally do, vibrate them rapidly like Hymen- optera. A large number of Longicorns stridulate loudly by rubbing a ridge inside the pronotum 011 a highly specialised, striate surface at the base of the scutellum, and therefore covered up when the Insect is contracted in repose. A few produce noise by rubbing the hind femora against the edges of the elytra, somewhat after the fashion of grasshoppers. In this case there appears to be comparatively little speciality of structure, the femora bearing, however, more or less distinct small granules. The species of the Hawaiian genus Plagithmysus produce sound in both these manners, the thoracic stridulating organ being beautifully de- veloped, while in some species the margin of the elytra and base of the femora are also well adapted for the purpose of sound- production, and in a few species of the genus there are also highly-developed stridulating surfaces on the hind and middle coxae. This is the only case in which a beetle is known to possess more than one set of sound-organs in the imago state. Three divisions of this family are distinguished, viz. — 1. Front coxae large and transverse ; protliorax with, distinct side mar- gins. Sub-fain. 1. PRIONIDES. 2. Front coxae not greatly extended transversely, thorax not margined ; last joint of maxillary palpus not pointed, usually broader (more or less) than the preceding joint. Sub-fun. 2. CKRAMBYCIDES. 3. Front coxae usually round and deeply embedded ; last joint of maxil- lary palpus pointed ; front tibiae with a more or less distinct, slanting groove on the inner side. Sub-fain. 3. LAJIIIDES. The Prionides are on the average considerably larger in size than the members of the other divisions, and they include some of the largest of Insects. The Amazonian Titanus giganteus and the Fijian Macrotoma keros are amongst the most gigantic. Some of the Prionides have a great development of the mandibles in the male sex analogous to that we have already noticed in Lucauidae. The larvae of the large Prionides appear in various parts of the world to have been a favourite food with native 1 Berlin, cnt. Zeitschr. xli. 1896, SB. p. 22. 288 COLEOPTERA CHAP. tribes, and Lumholz states that they are really good eating. In consequence of the destruction of forests that has progressed so largely of late years these gigantic Prionides have become much rarer. Several aberrant forms are included in Prionides. The genus Parandra has five-jointed tarsi ; the third joint being much smaller than usual, so that the fourth joint is not concealed by it. The Brazilian Hypocephalus armatus was for long a subject of dispute as to its natural position, and was placed by different authorities in widely -separated families of Coleoptera. The structure of this aberrant Longicoru seems to be only explicable on the hypothesis of warfare amongst the males.1 Nothing is, however, known as to the habits and history of the Insect, and only one or two specimens of the female have yet been obtained. The family Spondylidae has been proposed for some of these aberrant Longicorns, but as it includes but very few, and highly discrepant, species, it is neither natural nor of much use for systematic purposes. The Lamiides are the most highly specialised division of the Longicorns, and includes the larger number of the species. The front of the head is usually placed at right angles to the vertex, and in some cases (groups Hippopsini, Spalacopsini) it is strongly inflexed, so that the mouth is placed on the under side of the head. The extension of the eyes round the antennae is accom- panied by very curious shapes of those organs, and not infrequently each eye is divided into two more or less widely- separated parts, so that the Insect has, on the external surface, four eyes. Series VI. Rhynchophora. Head more or less prolonged in front to form a snout or beak, called rostrum. Tarsi four -jointed, usually at least the third joint broad and densely pubescent beneath. This enormous series includes about 25,000 species, and as may well be imagined shows a great variety of structure amongst its forms. The vast majority may, however, be readily recognised by the two characters mentioned above. There are some cases in which the beak is indistinct, and others in which the tarsi are 1 Sharp, Ann. Soc. ent. Eehjiqite, xxviii. 1884, CK. p. cvii. RHYNCHOPHORA 289 five-jointed (Dryophthorus), and even slender (Platypides). In these cases a close examination shows that the gular region on the middle of the back of the under surface of the head cannot be detected, and that the back of the prosternum is very strongly consolidated by the side-pieces of the thorax meeting together and being very firmly joined behind the coxae. The beak is in the great majority perfectly distinct, though it varies so extremely in form that it can only be briefly described by saying that it is a prolongation of the head in front of the eyes, or that the antennae are inserted on its sides near to, or far from, the tip. It has been ascertained in many cases that the rostrum is used by the female to assist in placing the eggs in suitable places, a hole being bored with it ; in some cases it is also used to push the egg far into the hole in which it has previously been placed by the ovipositor ; but there are many forms in which it is fairly certain that it is not so used. What purpose it serves in the male is totally unknown. In many members of the series, the rostrum differs in form in the two sexes, and in most, if not in all, these cases it is clear that the distinctions tend in the direction of making the beak of the female more efficient for the mechanical purpose we have mentioned. It was proposed by Leconte and Horn to separate this series from all the other Coleoptera as a primary division, and they looked on it as of lower or more imperfect structure. Packard has very properly protested against FlG- 14J.—&tgnorittiu monachus ?. . . J .r Madagascar. A, The imago ; B, front this interpretation ; and there Of pronotum, head, and rostrum. seems to be no reason whatever for considering the Rhynchophora as " lower " than other beetles ; indeed we should be inclined to place such forms as Calandrides VOL. vi U 290 COLEOPTERA amongst the most perfect of Insects ; their external structure (as shown by Eugnoristus monackus, Fig. 147) being truly admirable. Only four families of Ehynchophora can be at present accepted as satisfactory ; one of these — Curculionidae — includes an enormous majority of the whole series. Though it is probable that it will ultimately be divided into several families, the attempts to that end that have already been made are not satisfactory. Fam. jBO. Anthribidae. — Palpi usually not covered, but dis- tinct and flexible. Antennae often long, not elbowed, the first joint not very long. Third joint of tarsus small, usually much concealed Toy being embraced by the second joint. Pygidium exposed; pro- pygidium deeply grooved in the middle. This family includes 800 or more species, which are mostly tropical ; it is very sparsely represented in the faunas of Europe and North America. It is quite distinct from Curculionidae with which it was formerly associated. It contains many graceful Insects having a certain resemblance with Longicorns on account of the large development of the antennae. The habits and meta- morphoses are but little known. It seems probable that many species find their nutriment in old wood or boleti. The larvae of some genera (Cratoparis and Araeocerus) have legs, but in others the legs are wanting, and the larvae are said to completely resemble those of Curculionidae. In the larva of our tiny British species, Choragus sheppardi, the legs are replaced by three pairs of thoracic, sac-like pseudopods. This Insect makes burrows in dead branches FIG. 148. — Platyrhinus lati- nf horvthn,,,, Thp larvap nf thp o-pnim rostris, Anthribidae. Britain. C A, the perfect insect ; B, Brachytarsus have been ascertained to prey on Coccidae. Fam. 81. Curculionidae ( Weevils'}. — The beak of very variable length and thickness; the palpi small, nearly ahvays concealed within the mouth, short, and rigid. Labrum absent. Antennae of the majority elbowed, i.e. with the basal joint longer, and so formed that when it is laterally extended the other joints can be placed in a forward direction. This enormous family includes v RHYNCHOPHORA CURCULIONIDAE 2QI about 20,000 known species, and yet a large portion of the species yearly brought from the tropics still prove to be new. The rostrum or beak exhibits excessive variety in form, and is in many cases different in the sexes ; in this case it is usually longer and thinner in the female. As the rostrum is one of the chief characters by which a member of the family may be recognised, it is necessary to inform the student that in certain forms (the Australian Amycterides, e.g^) the organ in question may be so short and thick that it is almost absent. In these cases the Insect may be identified as a Curculionid by the gular area being absent on the under side of the head, and by the concealment of the palpi. The tarsi are usually of the same nature as those of Thytophaga, already described, but the true fourth joint is less visible. In the Brachycerides this joint is not present, and the third joint is not lobed. The palpi are flexible and more or less exserted in a very few species (Ehynchitides) ; in Ehinoma- cerides there is also present a minute labrum. The front coxae are deeply embedded, and in many forms the prosternum is peculiar in structure ; the side-pieces (epimera) meeting at the back of the prosternum in the middle line. This, however, is not universal in the family, and it occurs in some other beetles (e.g., Megalopodides of the Phytophaga). The larvae are without legs. They are vegetarian, the eggs being deposited by the mother-beetle in the midst of the food. These larvae may be distinguished from those of Longicorns by the general form, which is sub-cylindric or rather convex, not flattened, and more particularly by the free, exserted head, the mouth being directed downwards ; the attitude is generally a curve, and the anterior part of the body is a little the thicker. No part of plants is exempt from the attacks of the larvae of Curculionidae ; buds, twigs, leaves, flowers, fruits, bark, pith, roots and galls may each be the special food of some Curculionid. Certain species of the sub-families Rhynchitides and Attelabides prepare leaves in an elaborate manner to serve as food and dwelling for their young. If young birches, or birch bushes from 5 to 10 feet in height, be looked at in the summer, one may often notice that some of the leaves are rolled so as to form, each one, a little funnel. This is the work of Rhynchites (or Deporaus) letulae, a little Curculionid beetle (Fig. 149). An inspection of one of these funnels will show that it is very skilfully constructed. The 292 COLEOPTERA whole of a leaf is not used in the formation of a funnel, cuts being made across the leaf in suitable directions. The beetle stand- ing on a leaf, as shown in the figure, proceeds to cut with its mandibles an incision shaped like an erect S, commencing at a certain part of the circumference, and ending at the midrib of the leaf; the beetle then goes to the other side of the midrib, and continues its incision so as to form another S-like curve con- siderably different from the first ; being prostrate and less abrupt. Thus the blade of the leaf is divided into two halves by certain curved incisions, the midrib remaining intact. The little funnel- FIG. 149. — The leaf-rolling of Rhynchites betulae. Britain. A, Female beetle, magnified ; B, the beetle forming the first incision on a leaf ; C, the completed roll. (B and 6 after Debey.) twister now commences to roll up the leaf to form the funnel ; and this part of the work is greatly facilitated by the shape of the incisions. Going back to the spot where it commenced work, by the aid of its legs it rolls one side of the leaf round an ideal axis, somewhat on the same plan as that adopted by a grocer in form- ing a paper-funnel for sugar. The incisions are found to be just of the right shape to make the overlaps in the rolling, and to re- tain them rolled-up with the least tendency to spring back. After some other operations destined to facilitate subsequent parts of its task, the beetle enters the rolled-up part of the leaf and brings it more perfectly together; it again comes out and, pursuing a different system, holds on with the legs of one side of the body v RHYNCHOPHORA — CURCULIONIDAE 293 to the roll, and with the other legs drags to it the portion of the leaf on the other side of the midrib so as to wrap this part (i.e. the result of its second incision) round the part of the funnel already constructed. This being done the Insect again enters the funnel, bites three or four small cavities on the inside of the leafy wall and deposits an egg in each. Afterwards it emerges and fits the overlaps together in a more perfect manner so as to somewhat contract the funnel and make it firmer ; then proceeding to the tip, this is operated on by another series of engineering processes and made to close the orifice ; this part of the opera- tion being analogous to the closing by the grocer of his paper- funnel after the sugar has been put in. The operation of the beetle is, however, much more complex, for it actually makes a sort of second small funnel of the tip of the leaf, bends this in, and retains it by tucking in some little projections. The work, which has probably lasted about an hour, being now completed, the creature takes a longer or shorter rest before commencing another funnel. We have given only a sketch of the chief points of the work, omitting reference to smaller artifices of the craft master ; but we may remark that the curved incisions made by the beetle have been examined by mathematicians and duly extolled as being conducted on highly satisfactory mathematical principles. It is impossible at present for us to form any conception as to the beetle's conceptions in carrying out this complex set of operations. Our perplexity is increased if we recollect its life-history, for we then see that neither precept or example can have initiated its proceedings, and that imitation is out of the question. The eggs hatch in their dark place, giving rise to an eyeless maggot, which ultimately leaves the funnel for the earth. The parts of this maggot subsequently undergo complete change to produce the motionless pupa of entirely different form, from which emerges the perfect Insect. Hence the beetle cannot be con- sidered to have ever seen a funnel, and certainly has never witnessed the construction of one, though, when disclosed, it almost immediately sets to work to make funnels on the complex and perfect system we have so imperfectly described. More general considerations only add to the perplexity we must feel when reflecting on this subject. Why does the Insect construct the funnel at all ? As a matter of protection it appears to be of little use, for the larvae are known to suffer from the attacks 294 COLEOPTERA CHAP. of parasites as other Insects do. We have not the least reason for supposing that this mode of life for a larva is, so far as utility is concerned, better than a more simple and usual one. Indeed, extraordinary as this may appear, it is well known that other species of the same genus adopt a simple mode of life, laying their eggs in young fruits or buds. We think it possible, however, that a knowledge of the mode of feeding of this larva may show that a more perfect nutrition is obtained from a well- constructed cylinder, and if so this would to a slight extent satisfy our longing for explanation, though throwing no light whatever on the physiology or psychology of the artificer, and leaving us hopelessly perplexed as to why a beetle in ages long gone by should or could adopt a mode of life that by long pro- cesses of evolution should, after enormous difficulties have been overcome, attain the perfection we admire.1 Fam. 82. Scolytidae. — Eostrum extremely short, broad ; tibiae frequently denticulate externally; antennae short, with a broad club. This family is not at all sharply distinguished from certain groups of Curculionidae (from Cossonides e.g.}, but as the species have somewhat different habits, and in the majority of cases can be readily distinguished, it is an advantage to separate the two families. About 1400 species are at present known. Most of them are wood- and bark -feeders ; some bore into hard wood ; a few mine in twigs or small branches of trees, but the majority live in the inner layers of the bark ; and this also serves as the nidus of the larvae. A small number of species have been found to inhabit the stems of herbaceous plants, or to Live in dry fruits. Owing to their retiring habits they are rarely seen except by those who seek them in their abodes, when they may often be found in great profusion. The mother-beetle bores into the suitable layer of the bark, forming a sort of tunnel and depositing eggs therein. The young larvae start each one a tunnel of its own, diverging from the parent tunnel ; hence each batch of larvae produces a system of tunnels, starting from the parents' burrow, and in many species these burrows are charac- 1 For a more extensive account of Rhynchites betulae and others refer to Wasmann. Der Trichterwickler, Minister, 1884, and Debey, £eitraye zur Lcbens- und Entwickelungs-geschichte . . . der Attelabiden, Bonn, 1846. The first in- cludes an extensive philosophical discussion ; the second is a valuable collection of observations. v RHYNCHOPHORA SCOLYTIDAE BRENTHIDAE 295 teristic in form and direction, so that the work of particular Scolytids can be recognised by the initiated. The Platypides bore into the wood of trees and stumps ; they are chiefly exotic, and little is known about them. They are the most aberrant of all Ehynchophora, the head being remarkably short, flat in front, with the mouth placed on the under surface of the head, there being no trace of a rostrum : the tarsi are elongate and slender, the third joint not being at all lobed, while the true fourth joint is visible. Hence they have not the appearance of Ehynchophora. Some authorities treat the Platypides as a distinct family. Some of the members of the group Tomicides also bore into the wood. Eecent observations have shown that there is an important feature in the economy of certain of these wood- borers, inasmuch as they live gregariously in the burrow, and feed on peculiar fungi that develop there, and are called ambrosia. According to Hubbard,1 some species cultivate these fungi, making elaborate preparations to start their growth. The fungi, however, sometimes increase to such an extent as to seal up the burrows, and kill the Insects by suffocation. Scolytidae sometimes multiply to an enormous extent, attack- ing and destroying the trees in \vooded regions. Much dis- cussion has taken place as to whether or not they are really injurious. It is contended by one set of partisans that they attack only timber that is in an unhealthy, dying, or dead con- dition. It may be admitted that this is usually the case ; yet when they occur in enormous numbers they may attack timber that is in a sort of neutral state of health, and so diminish its vigour, and finally cause its destruction. Hence it is of great importance that they should be watched by competent foresters. The larvae of Scolytidae are said to completely resemble those of Curculionidae : except in the group Platypides, where the body is straight and almost cylindrical, and terminates in an oblique truncation bearing a short hard spine.2 Fam. 83. Brenthidae. — Form elongate ; rostrum straight, directly continuing the long axis of the body, often so thick as to form an elongate head; antennae not elbowed. The Brenthidae form a family of about 800 species, remarkable for the excessive 1 Bull. U.S. Dep. Agric. ent. New series, No. 7, 1897. - Ferris, Ann. Sci. Nat. (2) xiv. 1840, p. 89, pi. iii. 296 COLEOPTERA length "and slenderness of some of its forms, and for the extreme difference in the sexes that frequently exists. It is well represented in the tropics only, and very little is known as to the natural history and development. These beetles are stated to be wood-feeders, and no doubt this is correct in the case of the majority of the species ; but Mr. Lewis observed in Japan that Zemioses celtis and Cyphagogus segnipes are pre- daceous, and enter the burrows B C , of wood-boring Insects to search FIG. loO. — J^upsalis minuta. North America. A, Larva ; B, pupa ; C, for larvae as prey : they are female imago; D, head of male. (After very much modified in structure to permit this ; and as the other members of the group Taphroderides are similar in structure, it is probable that they are all predaceous. Nothing what- ever is known as to the larval history of these carnivorous forms. Indeed an uncertainty, almost complete, prevails as to the early stages of this family. Eiley has given a sketch of a larva which he had no doubt was that of Eupsalis minuta, the North American representative of the family ; if he is correct the larva differs from those of Curculionidae by its elongate form, and by the possession of thoracic legs : these, though small, are three-jointed. Descriptions, supposed to be those of Brenthid larvae, were formerly published by Harris and Motschoulsky ; but it is now clear that both were mistaken. In the higher forms of Brenthidae the rostrum of the female is perfectly cylindrical and polished, and the mandibles are minute, hard, pointed processes placed at its tip. This organ is admirably adapted to its purpose ; it being used for boring a hole in wood or bark, in which an egg is subsequently deposited. The males in these cases are extremely different, so that considerable curiosity is felt as to why this should be so. In some cases their head is thick, and there may be no rostrum, while large powerful mandibles are present. In other cases the rostrum is slender, but of enormous length, so that it may surpass in this respect the rest of v HRENTHIDAE AGLYCYDERIDAE 297 the body, although this itself is so drawn out as to be quite exceptional in the Insect world : l the antennae are inserted near the tip of the rostrum instead of near its base, as they are in the female. The size of the males is in these cases usually much larger than that of the female.- The males of some species fight ; they do not, however, wound their opponent, but merely frighten him away. In Eupsalis it appears that the rostrum of the female is apt to become fixed in the wood during her boring operations ; and the male then extricates her by pressing his heavy prosternum against the tip of her abdomen ; the stout forelegs of the female serve as a fulcrum and her long body as a lever, so that the effort of the male, exerted at one extremity of the body of the female, produces the required result at the other end of her body. The New Zealand Brenthid, Lasiorliynchus barbicornis, exhibits sexual disparity in an extreme degree : the length of the male is usually nearly twice that of the female, and his rostrum is enormous. It is at present impossible to assign any reason for this ; observations made at the request of the writer by Mr. Helms some years ago, elicited the information that the female is indefatigable in her boring efforts, and that the huge male stands near by as a witness, apparently of the most apathetic kind. Coleoptera of uncertain position. There are three small groups that it is impossible at present to place in any of the great series of beetles. Fam. 84. Aglycyderidae. — Tarsi three-jointed, the second joint lobed ; head not prolonged to form a beak. The two most important features of Ehynchophora are absent in these Insects, while the other structural characters are very imperfectly known, many parts of the external skeleton being so completely fused that the details of structure are difficult of appreciation. West- wood considered the tarsi to be really four-jointed, but it is not 1 In the males of the genus Cedeocera the tips of the elytra are drawn out into processes almost as long as the elytra themselves, and rivalling the forceps of earwigs. 2 The stature of the individuals of the same species is, in some of these Brenthidae, subject to extreme variation, especially in the males, some individuals of which — in the case of Brenthus anchorago — are five times as long as others. 298 COLEOPTERA CHAP. at all clear that the minute knot he considered the third joint is more than the articulation of the elongate terminal joint. The family consists only of two or three species of Aglycyderes, one of which occurs in the Canary Islands, and one or two in New Zealand and New Caledonia. The former is believed to live in the stems of Euphorbia canariensis ; FIG. 151. — Aglycyderes setifer. Canary Islands, a New Zealand species has A, Imago ; B, tarsus according to Westwood : -i x> j • j.- C, according to nature; D, maxilla; E, been foimd m Connection labium. with the tree-fern Cyathea dealbata. Fam. 85. Proterhinidae. — Tarsi three-jointed, the second joint lobed ; head of the male scarcely prolonged, but that of the female forming a definite rostrum.; maxillae and ligula entirely covered by the mentum. As in the preced- ing family the sutures on the under side of the head and pro- sternum cannot be detected. The minute palpi are entirely enclosed in the buccal cavity. There is a very minute true third joint of the tarsus, at the base of the ter- minal joint, concealed between the lobes of the second joint. The family consists of the genus Pro- terhinus ; it is confined to Hawaiian Islands, where these In- sects live on dead wood in the native forests. The genus is numerous in species and individuals. Strepsiptera (or Rhipiptera, Stylopidae). — Male small or minute; prothorax extremely small; mesothorax moderate, the elytra reduced to small, free slips ; metathorax and wings very large ; nervuration of the latter radiating, without cross nervules. Female a mere sac, with one extremity smaller and forming a sort of neck or head. These curious Insects are parasitic in the interior of the FIG. 152. — Proterhinvs Jecontel. Ha- waiian Islands. A, Male ; B, female ; C, front foot, more magnified. STREPSIPTERA 299 other Insects, of the Orders Hymenoptera and Hemiptera. Their structure and their life-histories entitle them to be ranked as the most abnormal of all Insects, and entomologists are not agreed as to whether they are aberrant Coleoptera or a distinct Order. The newly-hatched larva is a minute triunguliii (Fig. 154), somewhat like that of Meloe; it fixes itself to the skin of the larva of a Hymenopterous Insect, penetrates into the interior, and there undergoes its metamorphoses, the male emerg- ing to enjoy a brief period of an abnormally active, indeed agitated, existence, while the female never moves. It is important to note that these Strepsiptera do not, like most other internal parasites, produce the death of their hosts ; these complete their metamorphosis, and the development of the parasite goes on simultaneously with that of the host, so that the imago of the . ) FIG. 15-3. — Sexes of Strep- siptera. A, Male of Stylops dalii (after Cur- tis) ; B, female of Xenos rossii (after von Siebold). Strepsipteron is found only in the imago of the host.1 After the young Stylops has entered its host it feeds for a week or so 011 the fat-body (apparently by a process of suction), then moults and assumes the condition of a footless maggot, in which state it remains till growth is completed. At the latter part of this period the history diverges according to sex ; the female undergoes only a slight metamorphic development of certain parts, accompanied apparently by actual degradation of other parts ; while the male goes on to pupation, as is normal in Insects. (We may remark that the great features of the development of the sexes are parallel with those of Coccidae in Hemiptera.) When the Hymenopterous larva changes to a pupa, the larva of the Strepsipteron pushes one extremity of its body between two of the abdominal rings of its host, so that this extremity becomes external, and in this position it completes its metamorphosis, the 1 This remark applies to the Strepsiptera parasitic on Hymenoptera : nothing whatever is known as to the life-histories of the species that attack Hemiptera. 300 STREPSIPTERA CHAP. male emerging very soon after the host has become an active winged Insect, while the female undergoes no further change of position, lout becomes a sac, in the interior of which young develop in enormous numbers, finally emerging from the mother- sac in the form of the little triungulins we have already mentioned. This is all that can be given at present as a general account ; many points of the natural history are still obscure, others have been merely guessed ; while some appear to differ greatly in the different forms. A few brief remarks as to these points must suffice. Bees carrying, or that have carried, Strep- siptera, are said to be stylopised (it being a species of the genus Stylops that chiefly infests bees); the term is also used with a wider application, all Insects that carry a Strepsip- terous parasite being termed stylopised, though it may be a Strepsipteron of a genus very different from Stylops that attacks them. The development of one or more Strepsiptera in an Insect usually causes some deformity in the abdomen of its host, and effects consider- able changes in the condition of its internal organs, and also in some of the external char- acters. Great difference of opinion prevails as to what these changes are ; it is clear, how- FI<;. 154.— Young larva ever, that they vary much according to the of Stylops on a bee's- • -, -, -j- ,-, /. hair. Greatly magni- species, and also according to the extent of fled. (After Newport.) the stylopisation. Usually only one Stylops is developed in a bee ; but two, three, and even four have been observed : * and in the case of the wasp, Polistes, Hubbard has observed that a single individual may bear eight or ten individuals of its Strepsipteron (Xenos, n. sp. ?). There is no exact information as to how the young triungulius find their way to the bee -larvae they live in. Here again the discrepancy of opinion that prevails is probably due to great 1 Although not an invariable, it seems that it is a general rule that the Stylojjs produced from the body of one individual are all of one sex ; it has even been stated that female bees produce more especially female Stylops, and male bees male Stylops. If any correlation as to this latter point exist, it is far from general. STY LOPS 301 difference really existing as to the method. When a Stylops carried by an Insect (a Hymenopteron, be it noted, for we have no information whatever as to Hemiptera) produces young, they cover the body of the host as if it were powdered, being excessively minute and their numbers very great ; many hundreds, if not thousands, of young being produced by a single Stylops. The species of the wasp genus Polistes are specially subject to the attacks of Stylops ; they are social Insects, and a stylopised specimen being sickly does not as a rule leave the nest ; in this case the Stylops larva may therefore have but little difficulty in finding its way to a Hymeuopterous larva, for even though it may have to live for months before it has the chance of attaching itself to a nest -building female, yet it is clearly in the right neighbourhood. The bee genus Andrena has, however, quite different habits ; normally a single female makes her nest under- ground ; but in the case of a stylopised female it is certain that no nest is built, and no larvae produced by a stylopised example, so that the young triungulins must leave the body of the bee in order to come near their prey. They can be active, and have great powers of leaping, so that it is perhaps in this way possible for them to attach themselves to a healthy female bee. We have still only very imperfect knowledge as to the struc- ture and development of Strepsip- tera. Indeed but little informa- tion has been obtained since 1843.1 Before that time the mature female was supposed to be a larva, and the triungulins found in it to be parasites. Although the erroneous character of these views has been made clear, the problems that have been sug- gested present great difficulties. Apparently the change from the triungulin condition (Fig. 154) to the parasitic larvae (Fig. 1 5 5, A, B) is extremely great and abrupt, and it appears also that during 1 Von Siebold, Arch. Naturges. ix. 1843, pp. 137-161. NassonofFs recent paper is in Russian, but so far as \ve can gather (cf. Zool. Centralbl. i. 1894, p. 766), it does not add greatly to the data furnished by von Siebold. FIG. 155. — Portion of early stages of Xenos rossii. (After von Siebold.) A, Small male larva ; B, small female larva ; C, full-growu male larva ; D, full-grown female larva ; E, the so- called " cephalothorax " and adjacent segment of adult female. (The newly- hatched larva is very much like that of Stylops shown in Fig. 154.) 302 STREPSIPTERA the larval growth considerable sexual differentiation occurs (Fig. 155, C, D) ; details are, however, wanting, and there exists but little information as to the later stages. Hence it is scarcely a matter for surprise that authorities differ as to which is the head and which the anal extremity of the adult female. Von Siebold apparently entertained no doubt as to the part of the female that is extruded being the anterior extremity ; indeed he called it a cephalo thorax. Supposing this view to be correct, we are met by the extraordinary facts that the female extrudes the head for copulatory purposes, that the genital orifice is placed thereon, and that the young escape by it. Meinert l contends that the so-called cephalothorax of the adult is the anal extremity, and that fertilisation and the escape of the young are effected by the natural passages, the anterior parts of the body being affected by a complete degeneration. Nassonoff, in controversion of Meinert, has recently pointed out that the " cephalothorax " of the young is shown by the nervous system to be the anterior extremity. It still remains, however, to be shewn that the " cephalothorax " of the adult female corresponds with that of the young, and we shall not be surprised if Meinert prove to be correct. The internal anatomy and the processes of oogenesis appear to be of a very unusual character, but their details are far from clear. Brandt has given some particulars as to the nervous system ; though he does not say whether taken from the male or female, we may presume it to be from the former ; there is a supra -oesophageal ganglion, and near it a large mass which consists of two parts, the anterior repre- senting the sub-oesophageal and the first thoracic ganglia, while the posterior represents two of the thoracic and most of the abdominal ganglia of other Insects ; at the posterior extremity, connected with the other ganglia by a very long and slender commissure, there is another abdominal ganglion.2 It is a matter of great difficulty to procure material for the prosecution of this study ; the fact that the instars to be observed exist only in the interior of a few Hymenopterous larvae, which in the case of the bee, Andrena, are concealed under ground ; and in the case of the wasps, Polistes, placed in cells in a nest of wasps, adds greatly to the difficulty. It is therefore of interest to know that Strepsiptera occur in Insects with incomplete 1 Eut. Meddel. v. 1896. p. 148, and Ov. Danske Selsk. 1896, p. 67. 2 Horae Soc. cut. liuss. xiv. 1879, p. 14. STYLO PS 303 tb- raeus) with a strep- dorsal plates of the wasp's abdomen being removed, a, Projec- tion of Part of the parasite; b, line in- dicating the position °[ *e removed Dorsal metamorphosis. They have been observed in several species of Homoptera ; and the writer has a large Pentatomid bug of the genus Collided, , which bears a female Strepslpteron apparently of large size. This bug : is abundant and widely distributed in Eastern Asia, and it may prove compara- tively easy to keep stylopised examples under observation. Both v. Siebold and Xassonoff think parthenogenesis occurs in Strepsiptera, but there appear to be no facts to warrant this supposition. Von Siebold speaks of the phenomena of Strepsipterous reproduction as paedogenesis, or pseudo- j • i •,, paedogenesis, but we must agree with Meiiiert that they cannot be so classed. m i « ax • , T f i The males of Strepsiptera live for only a very short time, and are very difficult of observation. According to Hubbard the males of Xenos dash about so rapidly that the eye cannot see them, and they create great agitation amongst the wasps in the colonies of which they are bred. Apparently they are produced in great numbers, and their life consists of only fifteen or twenty minutes of fiery energy. The males of Stylops are not exposed to such dangers as those of Xenos, and apparently live somewhat longer — a day or two, and even three days are on record. The individuals of Andrena parasitised by Stylops are apparently greatly affected in their economy and appear earlier in the season than other individuals ; this perhaps may be a reason, coupled with their short lives, for their being comparatively rarely met with by entomologists. It is not possible at present to form a valid opinion as to whether Stylopidae are a division of Coleoptera or a separate Order. Von Siebold considered them a distinct Order, and Xassonoff, who has recently discussed the question, is also of that opinion. 1 Named by Mr. Distant Cnllidea baro ; according to the Brussels catalogue of Hemiptera, Chrysocoris grandis var. baro. CHAPTER VI LEPIDOPTERA OK BUTTERFLIES AND MOTHS Order VI. Lepidoptera. Wings four ; body and wings covered with scales usually varie- gate in colour, and on the body frequently more or less like hair : nervures moderate in number, at the periphery of one wing not exceeding fifteen, but little irregular ; cross- nervules not more than four, there being usually only one or two closed cells on each iving, occasionally none. Imago with mouth incapable of biting, usually forming a long coiled proboscis capable of protrusion. Metamorphosis great and, abrupt ; the wings developed inside, the. body ; the larva with large or moderate head and strong mandibles. Pupa with the appendages usually adpressed and cemented to the body so that it presents a more or less even, horny exterior, occasionally varied by projections that are not the appendages and that may make the form very irregular : in many of the smaller forms the appendages are only imperfectly cemented to the body. LEPIDOPTERA, or butterflies and moths, are so far as ornament is concerned the highest of the Insect world. In respect of intelligence the Order is inferior to the Hymenoptera, in the mechanical adaptation of the parts of the body it is inferior to Coleoptera, and in perfection of metamorphosis it is second to Diptera. The mouth of Lepidoptera is quite peculiar ; the pro- boscis— the part of the apparatus for the prehension of food — is anatomically very different from the proboscis of the other Insects that suck, and finds its nearest analogue in the extreme elongation of the maxillae of certain Coleoptera, e.g. Nemognatha. LEPIDOPTERA 305 The female has no gonapophyses, though in certain excep- tional forms of Tineidae, there are modifications of structure connected with the terminal segments, that have as yet been only imperfectly investigated. As a rule, the egg is simply deposited on some living vegetable and fastened thereto. Lepidoptera are the most exclusively vegetarian of all the Orders of Insects ; a certain number of their larvae prey on Insects that are themselves filled with vegetable juices (Coccidae, Fia. 157. — Metamorphosis of a Lepidopteroii (Rhegmatophila alpina, Notodontidae). (After Poujade, Ann. Soc. ent. France, 1891.) Europe. A, Egg : B, young larva, about to moult ; C, adult larva ; D, head and first body-segment of adult larva, magnified ; E, pupa, x f ; F, male moth in repose ; G, female moth in repose. Aphidae) and a very small number (Tinea, etc.) eat animal matter. In general the nutriment appears to be drawn ex- clusively from the fluids of the vegetables, the solid matter passing from the alimentary canal in large quantity in the form of little pellets usually dry, and called frass. Hence the quantity of food ingested is large, and when the individuals unduly increase in number, forest trees over large areas are sometimes completely defoliated by the caterpillars. Lepidoptera pass a larger portion of their lives in the pupal stage than most other Insects do ; frequently during nine months of the year the Lepidopteroii may be a pupa. In other Orders of VOL. VI X 306 LEPIDOPTERA Insects it would appear that the tendency of the higher forms is to shorten the pupal period, and when much time has to be passed between the end of the feeding up of the larva and the appearance of the imago, to pass this time as much as possible in the form of a resting-larva, and as little as may be in the form of a pupa ; in Lepidoptera the reverse is the case ; the resting-larva period being usually reduced to a day or two. Hence we can understand the importance of a hard skin to the pupa. There are, however, numerous Lepidopterous pupae where the skin does not attain the condition of hardness that is secured for the higher forms by the chitinous exudation we have mentioned ; and there are also cases where there is a pro- longed resting-larva period: for instance Galleria mellonella spins a cocoon in the autumn and remains in it as a resting larva all the winter, becoming a pupa only in the spring. In many of these cases the resting-larva is protected by a cocoon. It is probable that the chief advantage of the perfect chitinous exudation of the Lepidopterous pupa is to prevent the tiny, complex organisation from the effects of undue transpiration. Bataillon has suggested that the relation of the fluid contents of the pupa to air and moisture are of great importance in the physiology of metamorphosis. The duration of life is very different in various forms of Lepidoptera. It is known that certain species (Uphestia kuehniella, e.g^} may go through at least five generations a year. On the other hand, certain species that feed on wood or roots may take three years to complete their life-history ; and it is probable that some of the forms of Hepialidae are even longer lived than this. Lepidoptera have always been a favourite Order with ento- mologists, but no good list of the species has ever been made, and it would be a difficult matter to say how many species are at present known, but it can scarcely be less than 50,000. In Britain we have about 2000 species. The close affinity of the Order with Trichoptera has long been recognised : Reaumur considered the latter to be practically Lepidoptera with aquatic habits, and Speyer pointed out the existence of very numerous points of similarity between the two. Brauer emphasised the existence of mandibles in the nymph of Trichoptera as an important distinction : the pupa vi EXTERNAL STRUCTURE 307 of Micropteryx (Fig. 211) has however been recently shown to be similar to that of Trichoptera, so that unless it should be decided to transfer Micropteryx to Trichoptera, and then define Lepidoptera and Trichoptera as distinguished by the condition of the pupa, it would appear to be very difficult to retain the two groups as distinct. Structure of Imago. — The head of a Lepidopteron is in large part made up of the compound eyes ; in addition to these it frequently bears at the top a pair of small, simple eyes so much concealed by the scales as to cause us to wonder if seeing be carried on by them. The larger part of the front of the head is formed by the clypeus, which is separated by a well- FIG. 158. — External structure of a female butterfly, Anosia plexippus. (After Scudder.) a, Base of antenna ; b, pronotum ; 62, scutum of mesothorax ; c, clypeus ; ex, coxa ; d, scutellum ; dl, scutellum of metathorax ; e, post-scutellum ( = base of phragma) ; em, epimeron ; ep, episternum ; f, scutum of metathorax ; m, basal part of pro- boscis ( = maxilla) ; o, eye ; p, labial palp ; r, mesosternum ; s, prothoracic spiracle ; t, tegula ; tr, trochauter ; 1-9, dorsal plates of abdomen. marked line from the epicranium, the antennae being inserted on the latter near its point of junction with the former. There is sometimes (Saturnia, Castnia) on each side of the clypeus a deep pocket projecting into the head-cavity. The other parts of the head are but small. The occipital foramen is very large.1 The antennae are always conspicuous, and are very various in form ; they are composed of numerous segments, and in the males of many species attain a very complex structure, especially in Bombyces and Psychidae ; they doubtless function in such cases as sense-organs for the discovery of the female. The largest and most important of the mouth-parts are the maxillae and the labial palpi, the other parts being so small as to render their detection difficult. The labrum is a very short, 1 Kellogg, Kansas Quarterly, ii. 1893, p. 51, plate II. 308 LEPIDOPTERA comparatively broad piece, visible on the front edge of the clypeus ; its lateral part usually forms a prominence which has often been mistaken for a mandible ; Kellogg has applied the term " pilifer " to this part. In the middle of the labrum a small angular or tongue-like projection is seen just over the middle of the base of the proboscis ; this little piece is considered by several authorities to be an epipharynx. MANDIBLES. — Savigny, Westwood, and others considered the parts of the labrum recently designated pilifers by Kellogg to be the rudimentary mandibles, but Walter has shown that this FIG. 159. — Mouth of Lepidoptera. Tiger-moth, Arctia caja. A, Seen from front ; B, from front and below, a, Clypeus ; b, labrum ; c, epipharynx ; d, mandibnlar area ; d', prominence beneath mandibular area ; e, one side of haustelluni or pro- boscis ; /, maxillary palp ; g, labial palp. is not the case.1 The mandibles are usually indistinguish- able, though they, or some prominence possibly connected with them,2 may frequently be detected in the neighbourhood of the pilifers ; they are, according to Walter, largest and most perfectly developed in Eriocephdla, a genus that was not dis- tinguished by him from Micropteryx and was therefore termed " niedere Micropteryginen," i.e. lower Micropteryges. The opinion entertained by Walter that Micropteryx proper (his " hohere Micropteryginen ") also possesses rudimentary mandibles is considered by Dr. Chapman, no doubt with reason, to be erroneous.3 The mandibles, however, in the vast majority of Lepidoptera can scarcely be said to exist at all in the imago ; there being only an obtuse projection — - without trace of 1 Jena. Zeitschr. Naturw. xviii. 1885, p. 751. '-' The writer is not quite convinced that the supposed mandibles of these Macro- lepidoptera are really entitled to be considered as such. 3 Tr. ent. Soc. London, 1893, p. 263. MOUTH-PARTS 309 articulation — ou each side of the labrum ; and even this pro- jection is usually absent. Meinert recognised these projections as mandibles in Smerinthus populi, and Kellogg in Protoparce Caro- lina, another large Sphinx moth. They appear to be unusually well developed in that group. In Castnia they are even more definite than they are in Sphiugidae. The MAXILLAE are chiefly devoted to the formation of the proboscis. Their basal portions are anatomically very indefinite, though they exist very intimately connected with the labium. Each usually bears a small tubercle or a segmented process, the representative of the maxillary palpus. The proboscis itself con- sists of the terminal, or outer, parts of the two maxillae, which parts are closely and beautifully coadapted to form the spirally coiled organ, that is sometimes, though incorrectly, called the tongue. The exact morphology of the Lepidopterous proboscis has not been established. The condition existing in the curious family Prodoxidae (see p. 432), where a proboscis coexists with another structure called a maxillary tentacle, suggests a correspondence between the latter and the galea of a typical maxilla ; and between the proboscis and the lacinia or inner lobe of a maxilla : but J. B. Smith is of opinion that the tentacle in question is a prolongation of the stipes. The condition of the parts in this anomalous family (Prodoxidae) has not, however, been thoroughly investigated, and Packard takes a different view of the proboscis ; he considers that " it is the two galeae which become elongated, united and highly specialised to form the so-called tongue or glossa of all Lepidoptera above the Eriocephalidae." ] The proboscis in some cases becomes very remarkable, and in certain Sphingidae is said to attain, when unrolled, a length of ten inches. In some cases the maxillary lobes do not form a proboscis, but exist as delicate structures, pendulous from the mouth, without coadaptation (Zeuzera aesculi, the Wood-leopard moth). In other forms they are absent altogether (Cossus, e.g.}, and in Hepialus we have failed to detect any evidence of the existence of the maxillae. On the other hand, in Micropteryx the maxillae are much more like those of a mandibulate Insect ; and various other Microlepidoptera approach more or less a similar condition. In the genus last mentioned 1 Amer. Natural, xxix. 1895, p. 637. It should be recollected that many Lepidoptera do not possess any proboscis. 310 LEPIDOPTERA the maxillary palpi are largely developed, flexible and slender. According to Walter various forms of palpus intermediate between that of Micropteryx and the condition of rudimentary tubercle may be found amongst the Microlepidoptera.1 LABIUM. — The labial palpi are usually largely developed, though but little flexible ; they form conspicuous processes densely covered with scales or hairs, and curve forwards or up- wards, rarely downwards, from the under side of the head, some- what in the fashion of tusks. The other parts of the labium are frequently represented merely by a membranous structure, united with the maxillae and obstructing the cavity of the pharynx. Where the proboscis is absent it is difficult to find any orifice leading to the alimentary canal, such opening as may exist being concealed by the overhanging clypeus and labium. In some forms, Saturnia, e.g., there appears to be no buccal orifice whatever. In Hepialus the labium is in 'a very unusual condition ; it projects externally in the position usually occupied by the labial palpi, these organs being themselves extremely short. It is very difficult to form an opinion as to the structure of the labium and other mouth-parts when the maxillae are not developed, as in these cases the parts are of a delicate membranous nature, and shrivel after death. This is the explanation of the fact that in descriptive works we find vague terms in use such as " mouth aborted " or " tongue absent." The mouth of the Lepidopterous imago is a paradoxical structure ; it differs very greatly from that of the larva, the changes during metamorphosis being extreme. We should thus be led to infer that it is of great importance to the creatures ; but, on the other hand, the various structures that make up the mouth, as we have remarked, are frequently absent or reduced to insignificant proportions ; and even in forms where the apparatus is highly developed the individuals seem to be able to accomplish ovipositioii without taking food, or after taking only very minute quantities. It is therefore difficult to understand why so great a change should occur during the metamorphosis of the Insects of this Order. It has been ascertained that in some forms where the mouth is atrophied the stomach is in a correlative condition ; but we are not aware that any investigations have been made as to whether this correspondence is general or exceptional. 1 Jena. Zeitschr. Naturw. xviii. 1885, p. 168. vi EXTERNAL STRUCTURE 3 1 I The exact mode in which the proboscis acts is in several respects still obscure, the views of Burmeister and Newport being in some points erroneous. Towards the tip of the proboscis there are some minute but complex structures considered by Fritz Miiller to be sense -organs, and by Breitenbach to be mechanical instruments for irritating or lacerating the delicate tissues of blossoms. It is probable that Muller's view will prove to be correct. Nevertheless the proboscis has considerable power of penetration ; there being a moth, " Ophideres fullonica," that causes considerable damage to crops of oranges by inserting its trunk through the peel so as to suck the juices.1 The canal formed by each maxilla opens into a cavity inside the front part of the head. This cavity, according to Burgess,2 is a sort of sac connected with five muscles, and by the aid of this apparatus the act of suction is performed : the diverticulum of the alimentary canal, usually called a sucking-stomach, not really possessing the function formerly attributed to it. The PROTHORAX is very small, being reduced to a collar, be- tween the head and the alitrunk, of just sufficient size to bear the front pair of legs. Its most remarkable feature is a pair of pro- cesses, frequently existing on the upper surface, called " patagia." These in many cases (especially in Noctuidae) are lobes capable of considerable movement, being attached only by a narrow base. In Hepialus, on the contrary, they are not free, but are merely indicated by curved marks on the dorsurn. The patagia are styled by many writers " tegulae." They are of some interest in connection with the question of wing -like appendages on the prothorax of Palaeozoic insects, and they have been considered by some writers3 to be the equivalents of true wings. The MESOTHORAX is very large, especially its upper face, the notum, which is more or less convex, and in the higher forms attains a great extension from before backwards. The notum consists in greater part of a large anterior piece, the meso-scutum, and a 1 Amer. Natural, xiv. 1880, p. 313. 2 For an account of the structures at the tip of the proboscis of this moth, and of the beautiful manner in which the lobes of the maxillae are dovetailed together, see Francis Darwin, Quart. J. Micr. Sci. xv. 1875, p. 385. For details as to numerous proboscides, and as to the difficulties that exist in comprehending the exact mode of action of the organ, refer to Breitenbach's papers, especially Jena. ZeitscJir. Naturw. xv. 1882, p. 151. 3 See Cholodkovsky, Zool. Anz. ix. p. 615 ; Haase, t.c. p. 711 ; also Riley, P. ent. Soc. Washington, ii. 1892, p. 310. 3 I 2 LEPIDOPTERA smaller part, the meso-scutellum behind. In front of the scutum there is a piece termed prae-scutum by Burgess. It is usually small and concealed by the front part of the scutum ; but in Hepialus it is large and horizontal in position. It is of importance as being the chief point of articulation with the pro- thorax. The scutellum is more or less irregularly rhomboidal in form ; its hinder margin usually looks as if it were a lobe or fold placed in front of the base of the abdomen or metathorax, accord- ing to whether the latter is concealed or visible. In some of the higher forms this meso-scutellar lobe is prominent, and there may be seen under its projection a piece that has been called the post-scutellum, and is really the base of the great meso- phragma, a chitinous piece that descends far down into the interior of the body. In addition to the front pair of wings the mesothorax bears on its upper surface another pair of appendages, the tegulae : in the higher forms they are of large size ; they are fastened on the front of the mesothorax, and extend backwards over the joint of the wing with the body, being densely covered with scales so that they are but little conspicuous. These appendages are frequently erroneously called patagia, but have also been called scapulae, pterygodes, paraptera, and shoulder- tufts, or shoulder-lappets. The lower surface of the mesothorax is much concealed by the large and prominent coxae, but the sternum and the two pleural pieces on each side, episternum and epimeron, are easily detected. The area for attachment of the anterior wing on each side is considerable, and appears to be of rather complex structure ; its anatomy has been, however, but little studied. The METATHORAX is small in comparison with the preceding segment, to which it is intimately co-adapted, though the two are really connected only by delicate membrane, and can conse- quently be separated with ease by dissection. The metanotum consists of (1) the scutum, which usually appears externally as an anterior piece on each side ; (2) the scutellum, forming a median piece placed behind the scutum, which it tends to separate into two parts by its own extension forwards. In order to understand the structure of the metathorax it is desirable to dissect it off from the larger anterior segment, and it will then be found that its appearance when undissected is deceptive, owing to its being greatly arched, or folded in the antero- vi EXTERNAL STRUCTURE 3 1 3 posterior direction. A broad, but short phragma descends from the hind margin of the metascutellum into the interior of the body. It should be noted that though the metanotum is forced, as it were, backwards by the great extension of the inesonotum in the middle line of the body, yet at the sides the metanotum creeps forward so as to keep the points of attachment of the hind wings near to those of the front wings. In many forms of Hesperiidae, Sphingidae, Xoctuidae, etc, the true structure of the metanotum is further concealed by the back of the mesoscutellum reposing on, and covering it. Difference of opinion exists as to the thoracic SPIRACLES ; there is one conspicuous enough in the membrane behind the proiiotum, and it is thought by some writers that no other exists. West- wood and Scudder, however, speak of a mesothoracic spiracle, and Dr. Chapman considers that one exists. Minot describes1 a structure behind the anterior wing, and thinks it may be an imperfect spiracle, and we have found a similar stigma in Saturnia pavonia. At the back of the thorax there is on each side in some Lepidoptera (Noctuidae, Arctia, etc.), a curious large cavity formed by a projection backwards from the sides of the metasternum, and a corresponding development of the pleura of the first abdominal segment. Minot and others have suggested that this may be an organ of hearing. The ABDOMEN differs according to the sex. In the female seven segments are conspicuous dorsally, but only six ventrally, because the first segment is entirely membranous beneath, and is concealed between the second abdominal ventral plate and the posterior coxae. Besides these segments there are at the hind end two others smaller, more or less completely with- drawn into the body, and in certain cases forming an ovipositor. These nine segments are usually considered to constitute the abdomen ; but according to Peytoureau,2 a tenth dorsal plate is represented on either side of the anal orifice, though there is no trace of a corresponding ventral plate. In the male the segments, externally conspicuous, are one more than in the female. According to the authority quoted,3 this sex has also truly ten abdominal segments, the ninth segment being withdrawn to a greater or 1 Fourth Rep. U.S. Entom. Commission, 1885, p. 49. 2 C.R. Ac. Sci. Paris, cxviii. 1894, p. 360 ; and his Thesis, Bordeaux, 1895. 3 C.R. Ac. Sci. Paris, cxviii. 1894, p. 542. 3 I 4 LEPIDOPTERA less extent to the inside of the body, and modified to form part of a copulatory apparatus ; its dorsal portion bears a process called the " uncus " ; the anal orifice opens on the inner face of this process, and below it there is another process — developed to a greater or less extent — called the " scaphium." The ventral portion of the ninth segment bears a lobe, the " saccus " (Peytoureau, I.e.}. On each side of the ninth abdominal segment there is a process called the " valve," the internal wall of which bears some hook-like or other processes called " harpes " ; it is continued as a membrane surrounding the " oedeagus," or penis, and- — -bearing more or less distinct prominences — connects with the scaphium. In many forms the parts alluded to, other than the valves, are concealed by the latter, which **•. ^-^J^jLit^L^ ?ff come together when closed, and may be covered externally with scales like the rest of the abdomen. Peytou- reau considers that the uncus is really the dorsal plate of a tenth segment, zx" c and that the scaphium FIG. 160. — Ackerontia atropos. The termination of $ jg ^Q tenth ventral body, one side removed. IX, Ninth dorsal plate ; . IX', ninth ventral; s, lobe, saccus, of ninth plate. IhUS, according ventral plate ; X, tenth dorsal plate, or uncus ; £o £]}jg view the ninth sc, scaphium, or tenth ventral plate ; a, position of anus ; b, chitinised band of scaphium ; V, valve or segment IS extensive and clasper ; c, hooks, or harpes, of clasper ; j), penis complex beino1 very (or oedeagus). (After Peytoureau.) highly modified in all its parts : while the tenth segment is greatly reduced. The structure of the male organs is simpler in Lepidoptera, and less varied than it is in the other great Orders of Insects. There are seven pairs of abdominal spiracles on the upper parts of the membranous pleurae. LEGS. — The legs are long, slender, covered with scales, and chiefly remarkable from the fact that the tibiae sometimes bear articulated spurs on their middle as well as at the tip. The front tibia usually possesses on its inner aspect a peculiar mobile pad ; this seems to be in some cases a combing organ ; it also often acts as a cover to peculiar scales. The tarsi are five-jointed, with two small claws and a small apparatus, vi WINGS 3 1 5 the functional importance of which is unknown, between the claws. Wings. — The wings are the most remarkable feature of this Order ; it is to them that butterflies owe their beauty, the sur- faces of the wings being frequently adorned with colours and patterns of the most charming and effective nature. These effects are due to minute scales that are implanted in the wing- membrane in an overlapping manner, somewhat similar to the arrangement of slates on the roof of a house. The scales are very readily displaced, and have the appearance of a silky dust. We shall describe their structure and allude to their development subsequently. The wings are usually of large size in com- parison with the Insect's body : in the genus Morpho, the most gorgeous of the butterflies, they are enormous, though the body is small ; so that when deprived of these floats the Insect is insignificant. The great expanse of wing is not correlative with great powers of flight, though it is perhaps indicative of flying with little exertion ; for the small-winged Lepidoptera, Sphingidae, etc., have much greater powers of aerial evolution than the large- winged forms. The area of the wing is increased somewhat by the fact that the scales on the outer margin, and on a part or on the whole of the inner margin, project beyond the edges of the membrane that bears them : these projecting marginal scales are called fringes. In many of the very small moths the actual size of the wing-membranes is much reduced, but in such cases the fringes may be very long, so as to form the larger part of the surface, especially of that of the hind wings. Frequently the hind wings are of remarkable shape, being prolonged into pro- cesses or tails, some of which are almost as remarkable as those of Nemoptera in the Order Neuroptera. The wings are very rarely absent in Lepidoptera ; this occurs only in the female sex, no male Lepidopterous imago destitute of wings having been discovered. Although but little is known of the physiology of flight of Lepidoptera, yet it is clearly important that the two wings of the same side should be perfectly coadapted or correlated. This is effected largely by the front wing over- lapping the hind one to a considerable extent, and by the two contiguous surfaces being pressed, as it were, together. This is the system found in butterflies and in some of the large moths, such as Lasiocampidae and Saturniidae ; in these cases the hind 3 I 6 LEPIDOPTERA wing always has a large shoulder, or area, anterior to its point of insertion. In most moths this shoulder is absent, but in its place there are one or more stiff bristles projecting forwards and outwards, and passing under a little membranous flap, or a tuft of thick scales on the under face of the front wing ; the bristle is called the " freuulum," the structure that retains it a " retinaculum." In Castnia, (Fig. 162) and in some Sphingidae there is the un- usual condition of a highly-developed shoulder (s) coexisting with a perfect frenulum (/) and retinaculum (r~). The frenulum and retinaculum usually differ in structure, and the retinaculum in position, in the two sexes of the same moth ; the male, which in moths has superior powers of flight, having the better retaining organs. Hampson says " the form of the frenulum is of great use in determining sex, as in the males of all the forms that possess it, it consists of hairs firmly soldered together so as to form a single bristle, whilst in nearly all females it consists of three or more bristles which are shorter than that of the male ; in one female Cossid I have found as many as nine. Also in the large majority of moths the retinaculum descends from the costal nervure in the male, while in the female it ascends from the median nervure." l This sexual difference in a structure for the discharge of a function common to the two sexes is a very re- markable fact. There are a few — very few — moths in which the bases of the hind wings are not well coadapted with the front wings, and do not possess a frenulum, and these species possess a small more or less free lobe at the base of the front wing that droops towards the hind wing, and may thus help to keep up an imperfect connexion between the pair ; this lobe has been named a jugimi by Professor Comstock. Occasionally there is a jugum on the hind as well as on the front wing. There is usually a very great difference between the front and the hind wings ; for whereas in the front wing the anterior portion is doubtless of great importance in the act of flight and is provided with numerous veins, in the hind wing, on the other hand, the corre- sponding part has not a similar function, being covered by the front wing ; hence the hind wing is provided with fewer nervures in the anterior region, the divisions of the subcostal being less numerous than they are in the front wing. In the moths possessing a jugum the two wings differ but little from one 1 Fauna of British Imlia, Moths, i. 1892, p. 6. WING-NERVURES 3 I 7 another, and it is probable that they function almost as four separate wings instead of as two pairs. WING-NEKVURES. — The nervures or ribs of the wings are of great importance in Lepidoptera, as at present they furnish the chief characters for classification and for the discussions of phylogeuy that are so numerous in entomological literature. On looking at wings that have been deprived of their scales it will be noticed (Fig. 161) that the ribs are much more numerous at the outer margins than they are near the points of attachment of the wings, and that there is usually but one cell (or area com- pletely enclosed by ribs). This latter point is one of the chief peculiarities of the Lepidopterous wing ; in Insect-wings generally the number of cells in proportion to the area of the wings and to the number of nervures is greater than it is in Lepidoptera, for in the latter there are few or no cross-nervures. Hence there is sometimes no closed cell at all on the wing (Fig. 161, II. B). The maximum number of closed cells is six ; this is found in some species of Micropteryx, while in Hepialus there may be three or four ; but the rule is that there is only one cell in the Lepidopterous wing. When the number of cells is increased this is not necessarily due to an increase in the cross-nervures; and in fact it is generally due to irregular forking or to the sinuous form of the longitudinal nervures themselves (see wing of Castnia, Fig. 162, A.). Some authorities consider that all transverse or cross-veins in Lepidoptera are merely portions of longitudinal veins having diverted courses. When a portion of a nervure beyond the basal or primary portion serves as a common piece to two forked parts external to it, it is called a stalk (Fig. 162, A, e). There are cases in which the furcation takes place in the opposite direction, so that a nervure is double at the base of the wing (Fig. 161, I, A, la, and B, 1&). This important condition has not yet been adequately discussed. Turning to the mode of designation of the nervures,1 we may 1 It is impossible for us to treat of the difficulties that exist on this point, and we must refer the student to the pamphlet, "The Venation of the "Wings of Insects," by Prof. Comstock, Ithaca, 1895, being a reprint, with an important prefatory note, from the Elements of Insect Anatomy, by J. H. Comstock and V. L. Kellogg, also to Packard's discussion of the subject in Mem. Ac. Sci. Washington, vii. 1895, pp. 84-86. The method of Spuler, alluded to in these two memoirs, is based on development, and, when extended, will doubtless have very valuable results. See Spuler, Zeitschr. wiss. Zool. liii. 1892, p. 597. LEPIDOPTERA CHAP. commence by remarking that no system satisfactory from a practical as well as from a theoretical point of view has yet been devised. The diagrams given in figure 161 will enable us to explain the methods actually in vogue ; I. representing the system, dating from the time of Herrich - Schaeffer, chiefly used by British naturalists, and II. that adopted by Staudinger and Schatz in their recent great work on the Butterflies of the world. The three anterior nervures in both front and hind wings correspond fairly well, and are called, looking at them where they commence at the base of the wing, " costal," " subcostal," and SC3 FIG. 161. — Wing-nervuratiou of Lepidoptera. I, Diagram of moths' wings (after Hamp- son) ; If, of a butterfly's wings (Morpho menelaus 3, after Staudinger and Schatz). A, front, B, hind wing. I. — c, costal ; sc, subcostal ; m, median ; la, 1 b, Ic, in- ternal nervures ; /, frenulum ; 2, 3, 4, branches of median nervure ; 5, lower radial; 6, upper radial; 7-11, divisions of the subcostal; 12, termination of costal ; c, cell ; d, discocellular nervure. II. — C, costal ; SC, subcostal ; M, median ; SM and SN, submedian nervures ; 1A, inner-margin nervure ; UR, lower radial ; OR, upper radial ; SC1 to SC5, divisions of subcostal ; M1 to M3, divisions of median nervure ; C, cell ; DC, discocellulars. " median " nervures. The nervures near the inner margin of the wing (that is the lower part in our figures) differ much in the front and hind wings, consisting either of two or of three separate portions not joined even at the base. British entomologists call these "branches or divisions of the internal nervure " : the Germans call the more anterior of them the " submedian," and the more internal the "inner-margin nervure"; they are also frequently called anal nervures. The cross-nervure that closes the cell is called discocellular ; when apparently composed of two or three WING-NERVULES 319 parts joined so as to form angles, the parts are called, according to position, npper, lower, and middle discocellulars. One or more short spurs may exist on the front part of the basal portion of the hind wing ; these are called praecostal. The branches or terminal divisions of the nervures should be called iiervules ; they are usually mentioned by the numbers shewn in the diagram (Fig. 161, I.). In addition to this, it is only necessary to re- member that number 2 is always assigned to the posterior division of the median nervure, the nervules below this being all called 1, and distinguished by the addition of I2 a, J, c when requisite. This course is necessary, because if it were not adopted the corresponding nervules on the front and hind wings would bear different numbers. The use of this system of num- bers for the nervules is becoming general, and it answers fairly well for practical purposes. On the other hand, extreme discrepancy exists as to the nomenclature of the nervures and nervules, and there are almost as many systems as there are authorities. The normal number of nervules is, on the front wing, 11+1 or 2 inner marginal, and on the hind wing 7 + 2 or 3 inner marginal. In the aberrant moths of the genus Castnia the nervuration is unusually complex and irregular (Fig. 162), and an analogous condition occurs in our common Goat - moth (Cossus ligniperdci). In Hepialus and Micropteryx (the jugate moths of Comstock) the hind wings are less dissimilar in nervuration from the front \vings than they are in other Lepidoptera.1 Internal Anatomy.' — The alimentary canal extends as a long, 1 The structure and development of scales and nervures is dealt with as part of the brief study of the development of the wing, on p. 329, etc. 2 The internal anatomy of Lepidoptera has not been extensively studied. For information refer to Dufour, C.R. Ac. Paris, xxxiv. 