7 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 JUL 1 - 1P«1 ,9- 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. MACMILLAN AND CO., LIMITED NEW YORK: THE MACMILLAN COMPANY I 9O I All rights resen.. Family. 'PASSALIDAE (p. 192). LUCANIDAE p. 193). j'Coprides (p. 195). SC-ARABAEIIKVE I ^elolonthides (p. 198). (p. 194) - Rutelides (p. 198). Dynastides (p. 199). ^ Cetoniidi Cetoniides (p. 199). ClCINDELIPAE (p. 201). fCarabides (p. 206). CARABIDAE | Harpalides (p. 206). (p. 204) "I Pseudomorphides (p. 206). I. Morraolycides (p. 206). AMPHIZOIDAE (p. 207). PKLOBUDAE (p. 207). HALIPLIDAE (p. 209). DYTISCIDAE (p. 210). ( PAUSSIDAE (p. 213). GYRINIDAK (p. 215). HYDROPHILIDAK (p. 216). PLATYPSYLLIDAE (p. 219). LEPTINIDAE (p. 220). SILPHIDAE (p. 221). Sc'YDMAENIDAE (p. 223). (iXn.STIDAE (p. 223). PSKLAI'HIDAE (p. 223). STAPHYLINIDAE (p. 224). SPHAERIIDAE (p. 227). TRICHOPTERYGIDAE (p. 227). HYDROSCAI-HIDAE (p. 228). CoRYLOPHIDAE (p. 228). Sl'APHimiDAE (p. 229). SYKTELIIDAE (p. 229). HlSTERIDAE (p. 230). PHALACKIHAE (p. 231). NITIDULIDAE (p. 231). TROGOSITIDAE (p. 232). (Jnl.YDIIDAE (p. 233). l!ll YSODIDAE (p. 234). CrcrjiDAE (p. 234). CRYPTOPHAGIDAE (p. 235). HELOTIDAE (p. 235). THORICTIDAE (p. 236). KlIiiTYLIDAE (p. 236). M YCF.TiiPHACIKAK (p. 237). CiiCCIXELLIDAE (p. 237). KXDOMYCHIPAE (p. 239). MYCKTAKIHAK (p. 239). l,\Ti:ii)iii>AK (p. 240). AIUMERIDAK, (p. 240). DKUMESTIDAK (ji. 241). P,VI;KHIDAE (p. 242). CYATHOCEUIDAE (]i. 243). ( 1 I ui;\ ssl DAK i p. 2 l:>). HETEUni'llUlliAK 'p. 213). I'AKMD \i: |>. 243 . LDERODONTJDAE (p. 21 SCHEME OF CLASSIFICATION IX Order. Sub Order, Division, or Series. COLEOPTERA (continued) Polymorpha (continued] Heteromera (p. 262) Phytophaga (p. 276) Rhyncho- phora(p. 288) Strepsiptera (p. 298) Family. ClOIDAE (p. 245). SPHINDIDAE (p. 245). BOSTRICHIDAE (p. 246). Sub- Family or Tribe. Jf Ptinides (p. 246). Anobiides (p. 246). (P- 248) Lampyrides (p. 248). Telephorides (p. 248). TINIDAE (p. 246) MALACODEK- MID4E » 948^ MELYRIDAE (p. 252). CLERIDAE (p. 253) LYMEXYLONIDAE (p. 254). DASCILLIDAE (p. 255). RHIPICERIDAE (p. 256). ' ' Throscides (p. 260). Eucnemides (p. 260). Elaterides (p. 260). Cebrionides (p. 260). Perothopides (p. 260). . Cerophytides (p. 260). . BUPRESTIDAE (p. 261). ELATERIDAE (p. 256). TEXEBRIOXIDAE (p. 263). CISTELIDAE (p. 264). LAGRIIDAE (p." 264). OTHXIIDAE (p. 265). AEGIALITIDAE (p. 265). MONOMMIDAE (p. 265). NILIOXIDAE (p. 265). MELANDKYIDAE (p. 265). PYTHIDAE (p. 265). PYROCHROIDAE (p. 266). AXTHICIDAE (p. 266). OEDEMERIDAE (p. 266). MORDELLIDAE (p. 267). CAXTHARIDAE (p. 269). TRICTEXOTOMIDAE (p. 275). BRUCHIDAE (p. 276) ( Eupoda (p. 280). | CHRYSOMEL- | Camptosomes (p. 281). IDAE (p. 278)1 Cyclica (p. 282). Cryptostomes (p. 282). CERAMBYCIDAE f . - Cerambycides (p. - . ( Lamiides (p. 287). /' ANTHRIBIPAE (p. 290). | CURCULIONIDAE (p. 290). SCOLYTIDAE (p. 294). BRENTHIDAE (p. 295). f AGLYCYDERIDAE (p. 297). \ PROTERHINIDAE (p. 298). STYLOPIDAE (p. 298). SCHEME OF CLASSIFICATION Order. LEPIDOPTERA (p. 304) lib-Order, Division, FT mil \- Sub-Family or or Series. Tribe.' r [ Danaides (p. 344). Ithomiides (p. 346). Satyrides (p. 347). XYMPHALIDAE , Morphides (p. 348). (p. 343) " Brassclides (p. 349). Acraeides (p. 350). Rhopalocera Heliconiides (p. 351. (p. 341) " v Xyinphalides (p. 352). ERYCIXIDAE f Eryciiiides (p. 355). (p. 354) \ Libytheides (p. 355). LYCAEXIDAE (p. 356). PIERIDAE (p. 357). PAPILIOXIUAE (p. 359). ^HESPERIIDAE (p. 363. CASTXIIDAE (p. 371). XEOCASTXIIDAE (p. 372). SATURXIIDAE (p. 372). BRAHMAEIDAE (p. 374). CERATOCAMPIDAE (p. 375), BOMBYCIDAE (p. 375). EUPTEROTIDAE (p. 376). PEUOPHORIDAE (p. 377^. SPHIXGIDAE (p. 380). CUCYTIIDAE (p. 382). XOTODOXTIDAE (p. 383). CYMATOPHORIDAE (p. 386). SESIIDAE (p. 386). TlXAEGERIIDAE (p. 387). SYXTOMIDAE (p. 388,. ZYGAEXIDAE (p. 390). < HlMAXTOPTERIDAE (p. 392). HETEROGYXIDAE (p. 392). PSYCHIDAE (p. 392). COSSIDAE (p. 395). ARBELIDAE (p. 396). CHRYSOPOLOMIDAE (p. 396). Heterocera (p. 366) HEPIALIDAE (p. 396). CALLIDULIDAE (p. 400). DREPAXIDAE (p. 400). LlMACODIDAE (p. 401). MEGALOPYGIDAE (p. 404). THYRIDIDAE (p. 404). LASIOCAMPIDAE (p. 405). EXDIMIMIDAE (p. 406). PTEROTHYSAXIDAE (p. 406). LYMAXTRIIDAE (p. 406). HYP.SIDAE (p. 408). ARCTIIDAE (p. 408). AHARISTIDAE (p. 410). GEOMETRIDAE (p. 411). XoCTl'IDAE (p. 414). EPICOPEIIDAE (p. 418). UUAXIIDAE (p. 419). Kl'iri.KMIHAE (p. 420). PYRALIDAE (p. 420). I'l 1 Hi'l'lliiKIIiAE (p. 426). A 1,1 ii i in \i; p. 126). TORTRICIDAK (p. 427). TIXKIDAE (p. 428). I EllIOCEPHALIDAE (p. 'I:;.'! . I . MlCRdl'TERYGIDAE (p. K!.~> SCHEME OF CLASSIFICATION XI Order. Sub-Order, Division, or Series. Family. DIPTERA (p. 438) Sub-Family or Tribe. Orthorrha- pha Nemo- cera (p. 455) Orthorrha- pha Bra chycera (pp. 455, 478) Cyclorrha- pha As- chiza (pp. 455, 494) Cyclorrha- pha Schi- zophora (pp. 456, 503) I ' CECIDOMYIIDAE (p. 458). MYCETOPHILIDAE (p. 462). BLEPHAROCERIDAK (p. 464). CULICIDAE. (p. 466). CHIRONOMIDAE (p. 468). ORPHXEPHILIDAE (p. 470). PSYOHODIDAE (p. 470). DIXIDAE (p. 471). TiPULiDAF ( ptych°I'terinae (P- 4"2)- T^jS \ Limnohiinae (p. 473). ( Tipulinae (p. 475). BlBIONIDAE (p. 475). SlMULlIDAK (p. 477). (p. 478). STRATIOMYIDAE (p. 478). LEPTIDAE (p. 479). TABANIDAE (p. 481). ACANTHOMERIDAE (p. 483). THEREYIDAE (p. 484). SCEXOPIXIDAE (p. 484). NEMESTRINIDAE (p. 484). BOMBYLIIDAE (p. 485). ACROCERIDAE (p. 489). LOXCHOPTERIDAE (p. 490). MYDAIDAE (p. 491). ASILIDAE (p. 491). APIOCERIDAE (p. 492). EMPIDAE (p. 492). _ DOLICHOPIDAE (p. 493). ' PHORIDAE (p. 494). PLATYPEZIDAE (p. 496). • PIPUXCULIDAE (p. 496). CONOPIDAE (p. 497). I SYRPHIDAE (p. 498). MtTSCIDAE ACALYPTRATAE (p. 503). AXTHOMYIIDAE (p. 5*06). TACHIXIDAE (p. 507). DEXIIDAE (p. 510). SARCOPHAGIDAE (p. 510). MUSCIDAE (p. 511). OESTRIDAE (p. 514). Pupipara ( (pp. 456, - 517) HIPPOP,OSCIDAE (p. 518). BRAULIDAE (p. 520). j STKEBLIDAE (p. 521). I XYCTERIBIIDAE (p. 521). APHANIPTERA | PULICID,E ( , d Jive visible segments; the female with an ovipositor, usually retracted, transversely segmented, enveloping a Jine, pointed style. The larvae usually live in the cells of other Hijinenoptera. 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. da Buysson in Andre, Sjiec. gen. Hym. vol. vi. 1896. VOL. VI IE B HV.MEXOPTERA CHAP. 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 Cleptcs the abdomen is, however, similar in form to that of the Aculeate Hynien- 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 Euby- iiies have the same number of segments as other Hymenoptera Petiolata. The difference in this re- sprct 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 lie 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 tine rods or spiculae. There are no poison glands, except in t'leptes, which form appears to come very near to the Aculeate series. Some of the Cbrysi- didii i occasions use the ovipositor as a sting, though it is only capaldc, of iiillid.ing a very minute and almost innocuous wound. Although none of the Huby-flies attain a large size, they arc usually very conspicuous on account of their gaudy or brilliant colours. They are amongst the most restless and rapid of Insects ; FIG. 1. — Clirysis -iyiiita, ?. 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 Clirysis iijiiita nying about the cell of Odynerus parietum, a solitary wasp that provisions its nest with caterpillars; in this cell the (. '// i't/sis 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 Clirysis 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 Clirysis 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 Clirysis 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 Enf. Mag. vi. 1869, p. 153. HYMENOl'TERA CHAP. after emerges a perfect Chrysis of the most brilliant colour, and if it be a female indefatigable in activity. It is remarkable O V 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 (.'/trysts 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. shamj- haiensis really lives on a Hymenopterous parasite in the cocoon of the Lepidopteron. Parnopcs car tic a frequents the nests of Benibex rostra ta, 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 Pa mopes takes advantage of this habit by entering the cell and depositing there an egg which produces a larva that devours that of the L'emlex. 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). Usual/// 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 <_;ival scries, characterised by the fact that the ovipositor is ACULEATA 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 t\vo divisions characterised by the fact that the ovipositor in one retains its function, the egg FIG. 2. — Diagram of upper sur- face of Priocnemis affi-iiis 9, Pompilidae. o, ocelli ; 7J1, pronotuni ; Rz, mesonotum ; B3, scutellum of mesonotnm ; B4, post-scutelluni or middle part of metanotum ; B5, propo- deuni or median segment (see vol. v. p. 491) ; If', combing hairs, pecten, of front loot : C1, first segment of abdomen, here not forming a pedicel or stalk : Z)1, coxa; JL>'2, trochauter; Lt3, femur ; />6, calcaria or spurs of bind leg : 1 to 15, iierv- 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; }?,, anterior of hind, wing; 1J, median ; 15, posterior : I to XI, the cells, viz. I. upper 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.1 We have dealt with the external anatomy of Hymenoptera in 1 For new views on this subject see note on p. 602. HYMENOPTERA CHAl'. 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 Kraepelin. Sollmann, Carlet l and others. It is an extremely perfect me- chanical arrangement. The sting 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 part to form a PIG. 3.-Stingofhee. A, One of the needles chamber, through which the separated ; a, the barbed point ; 6, piston ; needles play ; the needles are f 1 I'l i i T? ' I" »"ii» t.' i'ij fijfi Oi'n i\-\ r\-\~t r\*F -flii. a B arm. B, Tr;uis\ cisc section of tic • i sting: dd, the two needles; e, bead for each Provided With a pro- the needles; /, director; g, jectillg piece, wllicll, aS the f poison. (After Carlet.) channel of pois 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 project ions on the needles, acting after the manner of a piston, carry the poison before them. The needles are so arranged on 1 Ann. Sd. Nat. (7} ix. 1890, p. 1. 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. £. Ac. Paris, cxviii. 1894, p. 873. 8 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 Hynienoptera. Sir S. Saunders gives the following statement as to the larva of a wasp of the genus Psiliglossa,1 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 Katzeburg." 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 Corel'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 Trans, cut. Sac. London, 1873, p. 408. - Zcitschr. iviss. Zool. xxv. 1875, p. 184. ACULEATAy — 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 !«>dy 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 G of the pair that form the director are FlG. 4.— Development of sting of differentiated secondarily from the the bee : A and C, ventral ; B, side view. A, End of abdomen primary pair ot these masses 01 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 Hymenoptera) 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. i. Jahrb. xxiv. 1896, p. 192. - Zeitscltr. iciss. Zool. xxx. 1878, p. 78. 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.) I O HYMENOPTERA CHAP. 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 hack to tegulae . 2. Entomophila [ = Fossores part] Pronotum reaching hack 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 Ashmend'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 body 'plumose ; parts of the mouth elon- gated, sometimes to a great extent, so as to form a protrusible apparatus, usual I;/ 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, gr<'lm IOSP some are simule FIG. 5.— Hairs of Bees : A, simple hair from abdomen of Osmia; 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, cnt. Soc. 1878, p. 169. 1 f \ \ \ \ \ , \ \ o '/ \l v v V v> y \ / C\ \ hair from abdomen of Jlegacfiile ; C, plumose hair from thorax of Mega- chile ; D, from thorax of Andrena dorsata ; E, from thorax of Prosopis. I 2 HYMENOPTERA CHAP. 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 Fir,. 6.— A. Worker of the honey-bee pollen aml though their hind-legS (Aixsmellijim), with pollen plates - -,•£-, la.i.-n ; B, basal portions of a are also highly modified, yet the middle-leg (trochanter with part of modifications do not agree with coxa and ot femur) with plumose hairs and grains of pollen ; c, one those of the female, and their fiuic- hair bearing pollen-grams. ftre in ^ probability sexu.,l. 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,Vfhere 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 nut clear. Woltl' says it is done 1))- an i-xn- dation from the tibia; 11. M idler by ;idmi,\t lire of nectar from tin.' 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, howrever, 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 lie 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 tha.t 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. HYMEN OPT ERA CHAP. submentum is articulated with the mentuui iu 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 lorum varies in shape in accord- ance with the length of the subinentuin. The lorum is a o 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 A'ylu- copa, where the submentum is unusually short, this part reposes 7. FIG. 7.— Side view of basal portions of proboscis of Bombiis. a, Epipharyugeal sclerites ; 6, arrow indicating the position of the entrance to pharynx, which is concealed by the epipharynx, c ; d, hypopharyugeal sclerites ; e, vacant space between the scales of the maxillae through which the nectar comes : /, lobe ; /', stipes ; <1. i. ISSt!, \>. -17. 2 See Fig. 2fi. p. 71. 3 Bull. Mas. Paris, i. 1895, p. 38. BEES HABITS 1,9 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 Hymeuoptera, 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 workers. 