1852, p. 748 ; Scudder, Butt. New England, i. 1889, p. 47 ; Minot and Burgess, Fourth Hep. V. S. Entom. Comm. 1885, p. 53. FIG. 162. — Whig - nervuration of Castnia. Undersides of, A, front, B, hind wings, la, 1b, 1c, Id, Inner marginal nervures ; 2, lower branch of median ; 8., subcostal of hind wing ; 12, subcostal of front wing ; e, " stalk " of 8 and 9 ; /, freuulum ; r, retiuaculum ; s, shoulder ; g, articulation of wing. 320 LEPIDOPTERA slender oesophagus through the length of the thorax, dilating when it reaches the abdomen to form a tubular stomach ; before this it is somewhat enlarged to form an indistinct crop, and gives off a large diverticulum usually called a sucking stomach. According to Burgess, this structure does not possess the function ascribed to it by this name, and he terms it a food-reservoir. The Mal- pighian tubes are six in number, three on each side, and each set of three unite to form a common tube opening into the posterior extremity of the stomach ; behind them the alimentary canal continues in the form of a slender, tortuous intestine, expanding FIG. 163. — Internal anatomy of Lepidoptera. Section of the body of a female butterfly, Anosia plexippns. (After Scudder.) The portion to the left of the vertical line more magnified. I. II. III. thoracic segments ; 1-9, abdominal segments ; «, antenna ; a, anus ; ac, aortal chamber ; ay1, etc., abdominal ganglia : agl1, agl-, accessory glands ; ao, aorta ; br, brain ; c, colon ; cp, copulatory pouch ; ex1, ex'2, ex3, coxae ; fr, food-reservoir ; gl, suboesophageal ganglion ; h, dorsal vessel ; i, intestine ; Im, area filled by wing muscles ; I. or, ovary, or egg-tubes of left side ; mv, Malpighian tube (the two others of the right side cut away, except small por- tions) ; mx, maxilla ; o, oviduct ; oo, its orifice ; oe, oesophagus ; ov.c, end of left ovary ; p, labial palp ; ph, pharynx ; r.ov, terminal parts of right ovarian tubes, turned to one side, after the tubes have been cut away ; sd, salivary duct ; sgl, salivary gland ; sp, spermatheca ; st, stomach ; tg, thoracic ganglia ; v, copulatory orifice. at the extremity of the body to form a rectum. The dorsal or circulatory vessel commences near the posterior extremity of the body, but in the front part of the abdomen is deflexed to pass under the great phragma into the thorax, where it rises abruptly to the dorsal wall, but is again abruptly deflexed, forming a loop, and is then prolonged above the oesophagus into the head : at the summit of the thoracic loop there may be a dilatation called the aortal chamber. The supra- and infra-oesophageal ganglia are consolidated into a mass pierced by the oesophagus : there is a minute frontal ganglion ; the ventral chain consists of three much approximated thoracic ganglia and four abdominal ganglia separated from the thoracic by a long interval. vi INTERNAL STRUCTURE EGG 321 The male sexual organs consist of the two testes placed in a common capsule, from which proceed a pair of contiguous vasa defereritia (dilated soon after their origin to form the vesiculae seminales) ; into each vas there opens a long, tubular gland ; the two vasa subsequently unite to form a long, coiled, ejaculatoiy duct. It is in the structure of the female sexual organs that the most remarkable of the anatomical characters of Lepidoptera is found, there being two external sexual orifices. The imago has, in the great majority of cases, four egg-tubes in each ovary ; the pair of oviducts proceeding from them unite to form a single un- paired (azygos) oviduct which terminates by an orifice quite at the posterior extremity of the body. There is a sac, the bursa copulatrix or copulatory pouch, which is prolonged in a tubular manner, to open externally on the eighth ventral plate : a tube, the seminal duct, connects the bursa with the oviduct, and on this tube there may be a dilatation — the sperrnatheca. Besides these structures two sets of accessory glands open into the oviduct, an unpaired gland, and a pair of glands. The development of these structures has been described by Hatchett Jackson,1 and exhibits some very interesting features. The exact functions of the bursa copulatrix and of the other structures are by no means clear. According to Biley,2 the spermatheca in Pronuba contains some curious radiate bodies, and Godman and Salvin describe some- thing of the same sort as existing in butterflies. Several varia- tions in the details of the structure of these remarkably complex passages have been described, and the various ducts are some- times rendered more complex by diverticula attached to them. Some noteworthy diversities in the main anatomical features exist. According to Cholodkovsky, there is but one sexual aperture — the posterior one — in Nematois metallicus ; while, according to Brandt, the number of egg-tubes in a few cases exceeds the normal — four — being in Sesia scoliaeformis fourteen. In Nematois metallicus there is individual variation, the number of tubes varying from twelve to twenty. The egg" has been more extensively studied in Lepidoptera. than in any other Order of Insects. It displays great variety : we meet with elongate forms (Fig. 164) and flat forms like buttons, while in Linifn-oil,^ (Fig. 83, Vol. V.) the egg is a 1 Tr. Linn. Soc. London (2), v. 1890, p. 143. - P. ent. Soc. Washington, ii. 1892, p. 305. VOL. VI Y 322 LEPIDOPTERA transparent scale of somewhat inconstant outline. Some are coloured and mottled somewhat after the fashion of birds'-eggs ; this is the case with some eggs of Lasiocampidae and Liparidae ; in some the sculpture of the egg-shell is of the most elaborate char- acter (Figs. 77, 78, Vol. V.). The egg-shell or chorion is, accord- ing to Korschelt l and others, a cuticular product of the epithelium of the egg-chambers of the ovaries. The number of eggs deposited by an individual differs greatly in different species, and has been ascertained to be variable within certain limits in the same species. Speyer thought about 250 to be the average number of eggs deposited by an individual. The number in the case of Aporia crataeyi is believed to be from 60 to 100, and in some Hepialus to be several thousands. The mode of deposition also differs greatly ; where the eggs are very numerous they seem to be discharged almost at random in suitable spots ; but moths such as Clisiocampa neustria fasten their eggs round the stems of the food-plant in a very perfect and artistic manner. Butterflies seem as a rule to prefer to oviposit by placing an egg here and there rather than risk many in one situation ; but to this there are many conspicuous exceptions especially in the cases where the larvae live gregariously, as in the Vanessae. Some moths cover the eggs with _=^ , ^^ =^ fur from their own body, which, in the cast1 of certain of the Eggers (Lasiocampidae), FIG. 164.— Egg of Orange- seems to have a special supply for the pur- tip butterfly, Euchloe cardamines, magni- pose. Ihe period that intervenes between fted. «, The egg of deposition and hatching of the eggs varies natural size on a stalk. J from a few days to many months. There seems to be, as a rule, comparatively little power of extending the period of latency beyond a single season ; though certain facts have been recorded that would lead us to believe that in Australia eggs may last over the proper time during a drought, and be hatched as soon as rain falls. Larva. — The young condition or larva of the Lepidopterous Insect is commonly called a caterpillar. It is a somewhat worm-like creature — in old English it was sometimes called 1 Ada Ac. German, li. 1887, p. 238. vi LARVA 323 palmer-worm — and is composed of a head and thirteen divisions or segments of the body ; the first three of the latter are called thoracic, the other ten, abdominal segments ; in most caterpillars the terminal two or three abdominal segments are more or less run together, and the ninth may be very small, so that the true number is indistinct. The first three segments bear each, on either side, a short limb, ending in a curved spine ; the next two (or three or more) segments are destitute of legs, but on some of the following divisions another kind of leg of a more fleshy character appears, while the body is terminated by a pair of these thick legs .of somewhat different form. The front legs are usually called the true legs, the others prolegs, but this latter designation is a most unfortunate one, the term " pro " being in entomology used to signify anterior ; it is therefore better to call the three anterior pairs thoracic legs, and the others abdominal feet, distinguishing the hind pair of these latter as claspers. There is, too, an unfortunate discrepancy amongst entomologists in their manner of counting the body-segments, some count the head as the first segment, while others apply this term to the first thoracic segment. The latter is the more correct course, for, as the head is not a single segment it should not be called such in a terminology that affects to be morphologically exact, not simply descriptive. The thoracic legs are transversely jointed (Fig. 165, B), but this is not the case with the abdominal feet, which are usually armed beneath with a circle, or with rows, of little hooks. The thoracic legs are, independent of their form, of a different nature from the abdominal, for these latter disappear subsequently, while the former give rise to the legs of the imago. The number of thoracic legs is always six, except in a few cases where there are none at all ; the abdominal feet are much more variable, and exhibit so many distinctions that we cannot here attempt to deal with them. M. Goossens has given a concise and interest- ing account of this subject,1 and Speyer ~ a summary of the variety in number and position. The anatomy of the larva is simple in comparison with that of the perfect Insect ; its main features will be appreciated from Fig. 165, from which it will be seen that the stomach is enormous, and the silk-vessels are also very extensive. There are three sets of glands opening by canals on the head, viz. the 1 Ann. Soc. ent. France, 1887, pp. 384-404, PI. 7. - Isis, 1845, p. 835. 324 LEPIDOPTERA salivary glands proper, which open into the cavity of the mouth, one close to the base of each mandible ; the silk-glands, which terminate by a common canal, continued externally as the spin- neret ; and the glands of Filippi situate in the head itself, and opening into the ducts of the silk-glands, near their union into a common duct. It should be recollected that Fig. 165 does not indicate all the details of the anatomy ; the muscular system, for instance, being entirely omitted, though there are an enormous number of muscles ; these however are not very complex, they being mostly repetitions in the successive seg- ments.1 The mouth -parts are very different from those of the FIG. 165. — A, Section of male caterpillar of Anosia plexippus — muscular and tracheal systems and fat-body not shown : I, pro-, II, meso-, III, meta-thorax ; 1-10, abdominal segments ; b, supra-oesophageal ganglion ; c, rectum ; d.v, dorsal vessel ; g3-g9, ganglia of ventral chain ; h, head ; i, intestine ; m.v, Malpighian tube ; n.c, nerve-cord of ventral chain ; oe, oesophagus ; s, spinneret ; s.o.g, infra-oesophageal ganglion ; st, stomach ; s.v, silk-vessel ; t, testis. B, One of the jointed prothoracic legs. C, An abdominal foot with its hooks. (After Scudder and Burgess, mag- nification about f.) perfect Insect, inasmuch as the maxillae and labial palpi, which are the most remarkable structures of the imago, are small, and are differently constructed in the caterpillar, while the mandibles, which are the largest organs of the caterpillar, disappear in the adult. The little organ by which the caterpillar exudes its silk is called a spinneret ; according to Packard it is a " homologue of the hypopharynx." It is a more or less prominent point on the middle of the labium (Fig. 166, #) and sometimes forms a conspicuous spine projecting downwards. The eyes are ex- tremely imperfect organs, consisting merely of six, in some cases 1 For anatomy of caterpillars refer to Lyonnet's famous work, Traite anatomiquc de la chenille qui rongc le bois de saule, La Haye, 1762. vi LARVA 325 fewer, transparent, somewhat prominent, little spaces placed on each side of the lower part of the head : they are called " ocelli," by Landois " ocelli compositi." Under each of these external facets there are placed percipient .« structures, apparently very imperfect functionally, the caterpillar's sight being of the poorest character.1 The spiracles of the caterpillar are nine on each side, placed one on the first thoracic segment and one on each of vy the first eight abdominal segments ; , ' FIG. 166. — Front view ot head of there are no true stigmata on the a. caterpillar, with the jaws spfnnrl inrl thirrl rhnrapio qpornpnr<* partially opened, a, Labrum ; tS; ft. mandible; c, antenna; d, though traces Of their rudiments Or ocelli ; e, maxilla ; /, lingua ; (j, • • ,• --11 spinneret ; J>, labial palp. vestiges are sometimes visible. In the caterpillar there are no traces of the external sexual organs, so that the two sexes cannot be distinguished on super- ficial inspection ; it was however long ago demonstrated by Herold 2 that the ovaries and testes exist in the youngest cater- pillars, and undergo a certain amount of growth and development in the larval instars ; the most important feature of which is that the testes are originally separate but subsequently coalesce in the middle line of the body, and become enclosed in a common capsule. In a few forms — especially of Liparidae — (Lymantriidue of modern authors) — the caterpillars are said to be of different colours in the two sexes. Most of what is known on this point lias been referred to by Hatchett Jackson.3 The SILK -GLANDS of Lepidoptera are of great interest from the physiological point of view, as well as from the fact that they have furnished for many ages one of the most beautiful of the adornments made use of by our own species. The sericteria, or vessels that secrete silk, are of simple structure, and differ greatly in their size in the various forms of the Order; they sometimes become of great length ; in the Silk-worm each of the two vessels is nearly five times as long as the body, while in Bombyx yamaniai and others, even this is exceeded. They 1 See Plateau, Bull. Ac. Bdgiquc, xv. 1888, p. 28 ; in reference to structure of ocelli, Blanc, Tete du Bombyx mori . . . 1891, pp. 163, etc. ; and Landois in X'-ltxchr. wiss. Zool. xvi. 1866, p. 27. - Et>tii-ii:ki'?iiiilexipPl'si 3-4 days old. I, pro-, II, meso-, III, meta-thorax ; 1-9, abdominal seg- ments ; «, anten- na (?) ; ac, aortal chamber ; ag1 - ag5, abdominal ganglia ; ag I, accessory glands ; ao, aorta ; br, brain ; c, colon ; cp, bursa copulatrix ; c>; cremaster ; fl, first femur ; fr, food-reservoir ; h, dorsal vessel ; i, part of intestine ; tnv, Malpighian tube ; mx, base of maxilla ; oe, oesophagus ; ov, ovary ; ph, pharynx; sd, salivary dnct ; sgl, salivary gland ; st, stomach ; t1, first tarsus ; tg, compound thoracic ganglion ; ts-, tf?, second and third tarsus.. (After Scudder. ) organs, but the respiratory openings are pervious. It has no means of locomotion, but it can move a certain number of the posterior segments (the number variable according to kind). In some cases it is provided with spines, " adminicula," by means of which, aided by the wriggling movements of the abdominal seg- ments, considerable changes of position can be effected. The pupae of the genus Micropt&ryx apparently use the legs . for locomotion, as do the pupae of Trichoptera. The study of the pupa of Lepidoptera is less advanced than that of the imago and larva, between which it is, in many points of structure, intermediate.1 The interior of the pupa contains a 1 The student will find important information as to the varieties of external form of pupae in Dr. T. A. Chapman's writings ; see especially Tr. ent. Soc. Loiidon, 1893, 1894, and 1896. CLrj syl- 328 LEPIDOPTERA quantity of cream-like matter, including the results of histolysis —but tliis, as well as the condition of the internal organs, differs much according to whether the change from the caterpillar to the moth is much or little advanced. Many pupae are protected by cocoons. These are masses of silk —very various in form — disposed by the caterpillar around itself during the last stage of its existence. Some of these cocoons are so perfect that the moth has considerable difficulty in escaping when the metamorphosis is complete. Various devices are- used for the purpose of emergence ; the Puss-moth excretes a corrosive fluid, containing potassium hydroxide, and then protects itself from this by retaining on the head while passing through it a shield formed of a portion of the pupa-skin.1 Lepidopterous pupae usually have the body terminated by a projection of very various and peculiar form called " cremaster." In certain cases these projections are used for the suspension of the pupa, and are then frequently provided with hooks (Fig. 177, 0, D). In other cases the cremaster is frequently called the anal armature (Fig. 205, B). The development of the wings of Lepidoptera has recently been much studied. It has been known since the time of Lyonnet, that the rudiments of the wings exist inside the body of the caterpillar when it is nearly adult. Verson considers that he has detected the rudiments in the silk-worm larva even before hatching, and lie attributes their origin to a of form of those cells that occupy modification FIG. 168. — Wing - rudiments of Pieris hypodernial brassicae. A, Rudiments of a wing , •, . ^ before the first moult of the cater- the sPots where the Spiracles pillar : ce, embryonic cells ; ch, ex- of the SCCOlld and third tllOl'- ternal cuticle ; h, hypodermis ; o. . . . , . , opening of the imagination; tr, acic segments might be looked trachea. B, posterior wing-rudiment for (ft will be recollected that of full - grown caterpillar ; b, semi- circular pad; c, a bundle of the there are no spiracles on these rolled tracheae ; e envelope ; ipedi- two thoracic segments ill Lepi- eel ; tr, trachea. (After Gonm.) r dopterous larvae). Gonin has examined the wing-rudiments in the caterpillar, a few days old, of Latter. Tr. ent. Soc. London, 1895, p. 399. vi DEVELOPMENT WINGS NERVURES 329 1'icris brassicae,1 and finds that the future wing is then indi- cated by a thickening and bagging inwards of the hypodermis, and by some embryonic cells and a trachea in close relation with this mass (.Fig. 168, A). The structure grows so as to form a sac projecting to the interior of the body, connected with the body- wall by a pedicel, and penetrated by a trachea forming branches consisting of rolled and contorted small tracheae (Fig. 168, B). If the body -wall be dissected off the caterpillar immediately before pupation the wings appear in crumpled form, as shown in Fi£. 169. This fact was known a of to the older entomologists, and gave si I rise to the idea that the butterfly could be detected in a caterpillar by merely stripping off the integument. The exact mode by which the wings become external at the time of appearance of the chrysalis is not ascertained ; but it would appear from Gonin's observations that it is not FIG. 169,-Auterior parts of a cater- by a process of evagination, but by pillar of P. ftrawicoe, the body- . ... wall having been dissected ofl, destruction Ot the hypodermis lying immediately before pupation. outside the wing. However this may "•. «'• Anterior and posterior 0 wings ; st 7, first spiracle : p, p , be, it is well kuOWll that, when the second and third legs. (After caterpillar's skin is finally shed and the chrysalis appears, the wings are free, external appendages, and soon become fastened down to the body by an exudation that hardens so as to form the shell of the chrysalis. Scales and nervures. — Before tracing the further develop- ment it will be well to discuss the structure of the scales and nervures that form such important features in the Lepidopterous wing. If a section be made of the perfect wing of a Lepidopteron, it is found that the two layers or walls of the wing are firmly held together by material irregularly arranged, in a somewhat columnar manner. The thickness of the wing is much greater where the section cuts through a nervure (Fig. 170, A). The nervures apparently differ as to the structures found in them. Spuler observed in a nervure of Triphaena pronuba, a body having in section a considerable diameter, that he considered to be a 1 Bull. Soc. Vaudoisc, xxx. 1894, No. 115. 330 LEPIDOPTERA trachea, and also a " wing-rib " and blood-cells. Pie remarks that even in uervures, perfectly formed as to their chitinous parts, either wing-rib or trachea or both may be absent.1 Schiiffer'J was unable to find any tracheae in the completed wings he examined, and he states that the matrix of the tracheae and even their inner linings disappear. The wing-ribs were, however, found by him to be present (Fig. 170, A and B). The scales that form so con- spicuous a feature in Lepidoptera exist in surprising profusion, and FIG. 170. — Structure of wing of imago. A, Transverse section of basal portion of wing [of Vanessa ?] containing a nervure ; c, cuticle ; fr, wing-rib ; y, wall of nervure ("Grundmembran ") ; /i, hypodermis ; p, connectingcolumns : r, lumen of nervure ; B, section of a rib ; b, one of the chitinous pro- jections ; sir, central rod. (After Schaffer.) FIG. 171. — Scales of male Lepidoptera. A, Scale from upper surface of Everes comyntas ; B, from upper surface of 1'ieris rapae ; C, from inner side of fold of inner margin of hind wing of Laertias philenor ; D, one of the cover-scales from the costal androconium of Eradamvs protects ; E, F, G, scales from andro- conium of Tlwrybespylades. (After Scudder). are of the most varied forms. They may be briefly described as delicate, chitinous bags ; in the completed state these bags are flattened, so as to bring the sides quite, or very nearly, together. Their colour is due to contained pigments, or to stria- tion of the exposed surface of the scale ; the latter condition 1 Zeitschr. wiss. Zool. liii. 1892, p. 623. - Zool. Jahrl. Anat. iii. 1889, p. 646. vi SCALES 331 giving rise to metallic " interference-colours." The walls of the scales are themselves, in some cases, tinted with pigment. It is said that some of the scales contain air, and that the glistening whiteness of certain scales is due to this. The exposed surface of the scale usually differs from the surface that is pressed down on the wing in being delicately and regularly striated ; the colours of the upper and under surfaces of a scale may also be quite different. Scales are essentially of the nature of hairs, and all " 8 the transitions between hairs and FlG. 172> _ insertion of scales. A. true scales may be found on the Socket holding the stalk in P _ . , mellonella ; B, insertion of the scale WlllgS ol certain Lepldoptera that Of Polyommatus phloeas. b, Base of bear botli hairs and scales, e.g. scale ; r> holding-ring ; w, surface of . ° wing. (After Spuler.) Jt/iomia. It has been calculated that there are a million and a half of scales on the wings of an individual of the genus Mbrpho. The scales are arranged on the wing in an overlapping manner, somewhat like slates on the roof of a house. Each scale has a short stalk, and is maintained in position by the stalk fitting into a cavity in a projection of the wing-membrane (Fig. 172). Androconia. — The males of numerous butterflies possess scales peculiar in kind and various in arrangement. They may be either irregularly scattered over the wing, or they may form very complex definite structures (Fig. 173). They were formerly called " plumules," but Scudder has replaced this name by the better one, " androconia." The function of the androconia is still obscure. An odour is believed to be connected with them. Thomas supposes 1 that these scales are hollow tubes in connec- tion with glands at their bases, and that matter secreted by the glands passes through the scales and becomes diffused. In nearly all Lepidoptera it is the male that seeks the female ; if therefore odorous scales were present in one sex only we should have supposed that this would have been the female rather than the male. As, however, the reverse is the case, the function of the androconia is supposed to be that of charming the female. Scudder considers that the covering part of the audroconial 1 Amcr. Natural., xxvii. 1893, p. 1018. 332 LEPIDOPTERA structures is sometimes ornamental. As a rule, however, the " l)rands " of male Lepidoptera detract from their beauty to our eyes. Fio. 173. — A, section of part of wing showing the complex androconia of Thanaos (ages, a Skipper butterfly. The turning over of the costal margin of the wing is in this case part of the arrangement. <<. Upper covering-scales attached to the costal portion of the under surface of the wing ; b, edge of costal margin of the wing ; c, costal nervure with its scales ; d, field of the wing next the costal nervure, bearing stunted scales : e, the androconia proper, or male scales ; f, posterior covering scales ; (/, lumen of the costal nervure : B, a portion of the costal area flattened out and seen from above ; lettering as before : C, section of androconium on the second nervure of Argynnis paphia. (After Aurivillius.) Resuming our consideration of the development of the wings, we may remark that the history of the changes during the pupal state is still imperfect. By the changes of relative size of the thoracic segments the hind wing is brought to lie under the anterior one (i.e. between it and the body), so that in the newly formed pupa the arrangement is that shown in Fig. 1*74. The wings are two sacs filled with material surrounding peri- tracheal spaces in which run tracheae. The subsequent history of the tracheae is very obscure, and contrary opinions have been expressed as to their growth and disappearance. We have alluded to the fact that in some nervures tracheae are present, while in others they are absent ; so that it is quite possible that WING-DEVELOPMENT 333 the histories of the formation of the nervures and of their relation to tracheae are different in various Lepidoptera. This conclusion is rendered more probable by the statement of Coni- stock and Xeedham,1 that in some Insects the '• peritracheal spaces " that mark out the position of the future nervures are destitute of tracheae. Goniii thinks the nervures are derived from the sheaths of the peritracheal spaces, and a review of all the facts suggests that the tracheae have only a secondary relation to the nervures, and that the view that a study of the pupal tracheae may be looked on as a study of the pre- liminary state of the nervures is not sufficiently exact. It is, however, probable that in Lepidoptera the pupal tracheae play an important though not a primary part in the formation of the nervures ; possibly this may be by setting up changes in the cells near them by means of the air they supply. Semper long ago discovered hypodermal cylinders tra- versed by a string (Fig. 170, B), placed near the tracheae in the pupa.'2 It appears probable that the "wing -ribs" found in the nervures (Fig. 170, Afr and B) are the final state of these cylinders, but the origin and import of the cylinders are still unknown. The formation of the scales of the wing commences very early— apparently soon after the casting of the larval skin — though the completion of the scales and their pigmentation is delayed to a late period of the pupal life. The scales are formed by special cells of the hypodermis that are placed deeper in the interior of the wing than the other hypodermal cells. Each scale is formed by one cell, and protrudes through the over- lying hypodermis ; the membrane into which the scales are inserted is a subsequently developed structure, and the beautiful 1 Amcr. Natural., xxxii. 1898, p. 256. a Zeitschr. wiss. Zool. viii. 1857, p. 326. FIG. 174. — Transverse section of part of the newly disclosed chrysalis of Pieris brassicae, showing the position and struc- ture of the wings, hanging from one side of the body. aa, Anterior wing ; up, pos- terior wing ; e, e, peritracheal spaces ; t, t, tracheae. (After Goniu.) 334 LEPIDOPTERA articulation of the scale with the wing takes place by a division of the stalk of the scale where it is encompassed by the mem- brane. Semper was not able to show that the scale-forming cells are certainly hypodermal cells, but this has since been demonstrated by Schaffer, who also shows that each of the cells contains an excretory vesicle. Very little is positively known as to the development of the colour in the wing-scales. It has been pointed out by Hopkins l that in some cases the colours are of the nature of urates ; that is, of excretory matter of the kind that usually passes from the body by direct channels, and in the case of Lepidoptera, by the Malpighian tubes. Miss Newbigin suggests that the organic pigments used in scale -coloration will be found to be of two FIG. 175. — Early condition of scales and nervures. (After Semper.) A, Section of portion of wing of pupa of Sphinx pinastri ; a, basal membrane with trachea beneath it ; c, scale-forming cell ; d, early state of a scale ; e, e, more advanced stages ; /, hypodermal cells. B, part of a cellular cylinder that excretes the nervure [or more probably the rib or " Rippe " of Schafl'er ; cf. Fig. 170, B] ; b. epithelial [hypodermal] cells ; a, central string [supposed by Semper to be a nerve]. kinds, urates and melanins, the urates being derivatives from nitro- genous, the melanins from carbonaceous, matters.2 Marchal, who has devoted a great deal of attention to the study of the Malpi- ghian tubes, informs us that the subdermal pigments of cater- pillars are frequently in large part deposits of urates, and he is of opinion that, the function of the Malpighian tubes being arrested at certain periods of the metamorphosis, elimination of the matter they separate when functionally active then takes place in a variety of other ways.3 A similar condition as to the melanin-pigments and the respiratory functions appears also 1 Phil. Trans. 186 B, 1896, No. 15. 2 Natural Science, viii. 1896, p. 94. 3 Bull. Soc. ent. France, 1896, p. 257. vi WING-PATTERN SENSITIVENESS 335 probable. The scales when first formed are pallid, and the physi- ology of their pigmentation is not fully ascertained ; it is, how- ever, known that when the scales are pallid the hypodermis is either pigrnented or in close contact with pigmentary matter, and that as the scales become coloured this pigmentation of the hypodermis diminishes ; so that it is clear that the colour of the scales is obtained from matter in the interior of the develop- ing wing, and probably by the agency of the hypodermis. The pattern on the wings of Lepidoptera is formed before the emergence from the pupa. In the Tortoiseshell butterfly, according to Schaffer, it commences to appear about the ninth day of the pupal life, and the pattern is completed about the eleventh or twelfth day. He also states that the process varies in its rapidity, and this, he thinks, may depend on the previous condition of the larva. According to Buckell the pupa of Nemeobius lucina is sufficiently transparent to allow the develop- ment of the colour of the imago to be watched. He says that the coloration occurred first in front ; that its entire production occupied less than twenty-four hours, and only commenced about forty-eight hours before the imago emerged.1 When the butter- fly leaves the pupal skin the wings are soft, crumpled sacs, of comparatively small size, but, as everyone knows, they rapidly expand and become rigid ; the physiology of this process is apparently still unknown. A great deal of evidence, both direct and indirect, has accumulated showing that the organisation of many Lepidoptera is excessively sensitive, so that slight changes of condition pro- duce remarkable results ; and it has also been shown that in the early part of the life this sensitiveness is especially great at the period of ecdysis. Numerous butterflies produce more than one generation a year, and sometimes the generations are so different that they have passed current with entomologists as distinct species. The phenomena of this character are styled " seasonal variations " or " seasonal dimorphism." It has, however, been shown that, by careful management, the eggs of a generation (say form a) may be made to produce form a, whereas in the usual course of nature they would produce form &. A very remarkable condition is exhibited by the North American Papilio ajax. There are three forms of the species, known as P. ajax, P. telamonides, 1 Ent. Record, vi. 1895, p. 258. 336 LEPIDOPTERA and P. marcellus. It is uncertain ho\v many generations there may be in one year of this species, as the length of the life- cycle varies greatly according to circumstances. But in West Virginia all the butterflies of this species that emerge from the chrysalis before the middle of April are the form marcel I us ; those produced between the middle of April and the end of May are telamonides ; while those that appear after this are ajax. P. telamonides is not, however, the offspring of marcellus, for both forms emerge from pupae that have passed through the winter (and are the offspring of ajax), those that emerge early being marcellus, those that appear later telamonides. In various parts of Asia and Africa the butterflies produced during the wet season differ more or less markedly from those of the same species produced during the dry season. These are called " wet " and " dry season " forms. Their aetiology has not been investigated, this discovery being comparatively recent. Turning to the early life we find that some larvae vary in colour, and that this variation is sometimes of a definite char- acter, the larva being one of two different colours- — green or brown. In other cases the variation of the species is less definitely dimorphic, a considerable range of variation being exhibited by the species. In tracing the life-histories of Lepi- dopterous larvae it is not rare to find species in which the larva abruptly changes its form and colour in the middle of its life, and so completely that no one would believe the identity of the individual in the two successive conditions had it not been shown by direct observation ; in these cases the change in appearance is usually associated with a change in habits, the larva being, perhaps, a miner in leaves in its first stages, and an external feeder subsequently. In the case of the larval variation we have alluded to above, it is understood that there is no marked change of habits. Poulton has shown l that it is not infrequent, for some of these latter kinds of variable larvae to change colour during life, and he considers that light or conditions of illumination, that he speaks of as " phytoscopic," are the in- ducing causes. Great difference is, however, exhibited according to species, some variable species not being so amenable to these influences as others are. In dimorphic forms the change was observed to take place at a moult, the larva changing its skin 1 Trans, cut. Soc. London, 1892, p. 293, etc. vr SENSITIVENESS MIMICRY 337 and appearing of another colour. In some cases the result of the change was to bring the colour of the larva into harmony with its surroundings, but in others it was not so. During the final stage many larvae are susceptible, the result being made evident only when the pupa is disclosed. Variably coloured pupae of certain species of butterflies have long been known, and it has been shown that some of the varieties can be induced by changing the surroundings. The result of the changes is in certain cases correspondence between the colour of the individual and its surroundings. In the case of other species having pupae of variable colour, the colour of the pupa is without relation to, or harmony with, the surroundings. Experiments have been made on pupae by Merrifield and others, with the result of showing that by changes of tempera- ture applied at certain moments some of the colours or marks of the butterfly that will emerge can be altered. It is found that in certain localities the colour of various kinds of butterflies more or less agrees, while it differs from that of the same butterflies found in other localities. Thus Weir speaks of a duskiness common to various butterflies in Java, and calls it " phaeism " ; and Bates states that in the Amazon valley numerous species of butterflies vary in a similar manner, as regards colour, in a locality. This phenomenon is now called " homoeochromatism," and is supposed to be due to the effect of local conditions on a susceptible organisation, though there is no experimental evidence of this. Mimicry. — There are many cases in Lepidoptera of species that depart more or less strongly in appearance from those forms to which they are considered to be allied, and at the same time resemble more or less closely species to which they are less allied. This phenomenon is called mimicry.1 Usually the resembling forms are actually associated during life. Bates, who observed this phenomenon in the Amazon valley, thought that it might be accounted for by the advantage resulting to the exceptionally coloured forms from the resemblance ; - it being assumed that these were unprotected, while the forms they resembled were 1 The term mimicry is sometimes used in a wider sense ; but we think it better to limit it to its original meaning. The word is a most unfortunate one, being both inadequate and inaccurate. 2 Trans. Linn. Soc. xxiii. 1862, p. 507. VOL. VI Z 338 LEPIDOPTERA believed to be specially protected by nauseous odours or taste. It was, in fact, thought that the destroying enemies were deceived by the resemblance into supposing that the forms that were in reality edible were inedible. This subject has been greatly discussed, and in the course of the discussion numerous cases that could not be accounted for by Bates's hypothesis have been revealed. One of these is the fact that resemblances of the kind alluded to very frequently occur amongst inedible forms. This also has been thought to be accounted for by a supposed advantage to the Insects ; it being argued that a certain number of " protected " forms are destroyed by enemies the instincts of which are faulty, and which therefore always require to learn by individual experience that a certain sort of colour is associated with a nasty taste. The next step of the argument is that it will be an advantage to a protected butterfly to form part of a large association of forms having one coloration, because the ignorant enemies will more easily learn the association of a certain form of coloration with nastiness ; moreover such destruc- tion as does occur will be distributed over a larger number of species, so that each species of a large, similarly coloured, inedible association will have a less number of its individuals destroyed. It is scarcely a matter for surprise that many naturalists are very sceptical as to these explanations ; especially as the pheno- mena are supposed to have occurred in the past, so that they cannot be directly verified or disproved. It has not, however, been found, as a matter of fact, that even unprotected butterflies are much destroyed in the perfect state by birds. Moreover, in endeavouring to realise the steps of the process of development of the resemblance, we meet with the difficulty that the amount of resemblance to the model that is assumed to be efficient at one step of the development, and to bring safety, is at the next step supposed to be inefficient and to involve destruction. In other words, while analysis of the explanation shows that it postulates a peculiar and well-directed discriminative power, and a persistent selection on the part of the birds, observation leads to the belief that birds have been but little concerned in the matter. If we add to this that there is no sufficient evidence that the species now similar were ever dissimilar (as it is sup- posed they were by the advocates of the hypothesis), we think it is clear that the explanation from our point of view is of but vi MIMICRY CLASSIFICATION 339 little importance.1 The comparatively simple, hypothetical explanation, originally promulgated by Bates, is sometimes called Batesian mimicry ; while the " inedible association " hypothesis is termed Miillerian mimicry. There is one branch of the subject of mimicry that we think of great interest. This is the resemblance between Insects of different Orders ; or between Insects of the same Order, but be- longing to groups that are essentially different in form and appearance. It is not infrequent for beetles to resemble Hymen- optera, and it is still more frequent for Lepidoptera to resemble Hymenoptera, and that not only in colour and form, but also in movements and attitude. Druce says : " Many of the species of Zygaenidae are the most wonderful of all the moths ; in some cases they so closely resemble Hymenoptera that at first sight it is almost impossible to determine to which Order they belong." 2 "W. Miiller says: "The little Lepidoptera of the family Glaucopides, that are so like certain wasps as to completely deceive us, have when alive exactly the same manner of holding their wings, the same restless movements, the same irregular flight as a wasp."3 Seitz and others record a case in which a Brazilian Macroglossa exactly resembles a humming-bird, in company with which it flies ; and the same naturalist also tells us 4 of a Skipper butterfly that greatly resembles a grasshopper of the genus Tettix, and that moreover makes movements like the jumping of grasshoppers. In most of these cases the probabilities of either original similarity, arrested evolution, or the action of similar conditions are excluded : and the hypothesis of the influence, by some means or other, of one organism on another is strongly suggested. The classification of Lepidoptera was said by Latreille a century ago to be a reproach to entomologists. Since that time an enormous number of new species and genera have been described, but only recently has much advance been made in 1 A summary of the chief aspects of the question is contained in Beddard's Aitinial Coloration, London, 1892. An account of the subject with numerous illus- trations has been given by Haase, " TJntersuchungeu iiber die Mimicry," Bibl. Zool. iii. 1893, Heft viii. Those who wish to see the case as stated by an advocate may refer to Professor Poulton's work, The Colours of Animals (International Scientific Series), Ixviii. London, 1890. - P. Zool. Soc. London, 1883, p. 372. 3 Kosmos, xix. 1886, p. 353. The Insects alluded to by both these naturalists are now, we believe, placed in the Family Syntomidae (see p. 388). 4 Stett. ent. Zeit. li. 1891, p. 264 ; and Ivi. 1895, p. 234. 340 LEPIDOPTERA the way of improvement of classification. The progress made has been limited to a better comprehension and definition of the families. The nervuration of the wings is the character most, in vogue for this purpose. As regards the larger groups, and Phylogeny, there is a general opinion prevalent to the effect that Micropterygidae, Eriocephalidae and Hepialidae are in a com- paratively primitive condition, but as to the relations of these families one with the other, or with other Lepidoptera, there is a wide difference of opinion. The primary divisions of the family most often met with in literature are : — either Ehopalocera ( = butterflies) and Hetero- FlG. 176. — Clubs of butterflies' antennae. Terminal portions of antenna of, 1, Pieris bras- sicae ; 2, Styx infernalis; 3, Hestia idea (sub-family Dan- aides) ; 4, Etidamus proteus, and 5, Limochores tawtias (Hesperiidae). (After Scluitz and Scudder.) cera ( = moths) ; or Macrolepidoptera and Microlepidoptera ; the Macrolepidoptera including the butterflies and large moths, the Microlepidoptera being limited to the families Tineidae (now itself in process of division into numerous families) and Tortricidae ; some entomologists including also Pyralidae, Ptero- phoridae and Orneodidae in Microlepidoptera. The division of all Lepidoptera into two series is merely a temporary device necessi- tated by imperfect acquaintance with morphology. The division into Macro- and Micro- lepidoptera is entirely unscientific. Series 1. Ehopalocera or Butterflies. — Antennae knobbed at the tip or thickened a little before the tip, without pectinations, projecting processes, or conspicuous arrangements of cilia. Hind wings with- out a frenulum, but with the costal nervure strongly curved at the base (Fig. 161, II, B). Series II. Heterocera or Moths. — Antennae various in form, only rarely knobbed at the tip, and in such cases a frenulum present. In the large majority a frenulum is present, and the costal nervure of the hind-wing is either but little arched at the base (as in Fig. 161, I, B) or it has a large area between it and the front margin ; but in certain families the hind wing is formed much as in Ehopalocera. BUTTERFLIES 341 It may be inferred from these definitions that the distinc- tion between the two sub-Orders is neither sharply defined nor of great importance. The club of the antenna of the Ehopalocera exhibits considerable variety in form (Fig. 176).1 Butterflies are as a rule diurnal in their activity and moths nocturnal ; but in the tropics there are numerous Heterocera that are diurnal, and many of these resemble butterflies not only in colour but even in the shapes of their wings. Series I. Rhopalocera. Butterflies. Classification and Families of Butterflies. — Although considerable unanimity exists as to the natural groups of butter- flies, there is much diversity of opinion as to what divisions are of equivalent value — some treating as sub-families groups that others call families — and as to the way the families should be combined. There is, however, a general agreement that the Hesperiidae are the most distinct of the families, and E. Renter considers them a distinct sub-Order with the name Grypocera,2 Four categories may be readily distinguished, as follows, viz. : — 1. The majority of butterflies ; having the first pair of legs more or less strik- ingly different from the other pairs ; frequently very much smaller and not used as legs ; when not very small, then differing according to sex of the same species, being smaller in the male than in the female ; the part most peculiar is the tarsus, which is modified in various manners, but in the males of this great series is always destitute of its natural form of a succession of simple joints five in number. There is no pad on the front tibia. Fain. NYMPHALIDAE, ERYCINIDAE, LYCAENIDAE. [The distinctions between these three families are found in the amount and kind of the abortion of the front legs ; for definition refer to the heading of each of the families.] 2. The front legs are in general form like the other pairs ; their tibiae have no pads; the claws of all the feet are bifid, and there is an empodium in connection with them. Fam. PIERIDAE. 1 For an account of the antennae of butterflies, see Jordan, Nov. Zool. v. 1898, pp. 374-415. - Haase first proposed the name Netrocera (Deutsche ent. Zeit. Lep. iv. 1891, p. 1) for Hesperiidae, as a division distinct from all other butterflies ; Karsch replaced the name in the following year by Grypocera, because Xdroccra is the name of a genus. 342 LEPIDOPTERA CHAP. 3. The front legs are like the other pairs ; their tibiae however pads ; the claws are large, not bifid, and there is no empodium ; the inetanotum is completely exposed at the base of the abdomen, Fain. PAPILIOXIDAE. 4. The front legs are like the other pairs ; their tibiae however possess pads ; the claws are small, toothed at the base, and there is an empodium ; the metanotum is concealed by the prolonged and overhanging mesonotum. Fain. HESPERIIDAE. The relations between the families Eiycinidae, Lycaenidae, and Nymphalidae are very intimate. All these have the front legs more or less modified, and the distinctions between the families depend almost entirely on generalisations as to these modifications. These facts have led Scudder to associate the Lycaenidae and Erycinidae in one group, which he terms " Rurales." It is however difficult to go so far and no farther ; for the relations between both divisions of Rurales and the Nymphalidae are considerable. We shall subsequently find that the genus Libythea is by many retained as a separate family, chiefly because it is difficult to decide whether it should be placed in Erycinidae or in Nymphalidae. Hence it is difficult to see in this enormous complex of seven or eight thousand species more than a single great Nymphalo-Lycaenid alliance. The forms really cognate in the three families are however so few, and the number of species in the whole is so very large, that it is a matter of great convenience in practice to keep the three families apart. It is sufficient for larger purposes to bear in mind their intimate connexions. The Papilionidae and Pieridae are treated by many as two sub-divisions of one group. But we have not been able to find any justification for this in the existence of forms with connect- ing characters. Indeed it would, from this point of view, appear that the Pieridae are more closely connected with the Lycaenidae and Erycinidae than they are with Papilionidae ; in one important character, the absence of the pad of the front tibia, the Nymphalo-Lycaenids and the Pierids agree. It has also been frequently suggested that the Papilionidae (in the larger sense just mentioned) might be associated with the Hesperiidae. But no satisfactory links have been brought to light ; and if one of the more lowly Hesperiids, such as Thanaos, be compared with one of the lower Papilionidae, such as Parnassius, very little approximation can be perceived. BUTTERFLIES 343 It appears, therefore, at present that Hesperiidae, Papi- lionidae, Pieridae, and the Nymphalo-Lycaenid complex are naturally distinct. But in the following review of the families and sub-families of butterflies, we shall, in accordance with the views of the majority of Lepidopterists, treat the Lycaenidae and Erycinidae as families distinct from both Nymphalidae and Pieridae.1 The number of described species of butterflies is probably about 13,000; but the list is at present far from complete; forms of the largest size and most striking appearance being still occasionally discovered. Forty years ago the number known was not more than one-third or one-fourth of what it is at present, and a crowd of novelties of the less conspicuous kinds is brought to light every year. Hence it is not too much to antici- pate that 30,000, or even 40,000 forms may be acquired if entomologists continue to seek them with the enthusiasm and industry that have been manifested of late. On the other hand, the species of Pthopalocera seem to be peculiarly liable to dimorphic, to seasonal and to local variation ; so that it is possible that ultimately the number of true species — that is, forms that do, not breed together actually or by means of inter- mediates, morphological or chronological — may have to be con- siderably reduced. In Britain we have a list of only sixty-eight native butter- flies, and some even of these are things of the past, while others are only too certainly disappearing. New Zealand is still poorer, possessing only eighteen ; and this number will prob- ably be but little increased by future discoveries. South America is the richest part of the world, and Wallace informs us that 600 species of butterflies could, forty years ago, be found in the environs of the city of Para. Fam. 1. Nymphalidae. — The front pair of legs much reduced in size in each sex, their tarsi in the male with l)ut one joint, 1 The literature of butterflies has become extremely extensive. The following works contain information as to general questions : 1, Scudder's Butterflies of Neiv England, a beautifully illustrated work completed in 1889, and replete with interesting discussions. 2, Staudinger, Schatz and Rober, Exotische Tagfalter, in three folio volumes (Fiirth. 1884-1887), with illustrations of exotic butterflies and a detailed sketch of their characters. 3, Enzio Reuter, "Tiber die Palpen der Rhopaloceren," in Acta Soc. Sci. Fenn. xxii. 1896, treating fully of classifica- tion and phylogeny. 344 LEPIDOPTERA 11 i on ah in the female there are usually five but without any claios. Pupa suspended ~by the tail so as to hang down freely. We include in this family several sub -families treated by some taxonomists as families; in this respect we follow Bates, whose arrangement1 still remains the basis of butterfly classification. With this extension the Nymphalidae is the most important of the families of butterflies, and includes upwards of 250 genera, and between 4000 and 5000 species. There are eight sub- families. It is in Nymphalidae that the act of pupation reaches its acme of complication and perfection ; the pupae hang suspended by the tail, and the cremaster, that is the process at the end of the body, bears highly - developed hooks (Fig. 177, C, D). The variety in form of the chrysalids is extraordinary ; humps or processes often project from the body, making the Insect a fantastic object ; the strange ap- pearance is frequently in- FIG.' 177.— Pupa of the Purple Emperor butterfly, creased by patches like Apatnra iris New Forest. A, Lateral, B, M Qr Q j^d dorsal aspect ; C, enlarged view of cremaster •- with the suspensory hook ; D, one hook still Various parts of the body. It is believed that the term chrysalid was first suggested by these golden pupre. The Purple Emperor, Apatura iris, differs strikingly in the pupa- as well as in the larva- stage from all our other Nymphalids ; it is of green colour, very broad along the sides, but narrow on the dorsal and ventral aspects (Fig. 177). The skin of this pupa is less hard than usual, and the pupa seems to be of a very delicate constitution. The Purple Emperor, like some of the Satyrides as well as some of its more immediate congeners, hibernates in our climate as a partially grown larva and passes consequently only a very brief period of its existence in the form of a pupa. Sub-Fam. 1. Danaides. — Front wing with inner -mar gin 1 Journal of Entomology, i. 1862, p. 218 : for early instars of South American Nymphalidae see Miiller, Zool. Jahrb. Syst. i. 1886, p. 417. vi RHOPALOCERA DAN AIDES 345 (submedian) nervwre, t>;ith a short fork at the base. Cell of hind icing closed. Front foot of the female ending in a corrugate knob. Caterpillars smooth, provided with a few long fleshy pro- cesses. The claws are in a variable state, being sometimes simple, as in Papilionidae, sometimes with an empodium, apparently of an imperfect kind. The Danaides are usually large Insects with an imperfect style of ornament and colour ; they have a great deal of black or very dark scaling, and in some Euploea this is agreeably relieved by a violet or purple suffusion, and these are really fine Insects. Usually there are large pale spaces, of some neutral indefinite tint, on which black blotches are dis- tributed in a striking but inartistic manner. In many of the species the markings are almost spot for spot the same on the upper and under sides. About seven genera and 250 species are recognised. Danaides occur in all the warmer parts of the world, but are most numerous in the Eastern tropics. In Europe the family is represented only by an Asiatic and African species, Limnas chrysippus, that has extended its range to Greece. Besides this another species, Anosia erippus, Cr. (unfortunately also called Anosia menippe, Hb., and Danais archippus or even D. plexippus) has in the last two or three decades extended its range to various islands and distant localities, concomitantly, it is believed, with an extension of the distribution of its food-plant, Asclepias. This Insect has several times been taken in this country, and may probably be a natural immigrant. It is a common butterfly in North America, where it is called the Monarch.1 Some, at least, of the Dauaides are unpleasant to birds in odour or in taste, or both. Among them there occur, according to Moore 2 and others, numerous cases of resemblance between forms that are thus protected. It is possible that the odour and taste are of some value to the Insects ; 3 as, however, butter- flies of any kind appear to be but rarely attacked in the imago- state by birds, and as their chief enemies are parasitic Insects that attack the larval instar, it is impossible to consider this protection of such prime importance to the species as many theorists assume it to be. 1 This is the subject of Scudder's Life of a Butterfly, 1893. - P. Zool. Soc. London, 1883, p. 205. 3 Finn, J. Asiat. Soc. Bengal, Lxvi. 1896, p. 528 ; Ixvii. 1897, p. 213. LEPIDOPTERA CHAP. Sub-Fam. 2. Ithomiides. — Differs from Danaides l>y the female front foot having a true, though somewhat abbreviate tarsus. The caterpillers have no long processes. There has been considerable difference of opinion as to this division of butter- flies. It is the family Neotropidae of Schatz, the Mechanitidae of Berg ; also the " Danaioid Heliconiidae " of several previous writers, except that Ituna and Lycorea do not belong here but to Danaides. Godmaii and Salvin treat it as a group of the Dauaid sub -family. The Ithomiides are peculiar to tropical America, where some 20 or 30 genera and about 500 species have been discovered. There is considerable variety amongst them. Ithomia and Hymenitis are remarkable for the small area of their wings, which bear remarkably few scales, these ornaments being in many cases FIG. 1/8. — Ithomia pusio. Brazil. _ _ J limited to narrow bands along the margins of the wings, and a mark extending along the discocellular nervule. Wallace says they prefer the shades of the forest and flit, almost invisible, among the dark foliage. Many of these species have the hind-wings differently veined in the two sexes on the anterior part, in connection with the existence in the male of peculiar fine hairs, placed near the costal and svibcostal veins. Tithorea and other forms are, how- ever, heavily scaled insects of stronger build, their colours usually being black, tawny-red or brown, yellow, and white. In the sub-fam. Danaides, according to Fritz Miiller, the male has scent- tufts at the extremity of the abdomen, whereas in Ithomiides analogous structures exist on the upper side of the hind-wing. Ithomiides have various colour-resemblances with members of the Heliconiides and Pieridae ; Tithorea has colour analogues in Heliconius, and Ithomia in Dismorphia (formerly called Leptalis). Crowds of individuals of certain species of Ithomia are occasion- ally met with, and mixed with them there are found a small number of examples of Dismorphia coloured like themselves. They are placed by Haase in his category of secondary models. Belt states that some Ithomiides are distasteful to monkeys and spiders, but are destroyed by Fossorial Hymenoptera, which use the butterflies as food for their young ; and he also says that vi RHOPALOCERA ITHOMIIDES SATYRIDES 347 they are very wary when the wasp is near, and rise off then- perches into the air, as if aware that the wasp will not then endeavour to seize them. " Much information is given about the habits by Bates in the paper in which he first propounded the " theory of mimicry." ' The larvae are said to live on Solanaceae. The genus Hamadryas is placed by some writers in Danaides, by others in Ithomiides ; and Haase has proposed to make it the group " Palaeotropinae." The species are small, black and white Insects, somewhat like Pierids. They are apparently hardy Insects, and are abundant in certain parts of the Austro-Malay region. Sub-Fam. 3. Satyrides. — Palpi strongly 2?)'essed together, set in front with long, stiff hairs. Front wings frequently with one or more of the nervures swollen or bladder-like at the base of the wing. Cells of both wings closed. Caterpillar thickest at the middle, the hind end of the body bifid. Pupa generally suspended by the cremastcr, without girth : but sometimes terrestrial. This is a very extensive group, consisting of upwards of 1000 species. The Insects are usually of small size, of various shades of brown or greyish colours, with circular or ringed marks on the under sides of the wings. It is found all over the world, and is well represented in Europe ; our Meadow-browns, Heaths, and Marbled- whites, as well as the great genus Erebia of the highlands and mountains belonging to it. Most of these Insects have but feeble powers of night, and rise but little from the surface of the ground. The caterpillars live on various grasses. They are usually green or brown, destitute of armature, and a good deal like the caterpillars of Noctuid moths, but the hind end of the body is thinner and divided to form two corners, while the head is more or less free, or outstanding. The pupae are of great interest, inasmuch as in a few cases they do not suspend them- selves in any way, but lie on the ground ; sometimes in a very feeble cocoon or cell. There are no cremasteral hooks. The pupae of the Grayling butterfly, Jfipparchia semele, has been found in loose soil a quarter of an inch below the surface. The chrysalis of the Scotch Argus, Erebia aethiops, was found by Mr. Buckler to be neither suspended nor attached, but placed in ;i perpendicular position, head upwards, amongst the grass. 1 Trans. Linn. Soc. xxiii, 1862, p. 495. LEPIDOPTERA CHAP. In the majority of cases the pupa is, however, suspended as is usual in Nymphalidae. Nothing is known as to the nature of the peculiar inflation of the bases of the nervures of the front wings ; it is well shown in our common species of Coenonympha ; this character is not, however, constant through- out the family. There is in South America a very remarkable group of Satyrides consisting of the genera Cithaerias and Haetera, in which the wings are very delicate and transparent, bearing on the greater part of their area remote fine hairs instead of scales ; there are nevertheless some scaled patches about the margins, and one or more of the ringed marks characteristic of the Satyrides ; while in some species the distal portions of the hind wings are tinted with carmine. The species of the genus Pierella connect these transparent Satyrids with the more ordinary forms. According to Wallace the habits of these fairy-like forms are those characteristic of the family in general. The genus Elymnias has been separated by some authorities as a sub-family, or even as a family, Elyrnniidae, chiefly on the ground of a slight peculiarity in the termination of the branches of the veins at the outer angle of the front wings. The Elymnias are said to be of a mimetic nature, having a greater or less resemblance to butterflies of various other divisions ; there is also a considerable difference in appearance between their own sexes. The larva of E. undularis is known ; it is of the form usual in Satyrides, and lives on the palm Corypha. About 5 0 species, ranging from India to Australia, with two in Africa, are known of this interesting group. Sub-Fam. 4. Morphides. — There is no cell on the hind wing, the discocellular nervule being absent (Fig. 1 6 1, II. B). Caterpillars smooth or spiny, with the extremity of the l)ody divided ; frequently yrerjarious. These Insects have become notorious from the extra- ordinary brilliancy of blue colour exhibited by the upper surface of the wings of the typical genus Morpho. The species ofMorpho are all Insects of large size, but with wings enormous in proportion to the body ; this latter part is carried in a sort of cradle formed by the inner parts of the margins of the hind wings. Although an arrangement of this kind is seen in numerous other butter- flies, yet there is perhaps none in which it is carried to quite such a pitch of perfection as it is in Morpho, where, on the under surface no part of the body behind the posterior legs can vi RHOPALOCERA MORPHIDES BRASSOLIDES 349 be seen. There are only about 100 species of Morphides, and 50 of these are included in Morpho, which is peculiar to tropical and sub-tropical America ; the other half of the family is divided among ten or twelve genera, found in the Indo-Malay region : there being none in Africa. The eastern Morphides, though fine Insects, are not to be compared, either in size or brilliancy, with their American allies. The species of Morpho are ap- parently found only in the great forests of South America, where they are far from rare ; some have a flapping and undulat- ing flight, straight onwards along the alleys of the forest, and near the ground ; others are never seen except steadily gliding with outstretched wings from 20 to 100 feet above the ground, where they move across sunny spaces between the crowns of the taller trees ; the low - flyers settle frequently on the ground to suck the juices from fallen fruit, but the members of the other section never descend to the ground. As regards the caterpillars, W. Miiller tells us l that the spines they are armed with break off, and enter the skin, if the creatures are carelessly handled. Four of the five species known to him are conspicu- ously coloured with black, red, yellow and white. The individuals are gregarious. The larvae of M. achilles sit in companies, often of more than 100 individuals, on trunks of trees, and so form a conspicuous patch. The caterpillars of M. epistropliis hang to- gether as red clumps on the twigs of their food-plants. Hence it appears that in this genus we have an exception to the rule that night-feeding caterpillars rest in a hidden manner during the day. Sub-Fam. 5. Brassolides. — Large butterflies, ivith the cell of the hind wing closed, and usually with a small adjoining predis- coidal cell. Larva not very spiny ; thinner' at the two ends, the tail bifid, the head perpendicular and margined with spines. This small sub-family includes less than 100 species arranged in about eight genera, all South American. They have the very unusual habit of resting during the day like moths, becoming active only late in the afternoon. They are truly noble- Insects ; although not possessed of the brilliant colours of Morpho, they are adorned, especially on the under surface, with intricate lines and shades most harmoniously combined, while the upper surface is frequently suffused with blue or purple. This sub-family 1 Kosmos, xix. 1886, p. 355. 350 LEPIDOPTERA -S attains its highest perfection in the genus Caligo ; they are enormous Insects, and some of them not rare. The larva of C. eurylochus (Fig. 179) during early life is green, and sits on the leaf of a Mum, but after the third moult it becomes brown and hides itself among the dry leaves. It is common in the gardens of Eio de Janeiro, where its pupae are found on the walls, like those of our white butterflies here. Sub - Fam. 6. Acraeides. — Sub- median nervure of fore wings not forked at the base; the median without spur. Cells closed. Palpi in section cylindric, sparingly set with hairs. Larva armed with 'branched spines. A somewhat monotonous and uninteresting division ; the size is moderate or small, and the colours not artistic, but consisting of ill-arranged spots ; the under side of the hind wings very frequently diver- sified by numerous line-like marks, radiately arranged, and giving place at the base to a few spots. There are about 200 species known, of which the majority are African ; there are but few Oriental or South American species. Some authorities consider there is only one genus, but others prefer to adopt seven or eight divisions. Alaena is now placed in Lycaenidae, though until recently it was considered to belong here. The females of some species possess an. abdominal pouch somewhat similar to that of Parnassius. The members of this sub -family are considered to be of the protected kind. vi RHOPALOCERA HELICONIIDES 351 Sub-Fam. 7. Heliconiides. — Submedian nervure of front wing not forked ; 'median with a short spur near the base. Cell of hind wing closed by a perfect nervule. Palpi compressed, with scales at the sides, in front covered with hairs. Male ivith an elongate unjointed, female with a four-jointed, front tarsus. Caterpillars set with branched spines. This family is peculiar to tropical America and consists of only two genera, Heliconius and JEueides, with about 150 species ; but it is one of the most characteristic of the South American groups of Butterflies. It is very closely allied to the Nymphalides, especially to the genera Metamorpha and Colaenis, but is readily distinguished by the perfectly-formed nervules that close the wing-cells. The wings are longer and narrower than in Nymphalides, and the colour, though exhibiting much diver- sity, is on the whole similar to that of the heavily-scaled forms of Ithomiides of the genera Tithorea, Melinaea, Melanitis ; there being in several cases a great resemblance between species of the two groups. A frequent feature in one group of Heliconius is that the hind wing bears a patch of red prolonged outwards by angular radiating marks. The individuals of certain species — H. melpomene and H. rhea — are known to execute concerted dances, rising and falling in the air like gnats ; when some of them withdraw from the concert others fill their places. H. erato exhibits the very rare condition of trichroism, the hind wings being either red, blue, or green. Schatz states that the different forms have been reared from a single brood of larvae. The cater- pillars of Heliconiides live on Passiflorae, and are said to be very similar to our European Argynnis-caierpillnrs. The chrysalids are very spinous. We may here remark that considerable con- fusion exists in entomological literature in consequence of Itho- miides having been formerly included in this sub-family ; for remarks formerly made as to " Heliconiides," but that really referred only to Ithomiides, have been interpreted as referring to Heliconiides of the present system. The Heliconiides seem remarkably plastic as regards colour, and are therefore exponents of " homoeochromatism." Bates says, as regards them : " In tropical South America a numerous series of gaily-coloured butterflies and moths, of very differ- ent families, which occur in abundance in almost every locality a naturalist may visit, are found all to change their hues and markings together, as if by the touch of an enchanter's wand, at 352 LEPIDOPTERA every few hundred miles, the distances being shorter near the eastern slopes of the Andes than nearer the Atlantic. So close is the accord of some half-dozen species (of widely different genera) in each change, that he had seen them in large collections classed and named respectively as one species." ] Many of them are believed to be permeated by nauseous fluids, or to possess glands producing ill-smelling secretions. Sub-Fam. 8. Nymphalides. — Cells, of loth front and hind wing, either closed only by imperfect transverse nervules or entirely open. Front tarsus of the male unjointed and without spines, of the female four- or Jive-jointed. Caterpillar either spined or smooth ; in the latter case the head more or less strongly horned or spined, and the apex of the body bifid. This sub- family is specially characterised by the open cells of the wings ; the discocellulars, even when present, being frequently so imperfect as to escape all but the most careful observa- tion. The Nymphalides include upwards of 150 genera and 2000 species. The divisions having smooth larvae are separated by Kirby 2 and others as a distinct sub-family (Apaturides). In Britain, as in most other parts of the world, Nymphalides is the predominant group of butterflies. We have eighteen species, among which are included the Fritillaries, Admirals, Purple Emperor, and the various Vanessa — Peacock, Camberwell Beauty, Eed Admiral, Tortoise-shells, and Painted Lady. All have spined caterpillars except the Emperor. In the temperate regions of the northern hemisphere Vanessa may be considered the dominant butter- flies, they being very numerous in individuals, though not in species, and being, many of them, in no wise discomfited by the neighbourhood of our own species. Several of them are capable of prolonging and interrupting their lives in the winged condition to suit our climate ; and this in a manner that can scarcely be called hibernation, for they frequently take up the position of repose when the weather is still warm, and on the other hand recommence their activity in the spring at a very early period. This phenomenon may frequently be noticed in the Tortoise-shell butterfly ; it is as if the creature knew that however warm it may be in the autumn there will be no more growth of food for its young, and that in the spring vegetation 1 P. ent. Soc. London, 1879, p. xxix. 2 Allen's Naturalists' Library, Butterflies, i. 1896. vi BUTTERFLIES — NYMPHALIDES 353 is sure to be forthcoming and abundant before long, although there may be little or none at the time the creature resumes its activity. It is probable that the habit may be in some way connected with an imperfect activity of the sexual organs. It should, however, be recollected that many larvae of butterflies hibernate as young larvae after hatching, and, sometimes, with- out taking any food. Pyrameis cardui, the Painted Lady, is, taking all into consideration, entitled to be considered the most ubiquitous of the butterfly tribe. Its distribution is very wide, and is probably still extending. The creature is found in enormous numbers in some localities, especially in Northern and Eastern Africa ; and when its numbers increase greatly, migration takes place, and the Insect spreads even to localities where it cannot maintain itself permanently. In Britain it is probably during some years nearly or quite absent, but may suddenly appear in large numbers as an immigrant. The favourite food of the larva is thistles, but many other plants serve the Insect at times. Vanessa, or Pyrameis,1 atalanta, the Eed Admiral, is common in the Palaearctic and Nearetic regions, and extends its range to various outlying spots. The most remarkable of these is the remote Hawaiian Islands, where the Insect appears really to be now at home, though it is associated with a larger and more powerful congener, P. tameamea. Another interesting Vanessid is Araschnia levana, which is peculiar to Europe, where it produces annually two generations so dissimilar to one another that they passed current as two species, V. levana and V. prorsa. Although intermediate forms are rare in nature they can be induced by certain treatments applied to the larvae under human control. The dead-leaf butterflies of the genus Kallima belong to Nymphalides. They are so shaped and coloured that when settled, with wings closed, on a twig, the appearance is exactly that of a dry leaf: the exposed surface is mottled with spots that look just like the patches of minute fungi, etc. that are so common on decaying vegetation. The colour and the spots on the under surface of this butterfly are very variable. According to Mr. Skertchly,2 we may presume that in the minute details of 1 A most unfortunate diversity exists in the generic names applied to these Vanessa, as well as in those of many other Lepidoptera. - Ann. Nat. Hist. (6), iv. 1889, p. 212. VOL. VI 2 A 354 LEPIDOPTERA these resemblances we have a case of hypertely similar to that of the resemblance to Insects' minings exhibited by certain marks on the tegmina of Pterochroza (mentioned in Vol. V. p. 322). In South America there is a somewhat peculiar genus of Nymphalides — Ageronia — that delights in settling on the trunks of trees rather than on flowers or leaves. It was long since noticed that the species of Ageronia make a clicking noise ; in some cases when on the wing, in other cases by moving the wings when the Insect is settled. The object of the noise is quite uncertain ; it has been suggested that it is done in rivalry or courtship, or to frighten away enemies. Bigg- Wether found, however, that in South Brazil there is a lazy little bird to which this sound serves as a signal, inducing it to descend from its perch and eat the clicker. The mode in which the noise is produced is not quite clear. Sir George Hampson has pointed out l that the fore wing bears at the extreme base a small appendage bearing two hooks, and that two other processes on the thorax play on these when the wing moves. His suggestion that these hooks are the source of the sound seems highly probable. There is a great variety in the larvae of Nymphalides. In the Vanessa group the body is armed with spines, each one of which bears shorter thorns, the head being unadorned. The Fritillaries (Argynnis, Melitaea) also have caterpillars of this kind. In many other forms the head itself is armed with horns or spines of diverse, and frequently remarkable, character. In Apatura and its allies the body is without armature, but the head is perpen- dicular, the vertex bifid and more or less prolonged. The caterpillar of our Purple Emperor, Apatura iris, is quite unlike any other British caterpillar ; in colour it is like a Sphingid larva — green with oblique lateral stripes of yellow and red — but in form it is slug-like, pointed behind, and it has on the head two rather long tentacle-like horns. In the South American genus Prepona, the larva of which in general form resembles that of Apatura, there are no anal claspers, but the extremity of the body is prolonged, forming a sort of tail. Fam. 2. Erycinidae (Lemoniidae of some authors). — The female lias six per/ ectly formed legs, though the front pair is smaller. The male has the coxae of the front legs forming a spine, and the tarsi unjointed, without claws. This family consists of about 1000 1 P. Zool. Soc. London, 1892, p. 191. vi BUTTERFLIES — ERYCINIDAE 355 species, usually of rather small size, exhibiting a great variety of shape and coloration, some of them being remarkably similar to some of the gay, diurnal moths of South America. The palpi are usually small, but in Ourocnemis they are large and porrect. The family is specially characteristic of tropical America, but there is one small group of 30 or 40 species, Nemeobiides, in the Eastern Hemisphere. "We have one species in Britain, Nemeobius lucina, the Duke of Burgundy Eritillary. Neither the larvae iior the pupae of Erycinidae present any well-marked characteristic feature, but exhibit considerable variety. According to Bar,1 some of the larvae are like those of moths ; the caterpillar of Meliboeus is said to be like that of a Liparis : the chrysalis has the short, rounded form of that of the Lycaenidae, and is sus- pended with the head down, and without a band round the body. The larvae of Eurygona are gregarious. The pupae of some other forms adhere, heads downwards, to branches. Scudder considers that this family is not distinct from Lycaenidae, and that the Central American genus Eumaeus connects the two. Eeuter also treats Erycinidae as a division of Lycaenidae. Sub-Fam. 1. Erycinides. — [Characters of the family.] Palpi not unusually large. We place all the Erycinidae in this sub- family except the following — Sub-Fam. 2. Libytheides. — Butterflies of average size, with the palpi large and porrect : the front legs of the male small, the tarsus reduced to one joint : the front leg of the female of the normal structure, and but little reduced in size. This division consists of the single genus Libythea, with only a score of species. They are Insects somewhat like Vanessa in appearance, but can- not fail to be recognised on account of the peculiar palpi. The genus is of very wide distribution, occurring in most parts of the warm and temperate continental regions, and it also occurs in Mauritius and the Antilles. The Libytheides have given rise to much difference of opinion amongst systematists, some of whom assign them as a sub- family to the Erycinidae, some to the Nyinphalidae ; while others treat them as a family apart. The families Nymphalidae, Ery- cinidae and Lycaenidae are so intimately allied, that Scudder is probably correct in considering them to form really one huge family ; if this view were adopted there would be no difficulty 1 Bull. Soc. cnt. France, 1856, pp. c, ci. 356 LEPIDOPTERA in locating Libytliea therein. If they be kept apart, it is almost necessary to separate Libythea also ; though possibly its claims to be placed in Erycinidae slightly preponderate. The recently described genus Ourocnemis to some extent connects Erycinides with Libythaeides.1 Fam. 3. Lycaenidae. — The front legs but little smaller than the others : in the male, however, the tarsus, though elongate, is only of one joint, and is terminated l>y a single claw. No pad on the front tibia. Claws not toothed. The Lycaenidae, or Blues, are, as a rule, of small size, but in the tropics there are many that reach the average size of butterflies, i.e. something about the stature of the Tortoise-shell butterfly. The family is one of the larger of the divisions of butterflies, considerably more than 2000 species being at present known, and this number is still rapidly increas- ing. Although blue on a part of the upper surface is a very common feature in the group, it is by no means universal, for there are many " Coppers," as well as yellow and white Lycae- nidae. Many species have delicate, flimsy appendages — tails — to the hind wings, but in many others these are quite absent ; and there are even tailed and tailless forms of the same species. The members of the group Lipteninae (Liptena, Vanessida, Mimacraea, etc.) resemble members of other sub-families of Nym- phalidae, and even of Pieridae. Lycaenidae are well represented wherever there are butterflies ; in Britain we have 1 8 species. The larvae of this family are very peculiar, being short, thicker in the middle, and destitute of the armature of spines so remark- able in many other caterpillars. It has of late years been fre- quently recorded that some of these larvae are attended by ants, which use their antennae to stroke the caterpillars and induce them to yield a fluid of which the ants are fond. G-uenee had previously called attention 2 to the existence of peculiar structures contained in small cavities on the posterior part of the cater- pillar of Lycaena baetica. These structures can be evaginated, and, it is believed, secrete a fluid ; Edwards and M'Cook are of opinion that they are the source of the matter coveted by the ants. The larvae are without spines. The caterpillars of the Blues have some of them strange tastes ; more than one has been recorded as habitually feeding on Aphidae 1 Baker, Tr. ent. Soc. London, 1887, p. 175, PI. ix. - Ann. Soc. ent. France (4), vii. 1867, p. 665, PI. xiii. vi BUTTERFLIES LYCAENIDAE PIERIDAE 357 and scale-Insects. The pupae are, like the larvae, of short inflated form. By a remarkable coincidence, the pupae of two species hear a considerable resemblance to the heads of monkeys, or mummies. The Lycaenid pupa is usually extremely consoli- dated, destitute of movement, and is supported — in addition to the attachment by the cremaster — by a silk thread girdling the middle. There are exceptions to these rules, and according to Mr. Eobson the pupa of Tajuria diaeus hangs free, suspended from a leaf, and can move the body at the spot where the abdominal segments meet the wing-cases in the dorsal line.1 Fam. 4. Pieridae. — The six legs well developed, and similar in the sexes ; there is no pad on the front tibia. The daws of all the feet are bifid, or toothed, and there is an empodium. There are upwards of 1000 species of Pieridae already known. Al- though several taxonomists treat the Pieridae and Papilionidae as only subdivisions of one family, yet they appear to be quite distinct, and the relationships of the former to be rather with Lycaeiiidae. In Pieridae, white, yellow, and red are the pre- dominant colours, though there is much black also. It has recently been ascertained that the yellow and red pigments, as well as the white, are uric acid or derivatives therefrom.2 The physiology of this peculiarity has not yet been elucidated, so that we do not know whether it may be connected with some state of the Malpighian vessels during metamorphosis. Our Garden-White, Brimstone, Clouded-yellows and Orange-tip butterflies belong to this family ; as does also the South American genus formerly called Leptalis. This generic name, which is much mentioned in literature owing to the resemblance of the species of the genus to Heliconiides, has now disappeared ; Leptalis having been divided into various genera, while the name itself is now considered merely a synonym, of Dismorphia. The African Insect, Pseudopontia paradoxa, has nearly trans- parent wings, no club to the antennae, a remarkably small cell on the wing, and an arrangement of the nervules not found in any other butterfly ; there being only ten nervules at the periphery of the front wing, and both upper and lower radial nervules uniting with the posterior branch of the subcostal. It has been treated as a moth by several entomologists. Aurivillius considers that it 1 J. Bombay Soc. ix. 1895, pp. 338-341. 2 Hopkins, Phil. Trans. 186 B, 1895, p. 661. 358 LEPIDOPTERA is certainly a butterfly ; but as the metamorphoses are unknown, we cannot yet form a final opinion as to this curious form. The extraordinary Peruvian Insect, Styx infernalis, is also placed in this family by Staudinger ; it is a small, pale Insect, almost white, and with imperfect scales ; a little recalling a Satyrid. It appears to be synthetic to Pieridae and Erycinidae. The caterpillars of Pieridae are perhaps the least remarkable or attractive of all butterfly -caterpillars ; their skins are as a rule bare, or covered only with fine, short down or hair ; their prevalent colour is green, more or less speckled with black and yellow, and they are destitute of any prominent peculiarities of external struc- ture. Pupation is accomplished by the larva fixing itself to some solid body by the posterior extremity, with the head upwards (or the position may be horizontal), and then placing a girdle round the middle of the body. The pupa never hangs down freely as it does in Nymphalidae. It has been FIG. 180. — Pupation of the • Orange-tip butterfly, ascertained by experiment that if the Euchloe cvrdamims. A, • dl d tfl } b fc tfa Ine completed pupa ; B, c the larva, with its girdle, tion can nevertheless be accomplished by prepared for the change. a considerable proportion of larvae. Some of the pupae are of very peculiar form, as is the case in the Orange-tip (Fig. 1 80, A) and Brimstone butterflies. The Orange- tip butterfly passes nine or ten months of each year as a pupa, which is variable in colour ; perhaps to some extent in conformity with its surroundings. The North American E. genutia has a similar life-history, but the larva leaves its Cruciferous food-plant, Wanders to an FIG. 1 81. —Newly-hatched larva of Enchloe car- oak tree, and there turns to damina. A, The larva in profile ; B, one segment more magnified, showing the liqmd- a pupa, resembling in colour bearing setae ; C, one of the setae still more the bark of the tree. magnified, and without liquid. It is not unusual for caterpillars to change their habits and BUTTERFLIES — PIERIDAE PAPILIONIDAE 359 appearance in a definite manner in the course of the larval life. The caterpillar of Euchloe cardamines exhibits a larval meta- morphosis of a well-marked character. The young larva (Fig. 181) is armed with peculiar setae, furcate at the tip, each of which bears a tiny ball of fluid. In this stage the caterpillar makes scarcely any movement. In the middle of the cater- pillar's life a new vestiture appears after an ecdysis ; numerous fine hairs are present, and the FIG. 182. —Larva of Euchloe cardamines in middle life. fluid - bearing spines A> the larva in profile ; B> one segment more masuified- nearly disappear, being reduced to a single series of spines of a comparatively small size on each side of the upper middle region of the body (Fig. 182). The colour is also a good deal changed, and concomitantly there is a much greater voracity and restlessness. Fam. 5. Papilionidae. — All the legs well developed. Claws large, simple, without empodium. Front tibiae with a pad. The metanotum free, conspicuously exposed between mesonotum and (ilii/nt/ten. This series of butterflies includes some of the most magnificent of the members of the Insect world. It is considered 1 iv some authorities to be the highest family of butterflies ; and in one very important feature — sexual differentiation — it cer- tainly is entitled to the rank. There are about 700 recorded species, the larger portion of which are included in the genus Papilio. The great variety of form has led to this genus being divided ; the attempts have, however, been partial, with the exception of an arrangement made by Felder, who adopted 75 sections, and a recent consideration of the subject by Haase, who arranges Felder's sections into three sub-genera. Many of the sections have received names, and are treated by some authors as genera, so that an unfortunate diversity exists as to the names used for these much-admired Insects. The genus is distributed all over the world, but is perhaps nowhere more numerous in species than in South America. Wallace informs us that the great 360 LEPIDOPTERA majority of the species of the Amazon valley frequent the shady groves of the virgin forest. In many cases the sexes are ex- tremely different in appearance and habits, and are but rarely found together in one spot. The genus Ornithoptera is closely allied to Papilio, and contains some of the most remarkable of butterflies, the homes of the species being the islands of the Malay Archipelago, and outlying groups of islands, there being a smaller number of species in the neighbouring continents. The females are of great size, and are so excessively different from their 362 LEPIDOPTERA CHAP. consorts of the other sex. as to arouse in the student a feeling of O surprise, and a strong desire to fathom the mysteries involved. It would be difficult to surpass the effective coloration of the males in many of the species of Ornithoptera ; they are, too, very diverse1 in this respect; 0. brookiana is of an intense black colour, with a band of angular green marks extending the whole length of its wings, while behind the head there is a broad collar of crimson colour. Perhaps the most remarkable of all is the 0. paradisen, recently discovered in New Guinea ; in this species the sexual disparity reaches its maximum. The female (Fig. 184) is a large, sombre creature of black, white and grey colours, but the male (Fig. 183) is brilliant with gold and green, and is made additionally remarkable by a long tail of unusual form on each hind wing. We may anticipate that these extraordinary cases of sexual total dissimilarity in appearance are accompanied by equally remarkable habits and physiological phenomena. In the case of 0. brookiana the female is extremely rare, so that the collector, Kiinstler, could only obtain fifteen females to a thousand males. According to Mr. Skertchly, instead of the crowd .of males being- eager to compete for the females, the reverse is the case ; the female diligently woos the male, who exhibits a reluctance to coupling. This observer apparently considered that the " emerald feathers " of the male are a guide or incitement to the female.1 In Africa Ornithoptera is to a certain extent represented by two extremely remarkable forms, Papilio zalmoxis and P. (Drurya] antimachus. There are about a dozen other genera of Papilionidae ; most of them contain but few species. Parnassius, however, is rich in species inhabiting the mountains and elevated plateaus of the northern hemisphere in both the Old and Xe\v Worlds ; it is remarkable for the small amount of scales on the wings, and for the numerous variations of the species. The female possesses a peculiar pouch at the end of the body ; although only formed during the process of coupling, it has a special and characteristic form in most of the species. The curious Indian genus Leptocircus has parts of the front wings transparent, while the hind pair form long tails. This genus is of interest in that 1 Ann. Nat. Hist. (6), iv. 1889, p. 213. We trust there will not be many more Kiinstlers, as this beautiful butterfly must certainly become extinct, if the female be really as rare as is supposed. vi BUTTERFLIES SKIPPERS 363 it is said to connect Papilionidae to some extent with Hesperiidae. The larvae of this family are remarkable on account of a curious process on the thoracic segment called an " osmeterium." It is usually retracted, but at the will of the caterpillar can be everted in the form of a long furcate or Y-shaped process ; there is a gland in the osmeterium, and as a result a strong odour is emitted when the exstulpation occurs. The pupation of Papilionidae is similar to that of Pieridae, the pupa being placed with the head upwards, fixed by the tail, and girt round the middle. A very curious diversity of pupation occurs in the genus Thais, in which the pupa is attached by the tail as usual, and — which is quite exceptional — also by a thread placed at the top of the head. Scudder thinks there is also a girdle round the middle, but Dr. Chapman inclines to the view that the thread attaching the head is really the median girdle slipped upwards. The pupation of Parnassius is exceptional, inasmuch as, like Satyrides, it is terrestrial, in a slight construc- tion of silk. Fam. 6. Hesperiidae (Skippers). — Six perfect legs : metanotum not free, largely covered ~by the mesonotum. A pad on the front tibia. Claws short and thick ; empodium present. Although this family has been comparatively neglected by entomologists, upwards of 2000 species and more than 200 genera are known, and it is not improbable that it may prove to be as extensive as Nymphalidae. We have already said that Hesperiidae is generally admitted to be the most distinct of the butterfly groups. It has been thought by some taxonomists to be allied to Papilionidae, but this is a mistake. It is undoubtedly more nearly allied to Heterocera, and when the classification of Lepidoptera is more advanced, so that the various natural groups placed in that sub-Order are satisfactorily distinguished, it is probable that Hesperiidae will be altogether separated from Bhopalocera. We have already mentioned that E. Eeuter considers the Hesperiidae to be phylo- genetically unconnected with Rhopalocera proper ; but though quite ready to admit that he will probably prove correct in this, we think Lepidopterists will not be willing to recognise the family as a sub-Order equivalent in value to all Heterocera. The body is shorter and thicker than it is in most butterflies, and is pointed at the tip rather than knobbed or bent down- wards ; the wings are less ample ; the antennae are not truly 364 LEPIDOPTERA knobbed, but are thicker before the actual tip, which is itself pointed and more or less bent backwards, so that the antennae are somewhat hook-shaped. In habits as well as structure the family is markedly distinct from butterflies ; the pupation is peculiar, and the name Skipper has been applied to the perfect Insects, because so many of them indulge in a brief, jerky flight, instead of the prolonged aerial courses characteristic of the higher butterflies. There is great difference among the members of the family, and some of them possess a very high development of the powers of locomotion, with a correspondingly perfect structure of the thoracic region, so that, after inspection of these parts, we can (juite believe Wallace's statement that the larger and strong- bodied kinds are remarkable for the excessive rapidity of their night, which, indeed, he was inclined to consider surpassed that of any other Insects. " The eye cannot follow them as they dart past ; and the air, forcibly divided, gives out a deep sound louder than that produced by the humming-bird itself. If power of wing and rapidity of flight could place them in that rank, they should be considered the most highly organised of butterflies." It was probably to the genera Pyrrhopyge, Ery tides, etc., that Mr. Wallace alluded in the above remarks. Although the Hes- periidae are not as a rule beautifully coloured, yet many of these higher forms are most tastefully ornamented ; parts of the wings, wing-fringes, and even the bodies being set with bright but agree- able colours. We mention these facts because it is a fashion to attribute a lowly organisation to the family, and to place it as ancestral to other butterflies. Some of them have crepuscular habits, but this is also the case with a variety of other Ehopalo- cera in the tropics. In their early stages the Skippers — so far as at present known — depart considerably from the majority of butterflies, inasmuch as they possess in both the larval and pupal instars habits of con- cealment and retirement. The caterpillars have the body nearly bare, thicker in the middle, the head free, and more or less notched above. They make much greater use of silk than other butterfly-larvae do, and draw together leaves to form caves for concealment, and even make webs and galleries. Thus the habits are almost those of the Tortricid moths. Pupation takes place under similar conditions ; and it is interesting to find that Chap- HESPERIIDAE SKIPPERS 365 man considers that the pupa in several points of structure re- sembles that of the small moths. Not only does the larva draw together leaves or stalks to make a shelter for the pupa, but it frequently also forms a rudimentary cocoon. These arrangements are, however, very variable, and the accounts that have been given indicate that even the same species may exhibit some amount of variation in its pupation. Scudder considers that, in the North American Skippers, the cremaster is attached to a single Y-like thread. In other cases there is a silk pad on the leaf for the cremaster to hook on. An interesting account given by Mr. Dudgeon of the pupation of a common Indian Skipper, Badamia exclamationis, shows that this Insect exercises considerable in- FIG. 185. —Pupation of Badamia exclamation is. (After Dudgeon. ,/. Bombay Soc. x. 1895, p. 144). A, One side of the leaf-cradle, the other (nearest to the observer) being broken away ; B, transverse sec- tion of entire cradle, a, The pupa ; b, fastenings of perpendicular threads round pupa ; c, cross thread retaining the leaf in cradle form ; !I yra pendularia). Certain of the larvae of Geometridae vary in colour, from shades of brown to green ; there is much diversity in this variation. In some species it is simple variation : in others it is dimorphism, i.e. the larvae are either brown or green. In other cases the larvae are at first variable, subsequently dimorphic. In Amplii- dasis betularia it would appear that when the larva is hatched the dimorphism is potential, and that the future colour, whether FIG. 202. — Larva of Amphidasis betularia, reposing on a rose-twig. x 1. Cambridge. GEOMETRIDAE 4 i 3 green or brown, is settled by some determining condition during the first period of larval life and cannot be subsequently modified.1 According to Poulton, the dark tint is due in A. betularia to colouring matter in the skin or immediately below it, and the green tint to a layer of fat between the hypodermis and the superficial muscles ; this layer being always green, but more brightly green in the larvae that are of this colour externally. Much discussion has occurred about these larval attitudes and colours, and it seems probable that Professor Poulton has over- rated the value of protection from birds, mammals and ento- mologists ; the chief destroying agents being other than these, and not liable to be thus deceived, even if the vertebrates are. In some cases such resemblance as undoubtedly exists is not made the best use of. The larva shown in figure 202 bore a wonderful resemblance, when examined, to the rose-twigs it lived on, but the effect of this as a concealing agent was entirely destroyed by the attitude ; for this, being on different lines to those of the plant, attracted the eye at once. This larva, and we may add numerous other larvae, could have been perfectly con- cealed by adopting a different attitude, but never did so ; the position represented being constantly maintained except while feeding. In some species of this family the adult females are without wings, or have them so small that they can be of no use for flight. This curious condition occurs in various and widely- separated groups of the Geometridae ; and it would be naturally supposed to have a great effect on the economy of the species exhibiting it, but this is not the case. Some of the flightless females affect the highest trees and, it is believed, ascend to their very summits to oviposit. It has been suggested that they are carried up by the winged males, but this is probably only an exceptional occurrence ; while, as they are known to be capable of ascending with rapidity by means of crawling and running, it may be taken for granted that this is the usual method with them. Some of these wingless females have been found in numbers on gas-lamps, and are believed to have been attracted by the light, as is the case with very many of the winged forms.2 1 See Poulton, Tr. ent. Soc. London, 1884, p. 51 ; op. cit. 1892, p. 293 ; and Bateson, p. 213 ; Gould, p. 215. 2 Giraud, Ann. Soc. ent. France (4), v. 1865, p. 105 ; Fauvel, I.e. Bull. p. liii. 414 LEPIDOPTERA Neither is the geographical distribution limited by this inferior condition of the most important of the organs of locomotion, for Cheimatobia Irumata (the Winter-moth) one of the species with flightless female, is a common and widely distributed Insect in Europe and North America. Although the classification of this family is based almost entirely on wing-nervuratiou, yet there are some divisions of the Geometridae in which this character is remarkably variable, certain individuals frequently exhibiting considerable abnor- mality.1 Amphidasis betularia is believed to have changed its variation considerably in the course of the last fifty years. Pre- vious to that time a black variety of the species was unknown, but it has now become common ; and it is believed that other species of Geometridae are in process of exhibiting a similar phenomenon.2 Fam. 37. Noctuidae (Owlet -Moths, Eulen of the Germans). — This very extensive assemblage consists of moths rarely seen in the day-time, of generally sombre colours, with antennae desti- tute of remarkable developments in the male (except in a small number of forms) ; proboscis and frenulum both present ; a com- plex sense-organ on each side of the body at the junction of the metathorax and abdomen. The number of species already known can scarcely be less than 8000 ; owing to their large numbers and the great general resemblance of the forms, their classifica- tion is a matter of considerable difficulty. Although the peculiar structure at the base of the thorax was long since pointed out, it has never received any thorough investigation. Few other remarkable structures have yet been discovered : the most in- teresting is perhaps the peculiarity in the hind wings of the males of certain Ommatophorinae recently pointed out by Sir G. F. Hampson 3 : in the genera Patula and Argiva the form of the hind wings is normal in the females, but in the male the anterior one-half of each of these wings is aborted, and the position of the nervures changed ; this condition is connected with the development of a glandular patch or fold on the wing, and is remarkable as profoundly affecting a structure which is 1 For a table, see Meyrick, I.e. 2 Barrett, "Increasing Melanism in British Geometridae," Ent. Monthly Mag. 1895, p. 198. 3 P. Zool. Soc. London, 1892, p. 192. NOCTUIDAE 4 i 5 otherwise so constant that the classification of the family is largely based on it. The larvae are as a rule destitute of the remarkable adorn- ments of hairs and armatures of spines that are so common in many of the families we have previously considered ; they are fond of concealing themselves during the day and coming out at night to feed ; many of them pass most of their time at, or beneath, the surface of the ground, finding nourishment in roots or the lower parts of the stems of plants ; this is notably the case in the genus Agrotis, which is perhaps the most widely distributed of all the genera of moths. Such caterpillars are known as Cut-worms in North America.1 The great resemblance, inter se, of certain of these Cut-worms, much astonished the American naturalist Harris, who found that larvae almost per- fectly similar produced very different moths. The majority of Noctuid larvae have the usual number of legs, viz., three pairs of thoracic legs, four pairs of abdominal feet and the terminal claspers. In some divisions of the family there is a departure from this arrangement, and the abdominal feet are reduced to three, or even to two, pairs. One or two larvae are known — e.g. Euclidia mi — in which the claspers have not the usual function, but are free terminal appendages. When the abdominal legs are reduced in number (Plusia, e.g.) the larvae are said to be Half-loopers, or Semi-loopers, as they assume to some extent the peculiar mode of progression of the Geometrid larvae, which are known as Loopers. In the case of certain larvae, e.g. Triphaena, that have the normal number of feet, it has been observed that when first hatched, the one or two anterior pairs of the abdom- inal set are ill developed, and the larvae do not use them for walking. This is the case with the young larva of our British Breplws notha (Fig. 203). Subsequently, how- ever, this larva undergoes a considerable change, and FIG. ZQB.—Brephos notha. Larva, newly . , n hatched. Britain. appears in the iorm shown in Fig. 204. This interesting larva joins together two or three 1 Although this term is widely used in North America, it is not in use in Eng- land, though it may possibly have originated in Scotland. See Slingerland, Bull. Cornell University Exp. Stat. 104, 1895, p, 555. 416 leaves of aspen and lives between them, an unusual habit for Noctuid larvae. When about to pupate it bores into bark or soft wood to change to a pupa, Fig. 205 ; the specimen represented closed the hole of entry by placing two separate doors of silk across the burrow, as shown at d. The anal armature of this pupa is ter- minated by a curious transverse process. The systematic position of this inter- FIG. 204. — Brephos notha. Adult larva. FIG. 205. — Breplws nntha . A, Pupa, ventral aspect ; B, extremity of body, magni- fied ; C, the pupa in wood ; d, diaphragms constructed by the larva. esting Insect is very uncertain: Meyrick and others associate it with the Geometridae. The larva of Leucania unipunctata is the notorious Army- worm that commits great ravages on grass and corn in North America. This species sometimes increases in numbers to a con- siderable extent without being observed, owing to the retiring habits of the larvae ; when, however, the increase of numbers has been so great that food becomes scarce, or for some other cause — for the scarcity of food is supposed not to be the only* reason — the larvae become gregarious, and migrate in enormous swarms : whence its popular name. The Cotton -worm, Aletia xylinae is even more notorious on account of its ravages. Riley states * that in bad years the mischief it commits on the cotton crop causes a loss of £6,000,000, and that for a period of fourteen successive years the annual loss averaged about £3,000,000. This caterpillar strips the cotton plants of all but their branches. It is assisted in its work by another highly destructive Noctuid caterpillar, the Boll -worm, or larva of Heliothis armigera, which bores into the buds and pods. This 1 Fourth Rep. U.S Ent. Commission, 1885, p. 3. vr HETEROCERA NOCTUIDAE 417 latter Insect attacks a great variety of plants, and has a very wide distribution, being found even in England, where happily it is always a rare Insect. In Britain, as well as in parts of Northern Europe, a Xoctuid moth, Charaeas graminis, occasionally increases to an enormous extent : its larva is called the Hill-grub and lives on the grass of pastures, frequently doing great damage in hill-lands. The in- crease of this moth seems to take place after the manner of an epidemic ; a considerable number of years may pass during which it is scarcely seen, and it will then appear in unusual numbers in widely separated localities. This moth lays a large number of eggs, and is not completely nocturnal in habits ; sometimes it may be seen on the wing in great numbers in the hottest sun- shine, and it has been noticed that there is then a great dispro- portion of the sexes, the females being ten or twenty times as numerous as the males. In Australia, the Bugong moth, Agrotis spina, occurs in millions in certain localities in Victoria : this moth hibernates as an imago, and it formerly formed, in this instar, an important article of food with the aborigines. The powers of increase of another Noctuid moth — Erastria scitula — are of great value. Its habits have been described by Rouzaud.1 On the shores of the Mediterranean the larva of this little moth lives on a Scale-Insect — Lecanium oleae — that infests the peach ; and as the moth may have as many as five genera- tions in a year, it commits laudable havoc with the pest. The larva is of remarkable form, very short and convex, with small head, and only two pairs of abdominal feet. The scale of the Lecanium is of larger size than is usual in that group of Insects, and the young larva of the Erastria buries itself, as soon as hatched, in one of the scales ; it destroys successively numerous scales, and after having undergone several moults, it finds itself provided, for the first time, with a spinneret, when, with the aid of its silk, it adds to and adapts a Coccid scale, and thus forms a portable habitation ; this it holds on to by means of the pair of anal claspers, which are of unusual form. The case is afterwards subjected to further alteration, so that it may serve as a protec- tion to the creature when it has changed to a pupa. This moth is said to be free from the attacks of parasites, and if this be the case it is probable that its increase is regulated by the fact that 1 Insect Life, vi. 1894 p. 6. VOL. VI 2 E 41 8 LEPIDOPTERA when the creature becomes numerous it thus reduces the food supply, so that its own numbers are afterwards in consequence diminished. One of the most remarkable genera of British Noctuidae is Acronycta? the larvae of which exhibit so much diversity that it has been suggested that the genus should be dismembered and its fragments treated as allied to several different divisions of moths. There are many points of interest in connection with the natural history of these Acronycta. A. psi and A. ridens are practically indistinguishable as moths, though the larvae are easily separated : the former species is said to be destroyed to an amazing extent by parasites, yet it remains a common Insect. The genus Apatela is very closely allied to Acronycta, and Harris says that " Apatela signifies deceptive, and this name was probably given to the genus because the caterpillars appear in the dress of Arctians and Liparians, but produce true owlet-moths or Noctuas." ' The species of another British genus, Bryopliila, possess the excep- tional habit of feeding on lichens. Some of the American group Erebides are amongst the largest Insects, measuring seven or eight inches across the expanded wings. The Deltoid moths are frequently treated as a distinct family, Deltoidae, perhaps chiefly because of their resemblance to Pyra- lidae. At present, however, they are considered to be separated from Noctuidae by no valid characters. Fam. 38 — Epicopeiidae. — The genus Epicopeia consists of only a few moths, but they are amongst the most extraordinary known : at first sight they would be declared without hesitation to be large swallow-tail butterflies, and Hampson states that they " mimic " the Papilios of the Polyxenus group. Very little is known about these extremely rare Insects, but the larva is stated, on the authority of Mr. Dudgeon, to surpass the moths themselves in extravagance ; to be covered with long processes of snow-white efflorescence, like wax, exuded from the skin, and to " mimic " a colony of the larva of a Homopterous Insect. Some ten species of this genus are known from Java, India, China, and Japan. In this family there is said to be a rudimentary frenu- lum, but it is doubtful whether the hairs that have given rise to this definition really justify it. 1 See Chapman, The Genus Acronycta and its Allies, London, 1893. 2 Insects Injurious, etc., Ed. 1862, Boston, p. 437. HETEROCERA URANIIDAE 419 Fam. 39. Uraniidae. — A family of small extent, including light-bodied moths with ample wings and thread-like antennae ; most of them resemble Geometridae, but a few genera, Urania and Nyctalemon, are like Swallow-tail butterflies and have similar habits. The Madagascar moth, Chrysiridia madagascar- iensis (better known as Urania rhipheus), is a most elegant and beautiful Insect, whose only close allies (except an East African congener) are the tropical American species of Urania, which were till recently treated as undoubtedly congeneric with the Madagascar moth. The family consists of but six genera and some sixty species. The question of its affinities has given rise to much discussion, but on the whole it would appear that these Insects are least ill-placed near Noctuidae.1 The larva of the South American genus Coro- nidia is in general form like a Noctuid larva, and has the normal number of legs ; it possesses a few peculiar fleshy processes on the back. A description of the larva of 4.-— ^ Chrysiridia madagascariensis has been widely spread ; but according to Camboue,2 the account of the metamorphoses, first given by Boisduval, is The larva, it ap- 8 in general A form that Of Coronidia, and FI«- 206.— Abdomen of Clirysiridia mada- gascariensis. A, Horizontal section show- ing the lower part of the male abdomen : 1, first segment ; 2, spiracle of second erroneous, pears, resembles segment ; 4-8, posterior segments. B, the abdomen seen from the side, with the segments numbered. The section is that of an old, dried specimen. has sixteen feet ; it is, how- ever, armed with long, spatu- late black hairs ; it changes to a pupa in a cocoon, of open network. In all the species of this family we have examined, we have noticed the existence of a highly peculiar structure that seems hitherto to have escaped observation. On each side of the second abdominal segment there is an ear-like opening (usually 1 See "Westwood, Tr. Zool. Soc. London, x. pp. 507, etc., for discussion of this question and for figures ; also E. Renter, Act. Soc. Sci. Fenn, xxii. 1896, p. 202. 2 Congr. Internal. Zool. ii. 1892, pt. 2, p. 180. 42O LEPIDOPTERA much concealed by overlapping scales), giving entrance to a chamber in the body ; this chamber extends to the middle line, being separated from its fellow by only a thin partition. At its anterior and lateral part there is a second vesicle -like chamber, formed by a delicate membrane that extends as far forwards as the base of the abdomen. There can be little doubt that this is part of some kind of organ of sense, though it is much larger than is usual with Insect sense-organs. Fam. 40. Epiplemidae. — Under this name Hampsoii has assembled certain Geometroid moths, some of them placed previ- ously in Chalcosiidae, some in Geometridae. They form a varied group, apparently closely allied to Uraniidae, and having a similar peculiar sense-organ ; but are distinguished by the presence of a frenulum. The larva seems to be like that of Uraniidae. Fam. 41. Pyralidae. — This division is to be considered rather as a group of families than as a family ; it includes a very large number of small or moderate-sized moths of fragile structure, frequently having long legs; antennae simple, only in a few cases pectinate ; distinguished from Noctuidae and all the other extensive divisions of moths by the peculiar course of the costal nervure of the hind wing, which either keeps, in the middle of its course, near to the sub-costal or actually, unites with it, subsequently again separating. Members of the Pyralidae are found in all lands; in Britain we have about 150 species. The larvae are usually nearly bare, with only short, scattered setae, and little coloration ; they have most varied habits, are fond of concealment, and are very lively and abrupt in movement, wriggling backwards as well as forwards, when disturbed ; a cocoon is formed for the metamorphosis. The family as a wThole consists of Insects of unattractive appearance, although it contains some very elegant and interesting moths and numerous forms of structural interest. In the genus Thiridopteryx little transparent spaces on the wings occur as a character peculiar to the males ; the spaces are correlative with a greater or less derangement of the wing-nervures. In some other forms there is a remarkable retinaculum, consisting of large scales, and this, too, is connected with a distortion of the wing- iiervures. The Pyralidae — Pyralites of Ragonot,1 Pyralidina of 1 Ragonot, Ann. Soc. ent. France, 1890 and 1891 ; and Meyrick, Tr. ent. Soc. London, 1890, p. 429. vi HETEROCERA PYRALIDAE 421 Meyrick — have recently been revised by two naturalists of dis- tinction almost simultaneously ; unfortunately their results are discrepant, Meyrick including Pterophoridae and Orneodidae, and yet admitting in all only eight families ; while Eagonot does not include the two groups named, but defines seventeen tribes of the two families — Pyralidae and Crambidae — that he admits. The Pyraustidae of Meyrick is an enormous division including the Hydrocampidae and Scopariidae of many authors, as well as the Pyraustinae proper and a small group of Eagonot's, the Homophysinae. The division Scopariinae is believed to be amongst the " most ancient " of Lepidoptera ; the food of the larvae consists of moss and lichens. This group is widely dis- tributed, being richly represented in Australia, New Zealand, and the Hawaiian Islands, as well as in Europe ; and probably really occurs wherever their food-plants exist accompanied by a tolerable climate. The statistics of the distribution of this group, so far as at present known, have been furnished by Mr. Meyrick, as follows : — European region, about 2 5 species ; Madeira, 3 ; St. Helena, 6 ; South Africa, 2 or 3 ; India, 9 : Malayan region, 3 or 4 ; Australia, 24 ; New Zealand, 64 ; Hawaiian Islands, 5 0 ; North America, 1 7 (one of them Euro- pean); South America, 10. The Hydrocampinae — the China- marks — are of great interest, as being amongst the few forms of Lepidoptera adapted for aquatic life. It is believed that all their larvae are aquatic, though of only a few is there much known. The diversity amongst these forms is of considerable interest. The habits of Hydrocampa nympliaeata were long since described by Eeaumur, and have more recently been dealt with by Buckler,1 W. Miiller 2 and Prof. Miall.3 Although there are some discrepancies in their accounts, due we believe to the observations being made at different periods of the life and under somewhat different circumstances, yet the account given by Miiller is we feel no doubt substantially correct. The larvae when hatched mine in the leaves of a water-plant for a short time — thirty hours to three days according to Buckler — and are completely surrounded by water, which penetrates freely into their burrows ; at this period the caterpillar breathes by its skin, the spiracles being very small, and the tubes leading from 1 Ent. Mag. xii. 1876, p. 210, and xvii. 1881, p. 249. 2 Zool. Jahrb. Syst. vi. 1892, p. 617. 3 Nat. Hist. Aquatic Insects, London, 1895. 422 LEPIDOPTERA . CHAP. them closed and functionless. After this brief period of mining life, the larva moults and then constructs a habitation by cutting a piece out of a leaf, and fastening it to the under side of another leaf; it is thus provided with a habitation, but it is one into which the water freely enters, and the respiratory apparatus remains in the state we have described. The Insect passes through several moults, and then hibernates in the water. On its revival in the spring a change occurs, and the larva constructs a portable, or we should rather say free, habitation out of two large pieces of leaf of lens-shape, fastened together at the edges ; but the larva has some method of managing matters so that the water can be kept out of this house ; thus the creature lives in air though immersed in the water. A correlative change occurs in the structure of the skin and tracheal system. The former becomes studded with prominent points that help to maintain a coat of air round the Insect, like dry velvet immersed in water ; the spiracles are larger than they were, and they and the tracheal tubes are open. One or two moults take place and the creature then pupates. There is a good deal of discrepancy in the accounts of this period, and it seems probable that the pupa is sometimes aerial, sometimes aquatic. Buckler's account of the formation of the case shows that the larva first cuts off, by an ingenious process, one piece of leaf, leaving itself on this, as on a raft : this it guides to a leaf suitable for a second piece, gets the raft underneath, and fastens it with silk to the upper portion, and then severs this, leaving the construction free ; afterwards the larva goes through a curious process of changing its position and working at the two extremities of the case, apparently with the object of making it all right as regards its capacity for including air and keeping out water. He believes that Keaumur was correct in his idea that the larva regulates the admission of air or of water to the case in conformity with its needs for respiration. Muller calls special attention to the great changes in habit and in the structure of the integument during the life of this larva ; but the reader will gather from what we relate as to various terrestrial Lepidopterous larvae, that these phenomena are not very dissimilar from what frequently take place in the latter ; a change of habits at some particular moult, accompanied by great changes in the integument, and even in the size of the stigmata, being of frequent occurrence. vi HETEROCERA PYRALIDAE 423 The larva of Nymphula stagnata, a close ally of H. nympliaeata, has aquatic habits of a somewhat similar but simpler nature ; while N. (Paraponyx) stratiotata is very different. This larva is provided with eight rows of tufts of flexible branchiae, occupying the position of the spots or setigerous warts usual in caterpillars, and reminding one of the spines of certain butterfly-larvae, though they are undoubtedly respiratory filaments. These caterpillars protect themselves by forming silken webs or cases, or by adopt- ing the case of some other larva, and are in the habit of holding on by the anal claspers, and rapidly and energetically moving the anterior parts of the body in an undulating fashion. The spiracles exist, but are functionless. The pupa lives under water, and has no branchiae ; but three of the pairs of abdominal spiracles are open, and project from the body. Mliller informs us that in a Brazilian Paraponyx these three pairs of spiracles were already large in the larva, though the other pairs were very small, or absent. He considers that the moth of this species descends beneath the water of a rapid stream, and fastens its eggs on the stems of plants therein. Cataclysta lemnata lives in a case of silk with leaves of duckweed attached to it, or in a piece of a hollow stem of some aquatic plant ; it is believed to breathe, like H. nympliaeata, at first by the integument and subsequently by open stigmata ; but particulars as to how it obtains the requisite air-supply are not forthcoming : the aquatic pupa breathes by three large abdominal spiracles like Paraponyx. Musotimidae1 is a small group of two or three genera found in Australia and Polynesia ; and the Tineodidae also consist of only two Australian genera. Siculodidae is likewise a small Antarctic group, placed by Meyrick in Pyralidina ; but his view is not accepted by Snellen and Kagonot. Epipaschiinae (formerly treated as a separate family) and Endotrichiinae are, according to Meyrick, subdivisions of the family Pyralidae proper, an enormous group of more than 100 genera. The Chrysauginae consist chiefly of American forms, and have not been treated by Meyrick ; some of this group have been classed with Tortricidae or Deltoidae on account of the undulating costa of the front wings and the long, peculiar palpi. The Galleriidae are a small group including Insects that live in bees'-nests, and feed on the wax 1 For Bibliographic references connected with the divisions of Pyralidae see Rugonot, Ann. Soc. cut. France (6), x. 1890, pp. 458, etc. 424 LEPIDOPTERA CHAP. etc. ; others eat seeds, or dried vegetable substances. Three out of our five British species of this family occur (usually gregariously) in bee - hives, and have the peculiar habit of spinning their cocoons together. The mass of common cocoons formed in this manner by Aphomia sociella is remark- ably tough and enduring ; portions of it are not infrequently picked up, and as the cocoons are of a peculiar tubular form their nature gives rise to some perplexity. Phycitidae * is another very large assemblage of Insects with very diverse habits. The frenulum and retinaculum are similarly formed in the two sexes : the males frequently have the basal-joint of the antennae swollen ; hence the term " Knot-horns " applied by collectors to these moths. The larvae of the species of Ephestia infest groceries, and most children have become to a slight extent acquainted with them amongst dried figs ; that of E. kuehniella has become very injurious in flour-mills, its enormous increase being due in all probability to the fact that the favour- able and equable temperature maintained in the mills promotes a rapid succession of generations, so that the Insect may increase to such an extent as to entirely block the machinery. Many of the Phycitidae feed on the bark of trees in galleries or tunnels constructed partially of silk. A very peculiar modification of this habit in Cecidipta excoecaria has been described by Berg. 2 In Argentina this Insect takes possession of the galls formed by a Chermes on Excoecaria liglandulosa, a Euphorbiaceous tree. The female moth lays an egg on a gall, and the resulting larva bores into the gall and nourishes itself on the interior till all is eaten except a thin external coat ; the caterpillar then pupates in this chamber. The galls vary in size and shape, and the larva displays much constructive ability in adapting its home to its needs by the addition of tubes of silk or by other modes. Some- times the amount of food furnished by the interior of the gall is not sufficient ; the larva, in such cases, resorts to the leaves of the plant for a supplement, but does not eat them in the usual manner of a caterpillar; it cuts 'off and carries a leaf to the entrance of its abode, fastens the leaf there with silk, and then itself entering, feeds, from the interior, on the food it has thus acquired. Another Phycitid, Dakruma coccidivora, is very 1 Monograph, by Ragouot, in Romanoff', Mem. Lep. vii. 1893. 2 Ent. Zeit. Stettin, 1878, p. 230. vi HETEROCERA — PYRALIDAE 425 beneficial in North America by eating large Scale-Insects of the Lecanium group, somewhat after the fashion of Erastria scitula ; it does not construct a case, but shelters itself when walking from one scale to another by means of silken tubes ; it suffers from the attacks of parasites.1 Oxychirotinae, an Australian group, is interesting because, according to Meyrick, it possesses forms connecting the Pterophoridae with the more normal Pyralids. Crambidae, or Grass-moths, are amongst the most abundant Lepidoptera in this country, as they include the little pule moths that fly for short distances amongst the grass of lawns and pastures ; they fold their wings tightly to their body, and have a head pointed in front, in consequence of the form and direction of the palpi. They sit in an upright position on the stems of grass, and it has been said that this is done because then they are not conspicuous. Perhaps : but it would be a somewhat difficult acrobatic performance to sit with six legs across a stem of grass. The larvae are feeders on grass, and construct silken tunnels about the roots at or near the surface. The Ancylolominae are included in Crambidae by Meyrick and Hampson. Schoenobiinae2 are included by Meyrick in Pyraustidae, but this view appears not to meet with acceptance, and the group is more usually associated with the Crambidae. Most writers place the anomalous genus Acentropus as a separate tribe, but it is associated by both Meyrick and Hampson with Sckoenobivs. This Insect is apparently the most completely aquatic of all the Lepidoptera, and was for long associated with the Trichoptera in consequence of its habits and of the scaling of the wings being of a very inferior kind. The males may sometimes be found in large numbers fluttering over the surface of shallow, but large, bodies of water ; the females are rarely seen, and in some cases have no wings, or have these organs so small as to be useless. The female, it would appear, comes quite to the surface for coupling, and then takes the male beneath the water. The larvae have the usual number of Lepidopterous feet, and apparently feed on the leaves of plants below water just as Lepidopterous larvae ordinarily do in the air. 3 They have no trace of gills, and their 1 Howard, Insect Life, vii. 1895, p. 402. 