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 f 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. o 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 Hyinenopterists 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-tongued 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) I>asygastres, those that carry it under the abdomen; some of the p;irasitie and other forms have been separated as (5) Denudatae (or ( 'iietilinae) : the l>ombi and the more perfectly social bees forming another group, viz. (G) Sociales. A group Andrenoides, or Pan urg ides, was also proposed for certain bees considered to belong to the Apidae though exhibiting many points of resent- i BEES — ARCHIAPIDES 21 blance 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 bees1 recognises no less than fourteen primary divisions, but is far from satisfactory. The two genera Prosopis and Spliecodcs 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- PfOSOpis must be parasites. This bridp 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 Hymcnoptcrorum, Leipzig, 10 vols. 1892-96 ; Bees, vol. x. - 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 CHAP. 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, Ly some of the non- parasitic forms, enables the bee to sweep the pollen towards its mouth. These observations show that the structural peculiarities of I'rosojtis 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 taxonomists. 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 Obtusilingurs 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 < inference 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 Spheco), ix. 1879, Xo. 4. 2 Act. 8uc. 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 .;-.\% :--.f^~'V'~r^f generations of the same species may vary. /^ 7 | Yerhoeff 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 the shaft. The larvae that are present ^T^h ^±Tl in the brood-chambers at any one moment differ much in their ages, a fact that throws some doubt 011 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. Yerhoeff states that many of the larvae are destroyed by mouldiness ; this indeed, he considers to lie the most deadly of the enemies of Aculeate Hymenoptera. The nest of Halictus maculatus has also been briefly described by Yerhoeff, 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 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.) 26 HYMENOPTERA CHAP. 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 Sti/lops, by which their form is more or less altered. 1 i/ -L ' v 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. E. C. L. Perkins recently captured a specimen of Halictus rul)icundus,fcom 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 1837 called attention to a remarkable relation existing between Andrena aterrimaand 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 the bee then maintams the parasite in its tracheal system of An- _ r Arena aterrima. (After position, and at the same time supplies it 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) on 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 9. Britain. carries loads of pollen, each about half its own weight, to its nest. The habits of this insect have been described by Hermann Mtiller.1 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 J'crh. Vcr. Eheinland, 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 bin- 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, Miiller 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 Ckalicodoma, 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 nut 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 orowth the larva becomes red and increases in weight from '0025 O y the artifice of building small stones into the walls of the cell ; the stones are selected with great care. When a cell about an inch in depth has been formed in this manner, the bee commences to fill it with food, consisting of honey and pollen ; a little honey is brought and is dis- charged into the cell, then some pollen is added. This bee, like other Dasygastres, carries the pollen by means of hairs on the under surface of the body ; to place this pollen in the cell the Insect therefore enters back- wards, and then with the pair of hind legs brushes and scrapes the under surface of the body so as to make the pollen fall off into the cell ; it then starts for Greece, a fresh cargo ; after a few loads have been placed in the recep- tacle, the Insect mixes the honey and pollen into a paste with the mandibles, and again continues its foraging until it has about half filled the cell ; then an egg is laid, and the apartment is at once closed with cement. This work is all accomplished, if the weather be favourable, in about two clays, after which the Insect commences the formation of a second cell, joined to the first, and so on till eight or nine of these receptacles have been constructed ; then comes the final operation of adding an additional protection in the shape of a thick layer of mortar placed over the whole ; the construction, when thus com- pleted, forms a sort of dome of cement about the size of half an orange. In this receptacle the larvae pass many months, exposed to the extreme heat of summer as well as to the cold of winter. The larvae, however, are exposed to numerous other perils ; and we have already related (vol. v, p. 540) how Lfitcospis gigas succeeds in perforating the masonry and depositing therein an egg, so that a Leucospis is reared in the cell instead of a Chalicodoma. FlG. 19. — ChalicoiliniKi ninri>riii. A, Male ; B, female. 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. Reaumur 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 a\vay ; 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 entomoloyiqucs. 4 vols. Paris, 1879 to 1891. 38 HYMENOPTERA CHAP. 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 du 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 Reaumur. 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 he observed that a Chalicodoma, on returning, found that another bee had during her absence taken possession of her partially completed cell, and 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 eno-ag-ed in testing, as it were, which was the more serious in its C> O O> 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 ;il\\;iys 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 Chali- codoma pyrenaica, which were removed to a distance of four kilometres and then liberated. About twenty of the individuals had been somewhat injured by the processes of capturing, mark- ing, and transferring, and proved unable to make a proper start. The others went off well when released, and in forty minutes the arrivals at the nest had already commenced. The next morning he was able to ascertain that fifteen at least had found their way back, and that it was probable that most of the uninjured bees had reached home ; and this although, as Fabre believed, they had never before seen the spot where he liberated them. These observations on the power of Chalicodoma to regain its nest attracted the attention of Charles Darwin, who wrote to M. Fabre, and suggested that further observations should be made with the view of ascertaining by means of what sense these bees were able to accomplish their return. For it must be borne in mind that this bee is very different from the domestic bee, inasmuch as it enjoys but a brief life in the winged state, and it is therefore to be presumed that an individual has no knowledge of such comparatively distant localities as those to which Fabre transported it. Further observations made by the Frenchman have unfortunately failed to throw any light on this point. Darwin thought it might possibly be some sensitiveness to magnetic conditions that enabled the bees to return home, and suggested that they should be tested as to this. Fabre accordingly made some minute magnets, and fixed one to each bee previous to letting them loose for a return journey. This had the effect of completely deranging the bees ; and it was there- fore at first thought that the requisite clue was obtained. It occurred to the experimenter, however, to try the plan of affixing small pieces of straw to the bees instead of magnets, and on this being done it was found that the little creatures were just as much deranged by the straws as they were by the magnets : thus it became evident that no good grounds exist for considering that the bees are guided by magnetic influences. One of the species * of Chalicodoma observed by Fabre fixes 1 The " ChaUcodome des galcts" or C. " dcs murailles" of the French writer ; in some places he speaks of the species as being C. mumrin, in others as C. parietina. 40 HYMENOPTERA CHAP. its nests to the small boulders brought down and left by the Khone on the waste places of its banks. This habit afforded Fabre an opportunity of removing the nests during the process of construction, and of observing the effect this produced on the architects. While a bee that had a nest partially constructed was absent, he removed the stone and the nest attached to it from one situation to another near at hand and visible from the original site. In a few minutes the bee returned and went straight to the spot where the nest had been ; finding its home absent it hovered for a little while around the place, and then alighted on the vacated position, and walked about thereon in search of the nest ; being after some time convinced that this was no longer there, it took wing, but speedily returned again to the place and went through the same operations. This series of manoeuvres was several times repeated, the return always being made to the exact spot where the nest had been originally located ; and although the bee in the course of its journeys would pass over the nest at a distance of perhaps only a few inches, it did not recognise the object it was in search of. If the nest were placed very near to the spot it had been removed from- say at a distance of about a yard — it might happen that the bee would actually come to the stone to which the nest was fixed, would visit the nest, would even enter into the cell it had left partially completed, would examine circumspectly the boulder, but would always leave it, and again return to the spot where the nest was originally situated, and, on finding that the nest was not there, would take its departure altogether from the locality. The home must be, for the bee, in the proper situation, or it is not recognised as the desired object. Thus we are con- fronted with the strange fact that the very bee that is able to return to its nest from a distance of four kilometres can no longer recognise it when removed only a yard from the original position. This extraordinary condition of the memory of the Insect is almost inconceivable by us. That the bee should accurately recognise the spot, but that it should not recognise the cell it had itself just formed and half-filled with honey-paste, seems to us almost incredible ; nevertheless, the fact is quite con- sistent with what we shall subsequently relate in the case of the solitary wasp BeTiibex. A cross experiment was made by taking away the stone with the attached nest of the bee while the latter i DASYGASTRES MASON-BEES INSTINCT 41 was absent, and putting in its place the nest of another indi- vidual in about the same stage of construction ; this nest was at once adopted by the bee, which indeed was apparently in no way deranged by the fact that the edifice was the work of another. A further experiment was made by transposing the positions of two nests that were very near together, so that each bee when returning might be supposed to have a free choice as to which nest it would go to. Unhesitatingly each bee selected the nest that, though not its own, was in the position where its own had been. This series of experiments seems to prove that the Chalci- doma has very little sense as to what is its own property, but, on the other hand, has a most keen appreciation of locality. As, however, it might be supposed that the bees were deceived by the similarity between the substituted nests, Fabre transposed two nests that were extremely different, one consisting of many cells, the other of a single incomplete cell ; it was, of course, a necessary condition of this experiment that each of the two nests, however different in other respects, should possess one cell each in similar stages of construction ; and when that was the case each bee cheerfully adopted the nest that, though very different to its own, was in the right place. This transposition of nests can be rapidly repeated, and thus the same bee may be made to go on working at two different nests. Suppose, however, that another sort of change be made. Let a nest, consisting of a cell that is in an early stage of construc- tion, be taken away, and let there be substituted for it a cell built and partially stored with food. It might be supposed that the bee would gladly welcome this change, for the adoption of the substituted cell would save it a great deal of work. Not so, however ; the bee in such a case will take to the substituted cell, but will go on building at it although it is already of the full height, and will continue building at it until the cell is made as much as a third more than the regulation height. In fact the bee, being in the building stage of its operations, goes on build- ing, although in so doing it is carrying on a useless, if not an injurious, work. A similar state ensues when the Insect ceases to build and begins to bring provisions to the nest ; although a substituted cell may contain a sufficient store of food, the bee goes on adding to this, though it is wasting its labours in so doing. It should be noted that though the bee must go through the 42 HYMENOPTERA CHAP. appropriate stages of its labours whether the result of so doing be beneficial or injurious, yet it is nevertheless to some extent controlled by the circumstances, for it does not in such cases complete what should have been the full measure of its own individual work ; it does not, for instance, raise the cell to twice the natural height, but stops building when the cell is about one-third larger than usual, as if at that stage the absurdity of the situation became manifest to it. Fabre's experiments with the Chalicodoma are so extremely instructive as regards the nature of instinct in some of the highest Insects, that we must briefly allude to some other of his observations even at the