2 Monograph by Hampson, P. Zool. Soc. London, 1895, p. 897-974. 3 Disque, Ent. Zeit. Stettin, li. 1890, p. 59. Cf. also Rebel, Zool. Jahrb. Syst. xii. 1898, p. 3. 426 LEPIDOPTERA CHAP. mode of respiration is unknown. A great deal has been written about these Insects, but really very little is known. They are abundant, though local in many parts of North and Central Europe ; some of the females have, as we have said, abbreviated wings, but how many species there are, and whether the modifica- tions existing in the development of the wings are constant in one species or locality, are unknown as yet. Fam. 42. Pterophoridae l (Plume-moths}. — Elegant Insects of small size, usually with the wings divided (after the fashion of a hand into fingers) so as to form feathers : the extent of this division is diverse, but the hind wings are more completely divided than the front, which indeed are sometimes almost entire. The group is placed by Meyrick in his Pyralidina, but there are many entomologists who look on it as distinct. It consists of two sub - families, Agdistinae and Pterophodnae, that have been treated as families by many entomologists. The Agdistiuae (of which we have a British representative of the only genus Agdistes) have the wings undivided. Pterophorinae have the hind wings trifid or (rarely) quadrifid, the front wings bifid or (rarely) trifid. The larvae of the Pterophorinae are different from those of Pyralidae, being slow in movement and of heavy form, covered with hair and living exposed on leaves ; the pupae are highly remarkable, being soft, coloured somewhat like the larvae, and also hairy like the larvae, and are attached somewhat after the manner of butterfly -pupae by the cremaster : but in some cases there is a slight cocoon. There is, however, much variety in the larval and pupal habits of the Ptero- phoridae, many having habits of concealment of divers kinds. We have thirty species of these lovely Plume-moths in Britain. The family is widely distributed, and will probably prove numerous in species when the small and delicate Insects existing in the tropics are more appreciated by collectors. Fam. 43. Alucitidae (Orneodidae of Meyrick and others).— The genus Alucita includes the only moths that have the front and hind wings divided each into six feathers. Species of it, though not numerous, occur in various regions. The larva and pupa are less anomalous than those of the Pterophoridae, though the imago is more anomalous. The caterpillar of our British A. /ml !/ I) are by 1 It is frequently said that one sex of a single species may be dimorphic in this respect, but we shall subsequently mention (in Blepharoceridae) that this is not yet sufficiently established. 444 DIPTERA CHAP. many identified as mandibles, while another pair of pointed pro- cesses (c c} are considered to be parts of a maxilla, and the palpi (//) are by some considered to be maxillary palps. The Danish entomologist, Meinert, has published the best anatomical descrip- tion of many of the diverse kinds of Dipterous mouth.1 He, however, takes a different view of the morphology ; he considers that not only may parts of the appendages of the mouth be much modified during the early stages of the individual development, but that they may be differently combined, even parts of the appendages of two segments being brought together in intimate combination. He has also pointed out that the mandibulate and sucking mouth are mechanical implements constructed on opposed principles ; the main object of a biting mouth being the fixing and perfecting of the articulations of the mouth, so that great power of holding may be attained with a limited but definite power of movement. In the sucking mouth the parts are in- timately associated for simple protrusion. Hence the two kinds of mouth must have been distinguished very early in the phylogeny, so that we must not expect to find a great corre- spondence between the parts of biting and sucking mouths. He apparently also considers that not only the appendages of a head-segment, but also part of the body of the segment, may be used in the construction of the mouth-organs. Meinert's views allow a much greater latitude of interpretation of the parts of the Dipterous mouth ; had he contented himself with enun- ciating them in the manner we have followed him in summarily describing, they would have been recognised as a formidable obstacle to the facile adoption of the ordinary views. He has, however, accompanied his general statement with a particular interpretation and a distinct nomenclature, neither of which is it possible to adopt at present, as they have no more justification than the ordinary view. So that instead of one set of doubtful interpretations we have two.2 In so difficult a question as homo- logising the trophi of different Orders of Insects we ought to use 1 Fluerncs Munddcle, Copenhagen, 1881, 91 pp. 6 plates ; Ent. Tidskr. i. 1879, p. 150 ; Beeher having given (Denk. Ak. Wien. xlv. 1882, p. 123) an interpreta- tion different from that of Meinert, this author set forth his general views in Zool. Anz. \. 1882, pp. 570 and 599. 2 The reader should not suppose that there are only two views as to the Dipterous mouth, for actually there are several ; our object is here only to give a general idea of the subject. STRUCTURE 445 exhaustively every method of inquiry : and from this point of view the development is of great importance. This has, however, as yet thrown but little light on the subject, this study being a very difficult one owing to the profound changes that take place during metamorphosis, the diversity of the parts in the early stages of Diptera, and the possibility that the larval conditions may themselves have been greatly changed in the course of the phylogeny. Miall informs us, however, that in Chironomus as well as in Corethra the new parts of the mouth of the imago are developed within those of the larva.1 This may permit of an identification of the main divisions of the mouth, at any rate in these cases. Lowne has to some extent traced the development in the blowfly, and he does not agree with the usual interpreta- tion of the parts in the adult. The mouth is of considerable importance in the classification of Diptera. The Nemocera are remarkable from the linear de- velopment and flexibility of the palpi, which are nearly always at least three- or four-jointed ; this condition occurring in no other Diptera. The palpi attain an extraordinary development in some Culicidae ; in the genus Megarrhina they are nearly as long as the body, and project in front of the head after the fashion of the palpi of Lepidoptera. In the Brachycera the sclerites or hard parts of the mouth reach a maximum of development, and in Tabanidae (Fig. 214), Nemestrinidae and Bombyliidae are often quite disproportionate to the size of the Insect. In many of the Eumyiid flies the soft parts are greatly developed, and capable of a variety of movement, the proboscis as a whole being protrusible, and having an elbow-joint in the middle. The thorax is remarkable from the absence of distinct separa- tion into the three divisions that may usually be so easily dis- tinguished in Insects. The perfect combination of the three segments adds much to the difficulty of arriving at general con- clusions as to the identification of the parts ; hence considerable difference of opinion still prevails. It was formerly supposed that a segment from the abdomen was added to the thorax of Diptera as it is in Hyiuenoptera, but this has been shown by Brauer to be erroneous. Indeed, according to Lowne, the abdo- minal cavity is increased by the addition of the small posterior area of the thorax ; it being the mesophragma that separates the 1 Tr. Linn. Soc. London (2) v. 1892, p. 271. 446 DIPTERA CHAP. second and third great divisions of the body-cavity. The pro- thorax is always small, except in a few of the abnormal wingless forms (Melophayus) ; in Nycteribia (Fig. 248) the mesothorax forms the anterior part of the body ; the head and such parts of the prothorax as may be subsequently discovered to exist being placed entirely on the dorsum of the body. The mesothorax in all the winged Diptera forms by far the larger portion of the thoracic mass, the prominent part of it, that projects backwards to a greater or less extent over the base of the abdomen, being the scutellum. The first or prothoracic stigma is remarkably large and distinct, and is by some called mesothoracic. Another large stigma is placed very near to the halter (or balancer) ; the meta- thorax being very small. An imperfect stigma is said by Lowne to exist in the blowfly near the base of the wing. The number of abdominal segments externally visible is very diverse ; there may be as many as nine (in the male Tipula), or as few as five, or even four, when the basal segment is much concealed ; the diminu- tion is due to certain segments at the extremity being indrawn and serving as a sort of tubular ovipositor in the female, or curled under the body and altered in forni in the other sex, so as to constitute what is called a " hypopygium." In the female of Tipulidae the body is terminated by some horny pieces forming an external ovipositor. In nearly all Diptera the feet are five- jointed ; the claws are well developed, there being placed under each of them a free pad or membrane, the " pulvillus " ; there may be also a median structure between each pair of claws, of diverse form, the "empodium." On the surface of the body of many flies there will be seen an armature of pointed bristles ; these flies are called " chaeto- phorous " ; where no regularly arranged system of such bristles exists the fly is " eremochaetous." In some families the arrange- ment of these bristles is of importance in classification, and a system of description has been drawn up by Baron Osten Sacken : this branch of descriptive entomology is known as chaetotaxy.1 The wings are of great importance in classifying Diptera ; but unfortunately, like the other parts, they have not received an exhaustive anatomical study, and Dipterologists are not agreed as to the names that should be applied to their parts. We give 1 Tr. cnt. Soc. London, 1884, p. 497. WINGS 447 below figures of two systems that have been used by eminent Dipterologists for the description of the nervures and cells. The comprehension of these features of the Dipterous wing will be facili- tated by noticing that the wing — being extended at right angles to the body — is divided by the longitudinal nervures into two great fields, anterior and posterior, with an interval between them : this interval is traversed only by a short cross-vein (marked x in Fig, 215 A, and i in B). This cross- vein may be placed near the base or nearer to the tip of the wing ; it is of importance because no nervure in front of the median area traversed by it can corre- A FIG. 215. — Nervuration of Dipterous wing. A, Wing of a Tipulid, accord- ing to Loew, who uses the following nomenclature : a, costal nervure ; b, mediastinal ; c, subcostal ; d, radial ; e, cubital ; /, discoidal ; y, postical ; h, anal ; i, axillar ; x, transverse, ?/, posterior transverse, nervure ; 1, 2, mediastinal areas ; 3, sub- costal ; 4, cubital ; 5, anterior basal ; 6, posterior basal ; 7, anal ; 8, pos- terior marginal ; 9, discoidal. B, Wing of an Acalypterate Muscid (Ortalis), according to Schiner, who uses the following nomenclature : (nervures, small letters ; cells, capi- tal letters) : a, transverse shoulder ; b, auxiliary ; c to h, first to sixth longitudinal ; i, middle transverse ; k, posterior transverse ; I, m, n, o, costa ; p, anterior basal transverse ; q, posterior basal transverse ; r, rudiment of a fourth nervure ; s, axillary incision : A, B, C, first, second, and third costal cells ; D, marginal ; E, sub-marginal ; F, G, H, first, second, and third posterior ; I, discal ; K, L, M, first, second, and third basal cells ; N, anal angle ; 0, alula. spond with a nervure placed behind it in another wing. The very different nature of the nervuration in the two wings we have figured will readily be appreciated by an inspection of the parts posterior to the little cross-vein. On the hind margin of the wing, near the base, there is often a more or less free lobe (Fig. 215, B, 0) called the " alula " : still nearer to the base, or placed 011 the side of the body, may be seen one or two other lobes, of which the one nearer the alula is called the " tegula," or (when a lobe behind it is also present) the " upper tegula," (the " anti- tegula " of Osten Sacken) ; the other being the " lower tegula." These two terms are erroneous, the word tegula being definitely applied to another part of the Insect-body. In speaking of this structure in the following pages, we have preferred to call it the 448 DIPTERA CHAP. ."squama."1 Those Muscidae in which the squama covers the halter like a hood are called" calypterate." In Fig. 216, we represent these structures, and in the explanation have mentioned the synonyms. The terms we think most applicable to the three lobes are alula, antisquama, squama. The squama may be called " calypter " when it covers the halter. The halteres — commonly called FIG. 216.— Parts at the base of the balancers or poisers — are perhaps wing in Cattiphora. a, Anal , . . angle or lobe of the wing; b, the most characteristic oi all the alula ; c, antisquama, squama Dipterous structures, though they are alaris, or antitegula ; d, squama, . ° . • squama thoracicalis, tegula, caly- absent in lllOSt Ot the lew WlllgleSS pter, or calyptron ; e, posterior formg of the Order. Outside the Dip- extremity (scutellum) of the * mesothorax ; /, scutum of meso- tera similar organs appear to exist thorax- only in male Coccidae. The pair of halteres is placed on the metathorax, one on each of the pleural regions. They are believed to be the homologues of the hind wings; Weinland states 2 that certain canals existing in the interior of the halter correspond to wing-iiervures. The halter may be described as a small rod-like body with a head like a pin, this terminal part being, however, rather variable in form. We have already stated that in many Diptera the squama forms a hood, the position of which leads to the belief that it is an important adjunct to the halter. Although the exact functions of the halteres are far from clear, it is certain that they are highly complex bodies, of extremely delicate structure : they are doubtless sense-organs, possessing as they do, groups of papillae on the exterior and a chordotonal organ (a structure for assist- ing the perception of sound) in the basal part ; each halter is provided with four muscles at the base, and can, like the wings, execute most rapid vibrations. Seeing that they are the homologues of wings, it is a remarkable fact that in no Diptera are they replaced by wings, or by structures intermediate between these two kinds of organs. Internal Structure. — Information about the internal anatomy 1 Osten Sacken, although making use of the terms tegula and antitegula, suggested the propriety of using squama and antisquama, as \ve have done. 2 Zeitschr. wiss. Zool. li. 1891, p. 55. vii ANATOMY LARVAE 449 is by no means extensive. The tracheal system is highly developed, and has air-sacs connected with it ; a large pair at the base of the abdomen being called aerostats by Dufour. Inside the thoracic spiracles there are peculiar structures supposed by some to be voice-organs, while the abdominal spiracles are said to be remarkably simple in structure. Lowrie says that there are ten or eleven pairs of spiracles in the Blow-fly ; one of these, near the base of the wing, is peculiar in structure, and may not be a true stigma ; he calls it a tympanic spiracle ; it seems doubtful whether there are more than seven abdominal pairs. The alimen- tary canal is very elongate, and is provided with a diverticulum, the crop; this is usually called the sucking stomach, though its func- tion is extremely doubtful. The Malpighian tubes are four in number, and are very elongate ; in several groups of Nemocera there are, however, five Malpighian tubes, a number known to occur in only very few other Insects. The nervous system is remarkable 011 account of the concentration of ganglia in the thorax, so as to form a thoracic, in addition to the usual cephalic, brain. For particulars as to the positions of the ganglia and the great changes that occur in the lifetime, the student should refer to Brandt, to Kiinckel, and to Brauer.1 Much information as to the internal anatomy of the Blowfly is given by Lowne, but it is doubtful to what extent it is applicable to Diptera in general.2 The larvae of Diptera are — so far as the unaided eye is concerned — without exception destitute of any kind of adorn- ment, the vast majority of them being of the kind known as maggots. None of them have true thoracic legs; though in the earlier groups, pseudopods or protuberances of the body that Serve as aids in loCOmo- Fio. 217.— Acephalous larva or maggot of the tion are Common. Unlike Wow-fly, with the head, «, extended. (After Lowne. ) what occurs in other Orders the arrangement of these pseudopods on the body differs greatly in various forms; in a few cases they are surmounted by 1 Brandt, Horae Soc. ent. Ross. xiv. 1878, p. vii. ; xv. 1879, p. 20. Brauer, Denk. Ak. Wien, xlvii. 1883, pp. 12-16. Kiinckel, C.E. Ac. Paris, Ixxxrx. 1879, p. 491. 2 Blow-fly, 1895 : in two vols. For Anatomy of Volucclla, see Kiinckel d'Herculais, Recherches sur Vorg. des Volucelles, Paris, 1875 and 1881. VOL. VI 2 G 45O DIPTERA CHAP. curved hairs. The most important distinction in external form in Dipterous larvae is that while those that are thorough maggots possess no visible head, others have a well-marked one (Fig. 225); these are therefore called " eucephalous " : they have a mouth of the mandibulate type. In some other Dipterous larvae the head is more or less reduced in size, and in the acephalous forms there is only a framework of a few chitinous rods to represent it. The nervous system in the most completely headless larvae is very remarkable, all the ganglia being concentrated in a single mass placed in the thorax. The tracheal system exhibits a great variety ; some larvae have stigmata arranged along the sides of the body after the fashion normal in Insect-larvae ; these are called " peripneustic " ; as many as ten pairs of stigmata may be present in these cases, but nine pairs is much more common. Other larvae have a pair of stigmata placed at the termination of the body, and another pair near the anterior extremity, the two pairs communicating by large tracheal trunks extending the length of the body ; .these larvae are said to be " amphipneustic " : this is the condition usual in the more completely acephalous larvae. Others have only the terminal pair of spiracles, and are styled " metapneustic." Some begin life in the metapneustic state and afterwards become amphipneustic. In the aquatic larva of Corethra there are no spiracles, though there is an imperfect tracheal system. Many Dipterous larvae that live in water or in conditions that prevent access of air to the body have remarkable arrangements for keeping the tip of the body in communication with the atmosphere. The stigmata in meta- pneustic and amphipneustic larvae are very remarkable compound structures, exhibiting however great diversity ; their peculiarities and uses are not well understood; it appears very doubtful whether some of them have any external opening. Eeference may be made, as to the variety of structure, to Meijere's paper l from which we take the accompanying figure of a posterior stigmatic apparatus in Lipara liccens. It appears that there is a compound chamber — " Filzkammer " — terminating externally in lobes or fingers — " Knospen " and appearing as marks on the outer surface: this chamber is seated on a tracheal tube, and is, Meijere thinks, probably a secondary growth of the trachea coming to the outer surface. It is traversed by what may be 1 Tijdschr. Ent. xxxviii. 1895, pp. 65-100. LARVA PUPA 451 ara luceiis. a, One of the three " Knospen " or lobes ; 6, external stigmatic scar ; c, internal scar ; d, stig- matic chamber (Filzkani- mer) ; e, trachea. (After Meijere.) considered the original tracheal tube, opening externally as an external stigmatic scar — " Stigmennarbe " — and with a second or inner scar placed internally. We may conclude from what is already known that these structures will be found to differ in the same larva according to the stage of its development. An extremely valuable summary of the characters and variety of Dipterous larvae has been given by Brauer,1 from which it appears that the larvae of the first half of the family exhibit great variety and have been much studied, FlG. 2i8.-The posterior while the more purely maggot-like forms stigma of the larva of Up- of the Muscidae have, with one or two exceptions, been little investigated. The pupal instar is of two distinct kinds. First, we meet with a pupa like that of Lepidoptera, viz. a mummy-like object, or pupa obtecta, in which there is a crisp outer shell, formed in part by the adherent cases of the appendages of the future imago. This condition, with a few exceptions to be subsequently noticed, obtains in the Nemocera and Brachycera. It is exhibited in various degrees of perfection, being most complete in Tipulidae ; in other forms the shell is softer and the appendages more pro- tuberant. The second kind of pupa is found in the Cyclor- rhaphous flies ; it has externally no marks except some faint circular rings and, frequently, a pair of projections from near one extremity of the body ; occasionally there is a single pro- minence at the other extremity of the body. This condition is due to the fact that the larva does not escape from the skin at the last ecdysis, but merely shrinks within it, so that the larval skin, itself contracted and altered by an excretion of chitin, remains and forms a perfect protection to the included organism. This kind of pupa looks like a seed, and is well exemplified by the common Blow-fly. The capacity for entering on- such a condition is evidently correlative with the absence of a larval head. The metamorphosis in this curious little barrel goes on in a different manner to what it does in the pupa 1 Denk. Ak. Wien, xlvii. 1883, pp. 1-100, pis. i.-v. 45 2 DIPTERA CHAP. obtecta. A good name for the whole structure of this instar has not been found. Older authors called it " pupa coarctata," or " nympha inclusa " ; Brauer speaks of it as a " compound pupa " ; ordinarily in our language it is called a " puparium," a term which is more applicable to the case alone. In species having a pupa obtecta the larval skin is cast after the chief processes of the external metamorphosis have occurred, and then an exudation of chitin hardens the general surface. In the " compound pupa " of the Blow-fly there is for a consider- able period no formed pupa at all, but merely a shell or case containing the results of histolysis and the centres for regenera- tion of new organs ; the chitin-exudation to the exterior of the larval skin occurs in the early part of the series of metamorphic changes, and the organism breaks down to a cream within the shell thus formed, and then gradually assumes therein the condition of a soft, nymphoid pupa. The exceptional conditions previously re- ferred to as exhibited by a few forms are certain cases in \vhich a more or less perfect pupa obtecta is found within the last larval skin, as is the case in Stratiomys. Another highly remarkable condition exists in the Hessian fly, and a few other Cecidomyiids, where the Insect apparently makes an exudation which it uses as a covering case, independent of the larval skin ; this latter being subsequently shed inside the case, so that this condition of coarctate pupa differs from that we have described as exist- ing in Cyclorrhaphous flies, although the two are superficially similar. In the Pupipara the larval stage is passed in the body of the mother, which produces a succession of young, nourished one at a time by the secretion of glands ; this young is born as a full-grown larva that becomes at once a pupa. Metamorphosis. — As it is in Diptera that the phenomena of Insect-metamorphosis have reached their highest development we endeavoured to give some idea of their nature in the previous volume, therefore we need give only a brief sketch of the chief features of Dipterous metamorphosis. The Blow-fly undergoes a rapid embryonic development, the later stages of which are, on the whole, of a retrogressive nature. On the emergence of the young maggot it feeds up rapidly, the rapidity varying greatly according to circumstances, and then when full-grown rests. While resting, a process of internal liquefaction, called histolysis, is going on, and the maggot contracts and exudes an excretion METAMORPHOSIS 453 that hardens its skin. At the time this hard skin has become complete, or soon after, the maggot inside has dissolved into a cream contained in a sac inside the shell ; this cream becomes reconstituted into a fly by a gradual process of growth and development of certain minute portions of the body — the imaginal discs or folds, the histoblasts and neuroblasts that were exempt from the histolytic process : in the early stages of the reconstitution the general structure is, of course, altogether vague, and this condition — purely one of transition — is called the pronymph ; the nymph becomes gradually developed : it corresponds vaguely with the pupa obtecta of the early groups of Diptera, but is soft like the pupa of Hymenoptera. This nymph gradually develops into the fly itself, the external parts being first completed and the internal organs elaborated subsequently. The sexual organs do not undergo metamorphosis like other internal organs, there being a gradual (though ir- regular or interrupted) growth of them in the young larva, till they are completed some time after the emergence of the perfect fly. The processes in the Blow-fly have been studied by numerous able histologists of various nationalities, and have recently been described by Lowne in our own language.1 Comparatively little has been done in studying the corresponding phenomena in other Diptera. Weismann has investigated the development of Corethra, and Miall that of Chironomus. These two flies belong to a division of Diptera different from that which includes the Blow-fly, and they display a condition of the metarnorphic processes allied to what occurs in Lepidoptera, as well as to that which takes place in the Blow-fly. Imaginal folds are formed, but they only appear much later in the life, and they are much less distant from the positions they will, when developed, occupy in the imago. In Chironomus, according to Miall, the imaginal folds only appear in the last larval instar, but they grow with such rapidity that the legs and wings of the future fly can be distinguished in the larva, even before pupation ; thus when the activity of the larva ceases but little change is required to complete the obtected pupa. In the Blow-fly some of the imaginal folds have been 1 Since our brief and imperfect sketch of metamorphosis appeared in Vol. V. of this series, Packard has treated the subject more fully in his Text-book of Entomology, New York, 1898 ; and Pratt has summarised the state of knowledge as to imaginal discs in Psyche, viii. 1897, p. 15, etc. 454 DIPTERA CHAP. traced back to the embryo ; how many centres for the new growth there may be is uncertain, for though there are upwards of sixty for the outer body, the number of regenerative centres for the internal organs is not ascertained. The peculiar central nervous mass, mentioned in our remarks on the larva, consists of two kinds of tissue mixed together in a complex manner ; one of these kinds is functionally active during the larval life and at the metamorphosis undergoes histolysis, while the other, or embryonic, portion develops into the nervous system of the fly. It forms no part of our task to deal with general subjects, but we may be pardoned for calling attention to the bearing the metamorphosis of the higher Diptera has on our ideas of heredity in Insects. The fly bears no resemblance whatever to the larva, and is only obtained by the organic destruction of the latter, which occurs before the perfection of the sexual organs takes place, and yet the fly reproduces itself only secondarily, but primarily gives rise to the totally different larva. It is supposed that the larval structures have been gradually acquired, and yet they are transmitted with the utmost faithfulness by the totally different fly. We can only conclude that that which is bequeathed in each species is the early state of a particular process of develop- ment from which the subsequent stages follow necessarily if the developing organism be placed in conditions having on it in- fluences like to those that influenced the ancestors. Classification. — The classification of Diptera is as yet very imperfect. Formerly they were divided into two great groups, Nemocera and Brachycera, according to the structure of the antennae, as previously mentioned. This division has been abandoned, and the term Brachycera is now applied to only a small part of the old section that bore the name. The primary division usually adopted at present is into Orthorrhapha and Cyclorrhapha. The characters of these two groups are based on the nature of the metamorphosis, and have been gradually elaborated by Brauer in various memoirs.1 The Orthorrhapha includes the forms with obtected pupae, the Cyclorrhapha those with a nymph-compound, as previously described. This distinction is of great importance, but unfortunately it is difficult to apply to the fly itself; the only character that can be used in connec- 1 Monograph of Oestridae, Verh. Ges. Wien, 1863, and other papers op. cit. 1864, 1867, 1869 ; also Denk. Ak. Wien, xlii. 1880, xlvii. 1883. CLASSIFICATION 455 tion with the imago is the existence of a suture over the insertion of the antennae in a portion, but not all, of the Cyclorrhapha.1 The next set of divisions used by Brauer divides the Order into four sections, viz. 1. Orthorrhapha Nematocera, 2. 0. Brachycera, 3. Cyclorrhapha Aschiza, 4. C. Schizophora. As these four groups are recognised more readily than the two major groups the student will do well at first to disregard the primary division and consider the Diptera as divisible into four great groups. To these four divisions we, however, add temporarily a fifth, viz. Pupipara. This is included by Brauer in Schizophora, but it appears to be really an unnatural complex, and had better be kept separate till it has been entirely reconsidered. These great sections may be thus summarised : — Series 1. Orthorrhapha Nemocera. — Antennae with, more than 6 segments, not terminated by an arista ; with the segments of the flagellum more or less similar to one another. Palpi slender and flexible, four- or five-jointed.2 Series 2. Orthorrhapha Brachycera. — Antennae variable, but never truly Nemocerous nor like those of Cyclorrhapha ; when an arista is present it is usually placed terminally, not superiorly ; when an arista is not present the flagellum terminates as an appendage consisting of a variable number of indistinctly separated segments ; thus the flagellum is not composed of similar joints ; [rarely are the antennae as many as seven-jointed]. Palpi only one- or two- jointed.3 Around the insertion of the antennae there is no definite arched suture enclosing a small depressed space. The nervuration of the wings is usually more complex than in any of the other divisions. Series 3. Cyclorrhapha Aschiza. Antennae composed of not more than three joints and an arista ; the latter is not terminal. Front of head without definite arched suture over the antennae, but frequently with a minute area of different colour or texture there. This group consists of the great family Syrphidae, and of four small families, viz. Conopidae, Pipunculidae, Phoridae, and Platypezidae. The section is supposed to be justified by its being Cyclorrhaphous in pupation, and by the members not possessing a ptilinum (or having no trace of one when quite mature). The Syrphidae are doubtless 1 Becher, Wien. Ent. Zcit. i. 1882, p. 49 ; for observation on connecting forms see Brauer, Verh. Ges. Wien, xl. 1890, p. 272. 2 The palpi are said to be of only one segment in some genera of Cecidomyiidae. The Cecidomyiidae are easily distinguished by the minute size — body not more than a line long — and by there not being more than six nervules at the periphery of the wing. Aedes (Culicidae) has also short palpi. 3 It is said by Schiner that in the anomalous genus Nemestrina the palpi are of three segments. 45 6 DIPTERA CHAP. a natural group, but the association with them of the other families mentioned is a mere temporary device. The greatest difficulty is experienced in deciding on a position for Phoridae, as to which scarcely any two authorities are agreed. Series 4. Cyclorrhapha Schizophora, or Eumyiid flies. The antennae consist of three joints and an arista. In the Calyptratae the frontal suture, or fold over the antennae, is well marked and extends downwards along each side of the face, leaving a distinct lunule over the antennae. In the Acalyptrate Muscids the form of the liead and of the antennae vary much and are less characteristic, but the wings differ from those of Brachycera by their much less complex nervuration. Series 5. Pupipara. These are flies of abnormal habits, and only found in connection with living Vertebrates, of which they suck the blood (one species, Braula caeca, lives on bees). Many are wingless, or have wings reduced in size. The young are produced alive, full grown, but having still to undergo a metamorphosis. Thia group consists of a small number of flies of which some are amongst the most aberrant known. This is specially the case with the Nycteribiidae. This Section will probably be greatly modified, as it is far from being a natural assemblage.1 The Sub-Order Aphaniptera, or Fleas, considered a distinct Order by many entomologists, may for the present be placed as a part of Diptera. It must be admitted that these sections are far from satis- factory. Brauer divides them into Tribes, based on the nature of the larvae, but these tribes are even more unsatisfactory than the sections, hosts of species being entirely unknown in the larval state, and many of those that are known having been very inadequately studied. We must admit that the classification of Diptera has at present advanced but little beyond the stage of arranging them in natural families capable of exact definition. We may, however, draw attention to the attempt that is being made by Osten Sacken to remodel the classification of the Nemo- cera and Brachycera by the combination of families into super- families.2 He proposes to divide the Nemocera into two super- families : 1. Nemocera Vera, including all the families from Cecidomyiidae to Tipulidae ; 2. Nemocera Anomala, consisting of the small families Bibionidae, Simuliidae, Blepharoceridae, Rhy- phidae and Orphnephilidae. For Orthorrhapha Brachycera he adopts the following arrange- 1 For tables of the families of flies the student may refer to Loew, Smithson- Misc. Coll. vi. Art. i. 1862 ; to Brauer, Denk. Ak. Wien, xlii. 1880, p. 110 (Orthorrhapha only) ; to Williston, Manual of N. American Diptera, 1896 ; to Schiner, Fauna austriaca, Diptera, Vienna, 1860, etc. 2 Berlin, ent. Zeitschr. xxxvii. 1892, p. 365, and xli. 1897, p. 365. vii BLOOD-SUCKING FLIES 457 ment : 1. Super- family Eremochaeta, for Stratiomyidae, Tabanidae, Acanthomeridae and Leptidae ; 2. Tromoptera, for Nemestrinidae, Acroceridae, Bombyliidae, Therevidae, and Scenopinidae ; 3. Ener- gopoda, for Asilidae, Dolichopidae, Empidae and Louchopteridae, Phoridae being included with doubt ; 4. Mydaidae remains isolated. This classification is based on the relations of the eyes and bristles of the upper surface, and on the powers of locomotion, aerial or terrestrial. At present it is not sufficiently precise to be of use to any but the very advanced student. Blood-sucking Diptera. — The habit of blood-sucking from Vertebrates is, among Insects, of course confined to those with suctorial mouth, and is exhibited by various Diptera. It is, however, indulged in by but a small number of species, and these do not belong to any special division of the Order. It is remarkable that as a rule the habit is confined to the female sex, and that a large proportion of the species have aquatic larvae. This subject has many points of interest, but does not appear to have yet received the attention it merits. We give below a brief summary of the facts as to blood-sucking Diptera. Series I. Nemocera. — In this section the habit occurs in no less than five families, viz. : Blepharoceridae. Curupira ; in the female only ; larva aquatic. Culicidae. Culex, Mosquitoes ; in the female only ; other genera, with one or two exceptions, do not suck blood ; larvae aquatic. Chironomidae. Ceratopogon, Midge ; in the female only ; ex- ceptional even in the genus, though the habit is said to exist in one or two less known, allied genera ; larval habits not certain ; often aquatic ; in C. bipunctatus the larva lives under moist bark. Psychodidae. Phlebotomus : in the female only (?) ; quite ex- ceptional in the family ; larva aquatic or in liquid filth. Simuliidae. Simulium, sand -flies; general in the family (?), which, however, is a very small one ; larva aquatic, food probably mixed vegetable and animal microscopic organisms. Series II. Brachycera. Tabanidae. Gad-flies : apparently general in the females of this family ; the habits of the exotic forms but little known ; in the larval state, scarcely at all known ; some are aquatic. 45 8 DIPTERA CHAP. Series IV. Cyclorrhapha Schizophora : Stomoxys, Haematobia ; both sexes (?) ; larvae in dung. [The Tse-tse flies, Glossina, are placed in this family, though their mode of parturition is that of the next section]. Series V. Pupipara. The habit of blood-sucking is probably common to all the group and to both sexes. The flies, with one exception, frequent Vertebrates; in many cases living entirely on their bodies, and apparently imbibing much blood ; the larvae are nourished inside the flies, not on the imbibed blood, but on a milky secretion from the mother. Sub-Order Aphaniptera. Fleas. The habit of blood-sucking is common to all the members and to both sexes. The larvae live on dried animal matter. Fossil Diptera. — A considerable variety of forms have been found in amber, and many in the tertiary beds ; very few members of the Cyclorrhaphous Sections are, however, among them ; the Tipulidae, on the other hand, are richly represented. In the Mesozoic epoch the Order is found as early as the Lias, the forms being exclusively Orthorrhaphous, both Nemocera and Brachycera being represented. All are referred to existing families. Nothing has been found tending to connect the Diptera with other Orders. No Palaeozoic Diptera are known. Series 1 Orthorrhapha Nemocera Fam. 1. Cecidomyiidae. — An extensive family of very minute and fragile flies, the wings of which have very few nervures ; the antennae are rather long, and are furnished with whorls of hair. In the case of some species the antennae are beautiful objects ; in Xylodiplosis some of the hairs have no free extremities, but form loops (Fig. 220). In the males of certain species the joints appear to be double, each one consisting of a neck and a body. Although comparatively little is known as to the flies themselves, yet these Insects are of importance on account of their preparatory stages. The larvae have very diverse habits ; the majority live in plants and form galls, or produce defor- mations of the leaves, flowers, stems, buds, or roots in a great variety of ways ; others live under bark or in animal matter ; some are predaceous, killing Aphidae or Acari, and even other CECIDOMYIIDAE 459 Cecidomyiids. The Xorth American Diplosis resinicola lives in the resin exuded as the results of the attacks of a caterpillar. The larva burrows in the semi-liquid resin, and, according to Osten Sacken,1 is probably amphipneustic. Cecidomyiid larvae are short maggots, narrowed at the two ends, with a very small head, and between this and the first thoracic segment (this bears a stigma), a small supplementary segment ; the total number of seg- ments is thirteen, besides the head; there are eight pairs of stigmata .-V FIG. 219. — Cecidomyia (Diplosis) buxi. Britain. A, Larva, magnified ; B, pupa ; C, imago ; D, portion of au- tenna. (After Laboulbene.) FIG. 220. — One segment of an- tenna of Xylodiplosis sp. ; a, Tip of one segment ; b, base of another. (After Janet.) on the posterior part of the body. Brauer defines the Cecido- myiid larva thus, " peripneustic, with nine pairs of stigmata, the first on the second segment behind the head ; two to nine on fifth to twelfth segments; body as a whole fourteen - segmented without a fully-formed head." The most remarkable peculiarity of Cecidomyiid larvae is that those of many species possess a peculiar organ — called breast-bone, sternal spatula, or anchor- process — projecting from the back of the lower face of the pro- thoracic segment. The use of so peculiar a structure has been much discussed. According to Giard,2 in addition to the part 1 Tr. A-nier. cnt. Soc. iii. 1871, p. 345. 2 Bull. Soc. ent. France, 1893, p. Ixxx. 460 DIPTERA CHAP. that protrudes externally, as shown in Fig. 2 1 9, A, there is a longer portion concealed, forming a sort of handle, having muscles attached to it. Some of these larvae have the power of executing leaps, and he states that such larvae are provided on the terminal segment with a pair of corneous papillae ; bending itself almost into a circle, the larva hooks together the breast-bone and the papillae, and when this connection is broken the spring occurs. This faculty is only possessed by a few species, and it is probable that in other cases the spatula is used as a means for changing the position or as a perforator. Some of the larvae possess false feet on certain of the segments. Williston says they probably do not moult. In the pupal instar (Fig. 219, B), the Cecidomyiid greatly resembles a minute Lepidopterous pupa. The Hessian fly, Cecidomyia destriwtor, is frequently extremely injurious to crops of cereals, and in some parts of the world commits serious depredation. The larva is lodged at the point where a leaf enwraps the stem ; it produces a weakness of the stem, which consequently bends. This Insect and C. tritici (the larva of which attacks the flowers of wheat) pupate in a very curious manner : they form little compact cases like flax-seeds ; these have been supposed to be a form of pupa similar to what occurs in the Blow-fly ; but there are important distinctions. The larva, when about to undergo its change, exudes a substance from its skin, and this makes the flax-seed ; the larval skin itself does not form part of this curious kind of cocoon, for it may be found, as well as the pupa, in the interior of the " flax-seed." Other Cecidomyiids form cocoons of a more ordinary kind ; one species, described by Ferris as living on Pinus maritima, has the very remarkable faculty of surrounding itself, by some means, with a cocoon of resin. Walsh describes the cocoon-forming process of certain Cecidomyiids as one of exudation and inflation ; Williston as somewhat of the nature of crystallisation. Some Cecidomyiids are said to possess, in common with certain other Diptera, the unusual number of five Malpighian tubes ; and Giard says that in the larva there is only a pair of these tubes, and that their extremities are united so as to form a single tube, which is twisted into an elegant double loop. Thirty years or more ago the Russian naturalist, Wagner, made the very remarkable discovery that the larva of a Cecidomyiid produces young ; and it has since been found by Meinert and CECIDOMYIIDAE 46 1 others that this kiud of paedogenesis occurs in several species of the genera Miastor and Oligarces. The details are briefly as follows : — A female fly lays a few, very large, eggs, out of each of which comes a larva, that does not go on to the perfect state, but produces in its interior young larvae that, after consuming the interior of the body of the parent larva, escape by making a hole in the skin, and thereafter subsist externally in a natural manner. This larval reproduction may be continued for several generations, through autumn, winter, and spring till the following summer, when a generation of the larvae goes on to pupation and the mature, sexually perfect fly appears. Much discussion has taken place as to the mode of origination of the larvae ; Carus and others thought they were produced from the rudimental, or immature ovaries of the parent larva. Meinert, who has made a special study of the subject,1 finds, however, that this is not the case ; in the repro- ducing larva of the autumn there is no ovary at all ; in the re- producing larvae of the spring-time rudimentary ovaries or testes, as the case may be, exist ; the young are not, however, produced from these, but from germs in close connection with the fat- body. In the larvae that go on to metamorphosis the ovaries continue their natural development. It would thus appear that the fat-body has, like the leaf of a Begonia, under certain circum- stances, the power, usually limited to the ovaries, of producing complete and perfect individuals. Owing to the minute size and excessive fragility of the Gall- midge flies it is extremely difficult to form a collection of them ; and as the larvae are also very difficult of preservation, nearly every species must have its life-history worked out as a special study before the name of the species can be ascertained. Not- withstanding the arduous nature of the subject it is, however, a favourite one with entomologists. The number of described and named forms cannot be very far short of 1000, and each year sees some 20 or 30 species added to the list. The number of unde- scribed forms is doubtless very large. The literature of the subject is extensive and of the most scattered and fragmentary character. The Cecidomyiidae have but little relation to other Nemocera, and are sometimes called Oligoneura, on account of the reduced number of wing-nervures. Their larvae are of a peculiar type 1 NaturMst. Tidskr. (3) viii. 1874, p. 34, pi. xii. 462 DIPTERA that does not agree with the larvae of the allied families having well-marked heads (and therefore called Eucephala), nor with the acephalous maggots of Eumyiidae. Fam. 2. Mycetophilidae. — These small /lies are much less delicate creatures than the Cecidomyiidae, and have more nervures in the wings ; they possess ocelli, and frequently have the coxae elongated, and in some cases the legs adorned with complex arrange- ments of spines : their antennae have not whorls of hair. Although very much neglected there are probably between 700 and 1000 species known ; owing to many of their larvae living in fungoid matter the flies are called Fungus-gnats. We have more than 100 species in Britain. Epidapus is remarkable, inasmuch as the female is entirely destitute of wings and halteres, while the male has the halteres developed but the wings of very reduced size. E. scabiei is an excessively minute fly, smaller than a common flea, and its larva is said to be very imjurious to stored potatoes. The larvae of Mycetophilidae are usually very elongate, worm - like maggots, but have a distinct, ¥iG.22i.—Mycetobiapaliipes. Britain. small head; they are peri- A, Larva; B, pupa: C, imago. (After Dufour.) . . , . -,. pneustic, having, according to Osten Sacken, nine pairs of spiracles, one pair prothoracic, the others on the first eight abdominal segments. They are usually worm- like, and sometimes seem to consist of twenty segments. Some of them have the faculty of constructing a true cocoon by some sort of spinning process, and a few make earthen cases for the purpose of pupation. The pupae themselves are free, the larval skin having been shed. The Mycetophilidae are by no means completely fungivorous, for many live in decaying vegetable, some even in animal, matter. The habits of many of the larvae are very peculiar, owing to their spinning or exuding a mucus, that reminds one of snail- slime ; they are frequently gregarious, and some of them have likewise, as we shall subsequently mention, migratory habits. Perris has described the very curious manner in which Sciophila vii MYCETOrHILIDAE 463 unimaculata forms its slimy tracks ; 1 it stretches its head to one side, fixes the tip of a drop of the viscous matter from its mouth to the surface of the substance over which it is to progress, bends its head under itself so as to affix the matter to the lower face of its own body ; then stretches its head to the other side and repeats the operation, thus forming a track on which it glides, or perhaps, as the mucus completely envelops its body, we should rather call it a tunnel through which the maggot slips along. According to the description of Hudson 2 the so-called New Zealand Glow-worm is the larva of Boleto- phila luminosa ; it forms webs in dark ravines, along which it glides, giving a considerable amount of light from the peculiarly formed terminal segment of the body. This larva is figured as consisting of about twenty segments. The pupa is provided with a very long, curiously-branched dorsal structure : the fly issuing from the pupa is strongly luminous, though no use can be discovered for the property either in it or in the larva. The larva of the Australian Ceroplatus mastersi is also luminous. Another very exceptional larva is that of Epicypta scatophora ; it is of short, thick form, like Cecidomyiid larvae, and has a very remarkable structure of the dorsal parts of the body ; by means of this its excrement, which is of a peculiar nature, is spread out and forms a case for enveloping and sheltering the larva. Ultimately the larval case is converted into a cocoon for pupation. This larva is so different from that of other Mycetophilidae, that Perris was at first unable to believe that the fly he reared really came from this unusually formed larva. The larva of Mycetobia pallipes (Fig. 221) offers a still more remarkable phenomenon, inasmuch as it is amphipneustic instead of peripneustic (that is to say, it has a pair of stigmata at the termination of the body and a pair on the first thoracic segment instead of the lateral series of pairs we have described as normal in Mycetophilidae). This larva lives in company with the amphipneustic larva of Rhyplius, a fly of quite another family, and the Mycetobia larva so closely resembles that of the Rhyphus, that it is difficult to distinguish the two. This anomalous larva gives rise, like the exceptional larva of Epicypta, to an ordinary Mycetophilid fly.3 1 Ann. Soc. ent. France (2) vii. 1849, p. 346. 2 Trans. New Zealand Inst. xxiii. 1890, p. 48. 3 Oaten Sacken, Berlin, ent. Zeitschr. xxxvii. 1892, p. 442; and Ferris, Ann. Soc. ent. France (2) vii. 1849, p. 202. 464 DIPTERA CHAP. But the most remarkable of all the Mycetophilid larvae are those of certain species of Sciara, that migrate in columns, called by the Germans, Heerwurm. The larva of Sciara militaris lives under layers of decomposing leaves in forests, and under certain circumstances, migrates, sometimes perhaps in search of a fresh supply of food, though in some cases it is said this cannot be the reason. Millions of the larvae accumulate and form them- selves by the aid of their viscous mucus into great strings or ribbons, and then glide along like serpents : these aggregates are said to be sometimes forty to a hundred feet long, five or six inches wide, and an inch in depth. It is said that if the two ends of one of these processions be brought into contact, they become joined, and the monstrous ring may writhe for many hours before it can again disengage itself and assume a columnar form. These processional maggots are met with in Northern Europe and the United States, and there is now an extensive literature about them.1 Though they sometimes consist of almost incredible numbers of individuals, yet it appears that in the Carpathian mountains the assemblages are usually much smaller, being from four to twenty inches long. A species of Sciara is the " Yellow- fever fly " of the Southern United States. It appears that it has several times appeared in unusual numbers and in unwonted localities at the same time as the dreaded disease, with which it is popularly supposed to have some connection. Fam. 3. Blepharoceridae.2 — Wings with no discal cell, hut witli a secondary set of crease-like lines. The flies composing this small family are very little known, and appear to be obscure Insects with somewhat the appearance of Empidae, though with strongly iridescent wings ; they execute aerial dances, after the manner of midges, and are found in Europe (the Pyrenees, Alps and Harz mountains) as well as in North and South America. Their larvae are amongst the most re- markable of Insect forms ; indeed, no entomologist recognises them as belonging to a Hexapod Insect when he makes a first 1 See Guerin-Meneville, Ann. Soc. cnt. France (2) iv. 1846 ; Bull. p. 8 ; and No\vicki, Verh. Ges. Wien, xvii. 1867, SB. p. 23. 2 For details as to the family cf. Osten Sacken, Berlin, cnt. Zeitschr. xl. 1895, p. 148 ; and for the larvae F. Miiller, Arch. Mus. Rio-Jan, iv. 1881, p. 47. The name " Liponeuridae " was formerly applied by some authorities to this family, but it is now generally recognised that Blepharoceridae is more legitimate. BLEPHAROCERIDAE 465 acquaintance with them. The larva of Curupira (Fig. 222) lives in rapid streams in Brazil, fixed by its suckers to stones or rocks. It consists only of six or seven divisions, with project- ing side-lobes ; the usual segmentation not being visible. There are small tracheal gills near the suckers, and peculiar scale-like organs are placed about the edges of the lobes. Miiller considers that the first lobe is " cephalothorax," corresponding to head, thorax and first abdominal segment of other larvae, the next four lobes he considers to correspond each to an \^v^/ abdominal segment, and the terminal mass ^B ^.., to four segments. He also says that certain minute points existing on the sur- face, connected with the tracheal system by minute strings, represent nine pairs of spiracles. These larvae and their pupae can apparently live only a short time after being taken out of the highly aerated water in which they exist, but Miiller succeeded in rearing several flies from a number of larvae and pupae that he collected, and, believing them to be all one species, he announced that the females exhibited a highly developed dimorphism, some of them being blood-suckers, others honey-suckers. It is however, more prob- able that these specimens belonged to two , FIG. 222. — Under surface of or three distinct species or even genera. This point remains to be cleared up. The larva we have figured is called by Miiller Paltostoma torrentium. It is certain, how- ever, that the Brazilian Insect does not belong to the genus Paltostoma, and it will no doubt bear the name used by Osten Sacken, viz. Curupira. The metamorphoses of the European Liponeura Irevirostris have been partially examined by Dewitz, who found the Insects in the valley of the Ocker in September.1 He does not consider the " cephalothorax " to include an abdominal segment ; and he found that two little, horn-like projections from the thorax of the 1 Berlin, ent. Zeit. xxv. 1881, p. 61 ; and cf. Brauer, Jf-'ien. ent. Zeit. i. 1S82, p. 1. VOL. VI 2 H the larva of Curupira ( Paltostoma ) torrentium , showing the suckers along the middle of the body, much magnified. Brazil. (After Fritz Miiller.) 466 DIPTERA CHAP. pupa are really each four-leaved. The pupa is formed within the larval skin, but the latter is subsequently cast so that the pupa is exposed ; its dorsal region is horny, but the under sur- face, by which it clings firmly to the stones of the rapid brook, is white and scarcely chitinised, and Dewitz considers that the chitinous exudation from this part is used as a means of fastening the pupa to the stones. Blepharoceridae possess, in common with Gulex, Psychoda and Ptychoptera, the peculiar number of five Malpighian tubes, and it has been proposed by Miiller to form these Insects into a group called Pentanephria. Fam. 4. Culicidae (Mosquitoes, Gnats). — Antennae with whorls of hair or plumes, which may be very dense and long in the male, though scanty in the female ; head with a long, projecting pro- boscis. Although there are few Insects more often referred to in general literature than Mosquitoes, yet the ideas in vogue about them are of the vaguest character. The following are the chief points to be borne in mind as to the prevalence of Mos- quitoes : — The gently humming Gnat that settles on us in our apartments, and then bites us, is a Mosquito ; there are a large number of species of Mosquitoes ; in some countries many in one locality ; in Britain we have ten or a dozen ; notwithstanding the multiplicity of species, certain Mosquitoes are very widely diffused ; the larvae are all aquatic, and specially frequent stagnant or quiet pools ; they are probably diffused by means of the water in ships, it being known that Mosquitoes were introduced for the first time to the Hawaiian Islands by a sailing vessel about the year 1828. Hence it is impossible to say what species the Mosquitoes of a given locality may be without a critical examina- tion. No satisfactory work on the Mosquitoes of the world exists. Urich states that he is acquainted with at least ten species in Trinidad. The species common in our apartments in Central and Southern England is Culex pipiens, Linn., and this species is very widely distributed, being indeed one of the troublesome Mosquitoes of East India. The term Mosquito is a Spanish or Portuguese diminutive of Mosca. It is applied to a variety of small flies of other families than Culicidae, but should be restricted to these latter. The irritation occasioned by the bites of Mosquitoes varies according to several circumstances, viz. the condition of the biter, the condition or constitution of the bitten, and also the species of Mosquito. Keaumur and MOSQUITOES 467 others believed that some irritating fluid is injected by the Mos- quito when it bites. But why should it want to irritate as well as to bite ? Macloskie, considering that the Mosquito is really a feeder on plant-substances, suggests that the fluid injected may be for the purpose of preventing coagulation of the plant-juices during the process of suction. It is a rule that only the female Mosquito bites, the male being an inoffensive creature, and pro- vided with less effectual mouth-organs; it has, however, been stated by various authors that male Mosquitoes do occasionally bite. It is difficult to understand the blood-sucking propensities of these Insects ; we have already stated that it is only the females that suck blood. There is reason to suppose that it is an acquired habit ; and it would appear that the food so obtained is not essential to their existence. It has indeed been asserted that the act is frequently attended with fatal consequences to the individual that does it. The proper method of mitigating their nuisance is to examine the stagnant waters in localities where they occur, and deal with them so as to destroy the larvae. These little creatures are remarkable from the heads and thorax being larger and more distinct than in other Dipterous larvae. Their metamorphoses have been frequently described, and recently the numerous interesting points connected with their life-histories have been admirably portrayed by Professor Miall,1 in an accessible form, so that it is unnecessary for us to deal with them. Corethra is placed in Culicidae, but the larva differs totally from that of Culex ; it is predaceous in habits, is very transparent, has only an imperfect tracheal system, without spiracles, and has two pairs of air-sacs (perhaps we should rather say pigmented struc- tures possibly for aerostatic purposes, but not suppliers of oxygen). The kungu cake mentioned by Livingstone as used on Lake Nyassa is made from an Insect which occurs in profusion there, and is compressed into biscuit form. It is believed to be a Corethra. One of the peculiarities of this family is the pre- valence of scales on various parts of the body, and even on the wings : the scales are essentially similar to those of Lepidoptera. Though Mosquitoes are generally obscure plain Insects, there are some — in the South American genus Megarrhina — that are elegant, beautifully adorned creatures. Swarms of various species of Culicidae, consisting sometimes of almost incalculable numbers 1 Natural History of Aquatic Insects, London, 1895, chap. ii. 468 DIPTERA CHAP. of individuals, occur in various parts of the world ; one in New Zealand is recorded as having been three-quarters of a naile long, twenty feet high, and eighteen inches thick. There is good reason for supposing that Mosquitoes may act as disseminators of disease, but there is no certain evidence on the subject. The minute Filaria that occurs in great numbers in some patients, is found in the human body only in the embryonic and adult conditions. Manson considers that the intermediate stages are passed in the bodies of certain Mosquitoes.1 Fam. 5. Chironomidae (Gnats, Midges}. — Small or minute flies of slender form, with narrow wings, without projecting rostrum, usually with densely feathered antennae in the male, and long slender legs. The flies of this family bear a great general resemblance to the Culicidae. They are much more numerous in species, and it is not improbable that we have in this country 200 species of the genus Chironomus alone. They occur in enormous numbers, and frequently form dancing swarms in the neighbourhood of the waters they live in. The species are frequently extremely similar to one another, though distinguished by good characters ; they are numerous about Cambridge. Many of them have the habit of using the front legs as feelers rather than as means of support or locomotion. This is the opposite of what occurs in Culicidae, where many of the species have a habit of holding up the hind legs as if they were feelers. The eggs of Chironomus are deposited as strings surrounded by mucus, and are many of them so transparent that the development of the embryo can be directly observed with the aid of the microscope. They are said to possess a pair of air-sacs. The larvae, when born, are aquatic in habits, and are destitute of tracheal system. They subsequently differ greatly from the larvae of Culex, inasmuch as the tracheal system that develops is quite closed, and in some cases remains rudimentary. There is, however, much diversity in the larvae and also in the pupae. The little Blood-worms, very common in many stagnant and dirty waters, and used by anglers as bait, are larvae of Chironomus. They are said to be al 'EyiiTriSe? of Aristotle. The red colour of these larvae is due to haemoglobin, a substance which has the power of attracting and storing oxygen, and giving it off to the tissues as they require it. Such larvae are able to live in burrows they construct 1 Tr. Linn. Soc. Land. (2) ii. 1884, p. 367. GNATS MIDGES 469 amongst the mud. Some of them, provided plentifully with haemoglobin, are in consequence able to live at great depths, it is said even at 1000 feet in Lake Superior, and come to the surface only occasionally. A few are able even to tolerate salt water, and have been fished up from considerable depths in the sea. It is a remarkable fact that these physiological capacities differ greatly within the limits of the one genus, Chironomus, for some of these species are destitute of haemoglobin, and have to live near the surface of the water ; these have a superior development of the tracheal system. The pupae of Chironomus have the legs coiled, and the thorax, instead of being provided with the pair of tubes or trumpets for breathing that is so common in this division of Diptera, have a pair of large tufts of hair-like filaments.1 A very curious form of parthenogenesis has been described by Grimm 2 as existing in an undetermined species of Chironomus, inasmuch as the pupa deposits eggs. Although this form of parthenogenesis is of much interest, it is not in any way to be compared with the case, already referred to, of Miastor (p. 4 6 1 ). The " pupa " is at the time of oviposition prac- tically the imago still covered by the pupal integument ; indeed Grimm informs us that in some cases, after depositing a small number of ova, the pupa became an imago. This partheno- genesis only occurs in the spring-generation ; in the autumn the development goes on in the natural manner. The case is scarcely entitled to be considered as one of paedogenesis. Gnats of this family, and believed to be a variety of Chiro- nomus plumosus, are subject to a curious condition, inasmuch as individuals sometimes become luminous or " phosphorescent " ; this has been noticed more specially in Eastern Europe and Western Asia. The whole of the body and legs may exhibit the luminous condition, but not the wings. It has been suggested by Schmidt that this condition is a disease due to bacteria in the body of the gnat.3 Ceratopogon is a very extensive genus, and is to some extent anomalous as a member of Chironomidae. The larvae exhibit considerable variety of form. Some of them are aquatic 1 For an extremely interesting account of Chironomus refer to Miall's book, already cited, and, for the larva, to the valuable work of Meinert on Eucephalous larvae of Diptera, Danske Selsk. Skr. (6) iii. 1886, p. 436. 2 Ann. Xat. Hist. (4) viii. 1871, p. 31. 3 Ibid. (6) xv. 1895, p. 133. 47° DIPTERA CHAP. in habits, but the great majority are terrestrial, frequenting trees, etc. The former larvae are very slender, and move after the manner of leeches ; they give rise to images with naked wings, while the terrestrial larvae produce flies with hairy wings. There are also important distinctions in the pupae of the two kinds ; the correlation between the habits, and the dis- tinctions above referred to, is, however, far from being absolutely constant.1 Certain species of midges are in this country amongst the most annoying of Insects ; being of very minute size, scarcely visible, they settle on the exposed parts of the body in great numbers, and by sucking blood create an intolerable irritation. Ceratopogon varius is one of the most persistent of these annoyers in Scotland, where this form of pest is much worse than it is in England ; in Cambridgeshire, according to Mr. G. H. Verrall, the two troublesome midges are the females of C. pulicaris and C. bipunctatus; Fam. 6. Orphnephilidae. — Small, brown or yellowish flies, bare of pubescence, ivith very large eyes contiguous in both sexes, and with antennae composed of two joints and a terminal bristle ; both the second joint and the bristle are, however, really complex. One of the smallest and least known of the families of Diptera, and said to be one of the most difficult to classify. The nervures of the wings are very distinct. Nothing is known of the habits and metamorphoses ; there is only one genus — Orphnephila ; it is widely distributed ; we have one species in Britain. Fam. 7. Psychodidae (Moth-flies). — Extremely small, helpless flies, usually with thickish antennae, bearing much hair, with wings broader than is usual in small flies, and also densely clothed with hair, giving rise to a pattern more or less vague. These flies are very fragile creatures, and are probably numerous in species. In Britain forty or fifty species have been recognised.2 A South European form is a blood-sucker, and has received the appropriate name of Phlebotomus. The life-history of Pericoma canescens has recently been studied by Professor Miall.3 The larva is of aquatic habits, but is amphibious, being capable of existing in the air ; it has a pair of anterior spiracles, by means 1 For metamorphoses of aquatic species of Ceratopogon, see Miall and Meinert, already quoted : for examples of the terrestrial species, and their illustrations, refer to Mik, Wien. ent. Zeit. vii. 1888, p. 183. 2 Monograph, Eaton, Ent. Mag. xxix. and xxx. 1893, 1894 : supplement op. cit. 1896, etc. 3 Tr. ent. Soc. London, 1895, p. 141. vii PSYCHODIDAE — DIXIDAE TIPULIDAE 47 I of which it breathes in the air, and a pair at the posterior extremity of the body, surrounded by four ciliated processes, with which it forms a sort of cup for holding air when it is in the water. The favourite position is amongst the filaments of green algae on which it feeds. A much more extraordinary form of larva from South America, doubtless belonging to this family, has recently been portrayed by Fritz Miiller, under the name of Maruina.1 These larvae live in rapid waters in company with those of the genus Curupira, and like the latter are provided with a series of suctorial ventral discs. Fritz Miiller's larvae belong to several species, and probably to more than one genus, and the respiratory apparatus at the extremity of the body exhibits considerable diversity among them. Fam. 8. Dixidae. — The genus Dixa must, it appears, form a distinct family allying the Culicid series of families to the Tipulidae. The species are small, gnat-like Insects, fond of damp places in forests. We have four British species (D. maculata, D. nebulosa, D. aestivalis, D. aprilina). The genus is very widely distributed, occurring even in Australia. The larvae are aquatic, and have been described by Eeaumur, Miall, and Meinert. The pupa has the legs coiled as in the Culicidae. Fam. 9. Tipulidae (Daddy-long-legs, or Crane-flies}. — Slender Insects with elongate legs, a system of wing-nervures, rather com- plex, especially at the tip ; an angulate, or open V-shaped, suture on the dorsum of the thorax in front of the wings : the female with the body terminated l>y a pair of hard, pointed processes, concealing some other processes, and forming an ovipositor. The curious, silly Insects called daddy-long-legs are known all over the world, the family being a very large one, and found everywhere, some of its members extending their range even to the most inclement climates. It includes a great variety of forms that would not be recognised by the uninitiated, but can be readily distinguished by the characters mentioned above. It is impossible to assign any reason of utility for the extreme elongation of the legs of these Insects ; as everyone knows, they break off with great ease, and the Insect appears to get on perfectly well without them. It is frequently 1 Tr. ent. Soc. London, 1895, p. 479. 47 2 DIPTERA CHAP. the case that they are much longer in the males than in the females. Other parts of the body exhibit a peculiar elongation ; in some forms of the male the front of the head may be prolonged into a rostrum. In a few species the head is separated by a great distance from the thorax, the gap being filled by elongate, hard, cervical sclerites; indeed it is in these Insects that the phenomenon, so rare in Insect- structure, of the elongation of these sclerites and their be- coming a part of the actual external skeleton, reaches its maximum. In several species of Eriocera the male has the antennae of extraordinary length, four or five times as long as the body, and, strange to say, this elongation is accompanied by a reduction in the number of the segments of which the organ is composed, the number being in the male about six, in the female ten, in place of the usual fourteen or sixteen. In Toxorrhina and Elephantomyia the proboscis is as long as the whole body. In other forms the wings become elongated to an unusual extent by means of a basal stalk. It is probable that the elongation of the rostrum may be useful to the Insects. Gosse,1 indeed, describes Limnobia intermedia as having a rostrum half as long as the body, and as hovering like a Syrphid, but this is a habit so foreign to Tipulidae, that we may be pardoned for suspecting a mistake. The larvae exhibit a great variety of form, some being terrestrial and others aquatic, but the ter- restrial forms seem all to delight in damp situations, such as shaded turf or rotten tree-stems. They are either amphi- pneustic or metapneustic, that is, with a pair of spiracles placed at the posterior extremity of the body ; the aquatic species frequently bear appendages or projections near these spiracles. The pupae in general structure are very like those of Lepidoptera, and have the legs extended straight along the body ; they possess a pair of respiratory processes on the thorax in the form of horns or tubes. There are more than 1000 species of these flies known, and many genera. They form three sub-families, which are by some considered distinct families, viz. : Ptychopterinae, Limno- biinae or Tipulidae Brevipalpi, Tipulinae or Tipulidae Longi- palpi. The Ptychopterinae are a small group in which the angulate 1 A Naturalist's Sojourn in Jamaica, London, 1853, p. 284. TIPULIDAE 473 suture of the inesonotum is indistinct ; the larvae are aquatic and have the head free, the terminal two segments of the body enormously prolonged (Fig. 223), forming a long tail bearing, in the Xorth American Bittacomorplia, two respiratory fila- ments. Hart l describes this tail as possessing a stigmatal opening at the extremity ; no doubt the structure is a compounded pair of spiracles. The pupa (Fig. 223, B) has quite lost the respira- tory tube at the posterior extremity of the body, but has instead quite as long a one at the anterior extremity, due to one tube of the pair normal in Tipulidae being enormously developed, while its fellow remains small. This is a most curious departure from the bilateral symmetry that is so constantly exhibited in Insect-structure. Our British species of Ptych- optera have the pupal respiratory tube as extra- ordinary as it is in jBittacomorpha, though the larval tail is less peculiar.2 This group should perhaps be distinguished from the Tipulidae as a separate family, but taxonomists are not yet unanimous as to this. Brauer considers that the head of the larva, and the condition of five Malpighian tubules in the imago, require the association of Ptychopterinae with the preceding families (Chirouomidae, etc.), rather than with the Tipulidae. The great majority of the Tipulidae are com- prised in the sub-family Limnobiinae — the Tipulidae Brevipalpi of Osten Sacken : 3 in them the last joint of the palpi is shorter or FIG. 223. — Bittaco- not much longer than the two preceding together. They exhibit great variety, and many of them are types of fragility. The common winter gnats of the genus Trichocera are a fair sample of this sub-family. The species of this genus mostly inhabit high latitudes, and delight in morpha davipes. North America x \. (After Hart.) A, Larva ; B, pupa : I, the left, r, the right respiratory tube. Bull. Illinois Lab., iv. 1895, p. 193. - M lull's Aquatic Insects, 1895, p. 174. 3 "Studies," etc., Berlin, ent. Zeitschr. xxxi. 1887. 474 DIPTERA CHAP. a low temperature ; it has been said that they may be seen on the wing in the depth of winter when the temperature is below freezing, but it is pretty certain that the spots chosen by the Insects are above that temperature, and Eaton states that the usual temperature during their evolutions is about 40° or 45° Fahr. They often appear in the damp conditions of a thaw when much snow is on the ground. T. simonyi was found at an elevation of 9000 feet in the Tyrol, crawling at a temperature below the freezing-point, when the ground was deeply covered with snow. T. regelationis occurs commonly in mines even when they are 500 feet or more deep. The most extraordinary of the Limuobiinae is the genus Chionea, the species of which are totally destitute of wings and require a low temperature. C. araneoides inhabits parts of northern Europe, but descends as far south as the mountains near Vienna ; it is usually said to be only really active in the depth of winter and on the surface of the snow. More recently, however, a large number of specimens were found by Professor Thomas in the month of October in his garden in Thuringia ; they were caught in little pit-falls constructed to entrap snails. The larva of this Insect is one of the interesting forms that display the transition from a condition with spiracles at the sides of the body to one where there is only a pair at the posterior extremity. A very peculiar Fly, in which the wings are reduced to mere slips, Hcdirytus ampJiibius, was discovered by Eaton in Kergueleii Land, where it is habitually covered by the rising tide. Though placed in Tipulidae, it is probably a Chironomid. The group Cylindrotomina is considered by Osten Sacken * to be to some extent a primitive one having relationship with the Tipulinae ; it was, he says, represented by numerous species in North America during the Oligocene period. It is of great interest on account of the larvae, which are in several respects similar to caterpillars of Lepidoptera. The larva of Cylindrotoma distincta lives upon the leaves of plants — Anemone, Viola, Stellaria — almost like a caterpillar ; it is green with a crest along the back consisting of a row of fleshy processes. Though this fly is found in Britain the larva has apparently not been observed here. The life-history of Phalacrocera replicata has been recently published by Miall and Shelford.2 The larva eats 1 Tr. ent. Soc. London, 1897, p. 362. 2 Tr. ent. Soc. London, 1897, pp. 343-361. TIPULIDAE BIBIONIDAE 475 submerged mosses in the South of England, and bears long forked filaments, reminding one of those of caterpillars. This species has been simultaneously discussed by Bengtsson, who apparently regards these Tipulids with caterpillar-like larvae — he calls them Erucaeformia1 — as the most primitive form of existing Diptera. The Tipulinae — Tipulidae Longipalpi, Osten Sacken2 — have the terminal joint of the palpi remarkably long, longer than the three preceding joints together. The group includes the largest forms, and the true daddy-long-legs, a Chinese species of which, Tipula brobdignagia, measures four inches across the expanded wings. The group contains some of the finest Diptera. Some of the exotic forms allied to Ctenophora have the wings coloured in the same manner as they are in certain Hymenoptera, and bear a considerable resemblance to members of that Order. Fam. 10. Bibionidae. — Flies of moderate or small size, some- times of different colours in the two sexes, with short, thick, straight, antennae; front tibiae usually with a long pointed process; coxae not elongate. Eyes of male large, united, or contiguous in FIG. 224. — Head of Bibio. x 10. A, Of male, seen from the front ; C, from the side ; a, upper, 6, lower eye ; B, head of female. front. The flies of the genvis Bibio usually appear in England in the spring, and are frequently very abundant ; they are of sluggish habits and poor performers on the wing. The differ- ence in colour of the sexes is very remarkable, red or yellow predominating in the female, intense black in the male; and 1 Acta Univ. Lund, xxxiii. (2) No. 7, 1897. 2 "Studies," etc., Berlin, ent. Zeitschr. xxx. 1886, p. 153. 476 DIPTERA it is a curious fact that the same sexual distinction of colour reappears in various parts of the world — England, America, India, and New Zealand ; moreover, this occurs in genera that are by no means closely allied, although allied species frequently have concolorous sexes. The eyes of the males are well worth study, there being a very large upper portion, and, abruptly separated from this, a smaller, differ- ently faceted lower portion, practically a separate eye ; though so largely developed the upper eye is in some cases so hairy that it must greatly interfere with the formation of a continuous picture. Carriere con- siders that the small lower eye of the male corresponds to the whole eye of the female. The larvae of Bibio (Fig. 225) are caterpillar- like in form, have a horny head, well de- veloped, biting mouth-organs, and spine-like processes on the body-segments. They are certified by good authorities1 to possess the ex- tremely unusual number of ten pairs of spiracles; a larva found at Cambridge, which we refer to Bibio (Fig. 225) has nine pairs of moderate spiracles, as well as a large terminal pair separated from the others by a segment without spiracles. The genus Diloplius is closely allied to Bibio, the larvae of which (and those of Bibionidae in general) are believed to feed on vegetable substances ; the parasitism of Dilophus vulgaris on the larva of a moth, Epino- FIG. 225. — Larva of tia (Chaetoptrio) liypericana, as recorded by Cam- Meade,2 must therefore be an exceptional case. . In the genus Scatopse there is a very im- portant point to be cleared up as to the larval respiratory system ; it is said by Dufour and Ferris 3 to be amphipneustic ; there are, however, nine projections on each side of the body that were considered by Bouche, and probably with good reason, to 1 Osten Sacken, Berlin, ent. Zeitschr. xxxvii. 1892, p. 450. 2 Entomologist, xiv. 1881, p. 287. This observation has never, we believe, been confirmed. 3 Ann. Soc. ent. France (2) v. 1847, p. 46. A K '* sp. bridge. x 5. VII BIBIONIDAE SIMULIIDAE 477 Cam- be spiracles. The food of Scatopse in the larval state is principally vegetable. The larva of Scatopse changes to a pupa inside the larval p skin ; the pupa is pro- vided on the thorax with two branched respiratory processes that project outside the larval skin.1 Lucas has given an in- teresting account of the occurrence of the larva of Bibio marci in enorm- ous numbers at Paris ; they lived together in masses, there being ap- parently Some Sort of FlG- 226.— Portion of integument of Bibio sp. bridge, v, lutersegmeiital processes ; s, spiracle. connection between the individuals.2 In the following year the fly was almost equally abundant. Owing to the great numbers in which the species of Bibionidae sometimes appear, these Insects have been supposed to be very injurious. Careful inquiry has, however, generally exculpated them as doers of any serious injury, though Dilophus febrilis — a so-called fever-fly — appears to be really injurious in this country when it multiplies excessively, by eating the roots of the hop- plant. Fam. 11. Simuliidae (Sand-flies, Buffalo-gnats}. — Small obese flies with humped back, rather short legs and broad wings, with short, straight antennae destitute of setae; proboscis not projecting. There is only one genus, Simulium, of this family, but it is very widely spread, and will probably prove to be nearly cosmo- politan. Some of the species are notorious from their blood-suck- ing habits, and in certain seasons multiply to an enormous extent, alight in thousands on cattle, and induce a disease that produces death in a few hours ; it is thought as the result of an instilled poison. S. columbaczense has occasioned great losses amongst the herds near the Danube ; in North America the Buffalo- and Turkey-gnats attack a variety of mammals and birds. In Britain 1 Ferris, in Ann. Soc. ent. France (2) v. 1847, p. 37, pi. i. 2 Ann. Soc. ent. France (5) i. 1871, Bull. p. Ixvii. 47$ DIPTERA CHAP. and other parts of the world they do not increase in numbers to an extent sufficient to render them seriously injurious : their bite is however very annoying and irritating to ourselves. In their early stages they are aquatic and require well aerated waters : the larvae hold themselves erect, fixed to a stone or some other object by the posterior extremity, and have on the head some beautiful fringes which are agitated in order to bring food within reach ; the pupae are still more remarkable, each one being placed in a pouch or sort of watch-pocket, from which projects the upper part of the body provided with a pair of filamentous respiratory processes. For an account of the interesting circum- stances connected with the metamorphoses of this species the reader should refer to Professor Miall's book ; and for the life- history of the American Buffalo-gnat to Biley.1 Fam. 12. Rhyphidae. — This is another of the families that have only two or three genera, and yet are very widely distributed. These little flies are distinguished from other Nemocera Anomala (cf. p. 456) by the presence of a disced cell ; the empodia of the feet are developed as if they were pulvilli, while the true pulvilli remain rudimentary. The larvae are like little worms, being long and cylindric; they are amphipneustic, and have been found in decaying wood, in cow-dung, in rotten fruits, and even in dirty water. The "petite tipule," the metamorphoses of which were described and figured by Reaumur, is believed to be the common Rhyphus fenestralis.2 R. fenestralis is often found on windows, as its name implies. Series 2. Orthorrhapha Brachycera Fam. 13. Stratiomyidae. — Antennae with three segments and a terminal complex of obscure joints, frequently bearing an arista : tibiae not spined ; wings rather small, the an- terior nervures usually much more strongly marked than those behind. The median cell small, placed near to the middle of the wing. Scutellum frequently spined ; terminal appendages of tli e tarsi small, but pulvilli and a pulvilliform empodium are 1 Rep. Dep. Agric. Ent. Washington, 1886, p. 492. 2 Cf. Reaumur, Mem. v. 1740, p. 21 ; and Ferris, Ann. Soc. ent. France (4) x. 1870, p. 190. STRATIOMYIDAE LEPTIDAE 479 This is a large family, whose members are very diversified, consequently definition of the whole is difficult. The species of the typical sub-family Stratiomyinae generally have the margins of the body prettily marked with green or yellow, and the scutellum spined. In the remarkable American genus, Hermetia, the abdomen is much constricted at the base, and the scutellum is not spined ; in the division Sarginae the body is frequently of brilliant metallic colours. The species all have an only imperfect proboscis, and are not blood-suckers. The larvae are also of diverse habits ; many of those of the Stratio- myinae are aquatic, and are noted for their capacity of living in salt, alkaline, or even very hot water. Mr. J. C. Hamon found some of these larvae in a hot spring in Wyoming, where he could not keep his hand immersed, and he estimated the temperature at only 20° or 30° Fahr. below the boiling-point. The larva of Stratiomys is of remarkably elongate, strap-like, form, much narrowed behind, with very small head ; the terminal segment is very long and ends in a rosette of hairs which the creature allows to float at the surface. After the larval skin is shed the pupa, though free, is contained therein ; the skin alters but little in form, and has no organic connection with the pupa, which merely uses the skin as a shield or float. These larvae have been very frequently described; they can live out of the water. Brauer describes the larvae of the family as "perip- neustic, some perhaps amphipneustic." Miall says there are, in Stratiomys, nine pairs of spiracles on the sides of the body which are not open, though branches from the longitudinal air-tubes pass to them. There are probably upwards of 1000 species of Stratiomyiidae known, and in Britain we have 40 or 50 kinds. The American genus Chiromyza, Wied., was formerly treated by Osten Sacken as a separate family, Chiromyzidae, but Williston places it in Stratiomyidae. Fam. 14. Leptidae, including Xylophagidae and Coenomyi- idae. — The Leptidae proper are flies of feeble build; antennae with three joints and a terminal bristle ; in the Xylophagidae the antennae are longer, and the third joint is complex. The wings have Jive posterior cells, the middle tibiae are spined. Pulvilli and a pulvilliform empodium present. The three families are considered distinct by most authors, but there has always been much difficulty about the Xylophagidae and Coenomyiidae, we therefore treat them 480 DIPTERA as sub-families. The Xylophaginae are a small group of slender Insects, perhaps most like the short-bodied kinds of Asilidae ; the third joint of the antenna is vaguely segmented, and there is no terminal bristle. Ehachicerus is a most anomalous little fly with rather long stiff antennae of an almost nemo- cerous character, the segments of which give off a short thick prolongation on each side, reminding one of a two-edged saw. The three or four British species of Xylophaginae are forest Insects, the larvae of which live under bark, and are provided with a spear-like head with which they pierce other Insects. The Coenomyiinae consist of the one genus Coenomyia, with two or three European and North American species. They are remarkably thick-bodied, heavy flies, reminding one somewhat of an imperfect Stratiomyid destitute of orna- mentation. The metamorphosis of C. ferruginea has been described by Beling.1 The larva is not aquatic, but lives in burrows or excavations in the earth where there are, or have recently been, rotten logs ; it is probably predaceous. It is cylindric, with an extremely small head and eleven other segments, the stigma on the first thoracic segment distinct ; the terminal segment is rather broad, and the structures surrounding the stigma are complex. The pupa has stigmata on each of ab- dominal segments 2 to 8. Not- withstanding that the fly is so different to Xylophagus, the larvae indicate the two forms as perhaps really allied. One of the Leptinae, Atherix ibis, has a singular mode of ovi- position (Fig. 227), the females of the species deposit their eggs in common, and, dying as they do so, add their bodies to the Common maSS, which becomes FIG. 227 .—Atherix ibis. A, The fly, nat. an agglomeration, it may be size. > B' mf s °f dea,d flies overhanging • water, much reduced. of thousands of individuals, and of considerable size. The mass is attached to a branch of a bush or to a plant overhanging water, into which it ulti- 1 Verh. Gcs. Wien, xxx. 1880, p. 343. LEPTIDAE TABANIDAE 481 mately falls. These curious accumulations are occasionally found in England as well as on the Continent, but no reason for so peculiar a habit is at present forthcoming. Still more remarkable are the habits of some European Leptids of the genera Vermileo (Psaitwiorycter of some authors) and Lamp- romyia, slender rather small flies of Asilid-like appearance, the larvae of which form pit-falls after the manner of the Ant-lion. According to Beling l the larva of Leptis is very active, and is distinguished by having the stigmatic orifice surrounded by four quite equal, quadrangularly placed prominences ; and at the other FIG. 228.— Larva of Vermileo degeeri (Psammorycter ver- mileo). A, lateral, B, dorsal view: p. an abdominal pseudopod ; st, stigma. Europe. (After Reaumur arid Brauer.) extremity of the body a blackish, naked, triangular plate ; on the under side of each of seven of the abdominal segments there is a band of spines. The larva of Atherix has seven pairs of abdominal feet. Altogether there are some two or three hundred known species of Leptidae ; our British species scarcely reach a score. They are destitute of biting-powers and are harmless timid creatures. Leptis scolopacea, the most conspicuous of our native species, a soft-bodied fly of rather large size, the wings much marked with dark colour, and the thick, pointed body yellowish, ] narked with a row of large black spots down the middle, is a common Insect in meadows. Fam. 15. Tabanidae (Breeze -flies, Cleggs, or Horse -flies, also frequently called Gad-flies'). — Proboscis fleshy, distinct, en- wrapping pointed horny processes, palpi distinct, terminal joint inflated, pendent in front of proboscis. Antennae projecting, four- jointed, second joint very short, third variable in form, fourth forming an indistinctly segmented continuation of the third, but not ending in a bristle. A perfect squama in front of the halter. Eyes large, very large in the males, but laterally extending, rather than globose. This large and important family of flies, of which 1 Arch. Naturyes. xli. i. 1875, p. 48. VOL. VI 2 I 482 DIPTERA CHAP. AVilliston states that 1400 or 1500 species are named, is well known to travellers on account of the blood - sucking habits of its members ; they have great powers of flight, and alight on man and animals, and draw blood by making an incision with the proboscis ; only the females do this, the males wanting a pair of the lancets that enable the other sex to inflict their for- midable wounds. They are comparatively large Insects, some of our English species of Tdbanus attaining an inch in length. The smaller, grey Haernatopota, is known to every one who has walked in woods or meadows in the summer, as it alights quietly on the hands or neck and bites one without his having previously been made aware of its presence. The larger Tabani hum so much that one always knows when an individual is near. The species of Chrysops, in habits similar to Haematopota, are remarkable for their beautifully coloured golden-green eyes. In Brazil the Motuca fly, Hadrus lepidotus, Perty, makes so large and deep a cut that con- siderable bleeding may follow, and as it some- times settles in numbers on the body, it is deservedly feared. The most remarkable forms FIG. 229.— Pangonia f longirostris. x ot labaniclae are the species 01 the widely dis- HardScke \^™ tributed genus Pangonia (Fig. 229). The pro- boscis in the females of some of the species is three or four times the length of the body, and as it is stiff and needle-like the creature can use it wThile hovering on the wing, and will pierce the human body even through clothing of considerable thickness. The males suck the juices of flowers. The Seroot fly, that renders some of the districts of Nubia uninhabitable! for about three months of the year, appears, from the figure and description given by Sir Samuel Baker, to be a Pangonia. Tabanidae are a favourite food of the fossorial wasps of the family Bembecidae. These wasps are apparently aware of the blood-sucking habits of their favourites, and attend on travellers and pick up the flies as they are about to settle down to their phlebotomic operations. The larvae of the Tabanidae are some TABANIDAE ACANTHOMERIDAE 483 of them aquatic, but others live in the earth or in decaying wood ; they are of predaceous habits, attacking and sucking Insect -larvae, or worms. Their form is cylindric, attemiate at the two extremities ; the slender small head is retractile, and armed with a pair of conspicuous, curved black hooks. The body is surrounded by several promi- nent rings. The breathing apparatus is apparently but little developed, and con- sists of a small tube at the extremity of the body, capable of being exserted or withdrawn ; in this two closely approxi- mated stigmata are placed. In a larva, probably of this family, found by the writer in the shingle of a shallow stream in the New Forest, the annuli are re- placed by seven circles of prominent pseudopods, on the abdominal segments about eight in each circle, and each of these feet is surmounted by a crown of small hooks, so that there are fifty or sixty feet distributed equally over the middle part of the body without refer- ence to upper or lower surface. The figures of the larva of T. cordiger, by Brauer, and of Haematopota pluvialis, by Ferris, are something like this, but .have no setae on the pseudopods. The meta- morphoses of several Tabanidae are described and figured by Hart ; x the pupa is remarkably like a Lepidopterous pupa. We have five genera and about a score of species of Tabanidae in Britain. Fam. 16. Acanthomeridae. — A very small family of two genera (Acanthomera and Rhaphiorliynchus) confined to America, and including the largest Diptera, some being two inches long. The antenna is terminated by a compound of seven segments and a style ; the proboscis is short, and the squama rudimentary. The general form reminds one of Tabanidae or Oestridae. A dried larva exists in the Vienna collection ; it is amphipueustic, and very remarkable on account of the great size of the anterior stigma. 1 Bull. Illinois Lab. iv. 1895. A FIG. 230.— Larva of a Taba- nid. [? Atylotus fulvus.] A, the larva, x 3 ; B, head ; C, end of body ; D, one of the pseudopods. New Forest. 484 DIPTERA CHAP. Fam. 17. Therevidae. — Moderate-sized flies, with somewhat the appearance of short Asilidae. They have, however, only a feeble fleshy proboscis, and minute claws, with pulvilli but no empodium ; the antennae project, are short, three -jointed, pointed. — The flies of this family are believed to be predaceous like the Kobber-flies, but they appear to be very feebly organised for such a life. We have about ten species in Britain, and there are only some 200 known from all the world. But little is known as to the meta- morphoses. Meigen found larvae of T. nobilitata in rotten stumps, but other larvae FIG. 231. — Thereva (Psilo- cephaia) confinis. A, have been recorded as devouring dead pupae Pupa ; B, larva Europe. or larvae of Lepidoptera. The larvae are said (After Perns. ) to be elongate, very slender, worm-like, and to have nineteen body-segments, the posterior pair of spiracles being placed on what looks like the seventeenth segment, but is really the eighth of the abdomen. The pupa is not enclosed in the larval skin ; that of Psilocephala is armed with setae and spinous processes, and was found in rotten wood by Frauenfeld. Fam. 18. Scenopinidae. — Rather small flies, without bristles. Antennae three-jointed, the third joint leather long, without ap- pendage. Proboscis not projecting. Empodium absent. These unattractive flies form one of the smallest families, and are chiefly found on windows. S. fenestralis looks like a tiny Stratiomyid, with a peculiar, dull, metallic surface. The larva of this species has been recorded as feeding on a variety of strange substances, but Osten Sacken is of opinion * that it is really predaceous, and frequents these substances in order to find the larvae that are developing in them. If so, Scenopinus is useful in a small way by destroying " moth," etc. The larva is a little slender, cylindrical, hard, pale worm of nineteen segments, with a small brown head placed like a hook at one extremity of the body and with two short, divergent processes at the other extremity, almost exactly like the larva of TJiereva. Full references to the literature about this Insect are given by Osten Sacken. Fam. 19. Nemestrinidae. — These Insects appear to be allied to the Bombyliidae. They are of medium size, often pilose, and 1 Ent. Mag. xxiii. 1886, p. 51. vii XKMESTRINIDAE BOMBYLIIDAE 485 sometimes with excessively long proboscis; antennae short, with a simple third joint, and a jointed, slender, terminal appendage ; the tibiae have no spurs, the empodium is pulmllus-like. The wing- nervuration is perhaps the most complex found in Diptera, there being numerous cells at the tip, almost after the fashion of Neuroptera. With this family we commence the aerial forms composing the Tromoptera of Osten Sacken. Nemestriuidae is a small family of about 100 species, but widely distributed. Megistorhynchus longirostris is about two-thirds of an inch long, but has a proboscis at least four times as long as itself. In South Africa it may be seen endeavouring to extract, with this proboscis, the honey from the flower of a Gladiolus that has a perianth just as long as its own rostrum ; as it attempts to do this when it is hovering on the wing, and as the proboscis is, unlike that of the Bombylii, fixed, the Insect can only succeed by con- trolling its movements with perfect accuracy ; hence it has great difficulty in attaining its purpose, especially when there is much wind, when it frequently strikes the earth instead of the flower. M. Westermann thinks * the life of the Insect and the appearance and duration of the flower of the Gladiolus are very closely con- nected. The life-history of Sirmoneura obscura has recently been studied in Austria by Handlirsch and Brauer.2 The larva is par- asitic on the larva of a Lamellicorn beetle (JRhizotrogus solstitialis) ; it is metapneustic, and the head is highly modified for predaceous purposes. The young larva apparently differs to a considerable extent from the matured form. The most curious fact is that the parent fly does not oviposit near the Larnellicorn-larva, but places her eggs in the burrows of some wood-boring Insect in logs ; the larvae when hatched come to the surface of the log, hold them- selves up on their hinder extremity and are carried away by the wind ; in what manner they come into contact with the Lamellicorn larva, which feeds in turf, is unknown. The pupa is remarkable on account of the prominent, almost stalked stigmata, and of two pointed divergent processes at the extremity of the body. This life-history is of much interest, as it foreshadows to some extent the complex parasitic life-histories of Bombyliidae. The Neines- trinidae are not represented in the British fauna, Fam, 20. Bombyliidae. — Body frequently fringed with down, 1 Ann. Soc. ent. France, ii. 1833, p. 492. 2 Wien. ent. Zcit. ii. 1883, pp. 11 and 24, pi. i. 486 DIPTERA or covered in large part with hair. Leys slender, claws small, without distinct empodium, usually with only minute pulvilli. Proboscis very long or moderate, antennae three-jointed, terminal joint not distinctly divided, sometimes large, sometimes hair-like. This is a very large family, including 1500 species, and is of great importance to both naturalist and economist. Two well- marked types, formerly treated as distinct families, are included in it — (1) the Bombyliides with very long exserted rostrum, and humped thorax ; and (2) Anthracides, with a short beak, and of more slender and graceful form. None of these flies are blood- suckers, they frequent flowers only, and use their long rostrums in a harmless manner. The members of both of these groups usually have the wings ornamented with a pattern, which in Anthrax is frequently very remarkable ; in both, the clothing of the body is frequently variegated. Their powers of flight are very great, and the hovering Bombylius of early spring is endowed with an unsurpassed capacity for movement, remaining perfectly still on the wing, and darting off with lightning rapidity ; Anthrax is also most rapid on the wing. In Britain we have but few species of Bombyliidae, but in warm and dry climates they are very numerous. The life-history of these Insects was till recently unknown, but that of Argyro- moeba (Anthrax) trifasciata has been described by the French naturalist, Fabre, who ascertained that the species is parasitic on the Mason-bee, Chalicodoma muraria, that forms nests of solid mas- onry. He endeavoured to dis- cover the egg, but failed ; the parent -fly oviposits, it appears, by merely dropping a minute egg while flying over the surface of the mass of masonry by which the grubs of the Chalicodoma are FIG. 232. — Argyromoeba tnfascwta. A, Young larva; B, adult larva; c, protected. Iromthis egg there pupa. France. (After Fabre.) ig hatched a minute delicate V6r- A, Greatly, B, C, slightly magnified. miform larva (Fig. 232, A). In order to obtain its food, it is necessary for this feeble creature to penetrate the masonry ; apparently a hopeless task, the animal l:i).M13YLIIDAE 487 beiug scarcely a twentieth of ail inch long and very slender ; it is, however, provided with a deflexed horny head, armed in front with some stiff bristles, while on the under surface of the body there are four pairs of elongate setae serving as organs of loco- motion ; thus endowed, the frail creature hunts about the sur- face of the masonry, seeking to find an entrance ; frequently it is a long time before it is successful ; but though it has never taken any food it is possessed of great powers of endurance. Usually, after being disclosed from the egg, it remains about fifteen days without stirring ; and even after it commences its attempts to enter the nest it is still capable of a long life without taking any food. Possibly its organisation will not permit it to feed (supposing any food were obtainable by it) without its growing somewhat thereafter, and if so, its chance of obtaining entrance through the masonry would be diminished. Abstention, it would appear, is the best policy, whether inevitable or not ; so the starving little larva continues its endeavours to find a chink of entrance to the food contained in the interior of the masonry. It has plenty of time for this, because it is better for it not to get into the cell of the bee until the grub is quite full grown, and is about to assume the pupal form, when it is quite incapable of self-defence. Finally, after greater or less delay, the persevering little larva succeeds in finding some tiny gap in the masonry through which it can force itself. M. Fabre says that the root of a plant is not more persistent in descending into the soil that is to support it than is this little Anthrax in insinuating itself through some crack that may admit it to its food. Having once effected an entrance the organisation that has enabled it to do so is useless ; this primary form of the larva has, in fact, as its sole object to enable the creature to penetrate to its food. Having penetrated, it undergoes a complete change of form, and appears as a creature specially fitted for feeding on the quiescent larva of the bee without destroying it. To accomplish this requires an extreme delicacy of organisation and instinct ; to bite the prey would be to kill it, and if this were done, the Anthrax would, Fabre supposes, ensure its own death, for it cannot feed on the dead and putrefying grub ; accordingly, the part of its body that does duty as a mouth is merely a delicate sucker which it applies to the skin of the Ohalicodoma-grub ; and thus without inflicting any perceptible wound it sucks day 488 DIPTERA CHAP. after day, changing its position frequently, until it has completely emptied the pupa of its contents, nothing being left but the skin. Although this is accomplished without any wound being inflicted, so effectual is the process that all the Chalicodoma is gradually absorbed. The time requisite for completely emptying the victim is from twelve to fifteen days ; at the end of this time the Anthrax-larvs, is full grown, and the question arises, how is it to escape from the cell of solid masonry in which it is imprisoned ? It entered this cell as a tiny, slender worm through a minute orifice or crack, but it has now much increased in size, and exit for a creature of its organisation is not possible. For some months it remains a quiescent larva in the cell of the Cli"/i.- codoma, but in the spring of the succeeding year it undergoes another metamorphosis, and appears as a pupa provided with a formidable apparatus for breaking down the masonry by which it is imprisoned. The head is large and covered in front with six hard spines, to be used in striking and piercing the masonry, while the other extremity of the body bears some curious horns, the middle segments being armed with rigid hairs directed back- wards, and thus facilitating movement in a forward direction and preventing slipping backwards. The pupa is strongly curved, and fixes itself by the aid of the posterior spines ; then, unbend- ing itself, it strikes with the armour of the other extremity against the opposing wall, which is thus destroyed piecemeal until a gallery of exit is formed ; when this is completed the pupa -skin bursts and the perfect fly emerges, leaving the pupa-case still fixed in the gallery. Thus this species appears in four consecutive forms — in addition to the egg — each of which is highly specialised for the purposes of existence in that stage. The habits of our British Bombylius major have been partially observed by Dr. Chapman,1 and exhibit a close analogy with those of Anthrax trifasciata. The bee-larva that served as food was in this case Andrena labialis, and the egg was deposited by the fly, when hovering, by jerking it against the bank in which the nest of the bee was placed. It has recently been discovered that the larvae of various species of Bombyliidae are of great service by devouring the eggs of locusts. Eiley found that the egg-cases of Caloptenus 1 Ent. Mag. xiv. 1878, p. 196. BOMBYLIIDAE ACROCERIDAE 489 spretus are emptied of their contents by the larvae of Systoechus oreas and Triodites mus. A similar observation has been made in the Troad by Mr. Calvert, who found that the Bombyliid, Callostoma fascipennis, destroys large quantities of the eggs of Caloptenus italicus. Still more recently M. Kiinckel d'Herculais has discovered that the destructive locust Stauronotus maroccanus is kept in check in Algeria in a similar manner, as many as 80 per cent of the eggs of the locust being thus destroyed in certain localities. He observes that the larva of the fly, after being full fed in the autumn, passes the winter in a state of lethargy — he calls it " hypnody " — in the egg-case of the locust, and he /> , i . ~ , , • , i FIG. 233. — Systropus crudelis. South further informs us that in the Mric&. ^ Pupa; B) imag0; ap_ Case Of Anthrax fenestralis, which pendages of the left side removed. , „ ... , (After Westwood.) devours the eggs of the large Ocnerodes, the lethargy may be prolonged for a period of three years. After the pupa is formed it works a way out of the case by means of its armature, and then again becomes for some days immobile before the perfect fly appears. Lepidopterous larvae are also attacked by Bombyliid flies. A species of Systropus has been recorded as destroying the larva of Limacodes. Several of the Bombyliids of the genus just mentioned are remarkable for the great resemblance they display to various Hymenoptera, some of them being very slender flies, like the thin bodied fossorial Hymenoptera. The difference between the pupa and imago in this case is very remarkable (Fig. 233). Fam. 21. Acroceridae or Cyrtidae.- — Flies of the average size, of peculiar form, the small head consisting almost entirely of the eyes, and bent down under the humped thorax : wings small, halteres entirely concealed by the very large horizontal squamae ; antennae very diverse.. The peculiar shape of these flies is an exaggeration of that we have already noticed in Bombylius. The mouth in Acro- ceridae is very variable ; there may be a very long, slender proboscis (Acrocera), or the mouth-parts may be so atrophied that it is doubtful whether even an orifice exists (Of/codes). There are but 490 DIPTERA CHAP. few species known, and all of them are rare ; l in Britain we have but two (Ogcodes gibbosus, Acrocera globulus}. The genus Pterodontia, found in North America and Australia, an inflated bladder -like form with a minute head, is amongst the most extraordinary of all the forms of Diptera. The habits are very peculiar, the larvae, so far as known, all living as parasites within the bodies of spiders or in their egg-bags. It appears, however, that the flies do not oviposit in appropriate places, but place their eggs on FIG. 234.— Megalylus gm- stems of plants, and the young larvae have ™-r 7*VA£°T ida,'l to find their way to the spiders. Brauer has Chili. (After West wood.) described the larva of the European Asto- mella lindeni? which lives in the body of a spider, Cteniza ariana ; it is amphipneustic and maggot-like, the head being extremely small. The larva leaves the body of the spider for pupation ; the pupa is much arched, and the head is destitute of the peculiar armature of the Bombyliidae, but has a serrate ridge on the thorax. Emerton found the larvae of an Acrocera in the webs of a common North American spider, Amaurobius sylvestris, they having eaten, it was supposed, the makers of the cobwebs. Fam. 22. Lcnchopteridae. — Small, slender flies, with pointed wings, short, porrect antennae, with a simple, circular third joint, bearing a bristle ; empodium very small, pulvilli absent. — Only one genus of these little flies is known, but it is apparently widely distributed, and its members are common Insects. They have the appearance of Acalyptrate Muscidae, and the nervuration of the wing is somewhat similar, the nervures being simple and parallel, and the minute cross -nervures placed near the base. The systematic position is somewhat doubtful, and the meta- morphoses are but incompletely known, very little having been added to what was discovered by Sir John Lubbock in 1862.3 The larva lives on the earth under vegetable matter ; it is very transparent, amphipneustic, with a peculiar head, and with fringes on the margins. This larva changes to a semi-pupa or apterous maggot-like form, within the larval skin ; the true pupa was 1 For figures, etc., cf. Westwood, Tr. ent. Soc. London, 1876, p. 507, pis. v. vi. 2 Verh. Ges. Wicn, xix. 1869, p. 737, pi. xiii. 3 Tr. ent. Soc. London (3) i. 1862, p. 338, pi. xi. vii LOXCHOPTERIDAE MYDAIDAE ASILIDAE 491 not noticed by Lubbock, but Frauenfeld1 has since observed it, though he only mentions that it possesses differentiated limbs and segments. The metamorphoses appear to be very peculiar. This fly requires a thorough study. Fam. 23. Mydaidae. — Large flies of elongate form ; the hind femora long and toothed beneath ; the antennae knobbed at the tip, projecting, rather long, the basal joint definite, but the divisions of the subsequent joints more or less indistinct. Empodium small. Wings frequently heavily piamented ; ivith a complex nervuration. These fine flies are exotic ; a few species occur in the Mediter- ranean region, even in the South of Europe ; the chief genus, Mydas, is South American, but most of the other genera are Australian or African. But little is known as to the life- histories. The larvae are thought to live in wood, and to prey on Coleopterous larvae. Fam. 24. Asilidae (Robber -flies*}. — Mouth forming a short, projecting horny beak, the palpi usually only small ; the feet generally largely developed ; the claws large, frequently thick and blunt, the pulvilli generally elongate, the empodium a bristle ; halteres free; no squama. The Asilidae is one of the largest families of flies, and probably includes about 3000 described species : as will readily be believed, there is much variety of form ; some are short and thick and extremely hairy, superficially resembling hairy bees, but the majority are more or less elongate, the abdomen being specially long, and having eight segments conspicuously displayed. The antennae are variable, but are three -jointed with a terminal appendage of diverse form and structure. They belong to the super-family Energopoda of Osten Sacken, but the association of Empidae and Dolichopidae with them does not seem to be very natural. In their perfect state these flies are most voracious, their prey being Insects, which they seize alive and impale with the rostrum. They are amongst the most formidable of foes and fear nothing, wasps or other stinging Insects being attacked and mastered by the stronger species without difficulty. They have been observed to capture even dragon-flies and tiger-beetles. As is the case with so many other Insects that prey on living Insects, the appetite in the Asilidae seems to be insatiable ; a single individual has been observed to kill eight moths in twenty minutes. They have 1 Ferh. Ges. Wien, xix. 1869, p. 941. 49 2 DIPTERA CHAP. been said to suck blood from Vertebrates, but this appears to be erroneous. The metamorphoses of a few species have been ob- served. Ferris has called attention to the close alliance between the larvae of Tabanidae and of Asilidae,1 and it seems at present impossible to draw a line of distinction between the two. So far as is known, the larvae of Asilidae are terrestrial and predaceous, attacking more particularly the larvae of Coleoptera, into which they sometimes bore ; in Laphria there are numerous pseudopods, somewhat of the kind shown in Fig. 230, but less perfect and without hairs ; the head and breathing organs appear to be very different. According to Beling's descriptions of the larvae of Asilus, the head in this case is more like that of the figure, but there are no pseudopods. The flies of Asilidae and Tabanidae are so very distinct that these resemblances between their larvae are worthy of note. Fam. 25. Apioceridae. — Moderate-sized flies marked with Hack and ivhite, with an appearance like that of some Muscidae and Asilidae ; with clear wings, the veins not deeply coloured ; antennae short, with a short, simple appendage ; no empodium. But little is known as to the flies of this family, of which only two genera, consisting of about a dozen species, are found in North America, Chili, and Australia. Osten Sacken is inclined to treat them as an aberrant division of Asilidae. Brauer looks on them as primitive or synthetic forms of much interest, and has briefly described a larva which he considers may be that of Apiocera, but this is doubtful ; it is a twenty-segmented form, and may be that of a Thereva.2 Fam. 26. Empidae. — Small or moderate-sized flies of obscure colours, grey, rusty, or black, with small head, somewhat globular in form, with three-jointed antennae, the terminal joint long and pointed ; usually there is a long slender beak ; the legs are elongate, frequently hairy ; the tarsi bear long pulvilli and a small em- podium. The Empidae are an extensive family of flies, with predaceous habits, the rostrum being used by the female as an instrument for impaling and sucking other flies. They are occasionally very numerous in individuals, especially in wooded districts. There is great variety ; there are nearly "200 species in Britain. The forms placed in the sub-family Hybotinae are curious slender little Insects, with very convex thorax and 1 Ann. Soc. ent. France (4) x. 1870, p. 221. 2 SB. Ak. Wien, xci. 1885, p. 392. vii EMPIDAE DOLICHOPIDAE 493 large hind legs. In Hemerodromia the front legs are raptorial, the femora being armed with spines on which the tibiae close so as to form a sort of trap. Many Empidae execute aerial dances, and some of the species of the genus Hilara are notorious for carrying veils or nets in the form of silken webs more or less densely woven. This subject is comparatively new, the fact having been discovered by Baron Osten Sacken in 1877,1 and it is not at all clear what purpose these peculiar constructions serve ; it appears probable that they are carried by means of the hind legs, and only by the males. Mik thinks that in H. sartor the veil acts as a sort of parachute, and is of vise in carrying on the aerial performance, or enhancing its effect ; while in the case of other species, H. maura and H. inter- stincta, the object appears to be the capture or retention of prey, after the manner of spiders. The source of the silk is not known, and in fact all the details are insufficiently ascertained. The larvae of Empidae are described as cylindrical maggots, with very small head, and imperfect ventral feet ; the stigmata are amphipneustic, the thoracic pair being, however, excessively small ; beneath the posterior pair there is nearly always a tooth- or spine-like prominence present. Fam. 27. Dolichopidae. — Graceful flies of metallic colours, of moderate or small size, and long legs ; usually with bristles on tin' thorax and legs, the halter es exposed, squamae being quite absent ; antennae of two short stout joints (of which the second is really two, its division being more or less distinct}, with a thread-like or hair-like appendage. Proboscis short, fleshy. Claws, pulvilli, and empodium small ; wings with a simple system of nervures, those on the posterior part of the wing are but few, there is no anterior basal cross-vein be- tween the disced and second basal cells, which therefore form but one cell. This is also a FlG>B23p5u~A;f very extensive family of flies, of which we term have probably about 200 species in Britain. pern's!)6 They are conspicuous on account of their golden, or golden-green colours, only a few being yellow or black. 1 Ent. Mag. xiv. 1877, p. 226 ; for a discussion of the subject see Mik, JVien. ent. Zeit. xiii. 1894, p. 273. 494 DIPTERA CHAP. The males are remarkable for the curious special characters they possess on the feet, antennae, face, or wings. These characters are not alike in any two species ; they are believed to be of the nature of ornaments, and according to Professor Aldrich and others are used as such in courtship.1 This family of flies approaches very closely to some of the Acalyptrate Muscidae in its char- acters. It is united by Brauer with Empidae to form the tribe Orthogenya. Although the species are so numerous and abundant in Europe, little is known as to their metamorphoses. Some of the larvae frequent trees, living under the bark or in the overflowing sap, and are believed to be carnivorous ; they are amphipneustic ; a cocoon is formed, and the pupa is remark- able on account of the existence of two long horns, bearing the spiracles, on the back of the thorax ; the seven pairs of abdominal spiracles being excessively minute.2 Series 3. Cyclorrhapha Aschiza Fam. 28. Phoridae. — Small flies, with very convex thorax, small head, very small two-jointed antennae, bearing a long seta ; femora more or less broad; wings with tivo dark, thick, approxi- mate veins, meeting on the front margin near its middle, and besides these, three or four very fine veins, that run to the margins in a sub-parallel manner without forming any cells or forks. This obscure family of flies is of small extent, but its members are ex- tremely common in Europe and North America, where they often occur in numbers running on the windows of houses. It is one of the most isolated FIG. 236.— Wing of Trineura groups of Diptera, and great difference aterrima, one of the Phor- of opinion prevails as to its classifica- idae. Britain. mi , • • T tion. Ihe wmg-iiervuration is peculiar (but varies somewhat in the species), the total absence of any cross -veins even on the basal part of the wing being remarkable. There are bristles on the head and thorax, but they are not arranged in a regular manner. The larvae live in a great variety of animal and vegetable decaying matter, 1 Amer. Natural, xxviii. 1894, p. 35. 2 Perris, Ann. Soc. ent. France (4) x. 1870, p. 321, pi. 4 ; and Laboulbene, op. cit. (5) iii. 1873, p. 50, pi. v. PHORIDAE 495 and attack living Insects, and even snails, though probably only when these are in a sickly or diseased condition. The metamorphoses of several species have been described.1 The larvae are rather slender, but sub-conical in form, with eleven segments and a very small head, amphipneustic, the body behind terminated by some pointed processes. The pupa is remarkable ; it is contained in a case formed by the contracted and hardened skin of the larva ; though it differs much in form from the larva the segmentation is distinct, and from the fourth segment there project two slender processes. These are breathing organs, attached to the prothorax of the imprisoned pupa ; in what manner they effect a passage through the hardened larval skin is by no means clear. Ferris supposes that holes for them pre-exist in the larval skin, and that the newly-formed pupa by restless movements succeeds in bringing the processes into such a position that they can pass through the holes. The dehiscence of the puparium seems to occur in a somewhat irregular manner, as in Microdon ; it is never Cyclor- rhaphous, and according to Ferris is occasionally Orthorrhaphous ; probably there is no ptilinum. The Insect recently described by Meinert as Aenigmatias blattoidcs? is so anomalous, and so little is known about it, that it cannot at present be classified. It is com- pletely apterous ; the arrangement f. . , , ! . TI ,1 L FIG. 237. — Aenimnatias bhdtoides. of the body-segments is unlike that x27- Denmark/ ( After Meinert.) of Diptera, but the antennae and mouth-parts are said to be like those of Fhoridae. The Insect was found near Copenhagen under a stone in the runs of Formica fusca. Meinert thinks it possible that the discovery of the male may prove Aenigmatias to be really allied to Fhoridae, and Mik suggests that it may be the same as Plaiyphora lubbocki, Verrall, known to be parasitic on ants. Dahl recently described a wingless Dipteron, found living as a parasite on land-snails in the Bismarck archipelago, under the name of Puliciphora lucifera, 1 Ferris, Ann. Soc. ent. France (4) x. 1870, p. 354. 2 Ent. Meddelehcr, ii. 1890, p. 213. DIPTERA and Wandolleck has recently made for this and some allies the new family Stethopathidae. It seems doubtful whether these forms are more than wingless Phoridae. Fam. 29. Platypezidae. — Small flies, ivith porrect three- jointed antennae, flrst two joints short, third longer, with a terminal seta; no bristles on the back; hind legs of male, or of both sexes, with peculiar, broad, flat tarsi ; the middle tibiae bear spurs; there is no empodium. Platypezidae is a small family of flies, the classification of which has always been a matter of considerable difficulty, and is still uncertain. The larvae are broad and flat, fringed at the margin with twenty-six spines ; they live between the lamellae of Agaric fungi. At pupation the form alters but little ; the imago emerges by a horizontal cleft occurring at the margins of segments two and four.1 We have four genera (Opetia, Platycnema, Platypeza, Callomyia), and nearly a score of species of Platypezidae in our British list, but very little seems to be known about them. There is much difference in the eyes of the sexes, in some at any rate of the species, they being large and contiguous in the male, but widely separated in the female. Fam. 30. Pipunculidae.2 — Small flies, with very short antennae bearing a long seta that is not terminal ; head almost globular, formed, except at the back, almost entirely by the large conjoined eyes ; the head is only slightly smaller in the female, but in the male the eyes are more approximate at the top. This is another of the small fami- lies of flies, that seems dis- tinct from any other, though possessing no very im- portant characters. In many of the flies that have very large eyes, the head is Fro. 238.— Head of Pipunculus sp. A, Seen from either flattened (i.e. COm- in front ; B side view, showing an antenna pressed from before back- magnified. Pyrenees. wards, as in Tabauidae, Asilidae), or forced beneath the humped thorax (as in Acro- ceridae), but neither of these conditions exists in Pipunculus ; in them the head extends far forwards, so that the area of the 1 Frauenfeld, Verh. Ges. Wien, xx. p. 37, pi. iii. 2 For monograph of Pipunculidae, see Becker, Berlin, ent. Zeitschr. xlii. 1897, pp. 25-100. vii PIPUNCULIDAE — CONOPIDAE 497 eye compared with the size of the body is perhaps greater than in any other Diptera. The general form is somewhat that of Anthrax, but the venation on the hind part of the wing is much less complex. There is a remarkable difference between the facets on the front and the back of these great eyes. We have three genera and about a dozen species of Pipunculidae in Britain but apparently they are far from common Insects. What is known about the life-history is almost confined to an imperfect observa- tion by Boheinan, who found the larva of P.Juscipes living after the manner of a Hymenopterous parasite in the body of a small Homopterous Insect.1 The pupa seems to be of the type of that of Syrphidae. Fam. 31. Conopidae. — Elegant flies of moderate size, of varied colours, with abdomen slender at the base, at the tip strongly incurved and thicker; antennae inserted close together on a prominence, three-jointed, first joint sometimes very short. The upper surface of the body without bristles or with butfeic. There is a slender, elongate proboscis, wliicli is retractile and usually invisible. This rather small family of flies includes some of the most remarkable forms of Diptera ; it includes two divisions, the Conopinae with long antennae terminated by a very minute pointed process, and Myopinae with shorter antennae bearing a hair that is not placed at the end of the third joint. The former are the more wasp-like and elegant ; the Myopinae being much more like ordinary flies, though they frequently have curious, inflated heads, with a white face. The mode of life of the larva of Conops is peculiar, it being parasitic in the interior of Bombus, or other Hymenoptera. They have been found to attack Bombus, Chalicodoma, Osmia, Vespa, Pompilus, and other Aculeates. Williston says that Orthoptera are also attacked. Conops has been seen to follow Bumble-bees and alight on them, and Williston says this act is accompanied by oviposition, the larva that is hatched boring its way into the body of the bee. Others have supposed that the flies enter the bees' nests and place their eggs in the larvae or pupae ; but this is uncertain, for Conops has never been reared from a bee-larva or pupa, though it has frequently been procured from the imago : cases indeed having been recorded in which Conops has emerged from the body 1 Ofv. Ak. Fork. xi. 1854, p. 302, pi. v., since confirmed by others, see Giard, C.R. Ac. Sci. cix. 1889, pp. 79 and 708. VOL. VI 2 K 49 8 DIPTERA CHAP. of a Bombus several months after the latter had been killed and placed in an entomologist's collection. The larva is broad, and when full grown apparently occupies nearly all the space of the interior of the abdomen of the bee ; it has very peculiar terminal stigmata. The pupa is formed in the larval skin, which is greatly shortened and indurated for the purpose ; this instar bears, in addition to the posterior stigmata, a pair of slightly projecting, anterior stigmata. We have several species of Conopidae in Britain; those belonging to the division Conopinae are all rare Insects, but the Myopinae are not so scarce ; these latter are believed to be of similar habits with the Conopinae, though remarkably little is known about them. This is another of the numerous families, the relations of which are still a subject for elucidation. Brauer places the Conopidae in his section Schizophora away from Syrphidae, but we do not com- prehend on what grounds ; an inspection of the head shows that there is no frontal lunule as there is in Eumyiidae ; both Myopa and Conops agreeing fairly well with Syrphus as to this. We therefore place the family in its old position near Syrphus till the relations with Acalyptsrate Muscidae shall be better established. Fam. 32. Syrphidae (Hover -flies}. — Of moderate or rather large size, frequently spotted or landed with yellow, with a thick fleshy proboscis capable of being withdrawn into a cleft on the under side of the head; antennae not placed in definite cavities, three-jointed (usually very short), and leaving a seta that is not terminal in position, and may be feathered. Squama variable, never entirely covering the halteres; the chief (third to fifth} longitudinal veins of the ivings connected near their termination by cross-veins and usually thus forming a sort of short margin parallel with the hind edge of the wing ; a more or less imperfect false nervure run- ning between the third and fourth longitudinal nervures ; no em- podium and generally no distinct system of bristles on the back of the body. The Syrphidae (Fig. 212) form one of the largest and best known of all the families of Hies ; they abound in our gardens where, in sunny weather, some species may be nearly always seen hovering over flowers, or beneath trees in places where the rays of the sun penetrate amidst the shade. There are two or three thousand species known, so that of course much variety exists ; some are densely covered with hair (certain Vohicella and others), many are of elegant form, and some bear a consider- vii SYRPHIDAE HOVER-FLIES 499 able resemblance to Hymenoptera of various groups. The peculiar reining of the wings permits of their easy identification, the line of two nervules, approximately parallel with the margin of the distal part of the wing (Fig. 212, D), and followed by a deep bay, being eminently characteristic, though there are some excep- tions ; there are a few forms in which the antennae are exceptional in having a terminal pointed process. The proboscis, besides the membranous and fleshy lips, consists of a series of pointed slender lancets, the use of which it is difficult to comprehend, as the Insects are not known to pierce either animals or vegetables, their food being chiefly pollen ; honey is also doubtless taken by some species, but the lancet -like organs appear equally ill -adapted for dealing with it. The larvae are singularly diversified ; first, there are the eaters of Aphidae, or green-fly ; some of these may be generally found on our rose-bushes or on thistles, when they are much covered with Aphids ; they are soft, maggot -like creatures with a great capacity for changing their shape and with much power of movement, especially of the anterior part of the body, which is stretched out and moved about to obtain and spear their prey : some of them are very transparent, so that the movements of the internal organs and their vivid colours can readily be seen : like so many other carnivorous Insects, their voracity appears to be insatiable. The larvae of many of the ordinary Hover-flies are of this kind. Eristcdis and its allies are totally different, they live in water saturated with filth, or with decaying vegetable matter (the writer has found many hundreds of the larvae of Myiatropa florea in a pool of water standing in a hollow beech-tree). These rat-tailed maggots are of great interest, but as they have been described in almost every work on entomology, and as Professor Miall l has recently given an excellent account of their pecu- liarities, \ve need not now discuss them. Some of the flies of the genus Eristcdis are very like honey-bees, and appear in old times to have been confounded with them ; indeed, Osten Sacken thinks this resemblance gave rise to the " Bugonia myth," a fable of very ancient origin to the effect that Honey-bees could be procured from filth, or even putrefying carcases, by the aid of certain proceedings that savoured slightly of witchcraft, and may therefore have increased the belief of the operator in the 1 Xatural History of Aquatic Insects, 1895, p. 198. 