risk of wearying the reader who feels but little interest in the subject of Insect intelligence. Having discovered that a mason-bee that was engaged in the process of construction would go on building to an useless or even injurious extent, Fabre tried another experiment to ascer- tain whether a bee that was engaged in the process of provision- ing the nest, would do so in conditions that rendered its work futile. Taking away a nest with completely built cell that a bee was storing with food, he substituted for it one in which the cell was only commenced, and therefore incapable of containing food ; when the bee with its store of provisions reached this should-be receptacle it appeared to be very perplexed, tested the im- perfect cell with its antennae, left the spot and returned again ; repeating this several times it finally went to the cell of some stranger to deposit its treasure. In other cases the bee broke open a completed cell, and having done so went on bringing provisions to it; although it was already fully provisioned and an egg laid therein : finally, the little creature having completed the bringing of this superfluous tale of provisions, deposited a second egg, and again sealed up the cell. But in no case does the bee go back from the provisioning stage to the build- ing stage until the cycle for one cell of building, provisioning, and egg-laying is completed : but when this is the case, the building of a fresh cell may be again undertaken. This is a good example of the kind of consecutive necessity that seems to be one of the chief features of the instinct of these industrious little animals. Another equally striking illustration of these peculiarities of instinct is offered by interfering with the act of putting the provisions into the cell. It will be recollected that i DASYGASTRES- — MASON-BEES — PARASITES 43 when the bee brings provisions to add to the stock, it carries both honey and pollen ; in order to deliver these it begins by entering head first into the cell and disgorging the honey, then emerging it turns round, enters backwards and scrapes off the pollen from its body. If after the honey has been discharged, the bee be interfered with and gently removed to a slight dis- tance with a straw, it returns to complete its task, but instead of going on with the actions at the point at which the interruption took place, it begins the series over again, going in — at any rate partially — head first, although it has no honey to discharge, and having performed this useless ceremony it then emerges, turns round and adds the pollen. This illustration is in some respects the reverse of what might have been expected, for the Insect here does not continue the act at the interrupted point, but begins the series of actions afresh. It would be reasonable to suppose that an Insect that takes the pains to provide for the safety of its progeny by constructing a complex edifice of cement, secures thereby the advantage of protection for its young. But this is far from being the case. Notwithstanding the cement and the thick dome of mortar, the Chalicodoma is extremely subject to the attacks of parasites. The work performed by the creature in constructing its mass of masonry is truly astounding ; Fabre calculated from measure- ments he made that for the construction and provisioning of a single cell, the goings and comings of the bee amounted to 15 kilometres, and it makes for each nest sometimes as many as fifteen cells. Notwithstanding all this labour, it would appear that no real safety for the larvae is obtained by the work. Some sixteen — possibly more — other species of Insects get their living off this industrious creature. Another bee, Stelis nasuta, breaks open the cells after they have been completely closed and places its o\vn eggs in them, and then again closes the cells with mortar. The larvae of this Stelis develop more rapidly than do those of the Chalicodoma, so that the result of this shameless proceeding is that the young one of the legitimate proprietor— as we human beings think it — is starved to death, or is possibly eaten up as a dessert by the Stelis larvae, after they have appropriated all the pudding. Another bee, Dioxys cincta, is even more audacious ; it flies about in a careless manner among the Chalicodoma at their 44 HYMENOPTERA CHAP. work, and they do not seem to object to its presence unless it interferes with them in too unmannerly a fashion, when they brush it aside. The Dioxys, when the proprietor leaves the cell, will enter it and taste the contents ; after having taken a few mouthfuls the impudent creature then deposits an egg in the cell, and, it is pretty certain, places it at or near the bottom of the mass of pollen, so that it is not conspicuously evident to the Chalicodoma when the bee again returns to add to or complete the stock of provisions. Afterwards the constructor deposits its own egg in the cell and closes it. The final result is much the same as in the case of the Stelis, that is to say, the Chalicodoma has provided food for an usurper ; but it appears probable that the consummation is reached in a somewhat different manner, namely, by the Dioxi/s larva eating the egg of the Chali- codoma, instead of slaughtering the larva. Two of the Hymenop- tera Parasitica are very destructive to the Chalicodoma, viz. Leiicospis gigas and Mo nodontomcrus nitidus ; the habits of which -ve have already discussed (vol. v. p. 54:!) under Chalcididae. Lainpert has given a list of the Insects attacking the mason-bee or found in its nests ; altogether it would appear that about sixteen species have been recognised, most of which destroy the bee larva, though some possibly destroy tlje bee's destroyers, and two or three perhaps merely devour dead examples of the bee, or take the food from cells, the inhabitants of which have been destroyed by some untoward event. This author thinks that one half of the bees' progeny are made away with by these destroyers, while Fabre places the destruction in the South of France at a still higher ratio, telling us that in one nest of nine cells, the inhabitants of three were destroyed by the Dipterous Insect, Anthrax trifasciata, of two by Leucospis, of two by Stelis, and of one by the smaller Chalcid ; there being thus only a single example of the bee that had not succumbed to one or other of the enemies. He has sometimes examined a large number of nests without finding a single one that had not been attacked by one or other of the parasites, and more often than not several of the marauders had attacked the nest. It is said by Lampert and others that there is a passage in Pliny relating to one of the mason-bees, that the Roman author had noticed in the act of carrying off stones to build into its nest ; being unacquainted with the special habits of the bee, he DASYGASTRES CARDER-BEE 45 seems to have supposed that the insect was carrying the stone as ballast to keep itself from being blown away. The bees of the genus Anthidium are known to possess the habit of making nests of wool or cotton, that they obtain from plants growing at hand. We have one species of this genus of bees in Britain ; it some- times may be seen at work in the grounds of our Museum at Cambridge : it is referred to by Gilbert White, who says of it, in his History of Selborne : " There is a sort of wild bee frequenting the garden-campion for the sake of its tomentum, which prob- ably it turns to some purpose in the business of nidincation. It is very pleasant to see with what address it strips off the pubes, running from the top to the bottom of a branch, and shaving it bare with the dexterity of a hoop -shaver. When it has got a bundle, almost as large as itself, it flies away, holding it secure between its chin and its fore legs." The species of this genus are remarkable as forming a con- spicuous exception to the rule that in bees the female is larger than the male. The species of Anthidium do not form burrows for themselves, but either take advantage of suitable cavities formed by other Insects in wood, or take possession of deserted nests of other bees or even empty snail-shells. The workers in cotton, of which our British species A. manic atum is one, line the selected receptacle with a beautiful network of cotton or wool, and inside this place a finer layer of the material, to which is added some sort of cement that prevents the honied mass stored by the bees in this receptacle from passing out of it. A. diadema, one of the species that form nests in hollow steins, has been specially observed by Fabre ; it will take the cotton for FIG. 20. — Anthidium manicatum, Carder- bee. A, Male ; B, female. 46 IIYMENOPTERA CHAP. its work from any suitable plant growing near its nest, and does not confine itself to any particular natural order of plants, or even to those that are indigenous to the South of France. When it has brought a ball of cotton to the nest, the bee spreads out and arranges the material with its front legs and mandibles, and presses it down with its forehead on to the cotton previously deposited ; in this way a tube of cotton is constructed inside the reed ; when withdrawn, the tube proved to be composed of about ten distinct cells arranged in linear fashion, and connected firmly together by means of the outer layer of cotton ; the transverse divisions between the chambers are also formed of cotton, and each chamber is stored with a mixture of honey and pollen. The series of chambers does not extend quite to the end of the reed, and in the unoccupied space the Insect accumulates small stones, little pieces of earth, fragments of wood or other similar small objects, so as to form a sort of barricade in the vestibule, and then closes the tube by a barrier of coarser cotton taken frequently from some other plant, the mullein by preference. This barricade would appear to be an ingenious attempt to keep out parasites, but if so, it is a failure, at any rate as against Leticospis, which insinuates its eggs through the sides, and frequently destroys to the last one the inhabitants of the fortress. Fabre states that these Anthidium., as well as J\fcf/»cJ/ i/c, will continue to construct cells when they have no eggs to place in them ; in such a case it would appear from his remarks that the cells are made in due form and the extremity of the reed closed, but no provisions are stored in the chambers. The larva of the Anthidium forms a most singular cocoon. We have already noticed the difficulty that arises, in the case of these Hymenopterous larvae shut up in small chambers, as to the disposal of the matters resulting from the incomplete assimilation of the aliment ingested. To allow the once-used food to mingle with that still remaining unconsumed would be not only disagreeable but possibly fatal to the life of the larva. Hence some species retain the whole of the excrement until the food is entirely consumed, it being, according to Adlerz, stored in a special pouch at the end of the stomach ; other Hymen- optera, amongst which we may mention the species of Osmici, place the excreta in a vacant space. The Anthidium adopts, however, a most remarkable system: about the middle of its i DASYGASTRES ANTHIDIUM 47 larval life it commences the expulsion of " frass " in the shape of small pellets, which it fastens together with silk, as the}7 are voided, and suspends round the walls of the chamber. This curious arrangement not only results in keeping the embarrassing material from contact with the food and with the larva itself, but serves, when the growth of the latter is accomplished, as the outline or foundations of the cocoon in which the metamorphosis is completed. This cocoon is of a very elaborate character ; it has, so says Fabre, a beautiful appearance, and is provided with a very peculiar structure in the form of a small conical pro- tuberance at one extremity pierced by a canal. This canal is formed with great care by the larva, which from time to time places its head in the orifice in process of construction, and stretches the calibre by opening the mandibles. The object of this peculiarity in the fabrication of the elaborate cocoon is not clear, but Fabre inclines to the opinion that it is for respiratory purposes. Other species of this genus use resin in place of cotton as their working material. Among these are Anthidium septemdentatum and A. bcllicosum. The former species chooses an old snail-shell as its nidus, and constructs in it near the top a barrier of resin, so as to shut off the part where the whorl is too small ; then beneath the shelter of this barrier it accumulates a store of honey-pollen, de- posits an egg, and completes the cell by another transverse barrier of resin ; two such cells are usually constructed in one snail-shell, and below them is placed a barricade of small miscellaneous articles, similar to what we have described in speaking of the cotton- working species of the genus. This bee completes its metamor- phosis, and is ready to leave the cell in early spring. Its con- gener, A. liellicosum, has the same habits, with the exception that it works later in the year, and is thus exposed to a great danger, that very frequently proves fatal to it. This bee does not completely occupy the snail- shell with its cells, but leaves the lower and larger portion of the shell vacant. Now, there, is another bee, a species of Osmia, that is also fond of snail-shells as a nesting-place, and that affects the same localities as the A. septemdentatum; very often the Osmia selects for its nest the vacant part of a shell, the other part of which is occupied by the Anthidium ; the result of this is that when the metamorphoses are completed, the latter bee is unable to effect its escape, and 48 HYMENOPTERA CHAP. thus perishes in the cell. Fabre further states with regard to these interesting bees, that no structural differences of the feet or mandibles can be detected between the workers in cotton and the workers in resin ; and he also says that in the case where two cells are constructed in one snail-shell, a male individual is produced from the cell of the greater capacity, and a female from the other. Osmia is one of the most important of the genera of bees found in Europe, and is remarkable for