500 DIPTERA CHAP. possibility of a favourable result. It was certainly not bees that were produced from the carcases, but Osten Sacken suggests that JBristalis-Qiea may have been bred therein. In the genus Volucella we meet with a third kind of Syrphid larva. These larvae are pallid, broad and fleshy, surrounded by numerous angular, somewhat spinose, outgrowths of the body ; and have behind a pair of combined stigmata, in the neighbour- hood of which the outgrowths are somewhat larger ; these larvae live in the nests of Bees and "Wasps, in which they are abundant. Some of the Volucella, like many other Syrphidae, bear a con- siderable resemblance to Bees or Wasps, and this has given rise to a modern fable about them that appears to have no more legiti- mate basis of fact than the ancient Bees-born-of-carcases myth. It was formerly assumed that the Volucella-la,rva,e lived on the larvae of the Bees, and that the parent flies were providentially endowed with a bee -like appearance that they might obtain entrance into the Bees' nests without being detected, and then carry out their nefarious intention of laying eggs that would hatch into larvae and subsequently destroy the larvae of the Bees. Some hard-hearted critic remarked that it was easy to understand that providence should display so great a solicitude for the welfare of the Volucella, but that it was difficult to comprehend how it could be, at the same time, so totally indifferent to the welfare of the Bees. More recently the tale has been revived and cited as an instance of the value of deceptive resemblance resulting from the action of natural selection, without reference to providence. There are, however, no facts to support any theory on the subject. Very little indeed is actually known as to the habits of Volu- cella in either the larval or imaginal instars ; but the little that is known tends to the view that the presence of the Volucella in the nests is advantageous to both Fly and Bee. Nicolas has seen Volucella zonaria enter the nest of a Wasp ; it settled at a little distance and walked in without any fuss being made. Erne has watched the Fb/wceZ/a-larvae in the nests, and he thinks that they eat the \vaste or dejections of the larvae. The writer kept under observation Fb£wce//a-larvae and portions of • the cells of Bombus, containing some larvae and pupae of the Bees and some honey, but the fly-larvae did not during some weeks touch any of the Bees or honey, and ultimately died, presumably of starvation. Subsequently, he experimented with Volucella-lavvde and a portion vii SYRPHIDAE HOVER-FLIES 50! of the comb of wasps containing pupae, and again found that the flies did not attack the Hymen optera ; but on breaking a pupa of the Wasp in two, the fly-larvae attacked it immediately and eagerly ; so that the evidence goes to show that the Volucella- larvae act as scavengers in the nests of the Hymenoptera. Klinckel d'Herculais has published an elaborate work on the European Volucella ; it is remarkable for the beauty of the plates illustrating the structure, anatomy and development, but throws little direct light on the natural history of the Insects. V. 'bonibylcms, one of the most abundant of our British species, appears in two forms, each of which has a considerable resem- blance to a Bombus, and it has been supposed that each of the two forms is specially connected with the Bee it resembles, but there is no evidence to support this idea ; indeed, there is some little evidence to the contrary. The genus Merodon has larvae somewhat similar to those of Volucdla, but they live in bulbs of Narcissus; M. equestris has been the cause of much loss to the growers of Dutch bulbs ; this Fly is interesting on account of its great variation in colour ; it has been described as a whole series of distinct species. The most remarkable of the numerous forms of Syrphid larvae are those of the genus Microdon (Fig. 239), which live in ants' nests. They have no resemblance to Insect -larvae, and when first discovered were not only supposed to be little Molluscs, but were actually described as such under the generic names of Parmula and Scutelligera. There is no appearance of segmenta- tion of the body ; the upper surface is covered by a sort of network formed by curved setae, which help to retain a coating of dirt ; there is no trace externally of any head, but on the under surface there is a minute fold in which such mouth-organs as may be present are probably concealed ; the sides of the body project so as to form a complex fringing arrangement ; the ter- minal stigmata are very distinct, the lateral processes connected with them (the " Knospen " of Dr. Meijere), are, however, very irregular and placed at some distance from the stigmatic scar. Pupation occurs by the induration of the external covering and the growth from it, or rather through it, of two short horns in front. Inside this skin there is formed a soft pupa, of the kind usual in Cyelorrhaphous flies ; the dehisceuce of the external covering is, however, of unusual nature, three little pieces being 502 DIPTERA separated from the anterior part of the upper surface, while the lower face remains intact. The account of the pupation given by Elditt : is not complete : the two horns that project are, it would appear, not portions of the larval skin, but belong to the head of the pupa, and according to Elditt are used to effect the dehiscence of the case for the escape of the fly ; there does not appear to be any head-vesicle. Nothing is known as to the details of the life of these anomalous larvae. M. Poujade has described two species found in France in the nests of the ant Lasius niger? The larva we figure was found by Colonel Yerbury in nests of an Atta in Portugal, and an almost identical FIG. 239. — Larva of Microdon sp. Portugal. A, Dorsal view of the larva, x 4 ; 1, the stigrnatic structure ; B, posterior view of stigmatic structure ; C, a portion of the marginal friiige of the body. larva was recently found by Mr. Budgett in Paraguay. The flies themselves are scarce, Microdon mutabilis (formerly called M. apiformis) being one of the rarest of British flies. They have the antennae longer than is usual in Syrphidae, and the cross- veins at the outside of the wing are irregularly placed, so that the contour is very irregular : the resemblance to bees is very marked, and in some of the South American forms the hind legs are flattened and hairy like those of bees. The oviposition of Microdon has been observed by Verhoeff ;3 he noticed that the fly was frequently driven away by the ants — in this case, Formica sanguinea — but returned undiscouraged to its task. A brief resume of the diverse modes of life of Syrphid larvae nas been given by Perils,4 and he also gives some information as to the curious horns of the pupae, but this latter point much 1 Ent. Zeit. Stettin, vi. 1845, p. 384, pi. i. 2 Ann. Soc. ent. France (6) iii. 1883, p. 23, pi. i. 3 Ent. Nadir, xviii. 1892, p. 13. 4 Ann. Soc. ent. France (4) x. 1870, p. 330. MUSCIDAE ACALYPTRATAE 503 wants elucidation. Whether the Syrphidae, or some of them, possess a ptilinum that helps them to emerge from the pupa is more than doubtful, though its existence has been affirmed by several authors of good repute.1 Series 4. Cyclorrhapha Schizophora Fam. 33. Muscidae acalyptratae. — This group of flies has been the least studied of all the Diptera ; it is generally treated as composed of twenty or thirty different families distinguished FIG. 240. — Diopsis apicalis. Natal. A, The fly ; B, ex- tremity of cephalic protuberance, more magnified. a, The eye ; b, the antenna ; c, middle of head, frout view ; c, ocelli. by very slight characters. It is, however, generally admitted by systematists that these assemblages have not the value of the families of the other divisions of Diptera, and some even go so far as to say that they are altogether only equivalent to a single family. We do not therefore think it necessary to define each one seriatim ; we shall merely mention their names, and allude to certain points of interest connected with them. Taken collec- tively they may be denned as very small flies, with three-jointed antennae (frequently looking as if only two -jointed), bearing a bristle that is not terminally placed ; frequently either destitute of squamae or having these imperfectly developed so as not to cover the halteres ; and possessing a comparatively simple system of nervura- tion, the chief nervures being nearly straight, so that consequently few cells are formed. These characters will distinguish the group 1 See on this difficult subject, Becker, Wien. ent. Zeit. i. 1882, p. 49. 504 DIPTERA CHAP. from all the other Diptera except from forms of Aschiza, and from certain Anthomyiidae, with both of which the Acalyptratae are really intimately connected. Considerable difference of opinion prevails as to the number of these divisions, but the families usually recognised are : — 1. Doryceridae. 12. Dryomyzidae. 21. Trypetidae. 2. Tetauoceridae. 13. Borboridae. ^ / Sapromyzidae 3. Sciomyzidae. 14. Phycodromidae. ' \incl. Lonchaeidae. 4. Diopsidae. 15. Thyreophoridae. 23. Rhopalomeridae. 5. Celyphidae. ,fi /Scatophagidae. 24. Ortalidae. g /Sepsidae ' \( — Scatomyzidae). I" Agromyzidae ' \incl.Piopliilidae. -.- /Geomyzidae 25. -I incl. Phytomyzi- - /Chloropidae ' \incl. Opomyzidae. ( dae. \ ( — Oscinidae). , s /Drosophilidae ; 26. Milichiidae. 8. Ulidiidae. \incl. Asteidae. 27. Octhiphilidae. 9. Platystomidae. 19. Psilidae. 28. Heteroneuridae. 10. Ephydridae. 2Q /Tanypezidae 29. Cordyluridae. 11. Helomyzidae. ' \.( = Micropezidae). Brauer associates Conopidae with Acalyptrate Muscids, and calls the Group Holometopa ; applying the term Schizometopa to the Calyptrate Muscidae. No generalisation can yet be made as to the larvae of these divisions, neither can any characters be pointed out by which they can be distinguished from the larvae of the following families. In their habits they have nothing specially distinctive, and may be said to resemble the Anthomyiidae, vegetable matter being more used as food than animal ; many of them mine in the leaves or stems of plants ; in the genus Dorycera the larva is aquatic, mining in the leaves of water-plants, and in Ephydridae several kinds of aquatic larvae are found, some of which are said to resemble the rat-tailed larvae of Syrphidae ; certain of these larvae occur in prodigious quantities in lakes, and the Insects in some of their early stages serve the Mexicans as food, the eggs being called Ahuatle, the larvae Pusci, the pupae Koo-chah-bee. Some of the larvae of the Sciomyzidae are also aquatic : that of Tetanocera ferruginea is said by Dufour to consist only of eight segments, and to be metapneustic ; Brauer considers the Acalyptrate larvae to be, however, in general, amphipneustic, like those of Calyptratae. The Chloropidae are a very important family owing to their occasional excessive multiplication, and to their living on cereals and other grasses, various parts of which they attack, sometimes causing great losses to the agriculturist. The species of the genus Chlorops are MUSCIDAE ACALYPTRATAE 505 famous for the curious habit of entering human habitations in great swarms : frequently many millions being found in a single apartment. Instances of this habit have been recorded both in France and England, Cambridge being perhaps the place where the phenomenon is most persistently exhibited. In the year 1831 an enormous swarm of C. lineata was found in the Provost's Lodge at King's College and was recorded by Leonard Jenyns ; in 1870 another swarm occurred in the same house if not in the same room.1 Of late years such swarms have occurred in certain apartments in the Museums (which are not far from King's College), and always in the same apartments. No clue whatever can be obtained as to their origin ; and the manner in which these flies are guided to a small area in numbers that must be seen to be be- lieved, is most mysterious. These swarms always occur in the autumn, and it has been suggested that the individuals are seeking winter quarters. Several members of the Acalyptratae have small wings or are wingless, as in some of our species of Borborus. The Diopsidae — none of which are European —have the sides of the head produced into long horns, at the extremity of which are placed the eyes and antennae ; these curiosities (Fig. 240) are apparently com- mon in both Hindostan and Africa. Iii the horned flies of the genus Elaphomyia, parts of the head are prolonged into horns of very diverse forms according to Fia 24i.—Cdyphus (Para- the species, but bearing on the whole a cdyphus)*?. West Africa. A, The fly seen from great resemblance to miniature stag- above ; a, scutellum ; b, horns. A genus (Giraffomyia) with a long neck, and with partially segmented appen- dages, instead of horns on the head, has been recently discovered by Dr. Arthur AVilley in New Britain. Equally remarkable are the species of Cclyphus ; they do not look like flies at all, owing to the scutellum being inflated and enlarged so as to cover all the posterior parts 1 London's Magazine, v. 1832, p. 302 ; P. ent. Soc. London, 1871, p. x. base of wing : B, profile, with tip of abdomen bent downwards ; «, scutellum ; b, b, wing ; c, part of abdomen. 506 DIPTERA CHAP. of the body as in the Scutellerid Hemiptera : the wings are entirely concealed, and the abdomen is reduced to a plate, with its orifice beneath, not terminal ; the surface of the body is highly polished and destitute of bristles. Whether this is a mimetic form, occurring in association with similar -looking Bugs is not known. The North American genus I'oxotrypana is furnished with a long ovipositor ; and in this and in the shape of the body resembles the parasitic Hymenoptera. This genus was placed by Gerstaecker in Ortalidae, but is considered by later writers to be a member of the Trypetidae. This latter family is of considerable extent, and is remarkable amongst the Diptera for the way in which the wings of many of its members are ornamented by an elaborate system of spots or marks, vary- ing according to the species. Fam. 34. Anthomyiidae. — • Flies similar in appearance to the House-fly ; the main vein posterior to the middle of the wing (4:th longitudinal} continued straight to the margin, not turned upwards. Eyes of the male frequently large and contiguous, bristle of antenna either feathery or bare. This very large family of flies is one of the most difficult and unattractive of the Order. Many of its members come close to the Acalyptrate Muscidae from which they are distinguished by the fact that a well- developed squama covers the halteres ; others come quite as close to the Tachinidae, Muscidae and Sarcophagidae, but may readily be separated by the simple, not angulate, main vein of the wing. The larval habits are varied. Many attack vegetables, produce disintegration in them, thus facilitating de- composition. Anthomyia brassicae is renowned amongst market gardeners on account of its destructive habits. A. cana, on the contrary, is beneficial by destroying the migratory Locust Schistocerca peregrina ; and in North America, A. angustifrons performs a similar office with Caloptenus spretus. One or two species have been found living in birds; in one case on the head of a species of Spermophila, in another case on a tumour of the wing of a Woodpecker. Hylemyia strigosa, a dung-frequenting species, has the peculiar habit of producing living larvae, one at a time ; these larvae are so large that it would be supposed they are full grown, but this is not the case, they are really only in the first stage, an unusual amount of growth being accomplished in this stadium. Spilogaster angelicae, on the other hand, according to vii ANTHOMYIIDAE TACHINIDAE 507 Portschinsky, lays a small number of very large eggs, and the result- ing larvae pass from the first to the third stage of development, omitting the second stage that is usual in Eumyiid Muscidae.1 Fam. 35. Tachinidae. — First posterior cell of icing nearly or quite closed. Squamae large, covering the li alter es : antennal arista bare : upper surface of body usually bristly. This is an enormous family of flies, the larvae of which live parasitically in other living Insects, Lepidopterous larvae being especially haunted. Many have been reared from the Insects in which they live, but beyond this little is known of the life-histories, and still less of the structure of the larvae of the Tachinidae, although these Insects are of the very first importance in the economy of Nature. The eggs are usually deposited by the parent-flies near or on the head of the B FIG. 242. — Uyimyia sericariae. A, The perfect fly, x 2 ; B, tracheal chamber of a silk- worm, with body of a larva of Ugimyia projecting ; a, front part of the maggot ; b, stigmatic orifice of the maggot ; c, stigma of the silkworm. (After Sasaki.) victim ; Riley supposed that the fly buzzes about the victim and deposits an egg with rapidity, but a circumstantial account given by Weeks 2 discloses a very different process : the fly he watched sat on a leaf quietly facing a caterpillar of Da tana engaged in feeding at a distance of rather less than a quarter of an inch. " Seizing a moment when the head of the larva was likely to remain stationary, the fly stealthily and rapidly bent her abdomen downward and extended from the last segment what proved to be an ovipositor. This passed forward beneath her body and between the tegs until it projected beyond and nearly on a level with the head of the fly and came in contact with the eye of the larva upon which an egg was deposited," making an addition to five already there. Ugimyia sericariae does great 1 Baron von Osten Sacken informs the writer that this statement has since been withdrawn by Portschinsky as being erroneous. 2 Etit. Amer. iii. 1887, p. 126. 508 DIPTERA CHAP. harm in Japan by attacking the silkworm, and in the case of this fly the eggs are believed to be introduced into the victim by being laid on mulberry leaves and swallowed with the food ; several observers agree as to the eggs being laid on the leaves, but the fact that they are swallowed by the silkworm is not so certain. Sasaki has given an extremely interesting account of the develop- ment of this larva.1 According to him, the young larva, after hatching in the alimentary canal, bores through it, and enters a nerve-ganglion, feeding there for about a week, after which the necessity for air becoming greater, as usual with larvae, the maggot leaves the nervous system and enters the trachea! system, boring into a tube near a stigmatic orifice of the silkworm, where it forms a chamber for itself by biting portions of the tissues and fastening them together with saliva. In this it completes its FIG. 243. — Diagrammatic section of silkworm to show the habits of Ugimyia. a, Young larva ; b, egg of Ugimyia in stomach of the silkworm ; c, larva in a nerve-ganglion ; d, larva entering a ganglion ; e, larva embedded in tracheal chamber, as shown in Fig. 242, B. (After Sasaki. ) growth, feeding on the interior of the silkworm with its anterior part, and breathing through the stigmatic orifice of its host ; after this it makes its exit and buries itself deeply in the ground, where it pupates. The work of rupturing the puparium by the use of the ptilinum is fully described by Sasaki, and also the fact that the fly mounts to the surface of the earth by the aid of this same peculiar air-bladder, which is alternately contracted and distended. Five, or more, of the Ugimyia- maggots may be found in one caterpillar, but only one of them reaches maturity, and emerges from the body. The Tachinid flies appear to waste a large pro- portion of their eggs by injudicious oviposition ; but they make up for this by the wide circle of their victims, for a single species has been known to infest Insects of two or three different Orders. The species of Miltogramma — of which there are many in Europe and two in England — live at the expense of Fossorial 1 J. Coll. Japan, i. 1886, pp. 1-46, plates i.-vi. TACHINIDAE 509 Hymenoptera by a curious sort of indirect parasitism. They are obscure little flies, somewhat resembling the common House-fly, but they are adepts on the wing and have the art of ovipositing with extreme rapidity ; they follow a Hymenopteron as it is carry- ing the prey to the nest for its young. When the wasp alights on the ground at the entrance to the nest, the Miltogramma swoops down and rapidly deposits one or more eggs on the prey the wasp designs as food for its own young. Afterwards the larvae of the fly eat up the food, and in consequence of the greater rapidity of their growth, the young of the Hymenopteron perishes. Some of them are said to deposit living larvae, not eggs. Fabre has drawn a very interesting picture of the relations that exist between a species of Miltogramma and a Fossorial Wasp of the genus Bembex} We may remind the reader that this Hymenop- teron has not the art of stinging its victims so as to keep them alive, and that it accordingly feeds its young by returning to the nest at proper intervals with a fresh supply of food, instead of provisioning the nest once and for all and then closing it. This Hymenopteron has a habit of catching the largest and most active flies — especially Tabanidae — for the benefit of its young, and it would therefore be supposed that it would be safe from the parasitism of a small and feeble fly. On the contrary, the Miltogramma adapts its tactics to the special case, and is in fact aided in doing so by the wasp itself. As if knowing that the wasp will return to the carefully-closed nest, the Miltogramma waits near it, and quietly selects the favourable moment, when the wasp is turning round to enter the nest backwards, and deposits eggs on the prey. It appears from Fabre's account that the Bembex is well aware of the presence of the fly, and would seem to entertain a great dread of it, as if conscious that it is a formidable enemy ; nevertheless the wasp never attacks the little fly, but allows it sooner or later to accomplish its purpose, and will, it appears, even continue to feed the fly-larvae, though they are the certain destroyers of its own young, thus repeat- ing the relations between cuckoo and sparrow. Most of us think the wasp stupid, and find its relations to the fly incredible or contemptible. Fabre takes a contrary view, and looks on it as a superior Uncle Toby. We sympathise with the charming French naturalist, without forming an opinion. 1 Souvenirs entomologiques, 1879, pp. 246-254. 5IO D1PTERA CHAP. Doubtless there are many other interesting features to be found in the life-histories of Tachinidae, for in numbers they are legion. It is probable that we may have 200 species in Britain, and in other parts of the world they are even more abundant, about 1000 species being known in North America.1 The family Actiidae is at present somewhat doubtful. According to Karsch,2 it is a sub-family of Tachinidae ; but the fourth longitudinal vein, it appears, is straight. Fam. 36. Dexiidae. — These Insects are distinguished from Tachinidae by the bristle of the antennae being pubescent, and the legs visually longer. The larvae, so far as known, are found in various Insects, especially in Coleoptera, and have also been found in snails. There are eleven British genera, and about a score of species. Fam. 37. Sarcophagidae. — Distinguished from Muscidae and Tachinidae by little more than that the bristle of the antennae is feathery at the base but hair-like and very Jine at the tip. — Sarcophaga cam-aria is one of the commonest British Insects; it is like the Blow -fly, though rather longer, con- spicuously grey and black, with the thorax distinctly striped, and the pulvilli very conspicuous in the live fly. Cynomyia mortuorum is a bright blue fly rather larger than the Blow-fly, of which it is a competitor ; but in this country an unsuccessful one. The larvae of the two Insects are found together, and are said to be quite indistinguishable. Cynomyia is said to lay only about half the number of eggs that the Blow-fly does, but it appears earlier in the year, and to this is attributed the fact that it is not altogether crowded out of existence by the more prolific Calliphora. The species of Sarcophagidae are usually viviparous, and one of them, Sarcophila magniftca (u-ohlfahrti), has the habit of occasionally depositing its progeny in the nostrils of mammals, and even of human beings, causing horrible sufferings and occasionally death : it is said to be not uncommon in Europe, but does not occur in Britain. The genus Sarcophaga is numerous in species, and many of them are beneficial. Sir Sidney Saunders found in the Troad that Locusts were destroyed by the larvae of a Sarcophaga living in their bodies ; and 1 A list of the Insects known to be attacked by Dipterous parasites has been given by Brauer and Bergenstamm, Denk. Ak. Wien, Ixi. 1895. - Berlin, ent. Zeit. xxx. 1886, p. 135. vii SARCOPHAGIDAE— MUSCIDAE 5 I I Kiinckel has recently observed that in Algeria several species of this genus attack Locusts and destroy large quantities by depositing living larvae in the Orthoptera. In North America the Army-worm is decimated by species of Sarcophaga. Many of these Insects, when food is scarce, eat their own species with eagerness, and it seems probable that this habit is beneficial to the species. The parent-fly in such cases usually deposits more eggs than there is food for, thus ensuring that every portion of the food will be rapidly consumed, after which the partially-grown larvae complete their development by the aid of cannibalism. It is thus ensured that the food will raise up as many individuals as possible. Fam. 38. Muscidae. — Bristle of antennae feathered. This family contains many of the most abundant flies, including the House-fly, Blue -bottles or Blow -flies, Green -bottles, and other forms which, though very common, are perhaps not dis- criminated from one another by those who are not entomologists. The larvae live on carrion and decaying or excrementitious matters. The common House-fly, Musca domestica, runs through its life-history in a very short time. It lays about 150 very small eggs on dung or any kind of soft damp filth ; the larvae hatch in a day or two and feed on the refuse ; they may be full-grown in five or six days, and, then pupating, may in another week emerge as perfect flies. Hence it is no wonder that they increase to enormous numbers in favourable climates. They are thought to pass the winter chiefly in the pupal state. The House-fly is now very widely distributed over the world ; it sometimes occurs in large numbers away from the dwellings of man. Of Blow- flies there are two common species in this country, Calliphora erythrocephala and C. vomitoria. The Green-bottle flies, of which there are several species, belonging to the genus Liwilia, have the same habits as Blow-flies, though they do not commonly enter houses. The larvae are said to be indistinguishable from those of Calliphora. The larvae of Eumyiid Muscidae are, when first hatched, metapneustic, but subsequently an anterior pair of stigmata appears, so that the larva becomes amphipneustic. They usually go through three stages, distinguished by the condition of the posterior stigmata. In the early instar these have fc single heart-shaped fissure, in the second stage two fissures exist, 5 1 2 DIPTERA CHAP. while in the third instar there is a greater diversity in the condition of the breathing apertures. The various forms of Muscidae show considerable distinctions in the details of their natural history, and these in certain species vary according to the locality. This subject has been chiefly studied by Portschinsky, a Russian naturalist, and a very interest- ing summary of his results has been given by Osten Sacken,1 to which the student interested in the subject will do well to refer. A few years ago a great deal of damage was caused in the Netherlands by Lucilia sericata, a Green-bottle-fly, extremely similar to our common L. caesar, which deposited its eggs in great quantities on sheep amongst their wool. This epidemic was attributed to the importation of sheep from England ; but, according to Karsch, there is reason to suppose that the fly was really introduced from Southern Europe or Asia Minor.2 The larvae, of species of the genus Lucilia sometimes attack man and animals in South America, but fortunately not in this country. The larva of Lucilia (Compsomyia) macellaria is called the screw- worm, and is the best known of the forms that infest man, the larvae living in the nasal fossae and frontal sinuses, and causing great suffering. The fly is common in North America, but is said never to attack man farther north than in Kansas. A little fly (Stomoxys calcitrans), very like the common house-fly though rather more distinctly spotted with grey and black, and with a fine, hard, exserted proboscis, frequently enters our houses and inflicts a bite or prick on us. It is commonly mistaken for an ill-natured house-fly that has taken to biting. It is frequently a source of irritation to cattle. A closely allied fly, Haematohia serrata, is very injurious to cattle in North America, but the same species causes no serious annoy- ance in England. We may mention that the various attacks of Dipterous larvae on man have received the general name " myiasis." The Tse-tse fly (Glossina-morsitans), another ally of Stomoxys, is not very dissimilar in size and shape to the blow -fly.3 1 Berlin, ent. Zeitsclir. xxxi. 1887, p. 17. 2 Biol. Centrum, vii. 1887, p. 521. 3 For an account of the habits of this fly, see Kirk, «7. Linn. Soc. viii. 1865, pp. 149-156 ; and for a bibliographic list, Wulp, Tijdschr. Ent. xxvii. 1884, p. xci. and pp. 143-140. MUSCIDAE TSE-TSE FLY 513 It bites man and animals in South Africa, and if it have previously bitten an animal whose blood was charged with the Haematozoa that really con- stitute the disease called Nagana (fly-disease), it inoculates the healthy animal with the dis- ease ; fortunately only some species are susceptible, and man is not amongst them. It has recently been shown by Surgeon Bruce l that this fly multiplies by producing, one at a time, a full-grown larva, which irnme- FIG. 244. — The Tse-tse fly (Glossina morsi- tans). A, The fly with three divisions diately changes to a pupa, as larva • cr°u°SaCiS pr°jecting ' B' adult do the members of the series Pupipara. There are already known other Muscid flies with peculiarities in their modes of reproduction, so that it is far from impossible that the various con- ditions between ordinary egg-laying and full-grown larva- or pupa- production may be found to exist. Although it has been supposed that the Tse-tse fly is a formidable obstacle to the occupation of Africa by civilised men, there is reason to suppose that this will not ultimately prove to be the case. It only produces disease when this pre-exists in animals in the neighbourhood ; only certain species are liable to it ; and there is some evidence to the effect that even these may in the course of a succession of generations become capable of resisting the disease inoculated by the fly. As long ago as 1878 Dr. Drysdale suggested 2 that this fly only pro- duces disease by inoculating a blood-parasite, and all the evidence that has since been received tends to show that his idea is correct. Although the facts we have mentioned above would lead to the supposition that Muscidae are unmitigated nuisances, yet it is probable that such an idea is the reverse of the truth, and that on the whole their operations are beneficial. It would be difficult to overestimate their value as scavengers. And in addition to this they destroy injurious creatures. Thus in Algeria Idia fasciata, a fly like the House - fly, destroys the VOL. VI 1 Prelimitiary Report on the Tse-tse Fly Disease, 1895. 2 P. Liverpool Soc. xxxiii. 1878, p. 13, note. 2 L 5 1 4 DIPTERA CHAP. dreaded migratory Locust Schistocerca peregrina in great quantities, by the larvae eating the eggs of the Locust. The female of this fly, in order to reach the desired food, penetrates from one to three inches below the surface of the ground. Fam. 39. Oestridae (Bot-flies]. — Rather large or very large flies, with, extremely short antennae, bearing a segmented arista, the front of the head prominent, the posterior part of the wings fre- quently rough, and with but few veins : the mouth usually atrophied, the trophi being represented only by tubercles ; larvae living in Verte- brates, usually Mammals, though it is possible that a few occur in Birds and even in Reptiles. This is a family of small extent, less than 100 species being known from all the world, yet it is of much interest on account of the habits of its members, which, though of large size, live entirely at the expense of living Verte- brates, to the viscera or other structures of which they have definite relations, varying according to the species. Some (Gastrophilus,Qtc,.} live in the alimentary canal; others (Hypoderma, etc.) are encysted in or under the skin; while others (Oestrus, etc.) occupy the respir- atory passages. As many of them attack the animals used by man, and some of them do not spare man himself, they have attracted much attention, and there is an extensive literature connected with them ; nevertheless the life-histories are still very incom- pletely known. Indeed, the group is from all points of view a most difficult one, it being almost impossible to define the family owing to the great differences that exist in important points. Some think the family will ultimately be dismembered ; and Girschner has recently proposed to treat it as a division of Tachinidae. The chief authority is Brauer, in whose writings the student will find nearly all that is known about Oestridae.1 Some of them exist in considerable numbers (it is believed that they are now not so common as formerly), and yet the flies are but rarely met with, their habits being in many respects peculiar. Some of them, for purposes of repose, frequent the summits of mountains, or towers, or lofty trees. Some have great powers of humming; none of them are known to bite their victims, indeed the atrophied mouth of most of the Oestridae forbids such a pro- ceeding. Some deposit their eggs on the hairs of the beasts from 1 We may specially mention the monograph of Oestridae, published in 1863 by the K. k. Zool. - Sot. Ges. Wien, and supplements in Wien. ent. Zeit. v. vi. 1886, 1887 ; these include copious bibliographic lists. OESTRIDAE BOT-FLIES 515 which the larvae are to draw their nutriment, but others place their larvae, already hatched, in the entrances of the nasal passages. They do not feed on the blood or tissues of their victims, but on the secretions, and these are generally altered or increased by the irritation induced by the presence of the un- welcome guests. It would appear, on the whole, that their presence is less injurious than would be expected, and as they always quit the bodies of their hosts for the purposes of pupation, a natural end is put to their attacks. We have ten species in Britain, the animals attacked being the ox, the horse, the ass, the sheep, and the red deer ; others occasionally occur in connexion with animals FIG. 245. — Cephalomyia maciilata, a Bot-fly of the camel. Arabia. A, The fly with extended wings ; B, under aspect of the head : a, antenna ; b, the obsolete mouth-parts. in menageries. The eggs of Gastrophilus equi are placed by the fly, when on the wing, on the hair of horses near the front parts of the body, frequently near the knee, and, after hatching, the young larvae pass into the stomach of the horse either by being- licked off, or by their own locomotion : in the stomach they be- come hooked to the walls, and after being full grown pass out with the excreta : the Bots — as these larvae are called — are some- times very numerous in the stomach, for a fly will lay as many as four or five hundred eggs on a single horse : in the case of weakly animals, perforation of the stomach has been known to occur in consequence of the habit of the Bot of burying itself to a greater or less extent in the walls of the stomach. Hypoderma bovis and H. lineata attack the ox, and the larvae cause tumours in the skin along the middle part of the back. It was formerly Sl6 DIPTERA CHAP. inferred from this that the fly places its eggs in this situation, and as the cattle are known to dread and flee from the fly, it was supposed to be on account of the pain inflicted when the egg was thrust through the skin. Eecent observations have shown that these views are erroneous, but much still remains to be ascer- tained. The details of oviposition are not yet fully known, but it appears that the eggs are laid on the lower parts of the body, especially near the heels, and that they hatch very speedily.1 As the imago of Hypoderma appears for only a very short period in the summer, the time of the oviposition is certain. The newly- disclosed larva is considerably different from the more advanced instar found in the skin of the back ; moreover, a long period of many months intervenes between the hatching of the larva and its appearance in the part mentioned. Brauer has shown that when the grub is first found in that situation it is entirely sub- cutaneous. Hence it would be inferred that the newly-hatched larva penetrated the skin probably near the spot it was deposited on, and passed a period in subcutaneous wandering, on the whole going upwards till it arrived at the uppermost part : that after moulting, and in consequence of greater need for air, it then pierced the skin, and brought its breathing organs into contact with the external air ; that the irritation caused by the admission of air induced a purulent secretion, and caused the larva to be enclosed in a capsule. Dr. Cooper Curtice has however found, in the oesophagus of cattle, larvae that he considers to be quite the same as those known to be the young of Hypoderma ; and if this prove to be correct, his inference that the young larvae are licked up by the cattle and taken into the mouth becomes probable. The larva, according to this view, subsequently pierces the oesophagus and becomes subcutaneous by passing through the intervening tissues. The later history of the grub is briefly, that when full grown it somewhat enlarges the external orifice of its cyst, and by contractions and expansions of the body, passes to the surface, falls to the ground, buries itself and becomes a pupa. If Dr. Curtice be correct, there should, of course, be as many, if not more, larvae found in the oesophagus as in the back of the animal ; but, so far as is known, this is not the case, arid we shall not be surprised if the normal course of development be found different from what Dr. Curtice supposes it to be. His 1 Riley, Insect Life, iv. 1892, p. 302. vii OESTRIDAE PUPIPARA 517 observations relate to Hypoderma lineata. Our common British species is usually supposed to be If. bovis ; but from recent ob- servations it seems probable that most of the " Ox-warbles " of this country are really due to the larvae of If. lineata. The history of Oestrus ovis, which attacks the sheep, is also incompletely known, but appears to be much simpler. This fly is viviparous, and deposits its young larvae at the entrance of the nasal passages of the sheep, thereby causing extreme annoyance to the animal. The larvae penetrate to the frontal sinuses to complete their growth. The duration of their lives is unknown, for it is commonly the case that larvae of various sizes are found together. Cephenomyia rufibarHs has recently been found in Scotland. It attacks the Red deer, and its life-history is similar to that of Oestrus ovis, though the larvae apparently prefer to attain their full growth in the pharynx of the deer. In reference to the Oestridae that attack man, we may merely mention that the larva of the Hypoderma of the ox is occasionally found in Europe infesting human beings, but only as an extremely rare and exceptional event ; and that only those engaged in attending on cattle are attacked ; from which it is inferred that the flies are deceived by an odour emanating from the garments. In America numerous cases are known of Oestrid larvae being taken from the body of man, but information about them is very scanty. It appears, however, that there are at least four species, one of which, Dermatobia noxialis, is known as a fly as well as a larva. Whether any of these are peculiar to man is uncertain.1 There are several larvae of Muscidae that have similar habits to the Oestridae ; hence the statements that exist as to larvae being found in birds and reptiles cannot be considered to apply to members of the latter family until the larvae have been studied by an expert. The family Ctenostylidae has been established by Bigot for a South American Insect, of which only a single individual exists in collections. It is doubtful whether it can be referred to Oestridae.2 Series V. Pupipara The four families included in this Series are, with the exception of the Hippoboscidae, very little known. Most of 1 See Blanchard, Ann. Soc,. ent. France (7) ii. 1892, pp. 109, 154. 2 See Bigot, Ann. Soc. ent. France (6) ii. 1882, p. 21, Brauer, Monograph, 1863, p. 51, and Wien. ent. Zeit. vi. 1887, p. 75. 5 1 8 DIPTERA CHAP. them live by sucking blood from Mammals and Birds, and some- times they are wingless parasites. The single member of the family Braulidae lives on bees. The term Pupipara is erroneous, and it would be better to revert to Reaumur's prior appellation Nymphipara. Mtiggenburg has suggested that the division is not a natural one, the points of resemblance that exist between its members being probably the results of convergence. Recent discoveries as to the modes of bringing forth of Muscidae give additional force to this suggestion. A satisfactory definition of the group in its present extent seems impossible. Fam. 40. Hippoboscidae. — Wings very variable, sometimes present and large, then with waved surface and thick nervures confined to the anterior and basal part ; sometimes mere strips, sometimes entirety absent. Certain members of this family are well known, the Forest-fly, or Horse-fly, and the Sheep-tick belonging to it. The proboscis is of peculiar formation, and not like that of other flies. Seen externally it consists of two elongate, closely adapted, hard flaps ; these are capable of diverging laterally to allow an inner tube to be exserted from the head. The details and morphology of the structure have recently been discussed by Miiggenburg.1 Melophagus ovinus, commonly called the Sheep-tick, is formed for creeping about on the skin of the sheep beneath the wool, and may consequently be procured with ease at the period of sheep- shearing : it has no resemblance to a fly, and it is difficult to persuade the uninitiated that it is such. Jfippobosca equina (called in this country the Forest-fly, perhaps because it is better known in the New Forest than elsewhere), looks like a fly, but will be readily recognised by the two little cavities on the head, one close to each eye, in which the antennae are concealed, only the fine bristle projecting. Very little seems to be known as to the Natural History of this fly. Lipoptena cervi lives on the Red deer ; the perfect Insect has apparently a long life, and both sexes may be. found in a wingless state on the deer all through the winter. When first disclosed in the summer they are how- ever provided with wings, but when they have found a suitable host they bite off, or cast, the wings. The female, it appears, does this more promptly than the male, so that it is difficult to get winged individuals of the former sex.2 Most of the known 1 Arch. Naturgesch. Iviii. i.1892, pp. 287-322, pis. XT. xvi. 2 Stein, Deutsche ent. Zcit. xxi. 1877, p. 297. HIPPOBOSCIDAE 519 Hippoboscidae live on birds, and are apparently specially fond of the Swallow tribe. They are all winged, though in some species the wings are very small. The bird- infesting Hippoboscidae have been very little studied, and will probably form a distinct family ; the antennae of Sten- opteryx hirundinis are quite different from those of Hippobosca. The devel- opment is remarkable, and has been studied by Leuckart l and by Pratt 2 in the case of Melophagus ovinus. The ovaries are peculiarly formed, and pro- duce one large egg at a time ; this passes into the dilated oviduct, and there goes through its full growth and a cer- tain amount of development ; it is then extruded, and undergoing little or no change of form becomes externally hardened by the excretion of chitin, passing thus into the condition of the Eumyiid pupa. Dufour thought that there is no larval stage in this Insect, but it is quite clear from later researches that he was wrong, and that a larval stage of a peculiar kind, but in some re- spects resembling that of the Eumyiid Muscidae, occurs. The larva has no true head, but the anterior part of the body is invaginated, and the most anterior part again protrudes in the invagination, so that two little passages appear on section (Fig. 246) ; the upper one leads to the stomach, which is of very large size. The tracheal system is peculiar ; it is metapneustic, there being neither anterior nor lateral spiracles. Pratt says that there is at first a single pair of terminal spiracles, and sub- sequently three pairs, hence he considers that the terminal part of the body corresponds to three segments. This is however probably a mistaken view ; it appears more probable that the so- called three pairs of stigmata really correspond with the complex 1 AWi. Ges. Halle, iv. 1858, p. 145. 2 Arch. Naturgesch. lix. i. 1893, p. 151. P FIG. 246. — Diagrammatic section of the larva of Melophagus ovinus. (After Pratt.) a, mouth ; b, suctorial pouch ; c, imaginal disc for adult head ; d, meso- and meta- notal discs, e, anterior trach- eal anastomosis ; /, first muscular belt ; g, transverse tracheal branch ; /t, the dorsal tracheal tube ; i, sex-organ ; k, Malpighian tube ; I, ter- minal part of intestine ; m, terminal chamber of tracheal tube ; n, stigmatic fossa ; o, terminal part of intestine ; p, anus ; q, anal disc ; r, ventral tracheal tube ; s, stomach ; t, nervous system ; it, discs for the three pairs of legs of the imago ; v, ventral pouch ; w, pharynx ; x, suctorial lip. 52O DIPTERA condition of the stigmata in the later instars of certain other Dipterous larvae. The MelopJiagus-lsLrva, is nourished by secre- tion from certain glands of the mother-fly ; this is swallowed and the stomach is greatly distended by this milky fluid. Probably it was this condition that induced Dufour to suppose the larva to be only an embryo. Some of the Hippoboscidae that live on birds take to the wing with great readiness, and it is probable that these bird- parasites will prove more numerous than is at present suspected. We may here notice an animal recently described by Dr. Adensamer and called Ascodipteron.1 He treats it as the female imago of a Pupiparous Dipteron. It was found buried in the skin of the wing of a bat of the genus Phyllorhina, in the Dutch East Indies, only one individual being known. It is entirely unsegmented, and externally without head. If Dr. Adensamer should prove to be correct in his surmise the creature can scarcely be inferior in interest to the Strepsiptera. Fam. 41. Braulidae. — This consists only of a minute Insect that lives on bees. The antennae are somewhat like those of the sheep-tick, though they are not so com- pletely concealed in the cavities in which they are inserted. Ac- cording to Miiggen- burg 2 a ptilinum exists, and he is also of opinion that al- though the parts of the mouth differ very much from those of Hippoboscidae they are essentially similar. Lucas says that Braula specially affects the thorax of the bee : Mliggenburg, that it is fond of the queen-bee because of the exposed membranes between the body- segments that exist in that sex. Whether this Insect is truly Pupiparous is unknown, though Boise states that a pupa is deposited in the cell of the bee by the side of the young larva of 1 SB. Ak. Wien. cv. 1896, Abtheil. i. p. 400. 2 Arch. Naturges. Iviii. i. 1892, p. 287. FIG. 247. — Braula coeca. (After Meinert.) BRAULIDAE STREBLIDAE NYCTERIBIIDAE 521 the bee, and appears as the perfect Insect in about twenty-one days. Mliggenburg suggests that Braula may be oviparous, as he has never found a larva in the abdomen. Packard says that on the day the larva hatches from the egg it sheds its skin and turns to an oval puparium of a dark brown colour. The Insect is frequently though inappropriately called bee-louse ; notwithstanding its name it is not quite blind, though the eyes are very imperfect. Fam. 42. Streblidae. — Winged ; possessing halteres ; the head small, narrow and free. These very rare Diptera are altogether problematic. According to Kolenati the larvae live in bats' excrement and the perfect Insects on the bats.1 If the former statement be correct the Insects can scarcely prove to be Pupipara. The wing-nervuration is, in the figures of the Eussiaii author, quite different from that of Hippoboscidae. The Streblidae have been associated by some entomologists with Nycteribiidae, and by "Williston with Hippoboscidae. Family 43. Nycteribiidae. — The species of this family are FIG. 248. — Nycteribia, sp., from Xantharpyia straminea. Aden. A, Upper surface of female, with head in the position of repose ; B, under surface of male. x -Jj2. found on bats ; they are apparently rare, and we have been able to examine only one species. The form is very peculiar, the 1 Home Soc. ent. Koss. ii. 1863, p. 90. ujlBRAR Y 522 DIPTERA APHANIPTERA Insects looking as if the upper were the under surface. They are wingless, with a narrow head, which reposes on the back of the thorax. The prothorax appears to be seated on the dorsum of the mesothorax. According to Miiggenburg there is no trace of a ptilinum. A brief note on the metamorphosis l by Baron Osten Sacken indicates that the mature larva differs from that of FIG. 249. — Anterior part of the body of Nycteribia sp., found on Xantharpyia straminea by Colonel Yerbury at Aden. A, Upper surface of female, with head extended ; B, under surface of male, with head extended ; C, claws of a foot. MelopJiagus in the arrangement of the stigmata ; they appear to be dorsal instead of terminal. There are apparently no characters of sufficient importance to justify the association of these Insects with the other divisions of Pupipara ; the sole ground for this connection being the supposed nature of the life-history of the larva. Sub-Order Aphaniptera or Siphonaptera (Fleas) Fam. Pulicidae. — Wingless, with the body laterally compressed, so that the transverse diameter is small, the vertical one great. The head indistinctly separated from the body, small, with short thick antennae placed in depressions somewhat behind and above the un- facetedeyes. These are always minute, and sometimes wanting. — 1 Tr. ent. Soc. London, 1881, p. 360. APHANIPTERA FLEAS 523 We all know that the Flea is so flat, or compressed sideways, that it does not mind the most severe squeeze. This condition is almost peculiar to it ; a great flattening of the body is com- mon in Insects — as is seen in another annoying Insect, the bed-bug — but the compression, in the flea, is in the reverse direction. In Other respects the Fl°- ^50.—ffystrichopsylla talpae, Britain. , „ , „ (After Ritsema. ) external anatomy 01 the flea shows several peculiarities, the morphological import of which has not yet been elucidated. The head is of very peculiar shape, small, with the antennae placed in an unusual position ; the clypeus is said to W be entirely absent, the front legs are articulated in such a manner that they have a large addi- tional basal piece — called by some anatomists the ischium — and in consequence appear to be placed far forwards, looking as if they were attached to the head ; the meso- and meta- thorax have certain flaps that have been con- sidered to be homologues of wings ; and the maxillary palpi are attached to the head in such a way that they appear to play the part of the antennae of other Insects (Fig. 250), and were actually considered to be the antennae by Linnaeus, as well as others ; the mouth- FIG. 251. — Mouth- , ,.™ , , parts of a flea, Ver- parts themselves are differently constructed mipsyiia alakurt from those of any other Insects.1 The maxillae pricking organ ; and labium are considered to be not only present, Lp. labial palp ; j^ wejj developed, the former possessing palpi Md. mandible ; & r MX. maxilla ; Mxp. moderately well developed, while the labial (1AfterWagne?.)1P' PalpS ™Q ™J larg6 and °f highly Peculiar form, being imperfectly transversely jointed and acting as sheaths ; the mandibles are present in the form of 1 The best general description of the external anatomy of the flea is to be found ill Taschenberg, Die Flohe, 1880. The morphology is better elucidated, though still incompletely, in Wagner's valuable " Aphanipterologische Studien," Horae Soc. ent. Ross, xxiii. 1889, pp. 199-260, 5 plates, and op. cit. xxxi. 1897, pp. 555-594, 3 plates. Cf. also K C. Rothschild, Nov. Zool. v. 1898, pp. 533-544, 3 plates. 524 APHANIPTERA a pair of elongate, slender organs, with serrated edges ; and there is an unpaired, elongate pricking-organ, thought by some to be a hypopharynx, and by others a labrum. The antennae are of unusual form, consisting of two basal joints, and, loosely con- nected therewith, a terminal mass of diverse form and more or less distinctly, though irregularly, segmented. The full number of ten stigmata exists, Wagner giving three thoracic, with seven abdominal, placed on segments 2-8 of the abdo- men ; but Packard thinks the supposed meta- thoracic stigma is really the first abdominal. Fleas undergo a very complete metamorphosis ; the larvae are wormlike, resembling those of Mycetophilid Diptera (Fig. 252). The egg of the cat's flea is deposited among the fur of the animal, but (unlike the eggs of other parasites) apparently is not fastened to the hair, for the eggs fall freely to the ground from infested animals; the young larva when hatched bears on the .head a curious structure for breaking the egg-shell. It has the mouth -parts of a mandibulate Insect and is peripneustic, having ten pairs of stigmata. It subsequently becomes of less elongate form. Flea-larvae are able to nourish themselves on almost any kind of refuse animal matter, Laboulbene having reared them on the sweepings of apartments ; they may FIG. 252.— Larva of f. ' „ , , , , Pulex serraticeps, perhaps sometimes ieed on blood ; at any rate the dog- and cat- the contents of the alimentary canal appear red flea. (After ' r Kiinckei.) through the transparent integuments. When full grown the larva makes a cocoon, and frequently covers it with pieces of dust. The perfect flea appears in a week or two thereafter ; the pupa has the members free. The food of the larvae of fleas has been much discussed and a variety of statements made on the subject. It has been stated that the mother-flea after being gorged with blood carries some of it to the young, but Kiinckei has shown that there is very little foundation for this tale. Enormous numbers of fleas are sometimes found in uninhabited apartments to which animals have previously had access, and these fleas will attack in numbers and with great eagerness any unfortunate person who may enter vii FLEAS 525 the apartment. The cat-flea can pass through its growth and metamorphosis with excessive rapidity, the entire development of a generation in favourable conditions extending but little beyond a fortnight.1 About a hundred kinds of fleas are known, all of which live on mammals or birds. Hystrichopsylla talpae (Fig. 250) is one of the largest, it occurs on the Mole. It was found by Kitsema in the nests of JBombus subterraneus (and was described under the name of Pulex obtusiceps}. As these nests are known to be harried by Voles, and as this flea has also been found on Field- mice, it is probable that the parasites are carried to the nests by the Voles. The species that chiefly infests man is Pulex irritans, an Insect that is nearly cosmopolitan, though arid desert regions are apparently unsuitable to it. Pulex avium occurs on a great variety of birds. P. serraticeps infests the dog and the cat, as well as a variety of other Mammals. It is a common opinion that each species of Mammal has its own peculiar flea, but this is far from correct. Fleas pass readily from one species of animal to another ; the writer formerly possessed a cat that was a most determined and successful hunter of rabbits, and she frequently returned from her excursions swarming with fleas that she had become infested with when in the rabbits' burrows ; her ears were on some occasions very sore from the flea-bites. Some of the fleas of other animals undoubtedly bite man. There appears, however, to be much difference in the liability of different individuals of our own species to the bites of fleas. Sarcopsylla penetrans differs in habits from other fleas, as the female buries the anterior parts of her body in the flesh of man or other Vertebrates, and the abdomen then becomes enormously enlarged and distended and undergoes a series of changes that are of much interest.2 While in this position the Insect dis- charges a number of eggs. This species multiplies sufficiently to become a serious pest in certain regions, the body of one man having been known to be affording hospitality to 300 of these fleas. Sarcopsylla penetrans is known as the Sand -flea, or chigger, and by numerous other names. Originally a native of tropical America it has been carried to other parts of the world. Another Sarcopsylla, S. aallinacea, attaches itself to the eyelids 1 Howard, full. Dep. Agric. Ent. N.S. No. 4, 1896. 2 Sclumkewitsch, Zool. Anz. vii. 1884, p. 673. 526 APHANIPTERA THYSANOPTERA CHAP. of the domestic fowl in Ceylon, and an allied form, Rhynclwpsylla pulex, fastens itself to the eyelids and other parts of the body of birds and bats in South America. In Turkestan Vermijjsylla alakurt attacks cattle — ox, horse, camel, sheep — fastening itself to the body of the animal after the fashion of a tick. Eetaining this position all through the winter, it becomes distended some- what after the manner of the Sand-flea, though it never forms a spherical body. The parts of the mouth in this Insect (Fig. 251) are unusually long, correlative with the thickness of the skins of the animals on which it lives. Grassi considers that the dog's flea, Pulex serraticeps, acts as the intermediate host of Taenia. Great difference of opinion has for long prevailed as to whether fleas should be treated as a Sub-Order of Diptera or as a separate Order of Insects. Wagner and Klinckel, who have recently discussed the question, think they may pass as aberrant Diptera, while Packard,1 the last writer on the subject, prefers to consider them a separate Order more closely allied to Diptera than to any other Insects. Although widely known as Aphan- iptera, several writers call them Siphonaptera, because Latreille proposed that name for them some years before Kirby called them Aphaniptera. Meinert considers them a separate Order and calls it Suctoria, a most unfortunate name. Order VIII. Thysanoptera. Small Insects, with a palpigerous mouth placed on the under side of the head and apposed to the sternum so as to be concealed. With four slender wings, fringed with long hairs on one or both margins, or with rudiments of wings, or entirely apterous. Tarsi of one or two joints, terminated ly a vesicular structure. The young resemble the adult in general form, but there is a pupal stadium in which the Insect is quiescent and takes no food. The tiny Insects called Thrips are extremely abundant and may often be found in profusion in flowers. Their size is only from -^j to -£- of an inch in length ; those of the latter magni- tude are in fact giant species, and so far as we know at present are found only in Australia (Fig. 253). As regards the extent 1 P. Boston Soc. xxvi. 1894, pp. 312-355. THRIPS 527 of the Order it would appear that Thysanoptera are insignificant, as less than 150 species are known. Thrips have been, how- ever, very much neglected by entomologists, so it will not be a matter for surprise if there should prove to be several thousand species. These Insects present several points of interest ; their mouth - organs are unique in structure ; besides this, they ex- hibit so many points of dissimilarity from other Insects that it is impossible to treat them as subdivisions of any other Order. They have, however, been considered by some to be aberrant Pseudoneuroptera (cf. Vol. V.), while others have associated them with Hemiptera. Both Brauer and Packard have treated Thysa- noptera as a separate Order, and there can be no doubt that this is correct. Thysano- ptera have recently been monographed by Uzel in a work that is, unfortunately for most of us, in the Bohemian language.1 The antennae are never very long, and are 6 to 9 -jointed. The head varies much, being sometimes elongate and tubular, but sometimes short ; it has, however, always the peculiarity that the antennae are placed quite on its front part, and that the mouth appears to be absent, owing to its parts being thrust against the under side of the thorax and concealed. Their most remarkable peculiarity is that some of them are asymmetrical : Uzel looks on the peculiar structure, the " Mundstachel," m, m 1 Monographic der Ordnung Thysanoptera, Koniggratz, 4to, 1895. FIG. 253. — Idolothrips spectrum. Australia. 528 THYSANOPTERA (Fig. 254) found on the left side of the body, as probably an enor- mous development of the epipharynx. Previous to the appearance of Uzel's work, G-arman had, however, correctly described the structure of the mouth;1 he puts a different interpretation on the parts; he points out that the mandibles (/), so-called by Uzel, are at- tached to the maxillae, and he considers that they are really jointed, and that they are lobes thereof; while the Mund- -T> stachel or piercer is, he considers, the left mandible ; the corresponding struc- ture of the other side being nearly entirely absent. He points out that the labrum and endocranium are also asymmetrical. We think Garman's view a reasonable one, and may re- mark that dissimilarity of the man- dibles of the two sides is usual in FIG. 254. — Face (with base of T n ,-, ,, -,., ! the antennae) of Aeoiothrips Insects, and that the mandibles may fasdata. (After Uzel.) a, be hollow for sucking, as is shown by Labrum ; b, maxilla with its . . ., T_ .. .. .. palp (c) ; bi, terminal part of the larvae ot Hemerobudes. There vertex near attachment of are usually three ocelli, but they are mouth-parts ; a, membrane . * between maxilla and mentum ; absent in the entirely apterous forms. e, mentum ending in a point The wi g appear to spring from near /,• g, membrane of ** attachment of the labial palp the dorsal surface of the body, not h ; i, ligula ; j, j the bristle- frnrn 4-V.p eirlpcj • HIP ant prior nair iy fixing itself to the body of the Thrips. Xematode worms and their eggs were found by Uzel in the body-cavity. He found no less than 200 Nematodes in one Thrips, and noticed that they had entirely destroyed the ovaries. Woodpeckers, according to him, tear off the bark of trees and eat the Thysanoptera that are concealed thereunder, though one would have surmised that these minute Insects are too small to be game for such birds. They have, it appears, no special protection, except that one species (a larva of Phloeothrips sp.) is said to emit a protective fluid. Parthenogenesis seems to be frequent amongst Thysanoptera, 1 See Lindemann, Bull. Soc. Moscou, Ixii. 1886, No. 2, p. 296, and Uzel, Mon. 1895, pp. 397, 398. vii THRIPS 531 . . . — _ — __ — , . and is found in concurrence with diversity as to winged and wing- less females of the same species, so as to have given rise to the idea that the phenomena in this respect are parallel with those that are more widely known as occurring in Aphidae. Under certain circumstances few or no males are produced (one of the cir- cumstances, according to Jordan, being season of the year), and the females continue the species parthenogeiietically. In other cases, though males are produced they are in very small numbers. Some species of Thysanoptera are never winged ; in others the individuals are winged or wingless according to sex. But there are other cases in which the female is usually wingless, and is exceptionally winged. The winged specimens in this case are, it is thought, of special use in disseminating the species. Jordan has suggested that these phenomena may be of a regular nature, but Uzel does not take this view. Another condition may be mentioned, in which the species is usually wing- less, but winged individuals of the male as well as of the female sex occasionally appear. Thrips lini apparently makes regular migrations, feeding at one time underground on the roots of flax, and then changing to a life in the open air on other plants. Xumerous forms of Thysanoptera, belonging to both of the o-reat divisions of the Order, have been found fossil in Europe and ^NTorth America, but all are confined to deposits of the Tertiary epoch. Of the 135 species known to Uzel, 117 are European ; they are divided into two Sub-Orders. 1, Terebrantia, in which the females are provided with an external toothed ovipositor, of two valves ; 2, Tubulifera, in which there is no ovipositor, and the extremity of the body is tubular in both sexes. The British species are about 50 in number, and were described by Haliday about 6 0 years ago ; * of late they have been very little studied. The name Physopoda or Physapoda is used for this Order, instead of Thysanoptera, by several naturalists. 1 Entomological Magazine, iii. 1836, p. 439, and iv. 1837, p. 144. HEMIPTEKA OK BUGS Order IX. Hemiptera. Mouth consisting of a proboscis or mobile beak (usually concealed by being bent under the body), appearing as a transversly- jointed rod or grooved sheath, in which are enclosed long slender setae (like horse-hairs). Wings (nearly always) four ; the anterior frequently more horny than the posterior pair, and folding flat on the back, their apical portions usually more membranous than the base (Heteroptera) ; or the four wings may cover the abdomen in a roof -like manner, and those of the anterior pair may not have the basal and apical parts of different consistences (Homoptera) ; sometimes all four of the wings are transparent. The young resembles the adult in general form ; the wings are developed outside the body, by growth, at the moults, of the sides of the hinder por- tions of the meso- and meta-notum ; the metanotal prolonga- tions being more or less concealed by the mesonotal. THE Hemiptera or Bugs are perhaps more widely known as Rhynchota. In deciding whether an Insect belongs to this Order the student will do well to examine in the first place the beak, treating the wings as subordinate in importance, their condition being much more variable than that of the beak. The above definition includes no reference to the degraded Anoplura or Lice. These are separately dealt with on p. 599 ; they are absolutely wingless, and have an unjointed proboscis not placed beneath the body, the greater part of it being usually withdrawn inside the body of the Insect. The Hemiptera are without exception sucking Insects, and CHAP. VIII BUGS 533 the mouth-organs of the individual are of one form throughout its life. In this latter fact, coupled with another, that the young are not definitely different in form from the adult, Bugs differ widely from all other Insects with sucking-mouth. They agree with the Orthoptera in the facts that the mouth does not change its structure during the individual life, and that the development of the individual is gradual, its form, as a rule, changing but little. In respect of the structure of the mouth, Orthoptera and Hemiptera are the most different of all the Orders. Hence, Hemiptera is really the most isolated of all the Orders of Insects. We shall subsequently see that, like Orthoptera, FIG. 255.