the diversity of instinct displayed in the formation of the nests of the various species. As a rule they avail themselves for nidification of hollow places already existing ; choosing excavations in wood, in the mortar of walls, and even in sandbanks ; in several cases the same species is found to be able to adapt itself to more than one kind of these very different substances. This variety of habit will render it impossible for us to do justice to this interesting genus within the space at FIG. 21. — Osmia tricornis, ?. Algeria. our disposal, and we must content ourselves with a con- sideration of one or two of the more instructive of the traits of Ositiia life. 0. tridentata forms its nest in the steins of brambles, of which it excavates the pith ; its mode of working and some other details of its life have been well depicted by Fabre. The Insect having selected a suitable bramble-stalk with a cut extremity, forms a cylindrical burrow in the pith thereof, extending the tunnel as far as will be required to allow the construction of ten or more "cells placed one after the other in the axis of the cylinder ; the bee does not at first clear out quite all the pith, but merely forms a tunnel through it, and then commences the construction of the first cell, which is placed at the end of the tunnel that is most remote from the entrance. This cavity is to be of oval form, and the Insect therefore cuts away more of the pith so as to make an oval space, but somewhat truncate, as it were, at each end, the plane of truncation at the proximal extremity being of course an orifice. The first cell i DASYGASTRES OSMIA 49 thus made is stored with pollen and honey, and an egg is deposited. Then a barrier has to lie constructed to close this chamber ; the material used for the barrier is the pith of the stem, and the Insect cuts the material required for the purpose from the walls of the second chamber ; the excavation of the second chamber is, in fact, made to furnish the material for clos- ing up the first cell. In this way a chain of cells is constructed, their number being sometimes as many as fifteen. The mode in which the bees, when the transformations of the larvae and pupae have been completed, escape from the chain of cells, has been the subject of much discussion, and errors have arisen from inference being allowed to take the place of observation. Thus Dufour, who noted this same mode of construction and arrange- ment in another Hymenopteron (Odyncrus nidulator}, perceived that there was only one orifice of exit, and also that the Insect that was placed at the greatest distance from this was the one that, being the oldest of the series, might be expected to be the first ready to emerge ; and as the other cocoons would necessarily be in the way of its getting out, he concluded that the egg that \vas last laid produced the first Insect ready for emergence. Fabre tested this by some ingenious experiments, and found that this was not the case, but that the Insects became ready to leave their place of imprisonment without any reference to the order in which the eggs were laid, and he further noticed some very curious facts with reference to the mode of emergence of Osmia tridentata. Each Insect, when it desires to leave the bramble stem, tears open the cocoon in which it is enclosed, and also bites through the barrier placed by the mother between it and the Insect that is next it, and that separates it from the orifice of exit. Of course, if it happen to be the outside one of the series it can then escape at once ; but if it should lie one farther down in the Indian file it will not touch the cocoon beyond, but waits patiently, possibly for days ; if it then still find itself con- fined it endeavours to escape by squeezing past the cocoon that intervenes between it and liberty, and by biting away the material at the sides so as to enlarge the passage ; it may succeed in doing this, and so get out, but if it fail to make a side passage it will not touch the cocoons that are in its way. In the ordinary course of events, supposing all to go well with the family, all the cocoons produce their inmates in a state for emergence within VOL. VI E 50 HYMENOPTERA CHAP. a week or two, and so all get out. Frequently, however, the emergence is prevented by something having gone wrong with one of the outer Insects, in which case all beyond it perish unless they are strong enough to bite a hole through the sides of the bramble-stem. Thus it appears that whether a particular Osmia shall be able to emerge or not depends on two things — (1) whether all goes well with all the other Insects between it and the orifice, and (2) whether the Insect can bite a lateral hole or not; this latter point also largely depends on the thickness of the outer part of the stem of the bramble. Fabre's experiments on these points have been repeated, and his results confirmed by Nicolas. The fact that an Osmia would itself perish rather than attack the cocoon of its brother or sister is certainly very remarkable, and it induced Fabre to make some further experiments. He took some cocoons containing dead specimens of Osmia, and placed them in the road of an Osmia ready for exit, and found that in such case the bee made its way out by demolishing without any scruple the cocoons and dead larvae that intervened between it and liberty. He then took some other reeds, and blocked the way of exit with cocoons containing living larvae, but of another species of Hymenoptera. Solcnius vagus and Osmia detrita were the species experimented on in this case, and he found that the Osmia destroyed the cocoon and living larvae of the Solenius, and so made its way out. Thus it appears that Osmia will respect the life of its own species, and die rather than destroy it, but has no similar respect for the life of another species. Some of Fabre's most instructive chapters are devoted to the habits and instincts of various species of the genus Osmia. It is impossible here to find space even to summarise them, still more impossible to do them justice ; but we have selected the history just recounted, because it is rare to find in the insect world instances of such self-sacrifice by an individual for one of the same generation. It would be quite improper to generalise from this case, however, and conclude that such respect for its own species is common even amongst the Osmia. Fabre, indeed, relates a case that offers a sad contrast to the scene of self- sacrifice and respect for the rights of others that we have roughly portrayed. He was able to induce a colony of Osmia tricornis (another species of the genus, be it noted) to establish itself and i DASYGASTRES LEAF-CUTTING BEES 5 I work in a series of glass tubes that he placed on a table in his laboratory. He marked various individuals, so that he was able to recognise them and note the progress of their industrial works. Quite a large number of specimens thus established themselves and concluded their work before his very eyes. Some individuals, however, when they had completed the formation of a series of cells in a glass tube or in a reed, had still not entirely completed their tale of work. It would be supposed that in such a case the individual would commence the formation of another series of cells in an unoccupied tube. This was not, however, the case. The bee preferred tearing open one or more cells already completed —in some cases, even by itself — scattering the contents, and de- vouring the egg ; then again provisioning the cell, it would deposit a fresh egg, and close the chamber. These brief remarks will perhaps suffice to give some idea of the variety of instinct and habit that prevails in this very interesting genus. Friese observes that the variety of habits in this genus is accompanied as a rule by paucity of individuals of a species, so that in central Europe a collector must be prepared to give some twenty years or so of attention to the genus before he can consider he has obtained all the species of Osmia that inhabit his district. As a prelude to the remarks we are about to make on the leaf-cutting bees of the genus Meyachile it is well to state that the bee, the habits of which were described by Eeaumur under the name of " 1'abeille tapissiere," and that uses portions of the leaves of the scarlet poppy to line its nest, is now assigned to the genus Osmia, although Latreille, in the interval that has elapsed since the publication of Reaumur's work, founded the genus Antliocopa for the bee in question. Megacliile is one of the most important of the genera of the Dasygastres, being found in most parts of the world, even in the Sandwich Islands ; it consists of bees averaging about the size of the honey-bee (though some are considerably larger, others smaller), and having the labrum largely developed ; this organ is capable of complete inflection to the under side of the head, and when in the condition of repose it is thus infolded, it underlaps and protects the larger part of the lower lip ; the mandibles close over the infolded labrum, so that, when the Insect is at rest, this appears to be altogether absent. These bees are called leaf-cutters, from their habit of forming the cells for their nest HYMENOPTERA CHAP. out of pieces of the leaves of plants. We have several species in Britain ; they are very like the common honey-bee in general appearance, though rather more robustly formed. These Insects, like the Osmiae, avail themselves of existing hollow places as receptacles in which to place their nests. M. alljocincta frequently takes possession of a deserted worm-burrow in the ground. The burrow being longer than necessary the bee commences by cutting off the more distant part by means of a barricade of foliage ; this being done, it proceeds to form a series of cells, each shaped like a thimble with a lid at the open end (Fig. 22, A). The body of the thimble is formed of large oval pieces of leaf, the lid of smaller round pieces ; the fragments are cut with great skill from the leaves of growing1 plants by the Insect, which seems to have an idea of the form and size of the piece of foliage necessary for each particular stage of its work. Home has given particulars as to the nest of MegacTiile a utltm- cina (fascieulata), an East Indian species.1 The material employed was either the leaves of the Indian pulse or of the rose. Long pieces are cut by the Insect from the leaf, and with these a cell is formed ; a circular piece is next cut, and with this a lid is made for the receptacle. The cells are about the size and shape of a common thimble ; in one specimen that Home examined no less than thirty-two pieces of leaf disposed in seven layers wTere used for one cell, in addition to three pieces for the round top. The cells are carefully prepared, and some kind of matter of a gummy nature is believed to be used to keep in FIG. 22. — Nidification o( leaf -cutting bee, Megachile anthracina. A, ..m- place the pieces forming the ill- cell separated with lid open; the terior * The ceR , d larva (a) reposing on the foocl ; B, p;ut of a string of the cells. (After end to end, as shown in Fig. 22, B ; five to seven cells form a series, and four or six series are believed to be constructed by one pair 1 Trims. Zool. ,SW. London, vii. 1870, p. 178. i BEES DASYGASTRES SOCIALES 5 3 of this bee, the mass being located in a hollow in masonry or some similar position. Each cell when completed is half filled with pollen in the usual manner, and an egg is then laid in it. This bee is much infested by parasites, and is eaten by the Grey Hornbill (Meniceros Mcornis*). Megachile lanata is one of the Hymenoptera that in East India enter houses to build their own habitations. According to Home both sexes take part in the work of construction, and the spots chosen are frequently of a very odd nature. The material used is some kind of clay, and the natural situation may be considered to be the interior of a hollow tube, such as the stem of a bamboo ; but the barrel of a gun, and the hollow in the back of a book that has been left lying open, have been occasionally selected by the Insect as suitable. Smith states that the individuals developed in the lower part of a tubular series of this species were females, " which sex takes longer to develop, and thus an exit is not required for them so soon as for the occupants of the upper cells which are males." J/. proxima, a species almost exactly similar in appearance to M. lanata, makes its cells of leaf-cuttings, however, and places them in soft soil. Eabre states that M. albocincta, which commences the formation of its nest in a worm -burrow by means of a barricade, frequently makes the barricade, but no nest ; sometimes it will indeed make the barricade more than twice the proper size, and thus completely fill up the worm burrow. Fabre considers that these eccentric proceedings are due to individuals that have already formed proper nests elsewhere, and that after completing these have still some strength remaining, which they use up in this fruitless manner. The Social bees (SOCIALES) include, so far as is yet known, only a very small number of genera, and are so diverse, both in habits and structure, that the propriety of associating them in one group is more than doubtful ; the genera are Bomlms (Fig. .'!.">1, vol. v.), with its commensal genus or section, Ps//A///-//.s (Fig. 23); Melipona (Fig. 24), in which Trigona and Tetragona may at present be included, and Apis (Fig. 6) ; this latter genus comprising the various honey-bees that are more or less com- pletely domesticated in different parts of the world. In the genus Boml'us the phenomena connected with the social life are more similar to what we find among wasps 54 HYMENOPTERA CHAP. than to what they are in the genus Apis. The societies come to an end at the close of the season, a few females live through the winter, and each of these starts a new colony in the following spring. Males, females and workers exist, but the latter are not distinguished by any good characters from the females, and are, in fact, nothing but more or less imperfect forms thereof; whereas in Apis the workers are distinguished by structural characters not found in either of the true sexes. Hotter has given a description of the commencement of a society of Bonibus lapidarius.1 A large female, at the end of May, collected together a small mass of moss, then made an expedition and returned laden with pollen ; under cover of the moss a cell was formed of wax taken from the hind-body and mixed with the pollen the bee had brought in ; this cell was fastened to a piece of wood ; when completed it formed a subspherical recep- tacle, the outer wall of which consisted of wax, and whose interior wras lined with honey-saturated pollen ; then several eggs were laid in this receptacle, and it was entirely closed. Hotter took the completed cell away to use it for museum purposes, and the following day the poor bee that had formed it died. From observations made on Bomb us agronun he was able to describe the subsequent operations ; these are somewhat as follows : — The tirst cell being constructed, stored, and closed, the industrious architect, clinging to the cell, takes a few days' rest, and after this interval commences the formation of a second cell ; this is placed by the side of the first, to which it is connected by a mixture of wax and pollen ; the second cell being completed a third may be formed ; but the labours of the constructor about this time are augmented by the hatching of the eggs deposited a few days previously ; for the young larvae, having soon disposed of the small quantity of food in the interior of the waxen cell, require feeding. This operation is carried on by forming a small opening in the upper part of the cell, through which the bee conveys food to the interior by ejecting it from her mouth through the hole ; whether the food is conveyed directly to the mouths of the larvae or not, Hotter was unable to observe ; it being much more difficult to approach this royal founder without disturbing her than it is the worker-bees that carry on similar occupations at a subsequent period in the history of the 1 Mt. Ver. Steiermark, xxxi. 1882, p. 69. SOCIALES BUMBLE-BEES 5 5 society. The larvae in the first cell, as they increase in size, apparently distend the cell in an irregular manner, so that it becomes a knobbed and rugged, truffle-like mass. The same thing happens with the other cells formed by the queen. Each of these larval masses contains, it should be noticed, sister-larvae all of one age ; when full grown they pupate in the mass, and it is worthy of remark that although all the eggs in one larval mass were laid at the same time, yet the larvae do not all pupate simultaneously, neither do all the perfect Insects appear at once, even if all are of one sex. The pupation takes place in a cocoon that each larva forms for itself of excessively fine silk. The first broods hatched are formed chiefly, if not entirely, of workers, but small females may be produced before the end of the season. Huber and Schmiedeknecht state that though the queen provides the \vorker-cells with food before the eggs are placed therein, yet no food is put in the cells in which males and females are produced. The queen, at the time of pupation of the larvae, scrapes away the wax by which the cocoons are covered, thus facilitating the escape of the per- fect Insect, and, it may also be, aiding the access of air to the pupa. The colony at first grows very slowly, as the queen can, unaided, feed only a small number of larvae. But after she receives the assistance of the first batch of workers much more rapid progress is made, the queen greatly restricting her labours, and occupying herself with the laying of eggs; a process that now proceeds more and more rapidly, the queen in some cases scarcely ever leaving the nest, and in others even becoming incapable of flight. The females produced during the inter- mediate period of the colony are smaller than the mother, but supplement her in the process of egg - laying, as also do the workers to a greater or less extent. The conditions that deter- mine the egg-laying powers of these small females and workers are apparently unknown, but it is ascertained that these powers vary greatly in different cases, so that if the true queen die the continuation of the colony is sometimes effectively carried on by these her former subordinates. In other cases, however, the reverse happens, and none of the inhabitants may be capable of producing eggs : in this event two conditions may be present ; either larvae may exist in the nest, or they may be absent. In the former case the workers provide them with food, and the 56 HYMENOPTERA CHAP. colony may thus still be continued ; but in the latter case, there being no profitable occupation for the bees to follow, they spend the greater part of the time sitting at home in the nest. Supposing all to go well with the colony it increases very greatly, but its prosperity is checked in the autumn ; at this period large numbers of males are produced as well as new queens, and thereafter the colony comes to an end, only a few fertilised females surviving the winter, each one to commence for herself a new colony in the ensuing spring. The interior of the nest of a bumble-bee (Boinbus) frequently presents a very irregular appearance ; this is largely owing to the fact that these bees do not use the cells as cradles twice, but form others as they may be required, on the old remains. The cells, moreover, are of different sizes, those that produce workers being the smallest, those that cradle females being the largest, while those in which males are reared are intermediate in size. Although the old cells are not used a second time for rearing brood they are nevertheless frequently adapted to the purposes of receptacles for pollen and for honey, and for these objects they may be increased in size and altered in form. It may be gathered from various records that the period required to complete the development of the individual Bombus about midsummer is four weeks from the deposition of the egg to the emergence of the perfect Insect, but exact details and information as to whether this period varies with the sex of the Insect developed are not to be found. The records do not afford any reason for supposing that such distinction will be found to exist : the size of the cells appears the only correlation, suggested by the facts yet known, between the sex of the in- dividual and the circumstances of development. The colonies of Bombus vary greatly in prosperity, if W7e take as the test of this the number of individuals produced in a colony. They never, however, attain anything at all approach- ing to the vast number of individuals that compose a large colony of wasps, or that exist in the crowded societies of the more perfectly social bees. A populous colony of a subterranean Bombus may attain the number of oOO or 400 individuals. Those that dwell on the surface are as a rule much less populous, as they are less protected, so that changes of weather are more i SOCIALES NESTS OF BOMBUS 57 prejudicial to them. According to Smith, the average number of a colony of B. muscorum in the autumn in this country is about 120 — viz. 25 females, 36 males, 59 workers. No mode of increasing the nests in a systematic manner exists in this genus ; they do not place the cells in stories as the wasps do ; and this is the case notwithstanding the fact that a cell is not twice used for the rearing of young. When the ground-space available for cell-building is filled the Bombus begins another series of cells on the ruins of the first one. From this reason old nests have a very irregular appearance, and this condition of seeming disorder is greatly increased by the very different sizes of the cells themselves. We have already alluded to some of these cells, more particularly to those of different capacities to suit the sexes of the individuals to be reared in them. In addition to these there are honey - tubs, pollen-tubs, and the cells of the Psithyrus (Fig. 23), the parasitic but friendly inmates of the Bombus- nests. A nest of Bombus, exhibiting the various pots projecting from the remains of empty and partially destroyed cells, presents, as may well be imagined, a very curious appearance. Some of the old cells apparently are partly destroyed for the sake of the material they are composed of. Others are formed into honey- tubs, of a make-shift nature. It must be recollected that, as a colony increases, stores of pro- visions become absolutely necessary, otherwise in bad weather the larvae could not be fed. In good weather, and when flowers abound, these bees collect and store honey in abundance ; in addition to placing it in the empty pupa-cells, they also form for it special receptacles ; these are delicate cells made entirely of wax filled with honey, and are always left open for the benefit of the community. The existence of these honey - tubs in 1 tumble-bees' nests has become known to our country urchins, whose love for honey and for the sport of bee-baiting leads to wholesale destruction of the nests. According to Hoffer, special tubs for the storing of pollen are sometimes formed ; these are much taller than the other cells. The Psithyrus that live in the nests with the Bombus are generally somewhat larger than the latter, and consequently their cells may be distinguished in the nests by their larger size. A bumble-bees' nest, composed of all these heterogenous chambers rising out of the ruins of former layers of cells, presents a scene of such apparent disorder that 58 HYMENOPTERA CHAP. many have declared that the bumble-bees do not know how to build. Although the species of Bombus are not comparable with the hive-bee in respect of the perfection and intelligent nature of their work, jet they are very industrious Insects, and the con- struction of the dwelling-places of the subterranean species is said to be carried out in some cases with considerable skill, a dome of wax being formed as a sort of roof over the brood cells. Some work even at night. Tea has recorded the capture of a species in Upper Burmah working by moonlight, and the same industry may be observed in this country if there be sufficient heat as well as light. Godart, about 200 years ago, stated that a trumpeter-bee is kept in some nests to rouse the denizens to work in the morning : this has been treated as a fable by subsequent writers, but is confirmed in a circumstantial manner by Hoffer, who observed the performance in a nest of B. ruderatus in his laboratory. On the trumpeter being taken away its office was the following morning filled by another individual. The trumpeting was done as early as three or four o'clock in the morning, and it is by no means impossible that the earliness of the hour may have had something to do with the fact that for 200 years no one confirmed the old naturalist's observation. One of the most curious facts in connection with Bomlnis is the excessive variation that many of the species display in the colour of the beautiful hair with which they are so abundantly provided. There is not only usually a difference between the sexes in this respect, but also extreme variation within the limits of the same sex, more especially in the case of the males and workers ; there is also an astonishing difference in the size of individuals. These variations are carried to such an extent that it is almost impossible to discriminate all the varieties of a species by inspection of the superficial characters. The struc- tures peculiar to the male, as well as the sting of the female, enable the species to be determined with tolerable certainty. Cholodkovsky,1 on whose authority this statement as to the sting is n uide, has not examined it iu the workers, so that we do not know whether it is as invariable in them as he states it to be in queens of the same species. According to Handlirsch,' each 1 Zont. An;, vii. 1884, p. 312. 2 SJ3. Gcs. Wien. xxxviii. 1888, p. 34. SOCIALES PSITHYRUS 59 species of Bombus has the capacity of variation, and many of the varieties are found in one nest, that is, among the offspring of a single pair of the species, but many of the variations are restricted to certain localities. Some of the forms can be considered as actual (" fertige ") species, intermediate forms not being found, and even the characters by which species are recognised being some- what modified. As examples of this he mentions Bombus silvarum and B. arenicula, B.pratorum and B. scrim sJtiranus. In other cases, however, the varieties are not so discontinuous, intermediate forms being numerous ; this condition is more common than the one we have previously described ; B. terrestris, B. horturum, B. lapidarius and B. pomorum are examples of these variable species. The variation runs to a considerable extent in parallel lines in the different species, there being a dark and a light form of each ; also each species that has a white termination to the body appears in a form with a red termination, and vice versd. In the Caucasus many species that have everywhere else yellow bands possess them white ; and in Corsica there are species that are entirely black, with a red termination to the body, though in continental Europe the same species exhibit yellow bands and a white ter- mination to the body. AVith so much variation it will be readily believed that much remains to be done in the study of this fascinating genus. It is rich in species in the Northern hemi- sphere, but poor in the Southern one, and in both the Ethiopian and Australian regions it is thought to be entirely wanting. The species of the genus Psithyrus (Apatkus of many authors) inhabit the nests of Bombus; although less numerous than the species of the latter genus, they also are widely distributed. They are so like Bombus in appearance that they were not distinguished from them by the earlier entomologists ; and what is still more remarkable, each species of Psithyrus resembles the Bombus with which it usually lives. There appear, however, to be occasional exceptions to this rule, Smith having seen one of the yellow- banded Psithyrus in the nest of a red-tailed Bombus. Psitliyrus is chiefly distinguished from Bombus by the absence of certain characters that fit the latter Insects for their industrial life ; the hind tibiae have no smooth space for the conveyance of pollen, and, so far as is known, there