—JSiisthenes pratti (Pentato- midae). China. A, Xymph : a, case of anterior, b, of pos- terior wing ; c, ori- fices of stink- glands ; B, tlie adult Insect. the Order appeared in the Palaeozoic epoch. Although a very extensive Order, Hemiptera have for some incomprehensible reason never been favourite objects of study. Sixty years ago Dufour pointed out that they were the most neglected of all the great Orders of Insects, and this is still true ; our acquaintance with their life-histories and morphology especially being very limited. There is probably no Order of Insects that is so directly con- nected with the welfare of the human race as the Hemiptera ; indeed, if anything were to exterminate the enemies of Hemiptera, we ourselves should probably be starved in the course of a few months. The operations of Hemiptera, however, to a large ex- tent escape observation, as their mouth-setae make merely pricks that do not attract notice in plants ; hence, it is probable that 534 HEMIPTERA CHAP. injuries really due to Hemiptera are frequently attributed to other causes. In the course of the following brief sketch of the anatomy and development of Hemiptera, we shall frequently have to use the terms Heteroptera and Homoptera ; we may therefore here mention that there are two great divisions of Hemiptera having but little connection, and known by the above names : the members of these two Sub-Orders may in most cases be dis- tinguished by the condition of the wings, as mentioned in the definition at the commencement of this chapter. External structure. — The mouth-parts consist of an anterior or upper and a posterior or lower enwrapping part, and of the organs proper, which are four hair-like bodies, dilated at their bases and resting on a complex chitinous framework. The lower part forms by far the larger portion of the sheath and is of very diverse lengths, and from one to four-jointed : it is as it were an enwrapping organ, and a groove may be seen running along it, in addition to the evident cross - segmentation. The upper covering part is much smaller, and only fills a gap at the base of the sheath ; it can readily be lifted so as to disclose the setae ; these latter organs are fine, flexible, closely connected, rods, four in number, though often seeming to be only three, owing to the intimate union of the components of one of the two pairs ; at their base the setae become broader, and are closely connected with some of the loops of the chitinous framework that is con- tained within the head. Sometimes the setae are much longer than the sheath ; they are capable of protrusion. Although varying considerably in minor points, such as the lengths of the sheath and setae, and the number of cross-joints of the sheath, these structures are so far as is known constant throughout the Order. There are no palpi, and the only additions exceptionally present are a pair of small plates that in certain forms (aquatic family Belostomidae) lie on the front of the proboscis near the tip, overlapping, in fact, the last of the cross-articulations. Simple as is this system of trophi its morphology is uncertain, and has given rise to much difference of interpretation. It may be granted that the two portions of the sheath are respectively upper lip, and labium ; but as to the other parts wide difference of opinion still prevails. On the whole the view most generally accepted, to the effect that the inner pair of the setae correspond VIII STRUCTURE 535 in a broad sense with maxillae of mandibulate Insects, and the outer pair with mandibles, is probably correct. Mecznikow, who studied the embryology,1 supports this view for Heteroptera, but he says (t.c. p. 462), that in Homoptera the parts of the embryo corresponding with rudimentary maxillae and mandibles disappear, and that the setae are subsequently produced from peculiar special bodies that are at first of a retort-shaped form ; the neck of the retort becoming afterwards more elongate to form the seta ; also that in the Heteropterous genus Gerris the embryology in general resembles that of Homoptera, but the FIG. 256. — Mouth - parts of Hemiptera. (After Wedde.) A, Section of the head and proboscis of Pyrrhocoris apterus : dr, gland; i.g, infra - oeso- phageal ganglion ; Ib, labium ; Ir, labrum ; m, muscles ; m1, muscle (de- pressor of labium) ; m2, muscle of syringe ; ph, pharynx ; s, setae ; s.g, supra - oesophageal gang- lion ; sp. dr, salivary gland ; spr, syringe : B, transverse section of pro- boscis of Pentatoma nifi- pes, at third joint of sheath : m, m, muscles ; md, mandibular seta ; mx, maxillary setae ; n, nerve ; p, the sheath or labium ; tr, trachea. development of the setae is like that of other Heteroptera (t.c. p. 478). This discontinuity in the development of the Homopterous mouth has since been refuted by Witlaczil,2 who found that the retort-shaped bodies really arise from the primary segmental appendages after they have sunk into the head. We are there- fore justified in concluding that the mouth-parts are at first similarly developed in all Hemiptera, and that this development is of a very peculiar nature. Smith is convinced that there are no traces of mandibular structure in any Hemiptera.3 On the other hand, numerous entomologists have supposed they could homologise satisfactorily various parts of the Hemipterous trophi with special parts of the 1 Zeitschr. wiss. Zool. xvi. 1866, p. 389. 2 Arl. List. Wien. iv. 1882, p. 415. 3 Tr. Amer. Phil. Soc. xix. 1896, p. 176. 536 JtfEMIPTERA maxillae and labivun of maiidibulate Insects. This point has recently been discussed by Marlatt l and by Heymons.2 From the latter we gather that the mode of growth is peculiar by the extension backwards of some of the sclerites, and their becoming confounded with parts of the wall of the head. From all this it appears that at present we cannot correctly go farther than saying that the trophi of Hemiptera are the appendages of three head-segments, like those of other Insects. The views of Savigny, Leon,3 and others to the effect that labial palpi, and even other parts of the labium of Mandibulata can be satisfactorily identified are not confirmed by Heymons. Underneath the pharynx, in the head, there is a peculiar structure for which we have as yet no English term. It was apparently discovered by Landois and Paul Mayer,4 and has been called " Wanzenspritze," which we translate as syringe. It may be briefly described as a chamber, into which the salivary ducts open, prolonged in front to the neighbourhood of the grooves of the setae in the rostrum ; behind, it is connected with muscles ; it has no direct connection with the pharynx, and though it was formerly supposed to be an organ of suction, it seems more prob- able that it is of the nature of- a force-pump, to propel the pro- ducts of some of the bug's glands towards the tips of the setae. The rostrum being extended from its position of repose, the tip of the sheath is brought into contact with the object to be pierced, the surface of which is probably examined by means of sensitive hairs at the extremity of the sheath ; these therefore functionally replace to some extent the palpi of other Insects. As a rule the sheath does not penetrate (though there is reason for believing that in various of the animal-feeding bugs it does so), but the setae are brought into action for piercing the skin of the plant ; they are extremely sharp, and the outer pair are usually barbed, so that when once introduced a hold is easily maintained. This being established it is thought that the salivary pump comes into play, and that a fluid is injected into the object pierced so as to give rise to irritation or congestion, and thus keep up a supply of fluid at the point operated on : this fluid extends along the grooved setae by capillary attraction, and the 1 P. ent. soc. Washington, iii. 1895, p. 241. 2 Ent. Xacltr. xxii. 1896, p. 173. 3 Zool. Am. 1897, No. 527, p. 73. 4 Arch. Anat. Physiol. 1874, p. 313, and 1875, p. 309. STRUCTURE 537 rapidity of the current is increased by a pumping action of the pharynx, and possibly by movements of the setae themselves. Though the setae are often extremely elongate — sometimes several times the length of the body — they are nearly always slender, and there is no reason to suppose that a perfect, or air-tight, tube is formed ; hence it is probable that capillary attraction is really the chief agent in the ingestion of the fluid. The slight diversity of structure of the Hemipterous trophi is in very striking con- trast with what we find in mandibulate Insects, and in the less purely suctorial Insects, such as Diptera and some divisions of Hymenoptera. Schiodte in com- menting on this has suggested that it is probably due to the small variety of actions the rostrum is put to.1 The head exhibits great variety of form ; in the Homoptera the front part is deflexed and inflexed, so that it is placed on the under surface, and its anterior margin is directed backwards ; it is often peculiarly inflated ; in the Lantern- flies or Fulgoridae (Fig. 282) to an incomprehensible extent. In the great Water-bugs, Belostomidae, there is on the under surface a deep pocket for each antenna, beautifully adapted to the shape of the curiously-formed ap- pendage (Fig. 279). The prothorax is always very distinct, frequently large, and in many of the Heteroptera (Fig. 257), as well as in the Homop- Fl«- W.-Saceoderu tvbcrndatus Gray. Brazil. (Fam. Reduviidae.) terOUS family, Membracidae (1 Ig. (Antennae absent in the specimen 283), assumes the most extraordinary represented.) shapes. Both meso- and meta-thorax are well developed. The former is remarkable for the great size of the scutellum ; in some cases (Plataspides, Scutellerides) this forms a large process, 1 For the structure and development of the Hemipterous trophi, see Mayer, Arch. Anat. Physiol. 1874 and 1875 ; Mecznikow, Zeitschr. wiss. Zool. xvi. 1866, p. 389 ; Geise, Arch. Naturgesch. xlix. 1, 1883, p. 315 ; Wedde, op. cit. li. 1, 1885, p. 113 ; Mark, Arch. mikr. Anat. xiii. 1877, p. 31 : Smith, 2V. Amer. Phil. Soc. xix. 1896, p. 176. HEMIPTERA that entirely covers and conceals the alar organs, so that the Insect has all the appearance of being apterous. The exact com- position of the abdomen has not been satisfactorily determined, opinions varying as to whether the segments are nine, ten, or eleven in number. The difficulty of determining the point is due to two facts : viz. the extreme modification of the terminal segments in connection with the genital appendages, and the prominence of the extremity of the alimentary canal. If this terminal projection is to be treated as a segment, it would appear that eleven segments exist, at any rate in some cases ; as the writer has counted ten distinct segments in a young Coreid bug, in addition to the terminal tube. This tube in some of the male Heteroptera is very subject to curious modifications, and has been called the rectal cauda. Verhoeff considers that ten seg- ments were invariably present in the females examined by him in various families of Heteroptera and Homoptera.1 In Aphidae (a division of Homoptera), Balbiani considers there are eleven abdominal segments present ; but he treats as a segment a pro- jection, called the cauda, situate over the anus ; this structure does not appear to be homologous with the rectal cauda we have just mentioned. In Coccidae the number of abdominal segments is apparently reduced. Schiodte states 2 that the older authorities are correct in respect of the stigmata ; there are, he says, in Heteroptera invariably ten pairs ; one for each thoracic segment ; and seven abdominal, placed on the ventral face of the pleural fold of the abdomen. In some cases there are additional orifices on the external surface that have been taken for stigmata, though they are really orifices of odoriferous glands ; these openings may exist on the metasterna or on the dorsal surface of the abdomen. The lateral margins of the abdomen are frequently greatly de- veloped in Heteroptera, and are called " connexivuni ; " the upper and lower surfaces of the body meeting together far within the marginal outline. Dr Anton Dohrn many years ago 3 called atten- tion to the extremely remarkable structure of the terminal segments in many male Hemiptera ; and the subject has been subsequently very imperfectly treated by the present writer and other ento- mologists, but it has never received the attention it deserves. Ent. Naehr. xix. 1893, p. 369. - Xaturhist. Tidskr. (3) vi. 1896 ; translated in Ann. X. Hist. (4), vi. 1870, p. 225. 3 Ent. Zeit. Stettin, xxvii. 1866, p. 321. STRUCTURE 539 The anterior In the females of numerous Heteroptera and Homoptera (Capsidae, Cicadidae, etc.) there is a well-developed ovipositor, that serves both as a cutting instrument to make slits in the stems of plants, and as a director to introduce the eggs therein. Verhoeff considers that it always consists of two pairs of processes (though one pair may be very small), one from the eighth abdominal segment, the other from the ninth.1 The antennae usually have very few joints, often as few as four or five, their maximum number of about twenty-five being attained in the males of some Coccidae, this condition being, however, present in but few of even this family. In Belostoma (Fig. 279) they assume extremely curious forms, analogous to what we find in the Coleopterous germs Hydropliilus. In addi- tion to the compound eyes, there are usually ocelli, either two or three in number, but wanting in many cases. The usual number of joints of the tarsi is three, but in Coccidae there is only one joint. The wings (Fig. 258) exhibit much diversity, pair usually differ greatly from the pos- terior ; they are called elytra, hemi-elytra or tegmina. This difference in the two pairs is the rule in the first of the great divisions of the Order, and the name Heteroptera is derived from the fact. In this Sub-Order the front wings close over the back, and are more or less horny, the apical part being, however, membranous. Systematists make use of the wings for the purpose of classification in Heterop- tera, and distinguish the following parts, " clavus," " corium," " membrane," the corium being the larger horny division, FIG. 258.— Alar organs of a the clavus the part lying next the scu- tellum and frequently very sharply dis- tinguished from the corium ; the mem- brane is the apical part. The outer or costal part of the wing is also often sharply delimited, and is called the " embolium ; " in the great family Capsidae and a few others, the outer apical part of the 1 Ent. Nachr. xix. 1893, p. 375. B clavus ; B, corium ; c, brane ; B, hind-wing. 540 HEMIPTERA corium is differentiated from the rest of the surface, and is termed the " cuneus." In Plataspides, one of the divisions in which the alar organs are entirely covered by the scutellum, they are modified in a very remarkable manner. In the Homoptera the divisions named above do not exist, and the wings in repose are placed in a different position, as stated in our definition of the Order. It is said to be very difficult to homologise the wing- uervures of Hemiptera, and nothing appears to be known as to the mode of their development. The alar organs in Hemiptera exhibit a very frequent form of variation within the limits of the same species ; this has not yet been elucidated.1 In some cases in the Heteroptera nearly all the individuals of a generation may have the wings aborted ; sometimes this occurs as a local variation. In Aphidae the occurrence of winged and wingless individuals is very common, and has even become an important factor in their extraordinary life cycles. (See Chermes, etc., subsequently.) Internal anatomy. — The alimentary canal presents consider- able diversity and some remarkable features. There is a slender tube-like oesophagus and a large crop. It is difficult to assign any of the parts posterior to this to the divisions usual in other Insects, and it is said that the distinction of parts histo- logically is as vague as it is anatomically. In the Heteroptera the Malpighian tubes open into two (or one) vesicular dilatations seated immediately in front of the short rectum : between this point and the crop there may be a very elongate, slender portion with one or more dilatations, these parts apparently replacing the true or chylific stomach. There is no gizzard. In the Homoptera the relations of the divisions of the alimentary canal are even more puzzling ; the canal is elongated and forms coils, and these are connected with tissues and tunics so as to make their dissection extremely difficult. List says that there are great differences in the alimentary canal among the members of the one family Coccidae. There are usually four Malpighian tubes, but in Coccidae there is only one pair, and in Aphidae none. The excretory cells of these tubes are in Hemiptera of remarkably large size. There is a large development of salivary glands, at least two pairs existing. There can be little doubt that some of their products are used for purposes of injection, as 1 On this subject, see Reuter, Ann. Soc. ent. France (5) v. 1875, p. 225. STRUCTURE 541 already described, though Kiinckel came to the conclusion that the saliva when placed in living plants is totally innocuous.1 The ganglia of the nervous system are all concentrated in the thorax and head. In some cases (in various Homoptera) the infra-oesophageal ganglion is placed at a distance from the supra- oesophageal ganglion, and may even be united with the thoracic mass of ganglia (Orthezia, etc.) ; in this case the chitinous frame- work of the mouth-parts is interposed between the supra- and the infra-oesophageal ganglia. In Pentatoma all the three gan- glionic masses are brought into close proximity, but in Nepa the thoracic mass of ganglia and the infra-oesophageal ganglion are widely separated. The ovarian tubes vary greatly in number : according to List in Orthezia cataphracta the number differs considerably in dif- ferent individuals, and even in the two ovaries of the same individual, the number being usually two. The testes are not placed in a common tunic, though they are frequently approxi- mated or even contiguous.2 The smell of bugs is notorious. In many species it is not unpleasant, though as a rule it is decidedly offensive. It is a remarkable fact that the structures connected with the production of this odour are different in many cases in the young and in the adult. The odour emitted by the latter proceeds from a sac seated at the base of the abdomen, and opening exteriorly by means of an orifice on each side of the metasternum ; while in the young there are two glands situated more dorsally and a little more backwards, and opening on two of the dorsal plates of the abdomen (Fig. 255, A).3 In the young the dorsum of the abdomen, where the stink-glands open, is exposed, but this part in the adult is covered by the wings. The odorific apparatus is specially characteristic of Heteroptera, and Kiinckel states that there is so much variety that generic and even specific characters might be drawn from conditions of the stink-glands. As a rule they are most constantly present in the plant-feeding forms ; in some essentially carnivorous forms (Eeduviidae, Nepidae, Xoto- 1 Ann. Soc. ent. France (4) vii. 1867, p. 45. 2 The chief work on the internal anatomy of Hemiptera is still Dufour's He- cherches anatomiqucs et physiologiques sur les Htmipteres, Mem. Savans Grangers, Paris, iv. 1833, p. 129. 3 Kiinckel, Ann. Soc. ent. France (4) vii. 1867, p, 45, and C.R. Ac. Paris, cxx. 1895, p. 1002. 542 HEMIPTERA nectidae) they are entirely absent. The offensive matter emitted by Notonecta is of a different nature, and is probably anal in origin. Metamorphosis or postembryonic development. — In the language of the systematists of metamorphosis, Hemiptera are said to be Homomorpha Paurometabola — that is, the young differ but little from the adult. According to Brauer's general- isations they are Menorhyiichous, Oligonephrous, Pterygogenea, i.e. they have a sucking mouth that does not change during life, few Malpighian tubes, and are winged in the adult state. It is generally admitted that the Homoptera do not completely agree with Heteroptera in respect of the metamorphosis, it being more marked in the former, and in Coccidae attaining (as we shall mention when discussing that family) nearly if not quite the condition of complete metamorphosis of a peculiar kind. Unfortunately we are in almost complete ignorance as to the details of the life-histories and development of Heteroptera, so that we can form no generalised opinion as to what the post- embryonic development really is in them, but there are grounds for supposing that considerable changes take place, and that these are chiefly concentrated on the last ecdysis. The young of some bugs bear but little resemblance to the adult ; the magnifi- cently-coloured species of Eusthenes (Fig. 255), before they attain the adult condition are flat, colourless objects, almost as thin as a playing-card ; it is well known that the extraordinary structures that cover and conceal the body in Plataspides, Scutellerides, Membracides, etc., are developed almost entirely at the last moult : it is not so well known that some of these changes occur with much rapidity. A very interesting account of the processes of colour- change, as occurring in Poecilocapsus lineatus at the last ecdysis, has been given by Lintner,1 and from this it appears that the characteristic coloration of the imago is entirely developed in the course of about two hours, forming a parallel in this respect with Odonata. When we come to deal with Aphidae we shall describe the most complex examples of cycles of generations that exist in the whole of the animal kingdom. Fossil Hemiptera. — Hemiptera are believed to have existed in the Palaeozoic epoch, but the fossils are not numerous, and opinions differ concerning them. Eugercon kockingi, a Per- 1 In Slingerland's Cornell Univ. Bull. No. 58, 1893, p. 222. vin FOSSIL FORMS CLASSIFICATION 543 miaii fossil, was formerly supposed to be a Homopterous Insect, but it is very anomalous, and its claim to a position in Hemip- tera is denied by Brauer,1 who considers it to be Orthopterous. It is now generally recognised that this fossil requires complete reconsideration. Another Permian fossil, Fulgorina, is admitted to be Homopterous by Scudder, Brauer and Brongniart. Scudder thinks the Carboniferous Phthanocoris was an Archaic Hetero- pterous Insect, and if correct this would demonstrate that both of the two great Sub-Orders of Hemiptera existed in Palaeozoic times. Brauer, however, is inclined to refer this fossil to Homoptera, and Brongniart 2 speaks of it as being without doubt a Fulgorid. Dictyocicada, RMpidioptera and Mcganostoma, from the Carboni- ferous shales of Commentry, have also been referred to Fulgoridae by Brongniart, but the evidence of their alliance with this group is far from satisfactory. In the Secondary epoch numerous Hemiptera existed, and are referred to several of the existing families. They come chiefly from the Oolite. In the Eocene of the Isle of Wight a fossil has been discovered that is referred to the existing Homopterous genus Triecphora. We are not entitled to conclude more from these facts than that Homoptera probably appeared before Heteroptera, and date back as far as the Carboniferous epoch. Classification and families. — No complete catalogue of Hemiptera exists, but one by M. Severin is in course of publica- tion. It is probable that there are about 18,000 species at present described, two-thirds of this number being Heteroptera. In Britain we have about 430 species of Heteroptera and 600 of Homoptera. The classification of the Order is not in a very advanced condition. The following table exhibits the views of Schiodte 3 in a modified form : — Front of head not touching the coxae. I. HETEROPTERA. Front of head much inflexed so as to be in contact with the coxae. II. HOMOPTERA. Sub-Order I. HETEROPTERA. Posterior coxae nearly globose, partly embedded in cavities, and having a rotatory movement. Mostly terrestrial forms. 1 . Trochalopoda. Posterior coxae not globose, larger, and not embedded ; their articulation with sternum almost hinge-like. Posterior aspect of hind femur usually 1 SB. Ak. Wicn. xci. 1 Abth., 1885, p. 275. " Lcs Insectes fossilcs, etc., 1894, p. 452. 3 Ann. Nat. Hist. (4) vi. 1870, p. 225. 544 HEMIPTERA more or less modified for the reception of the tibia when closed on it : mostly aquatic forms. 2. Pagiopoda. Division 1. TROCHALOPODA. This division includes the majority of the families of Heteroptera — viz. the whole of the terrestrial families except Saldidae, and it also includes Nepidae, a family of water-bugs. Division 2. PAGIOPODA. This includes . the six purely aquatic families of Heteroptera, except Nepidae, which appear to have very little connection with the other aquatic bugs. The only terrestrial Insects included in the family are the Saldidae ; in these the femora are not modified as they are in the aquatic forms. Hemiptera that live on the surface of water, not in the water, are classed with the terrestrial species. With these exceptions this arrangement agrees with that of Gymnocerata and Cryptocerata as usually adopted,1 and therefore followed in the following pages. Schiodte's characters, moreover, do not divide his two divisions at all sharply. Sub-Order II. HOMOPTERA. Tarsi usually three-jointed . . Series Trimera. „ ,, two-jointed . . ,, Dimera. „ „ of one joint . . ,, Monomera. The classification of Homoptera is in a most unsatisfactory state ; 2 no two authors are agreed as to the families to be adopted in the series Trimera. We have recognised only five — viz. Cicadidae, Fulgoridae, Membracidae, Cercopidae, and Jassidae. The Dimera consists of Psyllidae, Aphidae, Aleurodidae ; and the Monomera of Coccidae only. It is usual to associate the Dimera and Monomera together under the name of either Phytophthires or Sternorhyncha, but no satisfactory definition can be given of these larger groups, though it seems probable that the families of which they are com- posed are natural and distinct. Sub -Order I. HETEROPTERA. Series 1. Gymnocerata. The majority of the terrestrial families of Heteroptera form the series Gymnocerata, in which the antennae are conspicuous, and can be moved about freely in front of the head, while in 1 A table of the families is given by Ashmead, but does not work out quite satisfactorily, Entom. Americana, iv. 1888, p. 65 ; a brief table of the characters of the British families is given by Saunders, Hemiptera- Heteroptera of the British Islands, 1892, p. 12. 2 Those who wish to see tables of the families are referred to Ashmead, loc. cit. ; to Pascoe, Ann. Nat. Hist. (5) ix. 1882, p. 424 ; to Stal's Hemiptera Afri- cana, vol. iv. 1866 ; and for the families found in Britain to Edwards, Hemiptera- Homoptera of the British Islands. For a discussion in Danish on the value of the characters used, cf. Hansen, Ent. Tidskr. xi. 1890, pp. 19-76. HETEROPTERA PENTATOMIDAE 545 Cryptocerata they are hidden. The series Gymnocerata includes all the terrestrial Heteroptera, and the two families, Hebridae and Hydrometridae, which live on the surface of the water or in very damp places ; while Cryptocerata includes all the forms that live under water. Fam. 1. Pentatomidae. — Scutellum very large, at hast half as long us the abdomen, often covering the whole of the after-body and alar appendages. Antennae often Jive -jointed. Proboscis- sheath four -jointed. Ocelli two. Each tarsal claw with an appendage. — This, the largest and most important family of the Heteroptera, includes upwards of 4000 species, and an immense variety of forms. It is divided into no less than fourteen sub- families. The species of one of these, Plataspides, are remarkable for their short, broad forms, and the peculiar condition of the alar organs, which are so completely concealed by the great scutellum that it is difficult to believe the Insects arc not entirely apterous. The head is usually inconspicuous though broad, but in a few forms it is armed with horns. Though this sub-family includes upwards of 200 species, and is very widely dis- tributed in the Old World, it has no representatives in America. The Scutel- lerides also have the body covered by the scutellum, but their organs of flight are less peculiar than they are in the riataspides ; the Insects of this sub- family are highly remarkable on account of their varied and frequently vivid coloration ; some of them are metallic, and the colour of their integuments differs greatly in some cases, according to whether the specimen is wet or dry ; hence the appearance after death is often very different from that of the living specimen. These Insects are extremely numerous in species. The sub-family Phloeides (Fig. 259), on the contrary, includes only three or four South American species : they have no resemblance at all to other Pentatomidae ; they are flat, about an inch long, and look like scales of bark, in this respect agreeing with Ledra and some other Homoptera. The South American sub-family Cyrtocorides (Fig. 260) is of FIG. 259. — Phloea corticata. South America. VOL. VI 2 N 546 HEMIPTERA-HETEROPTERA CHAP. equally small extent ; the species are of strange irregular shapes, for which we can find no reason. The Tessaratomides includes many of the largest Hemiptera-Hetero- ptera, some of its members attaining two inches in length. The great family Pentatomidae, con- taining about 400 species, is represented in Britain by about 36 native species, the most interesting of which are perhaps those of the genus Acanthosoma. De Geer noticed long ago that the female of A. griseum exhibits great solicitude for its young, and his statement has since FIG. w.-cyrtocori, mon- been confirmed by Mr. Parfitt and the sirosus. South America. Eev. J. Helliiis, who found that the mother not only protects the eggs but also the young, and that for a considerable time after hatching.1 Very little is known as to the life-histories of Pentatomidae. In some cases the young are very different in appearance from the adults. The peculiar great scutellum is not developed till the mature condition is reached. But little attention has been given to the habits of Pentatomidae ; it is generally con- sidered that they draw their nutriment from plants ; the American Euthyrhynchus floridanus has, however, been noticed to suck the honey-bee, and we think it probable that a good many Pentatomids will be found to attack Insects. The term Pentatomidae as applied to this family is of modern origin : in most books the equivalent group is called Scutata, or Scutati, and the term Pentatomidae is restricted in these works to the sub-family called Pentatomides in the system we adopt. Fam. 2. Coreidae. — Scutellum not reaching to the middle of the body ; proboscis- sheath four-jointed ; ocelli present ; antennae generally elongate and four-jointed, inserted on the upper parts of the sides of the head ; femora not knobbed at the tip. — The members of this great family are easily recognised by the above characters ; formerly it was called Supericornia in connection with the characteristic position of the antennae. About 1500 species are known, and they are arranged in no less than twenty-nine sub-families. Many of them are Insects of large size, and they 1 Ent. Mag. vii. 1870, p. 53. HETEROPTERA COREIDAE 547 frequently have a conspicuous disc, or dilatation, on one of the joints of the antennae. Another very curious and, as yet, inex- plicable peculiarity very commonly met with among them, is that the hind legs may be of great size and deformed ; either the femora or the tibiae, or both, being very much distorted or armed with projections. Brilliant colour is here comparatively rare, the general tone being indefinite tints of browns, greys, or smoky colours. The South American genus Holymenia (Copius FIG. 261. — Diactor bilineatus. South America, x 4. FIG. 262. — PhyllomorpJia laciniata, carry- ing some of its eggs. Spain. of older authors) consists of slender forms, having the elytra transparent even on the basal part like Homoptera ; this and some other peculiarities give the species of this genus a certain resemblance to Insects of other Orders ; Westwood says that Diateina holymenoides (Diptera) greatly resembles a bug of the genus Holymenia. The tropical American genus Diactor consists of a few species of elegant colour having the hind legs very peculiarly shaped, the tibiae being flattened and expanded in a sail-like manner, and ornamented with agreeable colours different 548 HEMIPTERA-HETEROPTERA CHAP. from those on the rest of the body ; they are made more con- spicuous by the femora being remarkably long and thin ; it is probable that they are used as ornaments. The sub -family Phyllomorphides consists of about a dozen species, and is found in several of the western parts of the Eastern hemisphere, one species, P. laciniata, occurring in Southern Europe. This Insect is of very delicate texture, and the sides of the body are directed upwards and deeply divided so that a sort of basin is formed, of which the dorsum of the body is the floor ; the Insect is very spinose, and is thus enabled to carry its eggs, the spines helping to retain them in position on the back. It is said to be the male that thus carries the eggs. This species is able to stridulate, and when doing so vibrates its antennae with excessive rapidity. We have only about a score of species of Coreidae in Britain, and none of the remarkable forms of the family are among them. Fam. 3. Berytidae. — Very slender Insects with the first joint of the antennae and the femora thickened at the tips. — This small family was not distinguished from Coreidae by the older authors. It consists of about fifty species, eight of which are found in Britain. Fam. 4. Lygaeidae. — The characters are the same as those mentioned for Coreidae, except as regards the insertion of the antennae; the upper surface or face of the head is not so flat, but is transversely convex, so that seen in profile the antennae appear to be inserted well down on the sides of the head. — The name Infericornia was formerly applied to these Insects. They are on the average of smaller size than the members of the Coreidae or Pentatomidae, and are much less conspicuous in colour and form ; a good many of the larger Lygaeids are, however, variegate with black, yellow, and red. The family is very numerous in species, about 1400 being known; they are arranged in thirteen sub-families ; we have about sixty species in Britain, nearly all small. Eremocoris lives, when immature, in the nests of the wood-ant, according to Wasrnann. The family includes some notorious Insect-pests. The Chinch -bug, Missus leuco- pterus, commits very serious ravages on corn and grasses in North America. The Cotton-stainer, Dysdercus suturellus is also very injurious to cotton in certain parts of the New World : its growth has been described by Eiley,1 who thinks a dye valuable for 1 Insect Life, i. 1889, p. 234. via LYGAEIDAE — PYRRHOCORIDAE TINGIDAE 549 commercial purposes might be procured from the Insect. This bug has recently developed the habit of sucking oranges, and has thus become injurious in Florida, as the fruit readily decays after it has been punctured by these Insects. The phenomenon of " micropterism " is exhibited by numerous Lygaeids, as well as by Pyrrhocoridae. Fam. 5. Pyrrhocoridae. — Distinguished from Lygaeidae only by the absence of ocelli, and not recognised as a distinct family by all Hemipterists. About 300 species are included. Our only British member is the notorious Pyrrhocoris apterus ; it is, however, very rare in this country, though it abounds on the Continent, and has been the object of investigation by embryo- logists arid others. It displays in a most marked manner the curious dimorphism as to the alar organs that is so common in certain divisions of Hemiptera ; the elytra and wings being some- times normally developed, while in other cases the wings are entirely absent, and the horny, basal part of the elytra only is present. In some localities, and in some years, only the micro- pterous form is found, while on other occasions there may be a large percentage of the macropterous form. The abundance of this Insect has enabled the French chemist Physalix to obtain an amount of its colouring matter sufficient for analysis ; as the result he procured a substance, insoluble in water, very closely allied to carotine.1 The Oriental Insect Lohita grandis is one of the most remarkable of Bugs, the male of the Sumatran variety being over two inches in length, having enormously long antennae, and the abdomen extended to about twice the normal length, while the other sex is in the usual condition in these respects. The species is said to be injurious to the cotton-plant in India. Fam. 6. Tingldae. — Tarsi two-jointed. Elytra more or less reticulate, consisting of strong, irregular, thick lines forming a frame- work of cells, the enclosed part of the cell being of different texture and frequently transparent ; antennae with terminal joint more or less knob-like, the preceding joint very long ; ocelli ivanting ; pro- notum prolonged behind, covering the scutellum ; front coxae placed at the back of the thorax. — This is the first of a series of families with only two joints to the feet. These little bugs are very remarkable objects, and exhibit much variety in their peculiar 1 C.R. Ac. Sci. Paris, cxviii. 1894, p. 1282. 550 HEMIPTERA-HETEROPTERA FIG. 263. — Copium clavicorne. (After Riibsaamen.) x8 Europe. sculpture, which in numerous forms attains a condition of elegance well worthy of attention. There are nearly 300 species known, and in Britain we have about a score. The characters we have given above do not apply to the genus Piesma, though it is usually placed in this family ; its scutel- lum is not covered, and ocelli are present. Al- though but little is known as to the nature of the lives of Tingidae, yet it was pointed out long ago by Reaumur that a species of the family (probably C. clavi- corne, Fig. 263), lives in deformations of the flowers of the Labiate plant now called Teucrium chamaedrys ; Frauenfeld has more recently confirmed this observation, and shown that the closely allied C. te.uc.rii affects the flowers of T. montanum in a similar manner.1 Fam. 7. Aradidae. — Very flat, broad; scutellum exposed, large or moderate ; abdomen broader than the alar organs, which it frequently encases like a broad frame. Front coxae placed in the middle of theprosternum. — These very flat Insects, of obscure colour, have frequently very peculiar sculpture. They live under bark, or on fungi growing from bark, and are supposed to draw their nut- riment from the fungi, though but little is actually known as to their natural history. The family is almost cosmopolitan, and includes about 300 species, of which five occur in Eng- land. The small sub -family Isoderminae consists of a few species that are placed only TI • TJ ji FIG. 264. — Aradus orientalis. Siam. provisionally in Aradidae; they differ from the normal members by there being no groove on the 1 Verh. Ges. Wien. iii. 1858, p. 157. ARADIDAE — IIEBRIDAE — HYDROMETRIDAE 551 breast, so that the rostrum is free. Of the five species, three occur in Chili and Patagonia, two in Tasmania, and one in Australia. Fam. 8. Hebridae. — Minute lugs, of semiaquatic habits, clothed beneath with a dense, minute, silvery pubescence; antennae Jive-jointed ; legs of not more than average length ; elytra in larger part membranous. — This small family consists altogether of only about a dozen species ; we have two species of the genus Hebrus in Britain ; they are usually found in very wet moss. Fam. 9. Hydrometridae. — Form very diverse; antennae four-jointed, tarsi two-jointed. Coxae usually widely separated. Either wingless or with elytra of one texture throughout, having no membranous part. Under surface with a minute velvet -like pubescence. In many forms the legs are of great length. — Although of comparatively small extent — scarcely 200 species being at present known — this family is of great interest from the habit possessed by its members of living on the surface of water. In the case of the notorious genus Halobates (Fig. 265) the Insects can even successfully defy the terrors of Neptune and live on the ocean many hundi'eds of miles from land. There is great variety of form among Hydrometridae. The European and British genus Mesovelia is of short form, and but little dissimilar from ordinary land-bugs, with which, indeed, it is connected by means of the genus Hebrus, already noticed. Mesovelia represents the sub-family Mesoveliides, which, though consisting of only four species, occurs in both hemispheres, and in the tropics as well as in the tern- perate regions. Our species, M.furcata, walks on the surface of the water, the movements of its legs and the posi- tion of its coxae being those of land -bugs. Another British Insect — the highly remarkable Hydrometra stagnorum — is of excessively slender form, with long thin legs, by aid of which it Halobates sobrinus. Under surface of a female carrying eggs. Pacific Ocean (Marquesas). 552 HEMIPTERA-HETEROPTERA CHAP. walks on the surface-film of water, above which its body is held well separated. It is easily drowned, and if submerged it has great difficulty in escaping from the water. This genus repre- sents the sub -family Hydrometrides, and is apparently almost cosmopolitan. Velia currens is another common British Insect ; it loves the eddies and currents of backwaters on burns and streams, and is very abundant in Scotland. An American ally, Rhagovelia plumbea, appears to be not uncommon on the surface of the ocean in the Gulf of Mexico, near the shores. The great majority of the family belong to the division Gerrides, of which the curious, long Insects that float so lazily and skim so easily on the surface of quiet streams are typical. The species of the genus now called Gerris, but formerly known as Hydrometra are apparently distributed all over the world ; we have ten in Britain. They have very long legs, and on being alarmed move away with the greatest ease. The genus Hcdobates includes at present fifteen species. They are found on the ocean, where the surface-water is warm, in various parts of the world. They are destitute of any trace of alar organs, the meso- and meta-thorax are closely united and large, while the abdomen is very small, so that the body is of oval form ; the middle legs are thrown so far back that they are placed immediately over the posterior pair. When the sea is calm these Insects skim over the surface with rapidity, but disappear as soon as it becomes agitated. They are believed to feed on small animals recently deceased ; Witlaczil says on the juices of jelly-fish. The young are frequently met with, and there can be no doubt that the whole life-cycle may be passed through by the Insect far away from land. The Italian ship Vettor Pisani met with a bird's feather floating on the ocean off the Galapagos Islands, covered with eggs which proved to be those of Halobates in an advanced stage of development. It was formerly believed that the female carries the eggs for some time after their exclusion, and although this has since been denied, it is nevertheless an undoubted fact, for it was observed by Mr. J. J. Walker,1 to whom we are indebted for a specimen having the eggs still attached to the body, as shown in Fig 265. Mr. Walker believes the bugs shelter themselves when the sea is at all rough by keeping at a sufficient distance 1 Ent. Mag. xxix. 1893, p. 227. HYDROMETRIDAE 553 below the surface ; they can dive with facility, and are gregarious. They are frequently found close to the shore, and Mr. Walker has even met with them on land. The stink-glands of other Hemiptera are said by Nassonoff to be replaced in Halobates by peculiar ventral glands. An allied genus, Halobatodes, was supposed to be oceanic, but this is not the case, some of the species having been found recently in fresh water in India, and others in estu- aries at Port Darwin. A remarkable allied form, Jfermatobates haddoni, was recently discovered by Pro- fessor Haddon in Torres Straits. Apart from the oceanic life, Halolates is by no means the most ex- traordinary of the Hydrometridae. The Javanese Ptilomera laticaudata repeats some of its peculi- arities, and is of larger size, with the sexes very different. The most remarkable of the family is perhaps the fresh-water genus Rheumatoljates (Fig. 266), in which the males have peculiar prehensile antennae that look like legs. These curious Insects inhabit North America and the West Indies. We may here notice an enigmatic Insect called Hemidiptera haeckeli by Leon. From the single specimen known it is con- cluded that the Insect has only one pair of wings, and that they are attached to the metathorax. It is, however, possible, as FIG. 266. — Rheumatobates bergrothi. x 10. West Indies. (After Meinert.) 554 HEMIPTERA-HETEROPTERA CHAP. suggested by Bergroth,1 that the anterior pair have been detached by some accident. Fam. 10. Henicocephalidae. — Head swollen behind the eyes so as to form a sort of globe, on the anterior part of which the ocelli are placed. Rostrum extremely short. Elytra, rather large, of one consistence throughout ; conspicuously veined. — There is only one genus ; it is very widely distributed, about a dozen species being known ; one of these occurs in the south of Europe. These curious little bugs appear to be most nearly allied to the Eeduviidae. According to Westwood and others they are somewhat gregarious ; a Tasmanian species dances in the air after the fashion of midges or May-flies, and dispenses an agreeable, musk-like odour. Fam. 11. Phymatidae. — Front legs of peculiar structure, short and stout, with long coxae, short thick femora, and tibiae curvate, pointed ; frequently without tarsi. — The Insects of this family are FIG. 267. — Carcinocoris binghami (Phymatidae). Burma. believed to be predaceous, the structure of the legs being such as is called raptorial, and one species, Phymata erosa, being known to capture and suck honey-bees in North America. There are only about seventy species of Phymatidae known. We have 1 Wien. ent. Zc-it. xi. 1892, p. 169. PHYMATIDAE REDUVIIDAE 555 none in Britain, though there are a few in Southern Europe ; one of these, P. crassipes, extends as far north as Paris. The distinction of the family from Beduviidae is doubtful.1 There are a few very rare forms (Fig. 267) in which the front tibia is articulated to the femur in such a way that a pair of pincers is formed : the tarsus is in this form, as well as in some other Fhymatidae, absent. Fam. 12. Reduviidae. — Head more or less elon- gate, very movable, eyes placed much in front of the thorax, ocelli, when present, behind the eyes. Proboscis short, or moderately short, not ex- tending on to the breast, in repose curved under the head so as to form a loop there- with. Elytra, when present, consisting of three divisions. Tarsi three-jointed. — This is one of the largest and most important families of Hemi- ptera. Upwards of 2000 species are already known ; the habits seem to be chiefly of a predaceous nature, the creatures drawing their nutriment from the animal rather than from the vege- table kingdom, and their chief prey being in all probability other kinds of Insects. There is, perhaps, no family of Insects exhibit- ing a greater variety of form and colour. The Emesids are amongst the most delicate of Insects, equalling in this respect the daddy- 1 Monograph of Phymatidae : Handlirsch, Ann. Hofmus. Wien, xii. 1897, p. 127. . 268. — GhUianella ftliventris. Brazil. A, the female Insect. B, extremity of the body of the male. 556 HEMIPTERA-HETEROPTERA long-leg flies ; they are, however, highly predaceous ; their front legs are peculiarly formed for capturing and holding their prey, and have long coxae, like Mantis, so that these Insects are commonly mistaken for small or young Mantises, from which their sucking proboscis at once distinguishes them. This curious starved-look- ing form of bug reaches its maximum of peculiarity in the South American genus Ghili- anella (Fig. 268). Ac- cording to Pascoe the linear form enables the young larva to be carried about by the mother, the long slender abdo- men of the larva being curled around the thorax of the parent. Ploiaria pallida, from Woodlark Island, is an Insect of excessive fragility and elegance, with the long thin legs coloured with alternate patches of black on a white ground, giving rise to a very curious appearance remarkably analogous to what we find in some of the equally delicate daddy- long-leg flies. We have three species of Emesides in Britain, but most of our Keduviidae belong to the sub-family Nabides. These approxi- mate to ordinary bugs in appearance and characters more than do any other of the Keduviidae. One of our indigenous Nabides is of great interest from the curious resemblance it has to an ant (Fig. 269). The likeness is brought about by the sides of the base of the abdomen being very pallid in colour, except a dark mark in the middle ; this mark is in shape like the pedicel of an ant. Viewed in profile it is found that on the base of the abdo- men there is an elevation like the " scale " in this position in FIG. 269. — Nabis lativentris, young. Cambridge. A, Insect seen from above ; B, profile. REDUVIIDAE 557 ants, and that the abdomen is extremely ant-like in form. This resemblance is quite parallel with that of an Orthopteron to an ant (see Vol. V. p. 323); the Insect is by no means uncommon, and it is strange that this curious case of resemblance should hitherto have escaped notice. The bug runs about on plants and flowers, and is frequently in ^, j^ j./ company with ants, but we do not know msali#r whether it preys on them. Not the FIG. 270. — Ptilocnemus sidnicus. Australia. (After Mayr.) least remarkable of the facts connected with this Insect is that the resemblance is confined to the earlier instars ; the adult bug not being like an ant. We may here mention that there are numerous bugs that closely resemble ants, and that on the whole there is reason to be- lieve that the resem- bling forms are actually associated during life, though we really know very little as to this last point. The little sub-family Holoptilides, with twenty-five species, but FIG. 271. — Myiodocha tipulina. China. widely distributed ill the Easte hemisphere, is remarkable on account of the feathered 558 HEMIPTERA-HETEROPTERA CHAP. antennae and legs of its members (Fig. 270). Altogether four- teen sub-families are recognised, the most extensive one being Harpactorides, including a great variety of remarkable forms ; in the South American genus Notocyrtus (better known as Saccoderes, Fig. 257), the prothorax is swollen and covers the body to a greater or less extent in the fashion of a hood. In Yolinus and Eulyes the coloration is the most conspicuous system that could be devised, the sides of the abdomen (connexivum) being expanded into bright -red lobes on which are placed patches of polished -black. The most remarkable form of Eeduviid is, perhaps, one from China (Fig. 271) of considerable size, of great fragility, and greatly resembling, like some Emesides, a daddy-long-legs fly, though it does not belong to the Emes- ides. It is an altogether anomalous form. According to Seitz there is found on the Corcovado in Brazil a Eeduviid that exactly resembles one of the dark stinging-wasps of the genus Pepsis, and the bug makes the same sort of movements as the wasp does, though these are of a kind quite different from those of ordinary bugs.1 Although the attacks of Redu- viidae on animals are usually con- fined to the smaller and more FIG. 272. — Eggs of Endochus cinga- , „ , , . , ., . . , lensis. "The eggs are attached defenceless kinds, yet this is by no to a leaf and to each other by a means invariably the case ; there viscid substance ; eggs reel, the , cover pale yellow, with the club are in iact numerous species that do white at the tiP."-MS. note of not hesitate to attack man himself. E. E. Green. . . Several species of Reduvvus do this in Southern Europe, and are frequently met with in houses. R. personatus is the only species of the genus in England ; though far from common anywhere, it is sometimes found in houses, and is said to destroy the common bed-bug ; it is able to pass its whole existence in our habitations, for the young are found as frequently as the adult, and are usually concealed by a quantity of dusty matter, or refuse, adhering to the body. This habit of covering the body with some foreign substance is natural to the Insect, the young that are found on trees being covered with matter derived therefrom. Darwin has given us an account of 1 Ent. Zcit. Stettin, li. 1890, p. 281. vin AEPOPHILIDAE — CERATOCOMBIDAE CIMICIDAE 559 the Benchucha,1 a bug an inch long, which in South America attacks human beings after the fashion of the common bed-bug. In this case no ill-effects follow the attack, but in the case of Conorhinus sanguisuga in Arizona, great pain and inflammation ensue and may end in the gathering and discharge of pus. Not the least remarkable of characters of Reduviidae is the form of the eggs of some of the species (Fig. 272, and Vol. Y. Fig. 78, C) ; the egg bearing a peculiar operculum, the purpose of which is at present quite mysterious. Fam. 13. Aepophilidae. — A single species forms this family. It is of considerable interest, as it is incapable of flight, passing a large part of its life covered by the sea. Aepophilus bonnairei is a small Insect with quite short head, without ocelli, and with the organs of flight represented by a pair of very short elytra, with rounded hind-margins. It is found on the shores of Western France, and, as a great rarity, on our own south coast. It no doubt sucks small soft animals. In the Channel Islands it occurs in spots where it is nearly always covered by a con- siderable depth of water. Fam. 14. Ceratocombidae. — Minute lugs with ocelli and elytra. Rostrum free. Head not broad, somewhat prolonged in Jront ; eyes close to the thorax. Elytra usually without a dis- tinctly separated membrane. Tarsi three-jointed. — This family includes at present only a few, minute, fragile bugs, that have often been classified with Cimicidae or Anthocoridae. We have only two British species, one of which, Dipsocoris alienus, is common amongst the damp shingle at the margins of the burns and waters of Scotland. Fam. 15. Cimicidae. — Ocelli absent; elytra very short and broad, so that the broad abdomen is left uncovered. Head short and broad. Rostrum received in a groove beneath the head. Tarsi three-jointed. — Although this family consists of only a dozen species, it is the most notorious of all the Order, as it includes the detestable Cimex lectularius or common Bed-bug. This Insect is nowr peculiar to the habitations of man, and is said not to trouble savage races ; or rather it is supposed to be present only when the habitations have a certain degree of comfort and per- manence. It has no fixed period of the year for its development, but the generations succeed one another so long as the temperature 1 Naturalist's Voyage, ed. 1884, p. S30 ; chap. xv. 560 HEMIPTERA-HETEROPTERA is siifficiently elevated ; during too cold weather the Insects merely become stupefied, their lives being as it were interrupted till warmth returns. It is a favourite food with other Insects, and is destroyed by cockroaches and ants as well as by Eeduvius ; the small black ant Monomorium will, it is said, clear a house of the bed-bug in a few days. Nothing is really known as to the origin of this Insect ; it is now very widely distributed. The other species of the family frequent birds and bats, and are very similar to the common bug. The genus to which the bed-bug belongs is in many works called Acanthia instead of Cimex. Other authors apply the term Acanthia to Salda, but it is better to allow the name Acanthia to fall into disuse. Fam. 16. Anthocoridae. — Minute lugs, usually with ocelli and with elytra ; the latter occasionally abbreviated, but usually fully developed, with membranous tip. Head prolonged in the middle in front much beyond the insertion of the antennae ; eyes not far from the thorax. Rostrum free. — These small and obscure Insects appear to be rather numerous in species, and to be chiefly connected with woods and forests. Some of the species live in ants' nests. We have 27 British belonging to 11 genera. species About 200 species of the family are known. The members of the sub-family Microphy- sides are remarkable from the great dissimilarity of the sexes, for which it is not possible to assign any reason. Fam. 17. Polyctenidae. — Proboscis - sheath three - jointed, tarsi four -jointed, antennae four -jointed. Teg- mina quite short, of one con- sistence.— The four or five anomalous species forming this family are parasites on bats of the genus Molossus, and have been found in both the Eastern and Western hemispheres. Westwood, who first described FIG. 273. — Polyctenes fumarius. (After Westwood.) POLYCTENIDAE CAPSIDAE 56l them,1 treated them as aberrant Anoplura or Lice, but there do not appear to be any sufficient grounds for removing these para- sites from Hemiptera-Heteroptera. The condition of their alar organs reminds one of what exists in Cimex and Aepophilus, and the mouth is not known to possess any very peculiar structure. We have had no opportunity of making a thorough examination of Polyctenes, and therefore speak with some diffidence. Fam. 18. Capsidae. — Moderate-sized or small buys, of delicate consistence, without ocelli ; the elytra and wings usually large in proportion to the body, the former with two cells (occasionally FIG. 274. — Helopeltis sp. East India. only one) in the membrane. Antennae four-jointed, the second joint usually very long, the terminal two more slender than the others. The proboscis not received in a groove. Scutellum exposed, mode- rately large. Tarsi three-jointed. female with an ovipositor capable of exsertion. — This family is one of the most extensive of the Hemiptera ; we have about 170 species in Britain, where they are most abundant in the south. The exotic species have been but little collected. Their colours are usually delicate rather than vivid, and are never metallic. They frequent plants of all kinds, and many of them skip by the aid of their wings with great agility in the sunshine. The majority probably suck the juices of the plants, but some are known to prey on other Insects. The species of the Indian genus Jfelo- T r . ° FTG. 275. — Section of a stem with peltis (Fig. 274) are remarkable by egg of a Capsid bug allied possessing a knobbed spine projecting straight up from the scutellum, making the individual look as if it were a specimen with a pin through 1 Thesaurus ent. Oxoniensis, 1874, p. 197. VOL. vr 2 o to Helopeltis (Moesa-blight). x 5S. (After Dudgeon.) 562 HEMIPTERA-HETEROPTERA CHAP. it : they attack the tea-plant and do considerable damage. They are known as Mosquito-blight. The egg is of comparatively large size, and is placed by the bug in the stems of the tea-plant, but attached to one end of the egg are two long slender threads that project externally. A similar egg (Fig. 275) and method of oviposition have been described by Mr. Dudgeon as occurring in another species of Capsidae, called Moesa-blight, in India.1 Fam. 19. Saldidae. — Head short and broad, ivith large, pro- minent eyes. Ocelli present. Proboscis not applied to under surface of head or breast in repose. Scutellum large, not covered. Elytra covering the upper surface of the abdomen, formed of three distinct parts. Tarsi three-jointed. — These little bugs run with velocity over mud in damp places, or live in wet moss ; some of them can jump ; they are all of dark or obscure colour. There are only three genera : Salda, of which we have numerous British species, being the principal one. Series 2. Cryptocerata. The remaining families of Heteroptera are of aquatic habits, and form in nearly all works a separate division called Hemiptera Cryptocerata (or Hydrocorisae, or Hydrocores), distinguished by the antennae being apparently absent ; they are, however, realty present, being situate on the under side of the head, to which they are closely pressed, or in some cases placed in a pocket in front of each eye. There are six of these families. Schiodte is doubtless correct in treating this division as an unnatural one ; it is, however, generally adopted, and is convenient for the pur- poses of nomenclature and arrangement. Fam. 20. Galgulidae or Pelogonidae. — Form short and broad ; head very broad, with prominent eyes, ocelli present. Hind legs thin, formed for running. — The Insects of this family are but little known; they are only sub-aquatic in habits, frequent- ing damp places at the margins of streams and waters. The presence of ocelli distinguishes them from other water-bugs, with which indeed the Galgulidae appear to be but little related. There are only about twenty species of the family known. AVe possess none in Britain ; but one, Pelogonus marginatus, occurs 1 2nd. Mus. Notes, iii. No. 5, 1894, p. 53. CRYPTOCERATA NEPIDAE in South Europe. The other members of the family are very widely scattered over the surface of the earth. Fam. 21. Nepidae. — Abdomen furnished behind with a long slender siphon ; front legs more or less elongate for capturing prey, placed quite -at the front edge of the prothorax. — This family consists of two interest- ing but very dissimilar genera, Nepa and Ranatra. Both are widely distributed over the earth, and are rather numerous in species.1 We have one species of each genus in Britain. Nepa cinerea, the common " water - scorpion," is one of the commonest of Insects in Southern Britain, living con- cealed in shallow waters when nearly or quite stagnant. Ranatra linearis (Fig. 276) is much less common, and appears to be getting rarer ; it is not re- corded from farther north than Cambridge. The nature of the respir- atory arrangements in these Insects is of considerable in- terest ; the long tube at the extremity of the body consists of two parts (as shown in Fig. 276) brought together in the middle, one from each side. Lacaze-DllthierS States that the FIG. 276— Ranatra linear/*, with the two , T -, portions, a, of the respiratory siphon processes are elongated pleurae, separated. Cambridge. but in the young it is far from clear that this is the case. However that may be, they seem to convey air to the true breathing organs, situate inside the cleft on the apical part of the abdomen itself; but details as to the way in which transfer of air is effected along this 1 Ferrari, Monograph of Nepa, Ann. Hofmus. IVien, iii. 1888, p. 171. 564 HEMIPTERA-HETEROPTERA very protracted passage are not forthcoming. The develop- ment in Nepa has been studied to a certain extent. The apical stigmata are the only pair of the abdominal stigmata that exist in the imago of Nepa, the other six pairs being obliterated ; the third, fourth, and fifth, according to Schiodte, in a very peculiar manner : hence, as Martin says,1 the respiratory system is metapneustic. In an earlier stage of the life, however, these six pairs of stigmata exist in functional activity placed in a groove on the under surface of the body ; so that the condition is that termed peripneustic, and remains so till the final moult, when the long siphon appears. In the early life there is a short prolongation from the end of the body in connection with the pair of grooves alluded to, but it is a single unpaired organ, and does little therefore to explain the appear- ance of the siphon, which must, at present, be considered as being suddenly developed at the last moult. The eggs of Nepidae are remarkable objects ; that of the common water-scorpion bears seven filaments at one end (Fig. 277); while that of Ranatra is more elongate, and bears only two, very elongate, threads. These eggs are deposited in the stems of water-plants, being introduced therein, so that the body of the egg is concealed while the threads project : those of Ranatra are placed in stems floating on the water, and in consequence of the threads the stems look as if they were infested by some fungus. The struc- Egg of ture and formation of the eggs have been (After Korscheit) investigated with considerable detail by Kor- schelt.2 He looks on the filaments as pneu- matic, and considers that they supply a coating of air to the body of the egg; they consist of a spongy mass encircled by two layers of egg-shell, both of these latter being peculiar in struc- ture ; the spongy mass is continuous with a layer of the same kind of substance placed on the interior of the shell of the body i'JSutt. Soc. Philomat. (8) v. 1893, p. 57. There is some diversity of opinion as to the respiratory orifices, and some authorities say that thoracic stigmata exist even in the imago. 2 Ada Ac. German, li. 1887, p. 224, and Zeitschr. wiss. Zool. xliii. 1886, p. 537. FIG. 277. Nepa vni NEPIDAE NAUCORIDAE — BELOSTOMIDAE 565 of the egg. It will be recollected that we have described (p. 562) an egg, apparently of the same nature, deposited by Capsids in the stems of land plants, so that it is very doubtful whether the threads are really connected with the aquatic development of the embryo in Nepidae. But the most interesting feature connected with these eggs is, according to Korschelt, the mode of development of the filaments, which is sui generis ; the shell of the egg is developed in the ordinary manner as an exudation or excretion from epithelial cells ; but the shell of the filament is formed as an intracellular product ; a mode of chitin-formation that appears to be peculiar to this structure. Korschelt remarks that " it is in the highest degree worthy of attention how by any process of development through a large number of successive generations so complex a condition could be established as the result of adaptation to external conditions ; and this becomes even more interesting when we remember that highly peculiar special processes and departures from the usual modes of tissue- formation are necessary to permit the development of this apparatus." l Fam. 22. Naucoridae. — -No ocelli, and no terminal process to the body ; front legs inserted on or near the front of the prosternum. Anterior femora usually broad and fiat. — The members of this family are truly aquatic, and swim readily in the water. The family is small, including about nine genera and thirty species, but, like many water-Insects, the genera are widely distributed. We have two in Britain — one of them, Xaucoris, common ; the other, Aphelocheirus, rare. Fam. 23. Belostomidae.— -. 397 ; see on this organ also Mordwilko, Zool. Anz. xviii. 1895, p. 357. viii APHIDAE 589 organ may in some way replace the missing Malpighian tubes. Another highly peculiar structure is the siphons, frequently called nectaries, honey-tubes, or siphuncles. They are situated on the dorsal aspect of the fifth abdominal segment, but exist only in certain of the sub-families ; they are of very different lengths according to the species, and are capable of movement ; they open directly into the body cavity, though exceptional openings into the body cavity are extremely rare in Insects. They excrete a waxy matter, which first appears as oil-like globules. It was formerly supposed that they were the means of secreting the sugary matter, called honey-dew, so much prized by ants and some other Insects ; but this is now ascertained to be erroneous. This matter comes from the alimentary canal, and is secreted in large quantities by some species, Biisgen having observed that forty-eight drops, each about 1 mm. in diameter, were emitted by a single individual in twenty-four hours.1 Certain gall-dwelling Aphidae — Pemphigus, Chermes (Fig. 285), Schizo- neura — possess numerous wax glands ; these seem to replace the siphons, and excrete the peculiar, whitish flocculent matter that is so conspicuous in some of these Aphids. Earlier anatomists failed to find any dorsal vessel, and it is consequently reported in books to be absent. It has been, how- ever, recently detected by Witlaczil, and Mordwilko states that it does not differ from that of other Insects. We have already alluded to the fact that the mode of repro- duction of Aphids leads to an unrivalled increase. This, however, is not due to the prolificness of the individual, which, in point of fact, appears to be considerably below the average in Insects, but rather to the rapidity with which the young begin to reproduce. This has been discussed by Huxley, Buckton, and others. The first-named naturalist calculated that the produce of a single Aphis would, in the course of ten generations, supposing all the individuals to survive, " contain more ponderable substance than five hundred millions of stout men ; that is, more than the whole population of China." : It has since been contended that Professor Huxley's calculation was much below the mark. Although it is somewhat difficult to make a calculation dealing adequately with the actual facts, yet it is clear that the increase 1 Biol. Ccntralbl. xi. 1891, p. 193. 2 See, inter alia, "Webster, /. New York ent. Soc. i. 1893, p. 119. 590 HEMIPTERA-HOMOPTERA CHAP. of Aphids is such that, drawing as they do their nutriment directly from the plant in its growing state, in the course of two or three years there would be no nutriment available for other animals, except such as might be derived from plants not attacked by Aphids. The numbers of Aphidae would be so great that they could not be expressed by ordinary numerical methods, and their increase would be actually limited only by the relations existing between different kinds of plants, and between plants and Aphids. This result is avoided by the fact that Aphids are themselves the victims of a whole army of Insect enemies. They have the numerous members of a special group (Braconidae, Aphidiides) of minute Hymenoptera to live inside their bodies, and many Aculeate Hymenoptera depend entirely on the Aphidae as the source of food for their own progeny. The Lady-birds — Coceinellidae — live on .Aphids and Coccids, and themselves in- crease to such an extent as to be in many years a conspicuous part of the Insect world. Crowds of the larvae of Hemerobiids and Syrphids are constantly engaged in spearing and sucking the Aphides. Hence the old naturalist Bonnet said that, just as we sow grain for our benefit, Nature has sown Aphids for the benefit of multitudes of different Insects. He might have added that these different Insects are for the benefit of man, it being clear that without them the population of the world must rapidly decrease. Ants treat Aphidae more intelligently than most other Insects do, for they do not destroy the helpless creatures, but utilise their -products in the way man does those of the cows he keeps. The relations between ants and Aphids is itself an extensive chapter in Natural History ; many facts have been brought to light showing that the ants manage the Aphids in a prudent or intelligent manner, distributing them when too numerous in one place, keeping guard over them, even building shelters for them, and in some cases keeping them in direct association, by retaining the Aphids in their own dwellings. The further investigation of these points goes, the more it tends to raise the actions of the ants to the level we call in ourselves intelligent. It would even appear that the ants are acquainted with the migrations of the Aphids from one species of plant to another, Webster informing us that as the Aphis-population on an apple tree multiplied the ants in attendance anticipated their migration to wheat and grass ALEURODIDAE 591 by carrying them to those plants.1 We have nearly 200 species of Aphidae in Britain,2 and there may perhaps be 800 known altogether. To what extent they may occur in the tropics is undetermined. There are said to be no native species in New Zealand. Fam. 8. Aleurodidae. — Minute Insects, with four mealy wings, seven-jointed antennae, two-jointed feet, terminated Toy tivo claws and a third process. These minute Insects are at present a source of considerable perplexity, owing to the curious nature of their metamorphosis, and the contradictory accounts given of them. In the earlier stages they are scale -like and qui- escent, being fixed to the under side of a leaf. The French authors Signoret and Girard state that the young are hatched having visible ap- pendages and seg- mentation, but that after they are attached to the leaf the organs gradu- ally suffer atrophy. Maskell States the FIG. 287. — Instars of Aleurodes immaculata. Europe. Opposite, Saying that 290.— Instars of^octytopiwsato'. (After Ber- (/arodes) she becomes en- lese.) A, Egg ; B, young larva ; C, first male j ,1 nymph ; D, second male nymph ; E, adult male ; cysted, and apparently F> adult female. A11 equally m;iguifiea. x 20. suffers an almost com- plete histolysis, reappearing after a very long period (it is said it may be as much as seven years) in a considerably altered form. The post-embryonic development of Aspidiotus nerii has been studied by Schmidt 1 and Witlaczil,2 whose accounts agree except as to some points, such as the number of ecdyses. The young, or larva, is hatched with fairly well-developed legs, antennae, and rostrum; there is no external difference between the sexes. The larva selects some spot on the plant and drives its rostrum therein, thus becoming fixed ; moults occur, and the body excretes waxy matter from its sides in processes that fell together and form the shield; the female becomes much larger than the male. The legs and antennae of both sexes disappear, so that the power of movement is completely lost. The mouth-parts also atrophy. The female after this undergoes no further change, except that of growth in connection with ovarian development. The male, 1 Arch. Naturgesch. li. i. 1885, p. 169. ~ Zeitschr. wiss. Zool. xliii. 1886, p. 156. 596 HEMIPTERA-HOMOPTERA however, continues development ; notwithstanding the impossi- bility of taking food, owing to the absence of a mouth, it increases much in size, and the organs of the future perfect Insect commence to develop from imaginal discs in a manner similar to that which occurs in the Dipterous genus Corethra ; no mouth- parts are however developed, these being merely represented by spots of pigment, or rudimentary additional eyes. The wings are developed outside the body. Difference of opinion prevails as to the nature of the instars between the young larva and the imago. It is clear, however, that Fig. 291, D, corresponds fairly 5iv a FIG. 291. — Development of male of Aspidiotus nerii. A, Newly hatched larva; B, prae-pupal instar ; C, pupa before ecdysis ; D, pupa shortly before the emergence of the imago : a, antenna ; e, eye ; /, •wing-rudiment ; I, leg ; o, basal part of mouth-org ins. (After Schmidt.) Magnification not definitely stated. with the pupa of Insects with complete metamorphosis, and the instars shown in Fig. 291, B, C, may therefore be looked on as equivalents of the resting-larva stage of ordinary Insects with complete metamorphosis. Witlaczil considers this development to be a condition of incomplete, approaching very nearly to complete, metamorphosis. The condition is perhaps more pre- cisely estimated if we recollect that winged Insects are divided into two series, in one of which the wings are developed outside the body ; in the other, inside the body. The Insects with very complete metamorphosis all belong to the second of these two series, while in the male Coccid we have the highest form of metamorphosis attained by any of the first series. As regards the development of the female encysted nymph or pupa, previously alluded to as being found in the " ground-pearls " of vin COCCIDAE SCALE-INSECTS 597 the genus Margarodes, we can at present offer the reader no satisfactory account.1 Products of Coccidae. — Honey-dew is secreted by Coccidae, but as a rule not so extensively as by Aphidae and some other Homoptera ; nevertheless, it is often sufficient to make the plants frequented by Coccids very sticky and unclean. Some species make a really extensive exudation of such matter. Reaumur records that a Coccid, which is doubtless Lecanium persicae, excretes a supply of honey-dew that drips to the ground ; he says it tastes sweet and nice. The manna mentioned in the book of Exodus is pretty certainly the honey-dew secreted by Coccus (now Gossyparia) mannifera, which lives on T!<•" Bee-louse or -tick, 520 Bees, 10 f. Bees born of carcases, myth, 499 Bees' nest beetle, 235 Bees, stylopised, 300, 303 Beetles, 184 f. Bellesme, on buzzing, 19 Belostomidae, 534, 565 Bembecidae, 482 Bembecides, 119 f. Bembex, 509 ; B, rostrata, 4, 120, 120 i. : B. spinolae, 130 n. Benchucha bug, 559 Berosus, 218 Berytidae, 548 Bibio, 475, 476, 477 ; B. marci, 477 Bibionidae, 475 Birds and butterflies, 338 Biscuit-weevil, 247 Bitoma crenata, 233 BMacomorpha, 473 Black-fly, 530 Blanchard, on flies attacking man, 517 n. Blepharoceridae, 464 Blind beetles, 205, 221, 233 Blissus leucopterus, 548 Blister-beetles, 269 Blochmann, on founding new nests, 145 Blood-sucking, Diptera, 457 ; Mosquitoes, 467 Blood-worms, 468 Blow-flies, 511 Blue-bottles, 511 Bogus Yucca-moth, 433 Boletophila luminosa, 463 Boll- worm, 416 Bombardier-beetles, 201 Bonibus, 53 f. ; insect in nest of, 22 i ; fleas in nests of, 525 ; parasite of, 94, 497 ; proboscis of, 13 f., 14 ; B. agronim, 54 ; B. lapidarius, 54 ; B. muscorum, 57 ; B. variabilis, 60 Bombyces, 367 Bombycidae, 36S, 375, 406 Bombyliidae, 485 Bombylius major, 488 Bombyx mori, 375 j B. yamamai, 325 Book-worm, 247 Borboridae, o04 /In/'/H'i-HS, 505 Borocera madagascariensis, 405 Bostrichidae, 246 Bot-flies, 514 Brachelytra, 224 Brachycera, 441, 454 Brachycerides, 291 Brachyscelides, 592, 598 Brachytarsus, 290 6o6 INDEX Braconidae, 590 Bradypus cuculliger, Tineid on, 430 Brahmaeidae, 368, 374 Brain, 320 ; cephalic and thoracic, 449 Branchiae, 208, 244 Brands, 332 Brassolides, 349 Lrathinus, 223 Brauer, on Dipterous larvae, 451 ; on Oes- tridae, 514 Braula coeca, 520 Braulidae, 520 Breastbone, 459 Breeze-flies, 443, 481 Breitenbach, on proboscis of Lepidoptera, 311 n. Breithaupt, on proboscis of bee, 15 ; on deglutition of bees, 18 Breuthidae, 295 Brenthus anchorago, 297 Brephos notha, 416, 416 Brimstones, 357 Brontes planatus, 234 Brown-tail moths, 407 Bruchidae, 276 Bruchus fabae and B. lentis, 277, B. pisi, 277 Bryophila, 418 Buckell, on development of pattern, 335 Buffalo-gnats, 477 Bugong-moth, 417 Bugonia-myth, 499 Bull-dog ants, 171, 173 Bull's-horu thorn and ants, 168 Bumble bee — see Bombus Buprestidae, 261 Buprestis attenuata, supposed larvae of, 262 n. Burgess, on suction, 311 Burnet-moths, 390 Burrows, of Dasypoda, 27; of Halictus, 24, 25 ; of Odynerus, 74 Bursa copulatrix, 321 Burying-beetles, 221 Butterflies, 341 f. Buzzing, 19 Byrrhidae, 242, 255 Byrrhus pilula, 242 Bythoscopidae, 578 Byturus, 241 Cadphises moorei, 391 Calandrides, 289 Calcium oxalate, 406 Calicurgus, 101 ; C. hyalituitus, 102, 106 Caligo eurylochiis, 350 Callidea baro, 303 n. Callidulidae, 370, 400 Calliphora, 448 ; C. erythrocephala, C. vom- itoria, 511 Callirhipis dejeani, 256 Callomyia, 496 Callostoma fascipennis, 489 Caloptenus, 270 ; C. italicus, 489, C.spretus, 488, 506, enemies of Calypter, calypterate, 448 Calyptrate Muscidae, 448, 504 Camberwell Beauty, 352 Camel bot-fly, 515 Camponotides, 144 Camponotus, 145 ; C. ligniperdus, 138, 145, 147 ; G. pennsylvanicus, 138, 146 ; C. ntbripes, 131 ; C. rvfipes, 137 Camptosomes, 279, 281 Canephorinae, 394, 395 Cantharidae, 269 f. Cautharides, 270 Capsidae, 561 Capsus laniarius, 539 Carabidae, 204 f. Carabides, 206 Caraboidea, 190, 200 f. Carcinocoris, 554 Carder-bees, 45 f. 45 Cardiocondyla, 161 Cardiophorus, 258 Carlet, on sting, 6 ; on sound-organs of Cicada, 574 Caruivora, 200 Carotine, 549 Carpenter-bees, 33 Carpenter-worms, 395 Carpets, 411 Carpocapsa Juliana, C.pomonella, C.splen- dana, C. saltitans, 428 Carpophagus, 278 Carteria lacca, 597 Carus, on paedogeuesis, 461 Caryoborus, 278 Case, 281, 392, 393, 394, 417, 422, 423, 430, 431 Cassidides, 279, 283 Caste-production, 142 Castnia, 307, 309, 316, 319 ; C. cudesmia, C. therapon, 372 Castniidae, 369, 371 Castor canadensis, parasite of, 219 Cataclysta lemnata, 423 Caterpillar, 322, 324, 325 ; of Diptera, 474 Catopomorphus, 221 Cauda, 538, 588 Cave-beetles, 205, 221 Cebrionides, 260 Cecidipta excoecaria, 424 Cecidomyia buxi, 459 ; C. destructor, 460 : C. tritici, 460 Cecidomyiidae, 455 n., 458 Cecropia, plant and ants, 158 Cedeocera, 297 n. Cell, of wing, 317, 318 ; complete and in- complete, 116 n. Cells, formation of, by bees, 21, 22, 24, 25, 28, 33, 34, 35, 46, 48, 51, 52, 54, 56, 60 ; earthen, 72, 106 ; of Coelonites, 89 INDEX 607 Celyphidae, 504 Celyphus, 505 Cemonus unicolor, 128 Cephaloidae, 275 Cephalomyia maculata, 515 Cephaloon, 275 Cephalothorax, 465 ; of Stylops-\a,t\&, 302 Cephenomyia rufibarbis, 517 Cerambycidae, 278, 285 Cerambycides, 287 Ceramius, 89 ; C. lusitanicus, 89 Ceranchia, 374 Cerapachys, 175 n. Ceratina, 11, 32 Ceratocampidae, 368, 375 Ceratocombidae, 559 Ceratognathiui, 194, 195 Ceratonema, 401 Ceratopogon, 469 ; C. bipunctatus, G. puli- caris, C. rarius, 470 Cerceris, 125 ; C. arenaria, 125 ; C. bupresiicida, 125 ; C. labiata, 125 ; C. tuberculata, 126 Cercopidae, 577 Ceresa bubalus, C. taurina, 577 Cerocoma schaefferi, 275 Cerophytides, ££# Ceroplastes ceriferus, 597 Ceroplatus mastersi, 463 Cerura vinula, 383 Cervical sclerites, 472 Cetonia, in ants'-nests, 149 ; (7. floricola, 200 Cetoniides, ^95, 199 Chaerocampa, 380 ; recte Choerocampa Chaetophorous, 446 Chaetotaxy, 446 Chafers, 194 f. Chalcosiidae, 391, 420 Chalia hockingi, 394 CJudicodoma, 32, 35 ; C. muraria, 30, 35 f., 36, 254, 486 ; C. parietina, C. pyre- naica, 39 Change of habit in larva, 301, 431 Chapman, Dr. T. A., on Ghrysis, 3 ; on classification of pupae of Lepidoptera, 367 ; on Hepialus, 398 ; on Metoecus paradoxus, 268 ; on pupa of Lepidop- tera, 327 n. Charagia, 396 Chartergus chartarius, nest of, 82, 83 Cheilosia chrysocoma, 439 Oheimatobia brumata, 414 Clieliomyrmex, 180 Chelonariides, 242 Chelonia, 410 Chelostoma, 35 Chennium bituberculatmn, 224 Chermes, 583, 586, 587 ; C. abietis, 586, 587, 589 Cheshire, on proboscis of bee, 15 dagger, 525 Child, on sense-organ, 442 China-marks, 421 Chinch-bug, 548 Chionea araneoides, 474 Chiromyzidae, 479 Chironomidae, 468, 474 Chironomus, 440, 468 Chlamydes, 279 Chlorion, 110 Chloropidae, 504 Chlorops, 504 Choerocampa elpenor, 380 Choerocarapini, 381 Cholodkovsky on Chermes, 586 Choragus sheppardi, 290 Chorion, 322 Chrysalis, 326, 344 Chrysauginae, 423 Chrysididae, 1 f. Chrysiridia madagascariensis, 419 Chrysis bidentata, 3 ; C. ignita, 3 ; C. shanghaiensis, 4 Chrysochus pretiosus, 279 Chrysocoris grandis, 303 n. Chrysomelidae, 2 76, 278 f. Chrysomelides, 279 Chrysopolomidae, 396 Chrysops, 482 Cicada, 123; C. plebeia, 574; C. septen- decim, 569 Cicadellinae, 578 Cicadidae, 568 f. Cicindela hybrida, 202 Cicindelidae, 201 f. Cicinnus, 378 n. Cilix glaucata = spinula, 401 Cimex, 560 ; C. lectulariws, 559 Cimicidae, 559 Cioidae, 245 Cis melliei, 245 Cistelidae, 264 Cistus salvifolius, beetle-larvae in, 282 Cithaerias, 348 Citheronia, 375 Cixiides, 576 Cixius, 575 Clambidae, 223 Clasper, 314 Classification, of ants, 144 ; of bees, 20 ; of butterflies, 341 ; of Coleoptera, 189 ; of Diptera, 454 f. ; of Hemiptera, 543 ; of Hymenoptera Aculeata, 10 ; of Lepi- doptera, 339 f. ; of moths, 366 f. Clavicornia, 189, 213, 265 Clariger testaceus, 224 Clavigerides, 224 Clavus, 539 Clear-wings, 386 Cleggs, 481 Cleosiris, 400 Cleptes, 2, 4 Cleridae, 253 6o8 INDEX Click-beetles, 256 Clicking butterfly, 354 Clidicus, 223 Clisiocampa neustria, 322 Clothes-moths, 430 Clouded-yellows, 357 Clypeus, 307 Clythra in ants'-nests, 149 Clythrides, 279 Cnemidotus caesus, 209 Cnethocampa processioned, 376 Coarctate larva, 271 Coccidae, 592 f. ; destroyer of, 290 Coccidula, 239 Coccinellidae, 237 Coccus cacti, 598 ; G. mannifera, 597 Cochineal Insect, 598 Cochliopodidae, 402 n. Cochlophora, 394 Cockchafer, 198 Cockroach, parasite of, 269 Cock-tail, 225 Cocoon, 46, 55, 66, 109, 122, 328, 347, 373, 376, 384, 385, 391, 403, 404, 405, 407, 419, 424, 436, 460, 462, 494 ; flax-seed, 460 ; of ants, 134 ; aquatic, 280, 377 Cocytia durvillii, 382 Cocytiidae, 382 Codling-moth, 428 Coelioxys, 31 Coelonites, 89 ; C. abbreviatus. cells of, 89 Coenomyiaferruginea, 480 Coenomyiidae, 479 Coenonympha, 348 Colaenis, 351 Coleophora, 431 Coleoptera, 184 f. Colletes, 22 ; C. daviesanus, 30 Colobopsis, 138 Colon, 320 Colorado beetle, 278 Colour, corresponding with locale, 201 ; and surroundings, 337 ; of larva and habits, 336 ; of Sphingidae larvae, 381 ; physiology of larval, 413 ; of cater- pillars and sex, 325 ; development of, in Hemiptera, 542 ; of eyes, 440 Coluocera formicaria, 240 Colydiidae, 233, 234 Colydium, 233 Comb, 63, 64, 65, 78, 79 Combs and brushes, 134 Compound pupa, 452 Coinposmyia, 512 Comstock, on nervures, 317 n. Conchylidae, 427 Connexivum, 538 Conopidae, 497, 504 Conorhinus sanguisuga, 559 Copiopteryx, 373 Copium clavicorne, 550 Copius, 547 Copper butterflies, 356 Coprides, 195 f. Coprini, 195 n. Copris hispanus, 197 Copulatory pouch, 320, 321 Cordyluridae, 504 Coreidae, 546 Corethra, 467 Corium, 539 Corixa, 567 Corixidae, 567 Corn-leaves, larva on, 281 Coronidia, 419 Corotoca, 227 Corticaria, 240 Corylophidae, 228 Corynetides, 253 Coscinocera hercules, 372 Cossidae, 369, 395 Cossonides, 294 Cossus, 309 ; C. ligniperda, 319 Costal nervure, 318 Cotton-stainer bug, 548 Cotton-worm, 416 Courtship, 494 ; of Hepialus, 398 f. Coxa, 307 Crabro, 129 ; 0. cepludotes, 129 ; C. stirpicola, 130 n. Crabronides, 128 f. Crambidae, 425 Crane-flies, 471 Cratoparis, 290 Cremaster, 327, 328, 344, 426 Cremastochilini, 200 Cremastochilns, 200 Cremastogaster, 213, 165 ; C. tricolor, 168 Crepitation, 213, 214 Crioeerides, 279, 280 Crioceris asparagi, 281 ; C. merdigera, 281 Crossocerus, 130 ; C. wesmaeli, 130 Cryptocephalides, 279 Cryptocephalus, 282 Cryptocerata, 544 ; 562 f. Cryptocerini, 132, 134, 158, 159, 169 Cryptocerus, 138 ; C. atratus, 170 Cryptophagidae, 235, 237 Cryptophagus dentatus, 235 Cryptostomes, 279, 282 Cteniza ariana, destroyer of, 490 Ctenophora, 475 Ctenostylidae, 517 Ctenuchinae, 409 Cuckoo-bees, 22 Cuckoo-spit, 577 Cucujidae, 232, 234 Cucujos, 258 Cuculinae, 20 Cnlex pipiens, 466 Culicidae, 466 f. Cultelli, 443 INDEX 609 Cuneus, 539, 540 Cupesidae, 234 Curculionidae, 290 Curtice, on Hypodenna, 516 Curupira, 465 Cut-worms, 415 Cyathoceridae, 243 Cybister laterima.rgina.lis or roeseli, 210 : C. tripunctatvs, 211 Cybocephalus, 232 Cyclica, 279, 282 Cyclorrhapha, 454 ; C. Aschiza, 455, 494 f. ; C. Schizophora, 456, 503 f. Cylidriis, 253 Cylindrotomina, 474 Cymatophoridae, 368, 386 Cymbidae, 410 Cynomyia mortuorum, 510 Cyphagogus segnipes, 296 CypKanta, 368 n. Cyphonia clavata, 576 Cyphonidae, 255 Cyrtidae, 489 Cyrtocorides, 545 Cyrtocoris monstrosus, 546 Dacnides, 237 Dactylopius citri, 595 Daddy-long-legs, 471 Dakruma coccidivora, 424 Dalla Torre, Catalogue of Hymenoptera, 21 Danaides, 344, 347 Danaioid Heliconiidae, 346 Danais archippus, or plexippus, 345 Dances, 351, 464, 493, 554 Darwin, C., on Pelobius, 208 Darwin, F., on proboscis of Lepidoptera, 311 n. Dascillidae, 243, 255 Dascillus cervinus, 255 Dasychira pudibunda, 408 ; D. rossii, 407 Dasygastres, 20, 35 f. Dasypoda hirtipes, 27 Dead-leaf butterfly, 353 Death-watches, 248, 254 December-moth, 406 Deer bot-fly, 517 Deer-fly, 518 Delphacides, 576 Deltocephalus inimicus, 578 Deltoidae, 418, 423 Denudatae, 20, 29 Deporaus, 291 Dermatobia noxialis, 517 Dermestidae, 241 Deroca, 400 Derodontidae, 244, 253 Derodontus maculatus, 245 De Saussure, on wasps' nests, 81 Devil's coach-horse, 225 VOL. VI Dewitz, on development, of sting, 8 ; of thoracic appendages, 9 Dexiidae, 510 Diactor bilineatus, 547 Dianeura, 392 Diateina holymenoides, 547 Dichoptic, 440 Dicthadia, 178, 180 Dictyocicada, 543 Dilophus febrilis, 477 ; D. vulgaris, 476 Dimera, 544 Dimorphic, generations, 586 ; males, 161, 172 Dimorphism, 139 ; of wings, 549 Dinapate ivrightii, 246 Dingar, 70 Dinoponera grandis, 132, 134, 171 Dionychopus niveus, 410 Diopsidae, 503, 504, 505 Diopsis apicalis, 503 Dioptinae, 409 Dioptoma adamsi, 251 Dioscorea batatas, beetle-larvae in, 280 Dioxys cincta, 32, 43 Diphyllides, 237 Diplocotes, 248 Diplonychus, 566 Diploplectron, 119 Diploptera, 10, 71 f. Diplosara lignivora, 429 Diplosis, 459 ; D. resinicolu, 459 Dipsocoris alienus, 559 Diptera, 438 f. Dipterous parasitic larva, 26 Dirphia tarquinia, 377 Discocellular nervures, 318 Disnwrphia, 346, 357 Dissociation of embryo, 70 11. Dixa, 471 Dixidae, 471 Dohrn, Anton, on Hemiptera, 538 Dolichoderides, 157 Dolichopidae, 493 Dolichopus undulatus, 441 Dolichurus haemorrhous, 116 Donacia, 280 Donaciides, 279 Dorsal vessel, 320 ; 529 — see also Internal Anatomy Dorycera, 504 Doryceridae, 504 Dorylides, 174 f. Dorylini, 175, 177 Dorylus, 133, 177, 179 ; D. hdvolus, 178 Doryphora decemlineata, 278 Dragon, 383, 385 Drepanidae, 370, 400 Drepanosiphum platanoides, 585 Drepanulidae, 400 Drilides, 248 Driver ants, 178 2 R 6io INDEX Drones, 63, 67, 69 Drosophilidae, 504 Drurya, 362 Dryomyzidae, 504 Dryophthorus, 289 Dubois, on luminescence, 259 Dudgeon, on Badamia, 365 Dufour, on host helping parasite, 26 Duke of Burgundy fritillary, 355 Duration, of ant-colonies, 154 ; of wasp- colonies, 70 n . , 80 ; of life — see Longevity Durrant, on moth-cases, 431 Dutch bulbs, larva in, 501 Dyar, classification of larvae of moths, 367 Dycladia, 389 Dynastes, 199 Dynastides, 195, 199 Dysdercus suturellus, 548 Dytiscidae, 210 f. Dytiscus, 211 Earias, 410 Eau de Javelle, 368 n. Echinophthirius, 600 Eciton, 159, 175, f ; E. hamatum, 175, 177 Ecitonini, 174, 175 f. Ecpantheria, 409 Ectatomma auratum, 131 Ectrephes kingi, 248 Edible larvae, 287 Egg, 305, 435, 468 ; as food, 504, 568 ; of bot-fly, 514, 515 ; of Capsidae, 561 ; carried, 547, 551, 566 ; of Enclochus, 558 ; of Reduviidae, 559 ; of flea, 524 ; laid by pupa, 469 ; of Lepidoptera, 321, 322 ; of Nepa, 564 ; numerous, 397, few, 197 ; standing out string of, 378 ; swallowed, 508 Egg-tubes, 321 Eggers, 322, 405 Elaphidion villosum, 286 Elaphomyia, 505 Elateridae, 256 Elaterides, 260 Eleodes, 263 ElepJwntomyia, 472 Elmides, 244 Elymnias, 348 Elymniidae, 348 Elytra, 184, 186, 539 Embolium, 539 Embryonic dissociation, 70 n. Emenadia flabellata, 269 Emery on classification of ants, 144 ; on polymorphism in ants, 143 Emesiides, 555 Emperor-moth, 374 Empidae, 492, 494 Empodium, 446 Empretia stimulans, 403 Encyrtus, 34 ; Encyrtus fuscicollis, . em- bryology of, 70 Eiulomychidae, 237, 239 Endotrichiiuae, 423 Endromidae, 369, 406 Energopoda, 457, 491 Enhydrus, 216 Entomophila, 10 Enzyme, 259 Epeolus variegatus, 3C Ephestia kuhniella, 306, 424 Ephydridae, 504 Ephyfa pendidaria, 412 Epiblemidae, 427 Epicausis smithi. 409 Epichnopteryx, 395 Epicopeiidae, 368, 418 Epicranium, 307 Epicypta scatophora. 463 Epidapus scabiei, 462 Epilachnides, 238 Epimeron, 307 Epinotia funebrana, 428 ; E. hypericana, parasite of, 476 Epipaschiinae, 423 Epipharyngeal sclerites, 14 Epipharynx, 14, 308, 443, 600 Epiplemidae, 368, 420 Epipyrops, 404 Episternum, 307 Epitritus, 170 Epuraea, 232 Erastria scitula, 417 Erebia, B47 ; E. aethiops, 347 Erebides, 418 Eremochaeta, 457 Eremochaetous, 446 Eremocoris, 548 Ergatandrous, 140 n. Ergatogynous, 140 n., 142 Ergatoid, 140 Ericerus pela, 597 Eriocephala, 308 ; E. calthella, 434 Eriocephalidae, 433 Eriocera, 472 Eristalis, 499 Ermine-moths, 409 Erotylidae, 235, 236 Erucaeformia, 475 Erycides, 364 Erycinidae, 341, 354, 358 Erycinides, 355 Ethon, 262 Eucephalous larvae, 450 Eucern, ••'.' Eucharis myrmeciae, 173 Euchloe cardamines, egg, 322 ; larva, 358, 359 ; pupa, 358; E. yeiiutia, 358 Euchroma goliath, 261 Eucinetus, 256 Eucleidae, 401 En i-1 til id. mi, 415 INDEX Eucnemides, 260 Eudaemonia, 373 Eudamus proteus, 340 Eueides, 351 Eugereon hockingi, 542 Euglossa, 34 ; E. cor data, 35 Eugnoristus 'inonachus, 289 Eulema, 35 Eulen, 414 Eulyes, 558 Eumaeus, 355 Eumenes arbustorum, 73 ; £. coarctata, 73, 74 ; /?. conica, 74 ; .£. flavopicta, 72 ; jfcT. pomifvrmis, 72 ; J5. ungui- culata, 73 Eumenidae, 72 f. Eumolpides, 279 Eumyiid flies, ,£56 Euparagia, 89 Euphoria, 200 Euplocia, 408 Euploea, 345 Eupoda, 279, 280 Evpsalis minuta, 296 Eupterotidae, 565, 376 Ewrygona, larva, 355 Euschemon rafflesiae, 371 Eusemia villicoides, 410 Eusthenes pratti, 533 Euthyrhynchusfloridanus, 546 Excoecaria biglandidosa, 424 Excrement as covering, 281, 283, 463 — see also Adapted excrement. Excremental dwellings, 284, 379 External structure, of Aphidae, 588 ; of Chrysididae, 2 ; of Coleoptera, 185 ; of Diptera, 439 f. ; of fleas, 523 ; of Henii- ptera, 534 ; oflfepialus, 400 ; of Hymen - optera Aculeata, 5 ; of Lepidoptera, 307 f. ; of Thrips, 527 Exudation of fluid, 238 Eye-collar, 387 Eyes, four in number, 215, 251, 476 Fabre, J. H., on Ammophila, 111 ; on An- thrax, 486 ; on Bembex, 120 f. ; on Calicurgus, 101 ; on Chalicodoma, 37 f. ; on Eumenes, 72 ; on Halictus, 24 ; on Miltogramma, 509 ; on Osmia, 48 f. ; on Scarabaeu3, 196 ; on Scolia, 97 f. ; on Sitaris, 272 ; on Sphex, 108 ; on Stelis nasuta, 30 False coues of Chermes, 587 Families of moths, key to, 368 f. Feeding young, 147 Fertonius luteicollis, 130 Fever-fly, 477 Filaria, and Mosquitos, 468 Filicornia, 200 Finding nest, 38 f., 126 Finn, on protected butterflies, 345 n. Flagella, 384, 442 Flatides, 576 Flax-seed cocoon, 460 Fleas, 522 f. Fly-disease, 513 Food, abstinence from, 254 ; of bee- larvae, 19 ; small in amount, 277 Food-reservoir; 320 Footmen, 409 Forbes, on ant sounds, 155 Forel, Aug., on tropical American Ants, 138 ; on classification of Ants, 144 Forest-fly, 518 Formica exsectoides, 149 ; F. fusca, 137, 150, 151 ; F. nifa, 148, 154 ; F. san- guinea, 149 ; F. schtivfussi, 152 Formicidae, 131 f. Formicoxenus nitidulus, 148, 159 Fornax, 260 Fossil, Ants, 143 ; Beetles, 261 ; Diptera, 458 ; Hemiptera, 542 ; Thrips, 531 ; Wasps, 88 — see also Palaeozoic Fossores, 7, 10, 90 f., 346 ; classification, 93, Fossorial solitary wasps — see Fossores Founding new nests, Ants, 145 f. Frenulum, 316, 318, 319, 400 Friederich, on Parnid larvae, 244 Friese, on habits and classification of bees, 21 ; on hosts and parasites, 30 f. Fritillaries, 352, 354 Froghoppers, 577 Frog-spit, 577 Frontal ganglion, 320 Fulgora candelaria, 575 Fulgoridae, 543, 574 ; larva living on, 404 Fulgorina, 543 Fumea, 393, 395 Fungus cultivated by ants, 167 Fungus-gnats, 462 Funnel-twister, 292 Gad-flies, 481 Galian, J. C., on Praogena, 264 Galea, 309 Galerucides, 279 Galgulidae, 562 Galleria mellonella, 306, 331 Galleriidae, 423 Gall-midge-flies, 461 Galls, 262, 430, 424 ; of Coccidae, 598 ; of Aphids and Phylloxera, 587 ; of Psyllidae, 580 ; of Thrips, 530 Gauglbauer, on Staphyliuidae, 224 Garden-whites, 357 Garman, on mouth-parts of Thysanoptera, 528 Gastropacha quercifolin, 405 Gastrojjhili/a equi, 515 Gavara, 401 Gelechiides, 429 Gena, 185 Generations, 306 6l2 INDEX Geometers, 411 Geometridae, 368, 411, 416, 420 Geomyzidae, 504 Georyssidae, 243 Georyssus pygmaeus, 243 Geotrupes, stridulation of, 195 Gen-ides, 552 Gerris, 535, 552 Ghilianella filiventris, 555 Ghost-moths, 396 Gira/omyia, 505 Girdlers, 286 Glands, 321, 323, 331, 363, 399, 538, 553 ; accessory, 320 ; of Filippi, 324 ; mandibular, 216 ; salivary, 326 ; silk-, 325 ; stink-, 257 ; wax-, 589 Glaphyrini, 195 n. Glaphyroptera picta, 441 Glaucopides, 339 Glossa, 309 Glossina morsitans, 512, 513 Glow-worms ; 248 ; New Zealand, 363 Glyptus, 206 Gnats, 466, 468 Gnophaela, 409 Gnostidae, 223 Goat-moths, 395 — see also Cossus Godart on trumpeter- bee, 58 Godman and Salvin, on spermathecal bodies, 321 Gold-tail moths, 407 Gonapophyses, 9, 305 Gonin, on development of wing, 328, 329 Goossens, on legs of Lepidootera larvae, 323 Gossyparia, 597 Graber, on mouth of louse, 599 Grapholitha sebastianiae, 428 Grapholithidae, 427 Grass-moths, 425 Grayling, 347 Green, E. E., on classification of Coccidae, 593 Green-bottles, 511 Green-fly, 581 f. Ground-beetles, 204 f. Ground-pearls, 592, 598 — see also Mar- garodes Grypocera, 341 Guest-ant, 159 Gula, 185 Gymnocerata, 544, 544 f. Gymnodomes, 82 Gyrinidae, 201, 215 Gyrinus, 215 Haase, on mimicry, 339 n. Hadrus lepidotus, 482 Haematobia serrata, 512 Haematomyzus elephantis, 600 Haematopota, 482 ; H. pluvialis, 483, 443 Haemoglobin, 468 Haemonia, 280 ; H. curtisi, 280 Haetera, 348 Hag-moth, 403 Hairs, plumose or feathered, 11, 12 ; of Dermestid larvae, 241 — see also Setae Half-loopers, 415 Halias, 410 Halictus, 23 ; H. lineolatus, 24 : H. malachurus, 23 ; H. maculatus, 25 ; H. inorio, 24 ; H. quadricinct'us, 22, 25 ; II. rubicundus, 26 ; H. sexcinctus, 24, 269 Haliplidae, 209 Halirytus amphibius, 474 Halobates, 552 ; H. sobrinus, 551 Halobatodes, 553 Halteres, 438, 448, 593 Halticides, 278, 279 Hamadryas, 347 Hammock -moth, 379 Hampson, on classification of moths, 367 f. ; on clicking butterfly, 354 ; on frenu- lum, 316 Hampsonia pulcherrima, 391 Handlirsch, on Bombus, 58 Harpactorides, 558 Harpalides, 206 Harpalus, 205 ; H. caliginosns, 185 Harpes, 314 Hart, C. A., on larvae of Diptera, 473 Hart, J. H., on the parasol-ant, 142 Harvesting ants, 164 Hatchett Jackson, on colour of larvae, 325 Haustellata, 366 Haustellum, 308 Hawk-moths, 380 f. Head-vesicle, 442 Hearing, organs of, 191, 313 Heath-butterfly, 347 Hebridae, 551 Hebrus, 551 Hecatesia, 371 Heerwurm, 464 Heliconiidae, 346 Heliconiides, 351 Hdiconius, 346 ; H. erato, H. melpomene, H. rhea, 351 Heliothis armigera, 416 Helluodes taprobanae, 206 Helochares, 218 Hdodes, 255 Helomyzidae, 504 Hdopeltis, 561 Helotidae, 235 Hemaris, 383 Hemerodromia, 493 Hemidiptera hueckeli, 553 Hemi-elytra, 539 Hemileucidae, 374 Hemiptera, 532 f. INDEX 613 Henicocephalidae, 554 Hepialidae, 306, 369, 396 f. Hepialus, 309, 310, 311, 317, 319, 322 ; //. humuli and others, 396 f. ; H. lupuK- nus, 397 Heredity, 454 Jferiades, 35 Hermatobates haddon i, 553 Hermetia, 479 . Hesperiidae, 341, 342, 363 Hessian fly, 452, 460 Hestia idea, 340 Heterocera, 340, 366, f. Heteroceridae, 219, 243 Heterogenea, 402 Heterogeneidae, 402 Heterogyna, 10, 131 f. Heterogynidae, 369, 392 Heterogynis, 369 n., 392 Heteromera, 190, 262 f. Heteroneuridae, 504 Heteronotus trinodosus, 576 Heteroptera, 532, 534, 535, 539, 543 Heterotarsini, 264 Hexatoma pellucens, 441 Heylaerts, on Psychidae, 392 Hibernation, of Vanessa, 352 Hilara, 493 Hilbrides, 405 Hill-ant, see Formica rufa Hill-grub, 417 Himantopteridae, 392 Himera pennaria, 411 Hippobosca equina, 518 Hippoboscidae, 518 Hippopsini, 288 Hirmoneura obscura, 485 Hispa, 282 Hispides, 279, 282 Histeridae, 230 Histia, 391 Histoblasts, 453 Histolysis, 452, 595 Hockings, on stingless bees, 63 Hoffer, on Bombus, 54 Hollandiidae, 396 Hololepta, 230 Holometopa, 504 Holoptic, 440 Holoptilides, 557 Hiilymeiiia, 547 Homoeochromatism, 337, 351 Homoeoderus mellyi, 193 Homomorpha, 542 Homophysinae, 421 Homoptera, 532, 534, 535, 543, 544 ; parasite of, 303, 497 Honey, 18, 80 Honey-aut, 152 Honey-bee — see Apis mellifica Honey-dew, 580, 589, 597 Hook-tips, 400 Hoplopus, 74 Horn, G. H. , on classification of Carabidae, 206 ; of Silphidae, 223 Horn, W., on classification of Cicindelidae, 202 n. Hornet, 81, 87 Hornet's-nest beetle, 227 Horns as food, 430 Horse bot-fly, 515 Horse-flies, 481, 518 Hot springs, Insects in, 479 House-fly, 511 Hover-flies, 498 Hubbard, on ambrosia-beetles, 295 ; on Phobetron, 403 ; on Xenos, 303 Huxley, on Aphids, 585, 589 ; on sclerites of oesophagus, 15 Hybocampa milhauseri, 385 Hybotinae, 492 Hydnophytum, 139 ; H. montanum, 138 Hydrocampa nymphaeata, 421 Hydrocampidae, 421 Hydrocampinae, 421 Hydrocores, 562 Hydrocorisae, 562 Ilydrocyphon deflexicollis, 255 Hydrometra, 552 ; If. stagnorum, 551 Hydrometridae, 551 Hydrophilidae, 216 f. Hydrophilides, 219 Ilydrophilus piceus, 217 Hydroporides, 201 Hydropvrus, 211, 212 Hydroscaphidae, 228 Hydrous caraboides, 218 Hygrobia, 208 Hylecoetus dermestoides, 255 Hylemyia strigosa, 506 Hymenitis, 346 Hymenoptera Aculeata, 4 f . ; H. Tubuli- fera, 1 f. Hyper- metamorphosis, 270, 488 Hypertely, in Kallima, 354 Hyphydrus, 212 Hypnody, 489 Hypocephalus armatus, 288 Hypochlorite of potash, 368 u. Hypoderma bovis, H. lineata, 515 Hyponomeuta, parasite of, 70 n. Hypopharyngeal sclerites, 14, 17 Hypopharynx, 15 n., 324, 443, 524, 600 Hypopygium, 446 Hypsidae, 370, 408 Hypsoides radama, 376 Hystrichapsylla tulpae, 523 Idia fasciata, 513 Ittnlothi-ijin Kj>ecti-t>>», 527 Imaginal discs or folds, 596 Imbauba ant, 158 Individual, 585 Inedible associations, 338, 339 614 INDEX Infericornia, 548 Infra-oesophageal ganglion, 541 Inquilines, 30, 81 Insects as food, 417, 504, 568 Instars, of Aspidiotus, 596 ; of Coccidae, 595 ; of Epicauta, 271 Instinct, 235, 274, 373, 403, 424, 487, 546 ; of Ants, 590 ; of Bembex, 121 ; of Chalicodoma, 37 ; of Dasypoda, 28 ; of Melipona, 64 ; of MiUogramma and Bembex, 509 ; of Odynerus, 76 ; of Osmia, 48 f. ; of PmnpUus, 102 ; of Rhynchites, 292 ; of Trigona, 64 Internal anatomy, of Diptera, 449 ; of Hepialus, 400 ; of Hemiptera, 540 ; of Lepidoptera, 319 f . ; of larta of Lepi- doptera, 324 ; of Lice, 600 Internal nervures, 318 Iodine, 213 Ipides, 232 Ischium, 523 Ischnogaster, 82, 88 ; /. mellyi, 87 Isoderminae, 550 Isomera, 190 Issides, 576 Ithomia, 346 ; /. pusio, 346 Ithomiides, 346, 351 Ituna, 346 Ityraea nigrocincta, 576 Jassidae, 578 Jiga, or "mimic me," 92 Johnston's organ, 442 Jordan, on antennae of butterflies, 341 n. ; on Thysanoptera, 529 f. Jugatae, 366 Jugum, 316, 400 Jugurthia, 89 Julodis, 262 Jumping-beans, 428 Kallima, 353 Karbi, 63 Kellogg, on Lepidopterous structure, 307 f. Kentish glory, 406 Kermes, 597 Knot-horns, 424 Komarovia victoriosa, 99 Koo-chah-bee, 504 Kootchar, 63 Koptorthosoma, 70 n. Korschelt, on formation of eggs of Nepa, 564 Kiinckel d'Herculais, on Volucella, 501 Kungu cake, 467 Laap Insects, 581 Labella, 443 Labidus, 175, 176, 180 Labium of Lepidoptera, 310 Laboulbene, on sound - production by Arctiidae, 410 Lac, 597 Lacinia, 309 Laciniata, 366, 434 Lacon murinus, 257 Lacosoma chiridota, 378 Lady-birds, 237 Lagoa opercularis, 404 Lagoidae, 404 Lagria hirta, 264 Lagriidae, 264 Lake, colour, 597 Lamellicornia, 190 f. ; enemies of, 97 Lamiides, 2S7, 288 Lamprosomides, 279 Lampyrides, 248 Lampyris noctiluca, 250 Langelandia anophthcdma, 233 Languriides, 237 Lantern-flies, 575 Laparosticti, 195 n. Laphria, 492 Lapidicolous beetles, 205 Lappet-moth, 405 Laricobius, 253 Larra anathema, 117 ; L. pompiliformis, . 117 Larrada, 117 ; L. modesta, 118 Larrides, 116 f. Larvae, of beetles, 188 f., 188 ; of Chrysis, 3 ; of Dasypoda, 28 ; of Hymenoptera, 7 ; of Lepidoptera, 323 ; of Sphex, 109 Lasiocampidae, 369, 375, 405 Lasiorhynchus barbicornis, 297 Lasius alienus, 140 ; founding nest, 146 ; L. fuliginosus, 138, 153 ; L. niger, 153 Latridiidae, 240 Latridius minutus, 240 Latter, 0., on Puss-moth, 384 Leaf-cutting ants, 165 f. Leaf-nests (ants), 155 Lecanimn hesperidum, 594 ; L. oleae, 417 ; L. persicae, 597 Ledra, 545, 578 Legs, abdominal, 9 Leistus spinibarbis, 204 Lema indanopa, 281 Lemoniidae, 354 Leon, on Hemidiptera, 553 Lepidoptera, 304 f. ; L. Haustellata, L. Laciniata, 366 Leptalis, 346, 357 Leptidae, 479 Leptinidae, 220 Leptinillus, 221 Leptinus testacevs. 220 Leptis scolopacea, 441, 481 Leptocircus, 362 Leptoderini, 221 Leptogenys, 171 ; L. falcigera, 171 Leptomastax, 223 Leptothorax acervorum, 161 Lerp Insects, 581 INDEX 6l5 Leto, 397 ; L. vcnv.s, 396 Leucania unipunctata, 416 Leuckart, on Melophagus, 519 Leucospis, 46 ; L. gigas, 44 Leuthner, on Odontolabis. 193 Lihythea, 342 Libytheides, 355 Lice, 599 f. Ligula, 16 Limacodes, 489 Limacodidae 370, 401 ; parasite of, 4 Limnas chrysippus, 345 Limnichides, 242 Limnobia intermedia, 472 Limnobiinae, 472 Limochvres taumas, 340 Limothrips denticornis, 530 Lindemann, on injuries from Thrips, 530 Lingua, 16 Liugula, 15 Liometopum microcephalum, 158 Lipara lucens, 128, 451 Liparidae, 406 Liponeura brevirostris, 465 Liponeuridae, 464 Lipoptena cerci, 518 Liptena, 356 Lipteninae, 356 Lita solanella, 430 Lithophilus, 239 Lithosiidae, 408 Lithosiinae, 409 Llaveia axinus, 598 Lobster, 383 ; Lobster-moth, 385 Loepa newara, 374 Lohita grandis, 549 Lomaptera, 200 Lomechnsa, 142, 225 Lonchaeidae, 504 Lonchopteridae, 490 Longevity, 33, 135, 286, 306 ; of Cicada, 569 ; of Afelolontlia, 198 ; of Scarabaeus, 197 Longicoms, 285 Loopers, 411, 415 Lorum, 14, 14, 16 Lowue, on blow-fly, 449 ; on foot of Dytiscus, 211 Lucanidae, 193 Lticanus cervus, 194 ; antenna of, 191 Luciferase, Luciferine, 259 Lucilia, 511, 512 ; L. caesar, L. macel- laria, L. sericata, 512 Lnciola, 249 ; L. italica, 249 Ludia delegorguei, 373 Luminescence, 250, 258 f., 463, 469 Lunula, 442 Lutz, on exudation of Coccinellidae, 238 Lycaena baetica, 356 Lycaenidae, 341, 355, 356 Lycides, 248 Lycorea, 346 Lyctides, 246 Lygaeidae, 548 Lymaiitriidae, 370, 406 !llon navale, 254 Lymexylonidae, 254 Lyonuet, on anatomy of caterpillar, 324 u, Machaerota guttigera, 578 M'Cook, on honey-tub ants, 152 Macrocneme, 389 Macroglossiui, 380 Macrolepidoptera, 340 Macronychus quadrituberculatus, 244 Macrotoma heros, 287 Maggot, 449 Malachiidae, 252 Malachiiis aeneus, 252 Malacodermidae, 248, 252, 266 Malaxation, 110, 126 Malpighian tubes, 320, 334, 429, 449, 460, 466, 473, 529, 540, 588 Mamffio curtisea, 378 Man — see Manna Mandibles, of Lepidoptera, 308 ; of pupa, 436, 437 Mandibulata, 434, 536 Manna, 597 Manson, on Mosquitoes, 468 Mnntic/iel- liger, 152 ; M. mexicanus, 152 Myrmecodia, 139 Myrmecophilous Insects, 181 f. Myrmedonia, 226 Myrmica laevinodis, 148 ; M. r libra, 133 ; M. rubra, races ruginodis, scabrinodis, 163 Myrmicides, 158 Myrmicini, 159 Nabides, 556 Xabis laticentris, 556 Nacerdes melanura, 266 Naclia ancilla, 390 Nagana, 513 Nagel, cm digestion by injection, 212 Xagoda niyricans, 401 .\"" /' osella fungi, 228 Nassonoff, on Strepsiptera, 301 n., 302 Naucoridae, 565 Necrobia ruficollis, 253 Necrophorus, 221 Nectar, 18 Helens interruptus, antenna, 191 Nematobola orthotricha, 431 Nematodes, in Thysanoptera, 530 Nematois metallicus, 321 Nenieobiides, 355 Nemeobius lucina, 335, 355 Nemestrina, 455 n. Nemestrinidae, 484 Nemocera, 440 ; N. Anomala N. Vera 456 Nemognatha, 304 Nemosomides, 233 Neocastniidae, 372 Neolepidoptera, 366 Neotropidae, 346 Nepa, 541 ; N, cinerea, 563 Nepidae, 544, 563 Nepticula, 431 Nervous system, Coleoptera, 191 Nervules, 319, 429 Nervuration, of Diptera, 447 ; of Lepi- doptera, 317 f. Nervures, 318 , 319 ; development of, 329 f. ; swollen, 347, 348 ; of Eumenes, 73 Nests, of ants, 136 f.,155; of Formica fusca andSolenopsisfugax,137 ; ofPorphyras- pis, 284 ; of wasps, 79 f. 79, 81, 83, 87 Netrocera, 341 n. Neuroblasts, 453 Newbigin, Miss, on pigments, 334 Newport, on Meloe, 270 Nicagini, 195 Nicolas, on Halictus, 24 Niliouidae, 265 Xitidida, 232 Nitidulidae, 231, 235 Noctuidae, 311, 370, 410, 411, 414 f. Node, 131, 134 Noliuae, 409 Nolidae, 410 Xomada, 30 ; N. lathburiana 30 ; A". sexfasciata, 30 Nonne, 407 Nopal cactus, 598 Nosodendrides, 2^2 Notocyrtus, 558 Notodontidae, 305, 368, 383 Notodoutina, 411 Notouectidae, 567 Number of species : of Apidae, 10 ; of Butterflies, 343 ; of Coccidae, 593 ; of Coleoptera, 184 ; of Diptera, 438 ; of Fleas, 525 ; of Hemiptera, 543 ; of Lepidoptera, 306 ; of Lice, 600 ; of Thrips, 527 Nun, 407 Nurses, 66, 134 Nyctalemon, 419 Nyctemeridae, 409 Nycteolinae, 410 Nycteribia, 521, 522 Nycteribiidae, 521 Nymph, of Cicada, 569 ; of Thrips, 529 Nympha inclusa, 452 Nymphalidae, 341, 343 f. Nymphalides, 351 Nymphipara, 518 Nymphida stagnata, -V. stratiotata, 423 Nyssanides, 123 Oak-Pruner, 286 Obtusilingues, 20 Oceanic bugs, 552 Ocelli, 325 ; 0. compositi, 325 Ochthiphilidae, 504 Ocneria, 407 n. ; 0. dispar, 408 Ocnerodes, 489 Ocnogyna, 409 Ocijpus olens, 225 Odontolabis sinensis, 193 Odontomachi, 171, 173 Odour, of bugs, 541 6i8 INDEX Odynerus, 74 f., 269 ; 0. antilope, 75 ; 0. callosus, 76 ; 0. parietum, 3 ; 0. punctum, 77 ; 0. reniformis, 73, 75 ; 0. spinipes, 3, 76 Oecocecis guyonella, 430 Oecodoma, 137, 164, 165 ; Oe.cephalotes, 133 Oecophylla smaragdina, 147 Oecophoridae, 429 Oedeagus, .314 [recte aedeagus] Oedematopoda princeps, 387 Oedemeridae, 266 Oestridae, 514 Oestrus ovis, 517 Ogcodes, 489, 490 Oil-beetles, 269 Oinophila v-flavum, 430 Olethreutidae, ^7 Olibrus bicolor, 231 Oligarces, 461 Oligonephrous, 542 Oligoneura, 461 Ommatophorinae, 414 Oncideres, 286 Qpefro, 496 Ophideres fullonica, 311 Opomyzidae, 5ft£ Opostega, 429 Orange-tip, 357 — see also Euchloe Orectochilus, 216 Oreta hyalodisca, 400 Origin of parasitic bees, 32 Orneodidae, 5^0, 571, 426 Ornithoptera, 360 ; 0. brookiana, 362 ; 0. paradisea, 360, 361, 362 Orphnephilidae, 470 Ortalidae, 5ft£, 506 Ortalis, 447 Orthogenya, $% Orthezia, 541, 598 Orthogonius, 206 Orthoperus atomarius, 0. brunnipes, 228 Orthoptera, 555 ; parasite of, 497 Orthorrhapha, 454 ; 0. Brachycera, 478 f. ; 0. Nemocera, 455, 458 f. Oryctes nasicornis, 199 Oscinidae, 504 Osmeterium, 363 Osmia, 47, 48 £ ; enemy of, 100 ; hair of, 11 ; 0. cyanoxantha, 32 ; 0. leucmidana, 29 ; 0. tricornis, 48 ; 0. tridentata, 48 f. Osten Sacken on Bugonia, 499 ; on Chaetotaxy, 446 ; on classification of Diptera, 456 ; summary of Port- schinsky, 512 Othniidae, 265 Otiorhynchides, 437 Ourocnemis, 355, 356 Ovaries, 541, 602; in larva, 325 Oviduct, 320, 321 Oviposition, of Cicada, 571 ; of Nbtonecta, 567 ; of Tachina, 507 Ovipositor, 436, 506, 531, 539 Owlet-moths, 414 Ox-\varbles, 517 Oxybelus, 129 Oxychirotinae, 425 Ozaenides, 214 Pachypus, 187 Packard, on Hymenopterous metamor- phosis, 7 Pad, of Lepidoptera, 314 Paedogenesis, 303, 461 Pagiopoda, 544 Palaeolepidoptera, 366 Palaeomicra, 435 Palaeotropinae, 5^7 Palaeozoic Insects, 311, 542 Palmer-worm, 323 Palpicornia, 219 Paltostoma, 465 Palustra, 377 Pangonia longirostris, 482 Panomoea, 237 Panurgides, 20 Papilio, 359 ; P. ajax, forms of, 335 ; P. antimachus, 362 ; P. zahnoxis 362 Papilionidae, 342, 357, 359 Paracelyphus, 505 Paragia, 89 Parallel series in Aphidae, 585 Parandra, 288 Parapompilus gravesii, 105 Paraponera clavata, 172 Paraponyx, 423 Paraptera, 312 Parasites, among ants, 183 ; of mason- bee, 43 ; of larva of Andrena, 26 ; of Odynerus, 76 Parasitic, bees, 23, 29 f. ; Prosopis, 32 ; Diptera, 507 Parasyscia, 175 n. Parmida, 501 Partwssius, 342, 362 Parnidae, 219, 243, 255 Parnopes carnea, 4 Parnus, 244 Parthenogenesis, 24, 85, 86, 395, 430, 469, 530, 583, 594 Parthenogenetic young, 139 n. Passalidae, 192 ; larva, 192, 262 Passaloecus, 128 Patagia, 311, 312 Pattern, formation of, 335 Patula, 414 Paurometabola, 542 Paussidae, 201, 213 Paussus cepkalotes, etc., 214 Pavonia, 350 Pea-weevil, 277 Peacock butterfly, 352 Peal, on sound-producing ant, 156 Peckham, on Fossores, 130 n. ; on in- stinct, 70, 99 INDEX 619 Pectinicornia, 194 Pedicinus, 600 Pediculidae, 599 Pediculus capitis, 599, 601 ; P. melittae, 274 ; P. vestimenti, 601 Pedilidae, 266 Peduncle, 133, 134 Pegamyia inanis, 79 Pelobiidae, 207 Pelobius tardus, 208 Pelogonidae, 562 Pelopaeus, 110, 112 n. ; P. bilineatus, 114; P. laetus, 113, 117; P. madra- spatanus, 113 ; P. spirifex, 112 Peltasticta, 245 Peltides, 233 Pemphigus, 589 Pemphredon hiyubris, 128 Pemphredouides, 127 Penis, 314 Pentamera, 190 Pentanephria, 466 Pentatama, 541 ; P. rujipes, 535 Pentatomidae, 533, 545, 546 Pepsis, 104, 389 ; P.formosus, 105 Perez, on bee-parasitism, 32 ; on Hal ictus, 24 Pericoma canescens, 470 Pericopinae, 409 Peridrepana, 401 PerUitus, 282 Peripneustic, 450 Peritracheal spaces, 332, 333 Perkins, R.C.L., on bee and acarid sym- biosis, 70 ; 011 Odynerus, 76 ; on Prosopis, 21 Perophora batesi, P. melsheimeri, 377 ; P. sanguinolenta, 379 Perophoridae, 377 Perothopides, 260 Peytoureau, on morphology of abdomen, 313, 314 Phaeism, 337 Phalacridae, 231 Phalacrocera replicata, 474 Phaloniadae, 427 Phanaeus splendidulus, antenna of, 191 Pharynx, 320 Phaudinae, 392 Pheidole, 165 Pheidologeton Idboriosus, 169 ; /'. diversus, 167 Phenax, 575 P/iengodes hieronymi, 249 Phengodini, 251 PhUaenus spmnarius, 577 Philanthides, 124 f. Philanthus apivorus, 127 ; P. triangulum, 125 Phileurus didymus, antenna, 191 Philonthus nitidus, 225 Phlebotamus, 470 Phloea corticata, 545 Phloeides, 545 Phloeothrips fnimentarius, 530 Phobetron pithed um, 403 Phonapate, 246 Phoridae, 494 Phosphamus hemipterus, 249 Phosphorescence, 250 — see also Lumin- escence Phragma, 307, 313 Phragmocyttares, 81 Phthanocoris, 543 Phthiriasis, 601 Phthirius inguinalis, 601 Phycitidae, 424 Phycodromidae, 504 Phyllocnistis, 431 Phyllomorpha laciniata, 547, 548 Phyllm-hina, parasite of, 520 Phylloxera, 587 Phylogeny of butterflies, 343 n. Phymatidae, 554 Phymatopus, 399 Physapoda or Physopoda, 531 Phytomyzidae, 504 Phytophaga, 190, 237, 276 f. Phytophthires, 544 Phytoscopic effects, 336 Pierella, 348 Pieridae, 341, 357 Pieris brassicae, 340 ; development of wing, 328, 329, 333 Piesma, 550 Pigments, 330, 334, 357 Pilifer, 308 Pill-beetles, 242 Pinaridae, 405 Piophilidae, 504 Pipunculidae, 496 Pipunci'fn.1. 496 Pison, 118 Pit-falls, 481 Plagiolepis trimeni, 153 Plagithmysus, 287 Plant-lice, 581 f. Plants and ants, 183 Plataspides, 545 Platycnema, 496 Platypezidae, 496 Pli.it iipliiirn lnbfn>i-ki, 495 Platypides, 289, 295 Platypsyllidae, 219 Platypsyllus castoris, 219 Platysoma depressant, 230 Platystomidae, 504 Pita minvtissima, 567 Pliny, on Mason-bee, 44 Ploiaria pnUii.l.ii, 556 Plume-moths, 426 Plumules, 331 Pfa&ia, 415 Pochazia, 576 Podilegidae, 32 620 INDEX Poecilocampa populi, 406 Poecilocapsus lineatus, 542 Poecilocyttares, 81 Poyonomyrmex barbatus, 164 Pogonostoma, 203 Poison, of Hymenoptera, 7 f. Poison-glands, 2 Poisonous caterpillars, 376, 403, 404, 405 Polistes, 86 ; P. and Stylops, 301, 303 Pollen-gathering and -carrying, 11, 12 Polybia, nests of, 81, 82, 83 Polyctenes fumarius, 560 Polyctenidae, 560 Polyergus lucidus, 151 ; P. rufescens, 150 f. Polymorpha (Coleoptera), 189, 190, 213 f. Polymorphism, 139 f., 143 Polyphylla fullo, antenna, 191 Polyploca, 386 Polyplocidae, 386 Polyplocotes, 248 Polyrhachis, 155 ; P. pandurus, 156 ; P. spinigera, 138 Pompilidae, 93, 101 f. Pompilus, 103 ; P. polistoides, 104 ; /'. sericeus, 106 Ponera contracta, P. ergatandria, P.puncta- tissima, 172 Ponerides, 132, 170 f. Porphyraspis tristis, 284 Porphyrophora polonica, 597 Porrorhynchus, 216 Portschinsky, on habits and development of Muscidae, 507, 512 Post-metamorphic growth, 141 Post-scutellum, 307, 312 Potamogeton pectinatus, beetle on, 280 PotamophUus acumiiiatus, 244 Potassium hydroxide, 328, 384 Potato-beetle, 278 Pouch, abdominal, 350, 362 Poultou, on colours, 339, 336 Praecostal nervures, 319 Praescutum, 312 Pratt, on imaginal discs, 453 n. ; on Melo- phagus, 519 Prepona, larva, 354 Prey, of Fossores, table, 92 Pria dulcamarae, 232 Primitive, beetles, 251, 252 ; Diptera, 475 Priocnemis affinis, 5 ; P. bicolor, 107 Priodont, 193 Prionides, 287 Proboscis, 13, 14, 16, 17, 304, 307, 309, 311, 443, 482, 485, 532 Processional maggots, 464 Processionary caterpillars, 376, 408 Prodoxidae, 432 ; mouth, 309 Prodoxits, 433 Pro-legs, 323 Prolific, Aphids, 589 ; Coccids, 594 ; Hepialus, 397 ; Lice, 601 ; Meloe, 274 ; Stylops, 301 Prominents, 383 Pronuba, 321 ; P. yuccasetta, 432 ; P. si/n- ihetica, 432 Pronymph, 453 Propodeum, 131, 133 Propolis, 63 Propygidium, 187 Prosopis, 21, 22 ; hair of, 11 ; proboscis of, 17 ; P. signata, 21 Protection, 43, 413 ; of trees by ants, 158 ; of plant by ants, 168 Proterhinidae, 298 Proterhinus lecontei, 298 Protolepidoptera, 336 Protoparce Carolina, 309 Protopaussus, 214 Psammorycter vermileo, 481 Pselaphidae, 223 ; and ants, 182 Psen, atratus, P. concolor, 127 Psephenus, 244 Pseudholoptic, 440 n. Pseudocorylophidae, 228 Pseudodicfkadia, 180 ; P. incerta, 177 Pseudodoxia limulus, 431 Pseudomeria graeca, 99 Pseudomorphides, 206, 205 Pseudomyrma bicolor, 168 Pseudomyrmmi, 168 Pseudoneuroptera, 527 Pseudopaedogenesis, 303 Pseudopod, 188, 264, 267, 290, 449, 492 Pseudopontia paradoxa, 357 Pseudo-pupa, 271, 273 Pseudotetramera, 190 Pseudotrimera, 239 Pseudovespa, 88 Pseudovarium and Pseudovum, 584 Pseudovitellus, 588 Psilidae, 504 Psiliglossa, larva, 8 Psilocephala, 484 Psilura monacha, 407 Psithyrus, 53, 57, 59 f. ; P. campestris, 60 ; P. vestalis, 60 Psocidae, 248 Psyche helix, 394 Psychidae, 369, 392 Psychina, 394, 395, 404 Psychoda, 466 Psychodidae, 470 Psylla pyricola, 579, 580 ; /'. succincta, 579 ; P. buxi, 580 Psyllidae, 578 Pterocheilus, 76 Pterodecta, 400 Pterophoridae, 371, 425, 340, 426 Pterophorinae, 426 Pterostichus, 205 Pterothysanidae, 369, 406 Pterygodes, 312 Pterygogeuea, 542 Ptilinum, 442, 503, 520 INDEX 621 Ptilinus 2>ectinicornis, 253 Ptilocnemus sidnicvs, 557 Ptilomacra, 395 Ptilmnera laticaudata, 553 Ptinidae, 246 Ptomaphila lacrymosa, 222 Ptychoptera, 466 Ptychopterinae, 472 Ptyelus goudoti, 577 Pugs, 411 Pulex avium, P. irritans, P. serraticeps, 525 ; P. obtusiceps, 525 Pulicidae, 522 f. Puliciphora lucifera, 495 Pulvillus, 446 Pupa, of beetles, 188 f. ; coarctata, 452 ; obtecta, 227, 327, 451 ; depositing eggs, 469 ; hairy, 407, 426 ; of Lepi- doptera, 326 f. ; with mandibles, 436 Puparium, 452 Pupation, of Badamia, 365 ; of Parnctssius and Thais, 363 Pupipara, 456, 513, 517 Purple emperor, 344 Pusci, 504 Puss-moth, 328, 383, 406 Pygidium, 187 Pyralidae, 340, 370, 420 Pyralidina, 420, 426 Pyrameis atalanta, 353 ; P. ctirdui, 353 ; P. tammeamea, 353 Pyraustidae, 421 Pyrochroa rubens, 266 Pyrochroidae, 266 Pyrophorus, 258 ; P. noctilucus, 259 Pyrrhocoridae, 549 Pyrrhocoris apterus, 535, 549 Pyrrhopyge, 364 Pythidae, 265 Pytho depressus, 266 Quartenia, 89 Queen, 66, 67, 69, 140 Races, of Apis, 68 Radial nervures, 319 Raifray, on Pogonostoma, 204 ; on classi- fication of Paussidae, 214 ; on classifica- tion of Pselaphidae, 224 Railway-beetle, 251 Ranatra linearis, 563 Raptorial legs, 493, 554, 556 Reaumur, on Xylocopa, 33 Receptaculum seminis, 140 Rectal cauda, 538 Red admiral, 352 Red ant — see Formica rufa Reduviidae, 555 f. 537 Reduvius personatus, 558 Regimbart, on Gyrinidae, 216 Resemblance, between ant, wasp, and spider, 169 ; between Anlhophora and Bombus, 33; between Arctia villica and Eusemia villicoides, 410 ; between beetle-larva and Termite, 206 ; between Bombus and Eitlema, 35 ; between Bom- byliidae and Hymenoptera, 489 ; between bug and ant, 656, 557 ; bug and Tipulid, 556, 558 ; bug and fly, 547 ; in butter- flies, 348 ; between C'alliclulidae and Lycaenidae, 400 ; between Celyphus and Hemiptera, 505 ; between Cleridae and insects they destroy, 254 ; between Dioptinae and Ithomiides, 409 ; between Diptera and Hymenoptera, 499, 500 ; between Epicopeia and Papilio, 418 ; between Flatides and Lepidoptera, 576 ; of flies and bees, 502 ; to galls, 403 ; between host and parasite-bees, 30 ; between Insects of different Orders, 339 ; of Ithomiides to other butterflies, 346 ; between lady -bird and Endomy chid, 237 ; of larva to a colony of larvae, 418 ; of larva of Odynerus and of Chrysis, 4 ; between larvae, 162 ; in Limacodidae, 401 ; of Lobster caterpillar, 385 ; between Longicorns and Hymenoptera, 287 ; of moth to bird-excrement, 401 ; of parasite and prey, 95 ; of Pericopinae and Heliconiides, 409 ; between protected butterflies, 345 ; between Psithyrus and Bombus, 59 ; of Reduviid and Pepsis, 558 ; between Rhyphus- and Mycetobia- larvae, 463 ; of Syntomids to other Insects, 388 f. ; of Tipulids and Hymen- optera, 475 ; between two kinds of ants, 162 Resting-larva, 306 Retinaculum, 316, 319, 420 Retort-shaped bodies, in mouth of Hemi- ptera, 535 Reuter, E., on classification of butterflies, 343 n. Rhachicerus, 480 Rhagorelia plumbea, 552 Rhaphiorhynchus, 483 Rhegmatophila alpina, 305, 386 Rheumatobates bergrothi, 553 Rhinomacerides, 291 Rhinopsis, 115 ; R. rujicornis, 169 Rhino&imus, 266 Rhipicera mystacina, 256 Rhipiceridae, 256 Rhipidiini, 267 Rhipidioptera, 543 Rhipiphoridae, 267 Rhipiphorides, 268 Rhipiptera, 298 [in error for Rhiphiptera] Rhizophagus, 232 Rhizotrogus, 191 Rhodoneura, 405 Rhofjmus, 179, ISO Rhopalocera, 340, 341 f. Rhopalomdus anyuslicollis, 206 622 INDEX Rhopalomeridae, 504 Rhopalosoma poeyi, 100 Rhopalosomides, 100 Rhygchmm brunneum, R. carnaticum, jR. nitidulum, R. oculatum, 77 Rhynchites betulae, 291, 292 Rhynchitides, 291 Rhynchophora, 190, 277, 288 f. Rhynchophorous series, 240 Rhynchopsylla pulex, 526 Rhynchota, 532 Rhyphidae, 478 Rhyphus, 463 Rhysodidae, 201, 234 Riley, on Epicauta, 270, 271 ; on sperma- thecal bodies, 321 ; on Yucca-moth, 432 Ripidius pectinicornis, 269 Rippe, of Schaifer, 334 Robber-flies, 491 Rose-chafers, 200 Rosema, 401 Rostrum, 291, 472 Rothney, on Ampulex, 115 ; on Sima, 169 ; on Sphex, 110 Rothschild, N. C., on morphology of fleas, 523 n. Royal jelly, 66 Rozites gongylophora, 167 Ruby-wasps, 1 f. Rurales, 342 Rutelides, 195, 198 Saccoderes, 558 ; S. tuberculatus, 537 Saccus, 314 Sagra splendida, 279 Sagrides, 279 Salda, 560 Saldidae, 544, 562 Salivary, duct, 320 ; gland, 320 Sand-flea, 525; -flies, 477 Saperda populnea, 285, 286 Sapromyzidae, 504 Sapyga quinquepunctata, 100 Sapygides, 99 Sarcophaga, 510 ; S. camaria, 510 Sarcophagidae, 510 SarcojihUa magnified, S. tcoMfahrti, 510 Sarcopsylla gallinacea, S. penetrans, 525 Sarginae, 479 Saropoda, 32 Sarrothripua, 410 Sasaki, on parasite of silkworm, 508 Saturnia, 307, 310 ; S. pavonia, 313, 374 Saturniidae, 368, 372 Satyrides, 347 Sauba, or Sauva, ant, 137 Saunders, E., on feathered hairs, 11 ; on proboscis of bees, 1 6 Saunders, Sir S., on Hymenopterous larvae, 8 Scale, 131, 133, 315, 467 ; development of, 329 f. ; -formation, 333 ; -holder, 331 Scale-Insects, 592 f. ; enemy of, 356, 357, 417, 425, 430 Scalpella, 443 Scape, 441 Scaphidiidae, 229 Scaphisoma aguricinum, 229 Scaphium, 314 Scapulae, 312 Scarabaeidae, 194 f. Scarabaeiui, 196 Scarabaeus sacer, 196, 197 Scatomyzidae, 504 Scatophagidae, 504 Scatopse, 477 Sceliphron, 112 ; S. nigripes, 91 Scenopinidae, 484 Schaffer, on structure of wings and ner- vures, 330 Schiodte, on Anoplura, 599 f. ;, on Hemi- ptera, 543 Sch istocerca peregrina, enemy of, 506, 514 Schizocarpus mingaudi, 220 Schizometopa, 504 Schizoneura, 589 Schizophora, 455 Schmidt-Schwedt, on D&nacia, 280 Schoenbergia, 360, 361 Schoenobiinae, 4%5 Sciapteron, 387 Sciara militant, 464 Sciomyzidae, 504 Sciophila unimaculata, 462 Scolia bifasciata, S. haemon-hoidalis, 97 Scoliidae, 93, 94 f. Scoliides, 97 f. Scolytidae, 294 Scopariidae, J$l Scopariinae, 421 Scopelodes, 401 Scopulipedes, 30, 32 f. Screw-worm, 512 Scudder, on butterflies, 543 Scutata or Scutati, 546 Scutellerides, 545 ScuteUigera, 501 Scutellum, 307, 312, 537 Scutum, 307 ; S. proboscidis, 443 Scydmaenidae, 223 Scymnites, 238 Scymnus minimus, 238 Seasonal dimorphism or variation, 335 Seitz, on Syntomid resemblances, 388, 389 Semi-loopers, 415 Seminal duct, 321 Semi-pupa, 271 Semper, on development of wing, 333 Sense-organ, 442, 448 ; thoracico-abdo- miual, 414 ; in Uraniidae, 419 Sepsidae, 504 Sericaria mori, 375 INDEX 623 Sericteria, 325 Seroot-fly, 482 Serricornia, 189, 213, 255 Sesia, 387 ; S. scoliaeformis, 321 Sesiidae, 386, 388, 370 (for Syntomidae), 389 Setae, 534 f. ; aerostatic, 408 Setina, 410 Seventeen-year Cicada, 569 Sex, differences, 92, 95 ; production of, 32, 67 ; in larva, 325 Sexuparous, 586 Sharp, on classification of Dytiscidae, 213 n. Sheep, bot-fly, 517 ; -tick, 518 Shield, 592 Shoulder, -lappets, 312 ; -tufts, 312 ; of wing, 319, 316 Siagona, 206 Siculodidae, 423 Siebold, von, on Strepsiptera, 301 Sigara minutissima, 568 Sight, of Pompilus, 104 Silk-glands, 325 Silkworm, 375 ; affected by parasitic fly, 507, 508 ; Madagascar-, 405 Silpha, 221 ; Silpha atrata, S. laerigata, S. lapponica, 222 ; S. obscura, 222 ; S. opaca, S. thoracica, 222 ^Silphidae, 221 f., 252, 256 Sima, 168 ; S. leviceps, stridulating organ, 169 ; S. ntfonigra, 169 Simuliidae, 477 Simulium columbaczense, 477 Sinodendron cylindricum, 194 Siphon, 563, 581, 589 Siphonaptera, 522 f. Siphonophora, 239 Siphunculata, 600 Sitaris, 33 ; S. humeralis, 272 Sitodrepa, 247 Skippers, 363 Slave-making ant, 149, 150, 163 Sloth, 430 Slug-worms, 402 Smallest Insect, 228 Smerinthini, 380 Smerinthus populi, 309, 381 Smith, F., on Mellinus arrensis. 123 Snails, enemies of, 205, 222, 510 ; parasite of, 495 Social, bees, 35 ; wasps, 78, 84 Sociales, 20, 53 f. Solatium dulcamara, beetle on, 232 Soldiers, 132 Soldier-ant, 150 Solenobia, 395, 430 "psisfugax, 137 Solitary wasps — see Fossores and Eurne- nidae Song, of Cicada, 572 Soronia, 232 Sound-organs, 448 ; of Ageronia, 354 ; of Hecatesia, 371 ; of Cicada, 573, 574 — see also stridulating organs Sound-production, 155, 156 ; by Aegocera, 411 ; by Arctiidae, 410 ; by Sphingidae, 382 — see also Stridulation Spalacopsini, 288 Spatula, 459 Spencer, Herbert, on Weismann, 143 Spercheus emarginatus, 218, 219 Spermatheca, 320, 321 Spermophila, 506 Sphaeridiides, 219 Sphaeriidae, 227 Sphaerttes, 223 Sphaeritides, 229 Sphaerius acaroides, 227 Sphaerocarides, 279 Sphecia, 387 Sphecius speciosus, 123 Sphecodes, 21, 22 ; S. gibbus, 23, 23 ; S. rubicundus, 22 ; S. subquadratus, 23 Sphegidae, 93, 107 f. Sphegides, 107 f. Sphex coendeus, 110 ; S. flavipennis, 108 ; S. lobatus, 110 ; S. maxillosus, 108 Sphindidae. 245 Sphingidae, 309, 315, 316, 368, 380 f. Sphinx ligustri, 380 Spider parasite, 490 Spilosoma, 408 Spinneret, 324, 325, 403, 417 Spirachtha, 227 Spiracles, 188, 191 ; of Diptera, 449 f. ; of Hippoboscidae, 519 ; of Lepidoptera, 313, 314 ; of Lipara, 451 ; of Xepa, 564 ; of Thrips, 528 Spondyliaspis, 581 Spondylidae, 288 Springing plant-lice, 579 Spuler, on nervures, 317 n. Squama, 448 Squeakers, 209 Staetherinia, 401 Stag-beetles, 193 Stalk, 317, 319 Staphyliuidae, 223, 224 f. Staudinger, Schatz and Rober, on butter- flies, 343 n. Wi/iii-HHotits maroccanus, 489 Staur opus fag i, 385 Slelis minuta, 29 ; S. nasuta, 30, 43 ; S. xiijiiiita, 30 Stelocyttares, 81 Stenamma tcestwoodi, 159 Stenopteryx hintndinis, 519 Stephostethus, 240 Sternorhyncha, 544 Sterrkopteryx, 394 Stethopathidae, 496 Stigmata— see Spiracles Stigmatomma, 180 Stigmut pendvku, 128 624 INDEX Sting, 4, 5, 6, 58, 144 ; development of, 8, 9 Stinging, 98 ; by Calicurgus, 102 ; by Pompilidae, 104 ; by Sphex, 109 Stingless bees, fil Stink-gland, 257, 533 ; -vessel, 225 Stipes, 309 Stizinae, 123 Stomach, 320 Stomoxys calcitrans, 512 Stratiomyidae, 478 Stratiomys, 452 Straus -Durckheim, on Melolontha, 198 Strawberries, eaten by beetles, 205 Streblidae, 521 Strepsiptera, 180, 298 f. Streptoperas, 401 Stridulating organ, of Myrmica, 133 ; of Jfeterocerus, 243 ; of Passalus- larva, 192 ; of Sima lericeps, 169 Stridulation, of ants, 134 ; of Corixa, 568 ; of Criocerides, 281 ; of Dynastides, 199; of Geotrupes, 195 ; of Ipides, 232 ; of Lomaptera, 200 ; of Longicorns, 287 ; of larva of Lucanus cervus, 194 ; of Mega- lopides, 282 ; of Melolontha -larva, 198 ; of Alutilla, 94 ; of Pelobius, 208 ; of Phonapate, 246 ; of Phyllomorpha, 548 ; of Praogena, 264 ; of Siagona, 206 ; of Trox, 195 Strigil, 568 Striphuopterygidae, 376 Strongylognathus huberi, S. testaceus, 162 Strumigenys, 170 Style, 442 Stylopidae, 298 Stylopised bees, 26 Stylops (lalii, 299 Styx infernalis, 358, 340 Suana, 405 Subcostal nervure, 318 Submedian nervure, 318 Suboesophageal ganglion, 320 Sucking-stomach, 311, 449 Suction by Lepidoptera, 311 Suctoria, 526 Supericornia, 546 Swallow-flies, 519 Swarming of wasps. 70 n. Swarms/62, 65 67, 80, 135, 467, 505, 584 Swift- moths, 396 Symbiosis, of ants and plants, 139 ; of bee and Acarid, 70. See also Ants'- nest Insects, and Association Symbius blattarmn, 269 Symphily, 183 Syuecthry, 183 Synemon, 371 Synoeca cyanea, nest, 82 Syntelia westwoodi, 229 Synteliidae, 229 Syntomidae, 339 n., 369, 388 Syntomis phegea, 390 Syringe, 535, 536 Syrphidae, 439, 498 f. Systoechits oreas, 489 Systropus crudelis, 489 Tabanidae, 481, 492 Tabanus, 482 Tachinidae, 507, 514 Tacky sphex panzeri, 117 Tachytes, 116 ; destroyer of, 275 ; T. australis, 113, 117 ; T. pectinipes, 117 Tachytides, 116 Taenia, fleas as hosts of, 526 Tajuria diaeus, pupa, 357 Taleporia, 395 Taleporiidae, 430 Tanypezidae, 504 Taphroderides, 296 Tapinoma erraticum, 157 Tarantula-killer 105 Tarphius, 233 Tarsolepis, 383 Tasclienberg, on anatomy of flea, 523 n. Tascina, 372 Tea-plant bug, 562 Teara melanosticta, 408 Tegula, 71, 187, 307, 311, 312, 447 Tegmina, 539 Teleodont, 193 Telephorides, 248 Telmatophihts, 235 Temnochila coendea, 232 Temnochilides, 233 Tenebrio molitor, 263 Tenebriouidae, 263 Tenebroides mauritanica, 232 Tentacle, maxillary, 309, 432 Tenthrediuidae, parasite of, 4 Terebrantia, 531 Termites, 203, 206, 227, 231 Terrifying attitude, 384 Tesseratomides, 546 Testes, 321, 324, 400, 429 ; iu larva, 325 Tetanocera ferruginea, 504 Tetanoceridae, 504 Tetragona, 53, 61 Tetramera, 190 Tetramorium caespitum, 160, 163 Tettigometrides, 567 Teucrium, bug and galls on, 550 Thais, pupation of, 363 Thanaos, 342 ; T. tages, audroconia, 332 Therevidae, 484 Tli irlilnpteryx, 420 Thomas, on aiidrocouia, 331 Thorictidae, 236 Thorictus, 236 Thrips, 526 f. ; Thrlp* lini, 531 ; T. secalina, 530 Throscides, 260 625 Thyatira batis, T. derasa, 386 Thyniaridae, 392 Thynnides, 96 Thyreophoridae, 504 Thyrididae, 370, 404 Thyridopteryx ephemerae/ormis, 394 Thysanoptera, 526 f. Tiger-beetles, 201 f. Tiger-moths, 409 Tillus elongatus, 253, 254: Tinaegeriidae, 370, 387 Tinea, 305 ; T. pellionella, 429, 430 ; T. vastella, 430 ; T. vivipara, 430 Tineidae, 340, 370, 394, 427, 428 Tineodidae, 423 Tineola biselliella, 430 Tingidae, 549 Tipida brobdignagia, 475 Tipulidae, 471 f.; T. Brevipalpi, 472, 473 ; T. Longipalpi, 472, 475 Tipulinae, 475 Tiresias serra, 241 Titanus giganteus, 287 Tithorea, 346 Tomicides, 295 Tuiiiiii/iiiithus sublaevis, 161 Tongue, 309 Tortoise-shell butterflies, 352 Tortricidae, 340, 395, 427, 432 Tortricina, 395 Tn.i:nrrhina, 472 Tn.i-ntrypana, 506 Trechus, 205 Trichiini, 200 Trichocera, 473 Trichodes alvearius, T. ammios, T. apiarius, 254 Trkhophaga tapetzella, 430 Trichoptera, 306, 425 Trichopterygidae, 227 Trictiopteryx fascicularis, 227 Tricliroism, 351 Trichterwickler, 294 Trichura, 389, 390 Trictenotomidae, 275 Triecphora, 543 Trigona, 53, 61 ; T. carbonaria, 63 ; T. crassipes, 65 ; T. mosquito, 62 Trimera, 23S, 544 Trimeria, 89 Trineura aterrima, 494 Triodites mus, 489 Trioza rhamni, 580 Tripluiena, 415 Triphleps, 530 Tritoma bipustulata, 236 Triungulin, 262, 268, 270, 271, 272, 299, 300 Troehalopoda, 543, 544 Trochanter, 307 ; divided, 123 TrochHium, 387 Trogini, 195 VOL. VI Trogositidae, 232, 235 Trogosita mauritanica, 232 Tromoptera, 457 Troj)hi — see Mouth -parts Trox, stridulation, 195 Truffle-beetle, 222 Trumpeter bumble-bee, 58 Trypnnaeus, 230 Trypanidae, 395 Trypetidae, 504, 506 Trypoxylonides, 118 Trypoxylon, 118; T. albitarse, 118; T. ftgulus, 119 Tse-tse fly, 512, 513 Tubulifera, 1 f. Tubulifera (Thrips), 531 Tulip-tree, tubes on, 578 Turkey-gnats, 477 Turnip-flea, 278 Tusser, or Tussore, silk, 374 Tympanoterpes gigas, 572 Typhlatta, 179, 180 Typklopone, 178, 179, 180 Ugimyia sericariae, 507 Ulidiidae, 504 Ulopa, 578 Uncus, 314 Urania rhipheus, 419 Uraniidae, 368, 419 Uric acid pigments, 357 Urodon, 278 Uzel, on Thysanoptera, 527 Vanessa, 352 ; larva, 354 — see also Pyrameis and Araschnia Vanessula, 356 Vapourer-moths, 407 Variation, of Anomma burmeisteri, 179 ; of Bombus, 58 ; of larvae, 336 ; of Sphecodes, 23 ; of male and worker ants, 160 ; of workers and females, 162 ; due to parasites, 26 ; of larva and imago, 408 ; generic, 401 ; local, 398 ; in nervuration, 414 ; and dimor- phism in Geometrid-larvae, 412 ; of mandibles of Lucanidae, 193 ; iu colour of Psyllidae, 579 ; trichroism of hind wings, 351 ; in size of Breuthidae, 297 ; of time and form in Cicada, 570 ; in wings, 540 ; as to winged or wingless, 531 ; change in, 414 ; seasonal, 335 Vasa deferentia, 321 Veils, 493 Veins — see nervures VeliM currens, 552 Velleius dilatatus, 227 Verhoeff, on Agenia, 106 ; on Halictus, 25 ; on Siphonophora, 239 ; on Stelis minuta, 29 ; on terminal segments of beetles, 186 Vermileo degeeri, 481 9 «? ^ o 626 INDEX Vermipsylla alakurt, 523, 526 Yerson, on rudiments of wings, 328 Vertebrates, larvae of Diptera, attacking, 506, 510, 512, 514, 514, 517, 520; tick-fleas on, 526 Vespa, nests of, 79, 83 ; V. austriaca, 81, 88 ; V. crabro, 81 ; V. germanica, 79 Yespidae, 78 Viviparous, Aphids, 583 ; fly, 506, 511, 513, 518 f. ; moths, 430 ; Staphylinidae, 227 Voice — see Song, Sound-organs, Stridula- tion Volucella, 500 ; F. bombylans, 441 Wagner, on morphology of fleas, 523 n. ; on paedogenesis, 460 Walker, J. J., on Halobates, 552 Wallace, on flight of Hesperiidae, 364 Walsingham, Lord, on Tortricidae, 427 Walter, on mouth of Lepidoptera, 308, 310 Wandering ants, 175 f. Wanzenspritze, 536 Wasmann, on Ants'-nest Insects, 181 n., 183 ; on Lomechusa, 142, 226 ; on Weismanu, 143 Wasps, 71 f. WTasps'-nest, beetle, 235 ; Insect, 268 Water-scorpion, 563 Wax, 65, 575, 576, 597 Wax-glands, 589 Wax-hairs, 580 Wedde, on mouth of Hemiptera, 535 Weeping-trees, 577 Weevil, biscuit-, 247 ; pea-, 277 Weinland, on halteres, 448 Wet- and dry-season forms, 336 Whirligig- beetle, 215 White wax, 576, 597 Whittell, on Pelopaeus and Larrada, 117 Wielowiejski, on luminous organs, 250 Wing-cases, of beetles, 186, 270 Wing, of bugs, 539 ; of Diptera, 447 ; of Lepidoptera, 315 f. ; development of, 328 ; structure of, 329 Wingless — see Apterous Wingless and winged Aphids, 584 Wing-nervures — see Nervures Wing-rib, 330, 333 Wing-veins — see Nervures Winter-gnats, 473 WTinter-moth, 414 Winter-mother, 586 Wire-worm, 258 Wood-ant — see Formica rufa Wood-leopard moth, 309, 395 Woodpecker, Diptera in, 506 Workers, 54, 66, 67, 79, 85, 132, 140 Worm-eaten furniture, 248 Xantharpyia straminea, parasite of, 521, 522 Xenos, 303 ; X. rossii, 299, 301 Xestobium, 248 Xylocopa, 32, 34, 70 ; submentum of, 14 ; X. chloroptera, 34 ; X. violacea, 33 Xylodiplosis, 458, 459 Xylophagidae, 479 Xylophaginae, 480 Xylophilidae, 266 Xylotrupes gideon, 199 Yellow-fever-fly, 464 Yolinus, 558 Young carried, 556 Yucca-moth, 432 Zabrus, 205 Zaitha anura, 566 Zelotypia staceyi, 396 Zemioses celtis, 296 Zeuzera aesculi, 309, 395 Zeuzeridae, 395 Zygaenidae, 369, 388, 390, 392, 394 Zygia, 253 END OF VOL. VI Printed by R. & R. CLARK, LIMITED, Edinburgh. THE CAMBRIDGE NATURAL HISTORY. COMPLETE LIST OF SERIES. VOLUME I. Protozoa, MARCUS HAIITOG, M.A., Trinity College (Professor of Natural History in the Queen's College, Cork) ; Sponges, W. J. SOLLAS, Sc.D., F.R.S., St. John's College (Professor of Geology in the University of Oxford) ; Jelly-fish, Sea- Anemones, etc., S. J. HICKSON, M.A., Downing College (Beyer Professor of Zoology in the Owens College, Manchester) ; Star-fish, Sea-Urchins, etc., E. W. MAcBiUDE, M.A., St. John's College (Professor of Zoology, M'Gill Uni- versity, Montreal). VOLUME II. Flatworms, etc., F. W. GAMBLE, M.Sc. (Viet.), (Demonstrator and Assistant- Lecturer in Zoology in the Owens College, Manchester) ; Nemertines, Miss L. SHELDON, Newnham College; Thread-worms, etc., A. E. SHIPLEY, M.A., Christ's College ; Rotifers, etc., MARCUS HARTOG, M.A., Trinity College, D.Sc. (Lond.), (Professor of Natural History in the Queen's College, Cork) ; Polychaet Worms, W. B. BENHAM, D.Sc. (Lond.), Hon. M.A. (Oxon.), Aldrichian Demonstrator of Comparative Anatomy in the University of Oxford ; Earth- worms and Leeches, F. E. BEDDARD, M.A. (Oxon.), F.R.S. (Prosector to the Zoological Society) ; Gephyrea, A. E. SHIPLEY, M.A., Christ's College ; Polyzoa, S. F. HARMER, M.A., King's College. [Ready. VOLUME III. Molluscs, A. H. COOKE, M.A., King's College ; Brachiopods (Recent), A. E. SHIPLEY, M.A., Christ's College ; Brachiopods (Fossil), F. R. C. REED, M.A., Trinity College. [Heady. VOLUME IV. Spiders, Mites, etc., C. WARBURTON, M.A., Christ's College (Zoologist to the Royal Agricultural Society) ; Scorpions, Trilobites, etc., M. LAUKIE, B.A., King's College, D.Sc. (Edinb.), (Professor of Zoology in St. Mungo's College, Glasgow); Pycnogonids, etc., D'AucY W. THOMPSON, C.B., M.A., Trinity College (Pro- fessor of Zoology in University College, Dundee) ; Crustacea, W. F. R. 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