are only two sexes, males and per- fect females. The Bombus and Psithyrus live together on the best terms, and it appears probable that the latter do the former 6o HYMENOPTERA CHAP. no harm beyond appropriating a portion of their food supplies. Schmiedeknecht says they are commensals, not parasites ; Lut it must be admitted that singularly few descriptions of the habits and life-histories of these interesting Insects have been recorded. Hoffer has, however, made a few direct observations which confirm, and at the same time make UK ire definite, the vague ideas that have been generally prevalent among He took entomologists. FIG. 23. — Psitliyrus restalix, Britain. A. Female, x :] ; B. outer side of hind lee. found and home a nest bus variabilis, which contained also a female of Psitliyrus ccinipestris, so that he was able to make observations on the two. The PsitJiyrus was much less industrious than the Bombus, and only left the nest somewhat before noon, returning home again towards evening ; after about a month this specimen became still more inactive, and passed entire days in the nest, occupying itself in consuming the stores of honey of its hosts, of which very large quantities were absorbed, the Psitliyrus being much larger than the host-bee. The cells in which the young of the Psithyrus are hatched are very much larger than those of the Bombus, and, it may therefore be presumed, are formed by the Psitliyrus itself, for it can scarcely be supposed that the Bv minis carries its complaisance so far as to construct a cell specially adapted to the superior stature of its uninvited boarder. When a Psitkyrus has been for some time a regular inhabitant of a nest, the Bombus take its return home from time to time as a matter of course, displaying no emotion what- ever at its entry. Occasionally Hoffer tried the introduction of a Psitliyrus to a nest that had not previously had one as an in- mate. The new arrival caused a great hubbub among the Bombus, which rushed to it as if to attack it, but did not do so, and the alarm soon subsided, the Psitliyrus taking up the position in the nest usually affected by the individuals of the species. On i SOCIALES STINGLESS BEES 6 I introducing a female Psitliyrus to a nest of Bombus in which a Psitliyrus was already present as an established guest, the latter asserted its rights and drove away the new comer. Hoffer also tried the experiment of placing a Psitliyrus campestris in the nest of Bombus lapidarius — a species to which it was a stranger ; not- withstanding its haste to fly away, it was at once attacked by the Bombus, who pulled it about but did not attempt to sting it. When Psitliyrus is present in a nest of Bombus it apparently affects the inhabitants only by diminishing their stores of food to so great an extent that the colony remains small instead of largely increasing in numbers. Although Bombus variabilis, when left to itself, increases the number of individuals in a colony to 200 or more, Hoffer found in a nest in which Psithyrus was present, that on the 1st of September the assemblage consisted only of a queen Bombus and fifteen workers, together with eighteen speci- mens of the Psitliyrus, eight of these being females. The nests of Bombus are destroyed by several animals, probably for the sake of the honey contained in the pots ; various kinds of small mammals, such as mice, the weasel, and even the fox, are known to destroy them ; and quite a fauna of Insects may be found in them ; the relations of these to their hosts are very little known, but some undoubtedly destroy the bees' larvae, as in the case of Meloe, Mutilla and Conops. Birds do not as a rule attack these bees, though the bee-eater, M<:r<>p* "jiii'stcr, has been known to feed on them very heavily. The genera of social bees known as Melipona, Trigona or Tetra- gona, may, according to recent authorities, be all included in one genus, Melipona. Some of these Insects are amongst the smallest of bees, so that one, or more, species go by the name of " Mosquito- bees." The species appear to be numerous, and occur in most of the tropical parts of the continents of the world, but unfortunately very little is known as to their life-histories or economics ; they are said to form communities consisting at times of a countless number of individuals ; but it has not been thoroughly ascer- tained whether these are the produce of a single queen, as in the case of the hive-bee, or whether there may be more than one egg-producer in each community. The late F. Smith thought the former of these alternatives would prove to lie correct. These mosquito-bees are frequently spoken of as stingless bees, but this is not quite correct, for although they do not sting, 62 HYMENOPTERA CHAP. von Ihering1 says that all the essential elements of the sting are present, the pointed or penetrating part of the apparatus being stunted. It would serve no useful purpose to attempt to construct the social history of these stingless bees from the numerous brief scattered accounts in entomological literature, for they refer to different species ; it is, however, positively stated by Smith on the authority of Peckolt ~ that Trigona mosquito sends off swarms after- the manner of the hive-bee in this country, and that after search- ing six hives only one royal female could be found in each. The nests of many of these little bees are rich in honey, and they have a host of enemies from man and monkeys downwards : and as they do not defend themselves by stinging, it might be supposed they would have but a poor time of it. From the accounts that have been published we may, however, gather that they are rich in devices for the protection of their nests, and for the exclu- sion of intruders. Bates has given some particulars as to Mi-lipona, interrupts (fasci- culat(i) ; it is about one-third shorter than the hive-bee, and its colonies are composed of an im- mense number of individuals. The workers are usually occupied in gathering pollen ; but they also collect clay in a similar manner, and convey it to the nest, where it is used for building a wall to complete the fortification of the nest, which is placed either in a suitable bank, or in a trunk of a tree; in either situation it is completely built in with clay. A nest which Bates saw opened contained about two quarts of pleasantly-tasted liquid honey. Forty-five species of these little bees were found in different parts of the Amazons Valley, the largest kind being half an inch in length, the smallest very minute, not more than one-twelfth of an inch. These little creatures are thus masons as well as workers in wax and resin, and they are also gatherers of nectar, pollen, and resin. 1 Hut. Xtn-hr. xii. 1866, p. 177. ' Tr. cut. Xoc. London, 1868, p. 133. FIG. 24. — Mclipima sp. 9. Amazons. i SOCIALES STINGLESS BEES 63 According to Gosse, one of these bees is well known in Jamaica, where they are called " Angelitos," in consquence of their not sting- ing people. He observed a nest of this bee in a tree, and found it to be much infested by black ants anxious to obtain entrance to it ; three bees, however, stood sentinel in the entrance, so as to completely block it and keep out intruders, but the middle bee moved on one side out of the way directly one of its fellows wished to come in or out of the nest. The honey accumulated by this species is kept in clusters of cups about the size of a pigeon's egg, at the bottom of the hive and away from the brood- cells. The queen or mother-bee is lighter in colour than the others, and has the hind body twice the length of theirs. Hoc-kings 1 has given us some details as to the natural history of two of these bees that inhabit Australia, where they are called " Karbi " and " Kootchar," the first being, it is supposed, Trigona carbonaria, Smith: it is usually about three -sixteenths of an inch in length, the queen, when fully developed, being nearly twice that length. The comb is built in a most peculiar form, being, it is said, in the shape of a spiral staircase, and tapering towards the ends : honey -pots and pollen are constructed for the storage of food. The comb is encased in wax, and outside it a labyrinth of waxen passages is formed. The entrance to the colony is guarded by a line of bees who inspect every one that arrives, and it is surprising to see how soon a stranger is dis- covered and pounced upon before it has time even to alight ; the intruder, when caught, is held by several bees, who put it on the rack by holding and stretching out its limbs to their full extent, retaining it in this position for as long as an hour, by which time the unfortunate prisoner is usually dead. These bees, as well as 'many other allied species, fight desperately with their mandibles, and are apparently of a very fierce disposition. The other species, called " Kootchar," is said to produce a very large number of drones, and the habits and dispositions of the bees differ con- siderably from those of the " Karbi " : the entrance to their hive is guarded by a pipe of propolis (a sort of resinous wax) about an inch in length, having an exceedingly sticky outer edge, and it is by this pipe alone that access to the interior can be gained. At night the entrance is closed by numerous minute globules of semi-fluid gum placed against it, thus forming a thin wall full of air-holes. 1 Tr. cnt. Soc. London, 1884, p. 149. 64 HYMENOPTERA CHAP. The colonies of " Kootchar " can be united by taking away a queen and then packing her brood-nest, bees and all, against that of the colony it is to be joined to. This cannot be done with the ' Karbi." The account given by Mr. Hockings contains a great many other interesting details, and there can be no doubt that a full account of the natural history of these Insects would be very instructive. Fritz Miiller has recorded a singular case bearing on the instinct of these social Insects : he says that a nest of a small Triyona was built in a hollow tree, and that as a consequence of the irregularity of the hole the bees were obliged to give a very irregular shape to their combs of honey. These bees were captured and put in a spacious box (presumably together with the irregular comb, but this he unfortunately does not mention) : after a year, " when perhaps not a single bee survived of those which had come from the canella tree," they still continued to build irregular combs, though quite regular combs were built by several other communities of the same species that he had kept. These bees, he also tells us, do not use pure wax for the construc- tion of their combs, but mix it with resin or gum that gives it a peculiar odour and appearance. He captured two communities of a common Melipona, one of which had the combs made of dark reddish brown, the other of pale yellowish brown, wax, and in captivity in a distant locality each of the twro communities continued to form its comb in the same way, thus showing the continuity that prevails in these cases as long as circumstances permit. Miiller thinks this due to imitation, but it seems at least as probable that it is due to perception of the properties of the nest. The nest has a certain colour that the worker-bee matches. Several species of the Melipona, and Triijoim were imported from Brazil to France, and kept there for some time in captivity by M. Drory. Girard has published1 some details as to these colonies, and is of opinion that some of them indicate an in- telligence or instinct superior to that of the honey-bee. The <|iir-rn-bce of M. scutell - DIVISION II. DIPLOPTERA OR WASPS - EUMENIDAE, SOLITARY TRUE WASPS - YESPIDAE, 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 tea id c i .; the based seg- ments of the hind, bodi/ not bearing nodes or scales ; the hind tarsi formed for simple ti--- — 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 lias suggested that the folding is done to keep the delicate hind-margins of the wings from being frayed. HYMENOPTERA CHAP. 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. Eumeiiidae, Vespidae and Masaridae. We anticipate that Eumenidae and Vespidae will ultimately be found to constitute but one family. Fam. 1. Eumenidae — Solitary True Wasps. Clau's of the feet toothed or Infid ; middle tibiae with only one xjn/r at tip. Social assemblages are not formed, mid tin re is a n y/-y 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 we 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 flavouicta 9- TO- • i i -^ ii i Burma. The Wigs on the left difference in habits there seenw to be in the position of repose, to 110 satisfactory way of distinguishing 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 art- believed to be stung by the parent-wasp (as is the case in the II 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. When 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, secticm tlnou"h neg> *' °f o J_ in'i-its reniformis ; B, of Eumenes the little larva is Still enabled to arbiistonnn. «, The suspended egg reach it by the fact that the egg- »,',£. ^,"^t?™ 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. unguiculata, however, according to an imperfect account given by Perris, 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. to wood : B, 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 ccniica, according to Home, constructs in Hindostan clay-nests with very delicate walls. This species pro- visions its nest with ten or Uvelve green de- caterpillars ; on one occasion this ob- ^rver 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. ()
  • /i//rs 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 Eeaumur, of another by Dufour ; and recently Fabre has added to the accounts of these naturalists some important information drawn from his own II 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, Beaumur, or Dufour. 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. — Odynerus 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. Fa,bre 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 76 IIVMENOPTERA 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. (Pteroclieilus) 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, Argi/romoeba sinuata, takes advantage of the habit of the Odyne.rtis of leaving its nest open during the process of pro- visioning, and deposits also an egg in the nest ; the Odyncrus 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 Ariiyromoelxi hatches, and the maggot produced feeds on the caterpillars the wasp intended for its own offspring. Yerhoeff 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, 0. 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 Odynci'n*. 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 Achatinella 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, puncttim is fond of availing itself of holes in door-posts where large screws have heen ; 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. carnaticum seems to have very similar habits to its European congener, adapting for its use the hollow stems of bamboos. Home 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, E. nitidulum. This latter Insect, however, does not nidificate in the stems of plants, but constructs clay cells similar to those of Uumenes, and fixes them firmly to wood. Rhygchium Innineum is said by Sir Bicharcl Owen to obliterate hieroglyphic inscriptions in Egypt by its habit of building mud 78 11YMF,\OPTKRA CIIAI-. nests amongst them. An individual ol' this wasp was found by Pr. Birch when unrolling a mummy — "Then1 being every reason to believe that the In see I hail remained in the position in which it was found ever sinee tin1 last rites were paid to the aneieiit Egyptian." Fam. 2. Vespidae — Social Wasps. Claws of the feet simple, neither toothed nor bijid, middle tibiae •with tico spurs (ft the tip. Insects living in societies, for/// - inif a common dicellitii/ 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 eells, 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, buses 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 woodv fibre — amalgamated by means of IV O J 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 Vespidte than they do in that of the bees and fossorial Hymenoptera, In most of the nests of Yespida? 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 eells 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 imauo taking place in the cells after thev have been entirely O -L v v n SOCIAL WASI'S YKSPIDAK 79 a cjo-e> interval of 90 mm. between top of uest and surface ; ^> height of tne nest, 163 mm. the '-olouy; she lays the foundation of the cells, deposits the _ .- in them, feeds the young, arid thus rears a brood of work that ;it on'-'- ;i-.-ist her, and for the future relieve her of a con- -i'l'-mljle portion of her former occupations; the nest is by them ;nl"i/i'i/i/imryi iml fells. 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 ;is in ants. Very little exact information exists as to the habits and life- histories of the species. Christ and Drewsen, forty or fifty years ago, recorded that M. euro'paea lives in the nests of bees of the genus Jiombus, and Hoffer has since made some observations on the natural history of the same species in South East Europe, where this Mitt ill a is found in the nests of ten or eleven species of Bombus, being most abundant in those of B. ayrorum, and B. variabilis ; occasionally more individuals of Mnfilln than of bees may be found in a nest. He supposes that the egg of the Ma tHlu, is placed in the young larva of the Bombux, 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 Ill SCOLIIDAE— MUTILLIDES 95 much to be desired. From the observations of Radoszkowsky it is clear that other species of Mutillides are by no means confined to the nests of Bovibus 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 8 FIG. 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 ft -male 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 Q6 HYMENOPTERA CHAP. habits. The African and East Indian genus, Apterogyna, includes some extremely peculiar Hymenoptera ; the males have the wing nervuratioii 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 winy with three, or on/// two, sub-marginal cells ; the female wingless and with ///> thorax divided into three sub-equal FIG. 39. — Methoca ichneumonides. A, Male ; B, female. Britain. 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 nervuratioii 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. Thynnides 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 Ill 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 until 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 nervuratioii 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 Euclilora ; 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 haemorohoidalis 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 Srolia 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. Sapygldes. — Closely allied to the Scoliides, but j>os- 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. Peckhani 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. 100 HYMENOPTERA CHAT. FIG. 41. — $cij>i/yn -l-j/i'/tctata ?, Britain. is less interrupted ; the eyes are deeply emarginate ; the hind body is not spinose at the apex. The economy of Sapygn, 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 h\ -pel-metamorphosis (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. AVe have two species of Sapyga in Britain ; they differ in , *•• colour, and the sexes of S. 5 -punctata also differ in this respect ; the a bdomen , spot t e d with white in both sexes, is in the female variegate with red. Smith found our British Sapyga o- punctata carrying cater- pillars. "CR- Sub-Fam. 5. Rhopalo- somides. --Antennae elongate, spinigerous ; FIG. 42. — Rhopalosoma poeyi. A, female imago ; ocelli very prominent ; B< IVoilt of " Cuba" (After Westwood-) tarsi of peculiar structure, their claws bifid. This sub-family has recently been proposed by Ashmead J for 1 P. cut. Soc. Washington, iii. 1896, p. 303. in FOSSORES 101 an extremely rare American Insect that had previously been placed by Cresson among parasitic Hymenoptera. Westwood classed RJiopalosoma among Diploptera, saying of it " animal quoad affmitates 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 inform, 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 102 HYMENOPTERA CHAP. 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 ma.y 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 winch 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 1'oiupilid, yet if the two be confined together in a vase, both are FIG. 43. — Calicurgus hyalinatus ?. Britain. ill 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 Pompilus 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 removing, 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 104 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 2^olistoides. 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 Hew 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 Pe^)sis, a genus peculiar to America, whence upwards of 200 species are already known.1 Some of them ;iltain a length of two inches or more, and are able to conquer the largest spiders ; even the formidable Mygale 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. Zcitsclir. xxxix. 1894. in POMPILIDAE IO5 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 hentzii, 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 Pcpsis, 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 Pcpsis. 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. Parcqiompilus 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 vise for flight. P. gravesii is an inhabitant of Chili. Agenia carbonaria and A. liyalipennis 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. liycdipennis 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. 106 HYMENOPTERA CHAP. 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 innexed, while 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 un 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 lii/nli nutus, 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 liabits 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, in 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 ; when the stigmatic lobes extend as far back as the wing -insertion, they are placed below it and separated l>y 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 Kohl x 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. Wicn. 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 mesonoturn, not of the metanotum, as there stated. IO8 HVMENOPTERA 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 Sphcx 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 Spliex, 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 ^l>]iexs 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 IOQ 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 Spliex, 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 Spliex 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 1 2 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 I I O HVMENOPTERA CHAP. 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 cpuite 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. Sphex coendetis 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 Pelopacus (Sceliphron) coendcus. S. coeridcus is no doubt the same as S. (Chlorion) Inlmtt/s, 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 X/i/K'.i- 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 Itothney repeated the experiment ; in due course the same series in SPHEGIDAE — SPHEGIDES I I I uf operations was performed, and were repeated many times, the Sphex 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- phila selecting different grubs for the purpose. A. liirsuta 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 lias 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. ajfinis ; 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 motliQT-Ammojyhila 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 names, 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. TWTO or thivr 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. Pelopae.us (Scdipliroti) is a genus including many species ; * 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 ,sv/7/y>A/-n// \\\\<\ various other genera. We 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 113 to be specially .attached to the habitations of human beings. Both has given an account of the habits of P. (Scelipliron} 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. Both 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 Leucospid parasite. Tachytes 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. (SceUpliroti) madraspcdanus 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 T HYMENOPTERA CHAP. 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. (Sceliphroii) bilineatus, formerly thought to be a variety of P. 'inadraspatanv-S, builds its nests in hedges and trees. Sub-Fam. 2. Ampulicides. — Prothorax long and narrow. forming a neck in front ; chjpeus 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 Male. four times its own size, suc- ceeds, after a struggle, in sting- ing it; the cockroach instantly becomes quiet and submissive, and suffers itself to lie lei] away and placed in confinement in some Fid. 4i.— Am/in/' '• cnmpressa. East India. 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 Eothney in reference to the habits of A. (Elii- nopsis) rujicornis 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 rufonigra, 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 \vere partially known to Reaumur, 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 Ampidex 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 Dolicliurus is by some entomologists considered the type of a sub-family allied to the Ampulicides ; 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 Il6 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. haeinorrhous lives at the expense of Loloptera deei/iicn*, 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 loch/ not pt'' fi/n'n ; inconspicuous. Marginal cell of the front wings culate,1 or mandibles excised externally, or loth. This group is by some writers called Tachy tides instead of Larrides, as owing to a change of nomenclature Txcliytcs 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 " Miscoplt us group " of Kohl. The species of the genus Tachy tes 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 Spltex 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 w;is 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 lie appendiculate. Tin- nervnres I'reijiiently extend beyond the complete cells towards the outer margin, forming " incomplete " cells: only complete cells are counted, except when "incomplete" is mentioned. Ill SPHEGIDAE — LARRIDES 117 FIG. 45. — Tachytes pectinipes ?. Britain. 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 Tacliytcs 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. Larra anathema chooses mole-crickets as the viand for its young, and Tachysphex panzeri selects grasshoppers of the family Acridiidae. Larra pompiliformis ( = Tachytes nigcr, Fabre) some- times associates itself with Sphex flavipennis (? 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 Spliex, 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 (Sceliphrori) 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 consecpuences of the intruder's operations ; I I 8 HYMENOPTERA CHAP. 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 lie 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 Larradn 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 nivde^in, 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 Lan-ide* 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 ;m- apparently rather fond of human propinquity, and build clay- or mud-nests in or inMi' houses. T. albitarse has this habit, and is well known in Southern Brazil under the name of " Marimbouda da casa " Ill 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 bus and cockroaches FlG' 46 —Astata male- Britaln- being their disagreeable char- 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 emarginale externally ; kind body stout, not pedicellate. The elongation of the labruni, though one of the most trust- worthy of the characters of the Bembecides, cannot be altogether I2O HYMENOPTERA CHAP. 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 !:<• in hex 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 FIG. 47. — Bembex rostrata Europe. 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 Hies away: to proceed possibly with the formation 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 Benibex 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 lie 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 Bcmlex 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 HVMENOPTERA 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 Bmibex 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 Bemlex 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. These1 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 Sphecius 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, when 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. — Lcibrum short; mandibles entire on the outer edge; hind liody usually not pedicellate; wing with the marginal cell not appendicidate. 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 MeUinus, in which the abdomen is pedi- cellate (Fig. 48), while others treat that genus as forming a distinct sub-family, Mellinides. Kohl leaves MeUinus 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. MeUinus 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 CHAP. 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 Mellinus ? and is it found necessary to adopt some fresh contrivance in order to * accomplish its ends ( if so, it is FIG. 48. — Mellinus arcensis ?. Britain. i .c • i T not deficient in devices. noticed once or twice, what I took to he a dead specimen of Mellinus, lying on patches of cow-dung ; but on 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 Prance Mellinus salnilosus 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 Hymeuopteron 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. — Laltnun small ; anterior icings ivith three complete, submarginal o /As ; him I l>»t/// constricted at the base Imt not so as to form a slender pedicel. This sub-family contains Insects resembling wasps or Tra- limnides in appearance, and is, as regards the pronotal structure, Ill 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 triaiiyulttm 6- Britain. of the nature of which we are unaware, that determines the selection made by the Insect. In the case of our British species of Cerceris, Smith observed C. arenaria carrying to its nest Cur- culionidae of very diverse forms ; while C. labiata used a beetle —Haltica tabida — of the family Chrysomelidae. The beetles, after being caught, are stung in the chief articulation of the body, that, namely, between the pro- and mesothorax. Cerceris lupresticida confines itself exclusively to beetles of the family Buprestidae. It was by observations on this Insect that Dufour first discovered the fact that the Insects stored up do not decay : he thought, however, that this was due to the liquid injected by the wasp exercising some antiseptic power; but the observations of Fabre have shown that the pre- servation in a fresh state is due to life not being extinguished ; the stillness, almost as if of death, being due to the destruction of the functional activity of the nerve centres that govern the movements of the limbs. 126 IIYMENOPTERA CHAP. It has long been known that some species of Cerceris prey on bees of the genus Hal ictus, and Marchal has recently described in detail the proceedings of C. ornata. This Insect catches 'a Halictus on the wing, and, holding its neck with the mandibles, bends her body beneath it, and paralyses it by a sting admin- istered at the front articulation of the neck. The Halictus is subsequently more completely stunned or bruised by a process of kneading by means of the mandibles of the Cerceris. Marchal attaches great importance to this " malaxation " ; indeed, he is of opinion that it takes as great a part in producing or prolonging the paralysis as the stinging does. Whether the malaxation would be sufficient of itself to produce the paralysis he could not decide, for it appears to be impossible to induce the Cerceris to undertake the kneading until after it has reduced the Halictus to quietude by stinging. Fabre made some very interesting observations on Cerceris tnlerculiita, their object being to obtain some definite facts as to the power of these Insects to find their way home when removed to a distance. He captured twelve examples of the female, marked each individual on the thorax with a spot of white paint, placed it in a paper roll, and then put all the rolls, with their prisoners, in a box ; in this they were removed to a distance of two kilometres from the home and then released. He visited the home five hours afterwards, and was speedily able to assure himself that at any rate four out of the twelve had returned to the spot from whence they had been transported, and he enter- tained no doubt that others he did not wait to capture had been equally successful in home- finding. He then commenced a second experiment by capturing nine examples, marking each with two spots on the thorax, and confining them in a dark box. They were then transported to the town of Carpentras, a distance of three kilometres, and released in the public street, " in the centre of a populous quarter," from their dark prison. Each Cerceris on being released rose vertically between the houses to a sufficient height, and then at once passed over the roofs in a southerly direction— the direction of home. After some hours he went back to the homes of the little wasps, but could not find that any of them hail then returned; the next day he went again, and found that at any rate five of the Cerceris liberated the previous day were then at home. This record is of considerable in SPHEGIDAE — MIMESIDES I2/ interest owing to two facts, viz. that it is not considered that the Cerceris as a rule extends its range far from home, and that the specimens were liberated in a public street, and took the direc- tion of home at once. Philanthus apivorus is one of the best known of the members of this sub -family owing to its habit of using the domestic honey-bee as 'the food for its offspring. In many respects its habits resemble those of Cerceris ornata, except that the Pkil- anthus apparently kills the bee at once, while in the case of the Cerceris, the' Hal-ictus it entombs does not perish for several days. The honey-bee, when attacked by the Philanthus, seems to be almost incapable of defending itself, for it appears to have no power of finding with its sting the weak places in the armour, of its assailant. According to Fabre, it has no idea of the Phil- anthus "being the enemy of its race, and associates with its destroyer on amicable terms previous to the attack being made on it. The Philanthus stings the bee on the under- surface of the mentum ; afterwards the poor bee is subjected to a violent process of kneading, by which the honey is forced from it, and this the destroyer greedily imbibes. The bee is then carried to the nest of the Philanthus. This is a burrow in the ground ; it is of unusual depth — about a yard according to Fabre — and at its ter- mination are placed the cells for the reception of the young ; in one of these cells the bee is placed, and an egg laid on it : as the food iu this case is really dead, not merely in a state of anaesthesia, the Pkilanthus does not complete the store of food for its larvae all at once, but waits until the latter has consumed its first stock, and then the mother-wasp supplies a fresh store of food. In this case, therefore, as in Bembex, the mother really tends the offspring. Sub-Fam. 9. Mimesides. - - Small Insects with pedicellate hind body, tlie pedicel not cylindric ; mandibles not excised ex- ternally ; inner margin of eyes not concave ; middle tibia with one spur ; wings with two, or three, submarginal cells. Mimesides is here considered to include the Pemphredonides of some authors. Mimesides proper comprises but few forms, and those known are small Insects. Psen concolor and P. a.tratus form their nests in hollow stems, and the former provisions its nest with Homopterous Insects of the family Psyllidae. Little 128 HYMENOPTERA CHAP. FIG. 50. — Mimesa bicolor f, Britain. information exists as to their liabits ; but Verhoeff states that the species of Pscn — like mem- bers of the Pemphredoninae— do not form cocoons. The Pemphredonine subdivi- sion includes numerous small and obscure Insects found chiefly in Europe and North America (Fig. 51, P. lugubris)', they resemble the smaller black species of Cra- bronides, and are distinguished from them chiefly by the exist- ence of at least two complete, submarginal cells on the an- terior wing instead of one. The species of Passaloecus live in the burrows that they form in the stems of plants ; Pemphredon lugubris frequents the decayed wood of the beech. The larva and pupa of the latter have been described by Verhoeff; no cocoon is formed for the metamorphosis. Both these genera provision their nests with Aphidae. This also the case with Stt pendulus, but the burrows of this species form a com- plex system of diverticula proceeding from an irregu- lar main channel formed in the pithy stems of bushes. Cemonus unicolor, according to Giraud, forms its burrows in bramble - stems, but it also takes advantage, for the purposes of nidification, of the abandoned galls of Ct/nij>n, and also ol a peculiar swelling formed by a fly — Llpm-n lucens —on the common reed, Arundo p/i /•/ mites. This species also makes use of Aphidae, and Verhoeff states that it has only an imperfect instinct as to the amount of iood it stores. Sub-Fam. 10. Crabronides --Pi'onoitun short, front u-rmj u-iih one co////>/i fr submarginal and two discoidal cell* : hind body s FIG. 51. — Pemphredon luyitbris 9. Britain. Ill SPHEGIDAE CRABRONIDES 129 /•(triable in form, pedicellate in some abnormal forms, but more usually not stalked. The Crabronides ( Vespa crabro, the hornet, is not of this sub- family) are wasp-like little Insects, with unusually robust and quadrangular head. They frequently have the hind tibiae more or less thickened, and the clypeus covered with metallic hair. It appears at present that they are specially attached to the tem- perate regions of the northern hemisphere, but this may possibly be in part due to their having escaped attention elsewhere. In Britain they form the most im- portant part of the fossorial Hymenoptera, the genus Crabro (with numerous sub- genera) itself comprising thirty species. The males of some of the forms have the front tibiae and tarsi of most extraordinary shapes. They form burrows in dead wood, or in pithy stems, (occasionally in the earth of cliffs), and usually store them with Diptera as food for the larvae : the wings and dried portions of the bodies of the flies consumed by Crabronides are often exposed to view when portions of old wood are broken from trees. The genus Oxybelus is included by some systematists, but with doubt, in this sub-family ; if not placed here, it must form a distinct sub-family. It has the metathorax spinose, and the sub- marginal and first discoidal cells are not, or are scarcely, separated. Crabro leucostomus has been observed by Fletcher to form cells for its larvae in the soft wood of broken willows : the food stored therein consists of two-winged flies of the family Dolicho- podidae. This Crabro is parasitised by an Ichneumonid of the genus Tryphon, and by a two-winged fly of uncertain genus, but belonging to the family Tachinidae. The metamorphoses of Crabro clirysostomus have been briefly described by Verhoeff: the food stored consists of Diptera, usually of the family Syr- VOL. VI K FIG. 52. — Crabro cephalotes ? . Britain. 130 HYMENOPTERA CHAP, in phidae ; the larva spins an orange-red cocoon, passes the winter therein, and assumes the pupal form in the spring ; there is, he says, a segment more in the female pupa than there is in the male. The species of the sub-genus Crossocerus provision their nests with Aphididae, but C. wesmaeli makes use, for the purpose, according to Ferton, of an elegant little fly of the family Tipulidae ; according to Pissot this same wasp also makes use of a species of Typldocylta, a genus of the Homopterous division of Rhynchota. Supposing there to be no mistake as to this latter observation, the choice of Diptera and of Homoptera by the same species indicates a very peculiar habit. Fertonius (Crossocerus} luteicollis in Algeria forms cells at a slight depth in sandy soil, and provisions them with ants. The ant selected is Tapinoma erraticum, and the individuals captured are the wingless workers. The mode of hunting has been de- scribed by Ferton ; the \vasp hovers over one of the ant-paths at a distance of a few millimetres only above the surface, and when an ant that is considered suitable passes, the Fertonius pounces on it, stings it, and carries it off to the burrow ; forty or fifty ants are accumulated in a cell, the egg is laid in the heap of victims about one-third of the depth from the bottom; the resulting larva sucks the ants one by one, by attaching itself to the thorax behind the first pair of legs. There is a very interesting point in connection with the habits of this species, viz. that the ants are not only alive, but lively ; they have, however, lost the power of co-ordinating the movements of the limbs, and are thus unable to direct any attack against the feeble larva. Ferton thinks there are three generations of this species in a single year. NOTE. — In a note on p. 99 we have mentioned the new publication of Mr. and Mrs. Peckham on the habits of Fossores. We may here add that it contains much fresh information on these Insects, together with criticisms of the views of Fabre and others. One of the points most noteworthy is that they have observed Crabro stirpicola working night and day for a period of forty-two consecutive hours. They made experiments on Sembex spinolae with a view of ascertaining whether the female provisions two nests simul- taneously ; as tlie result they think this improbable. If the female Beinbeeid make nests only consecutively, it is clear it must have but a small fecundity. The larval life extends over about fifteen days ; and if we allow three months as the duration of life of a female, it is evident that only about six young can be produced in a season. CHAPTER IV HYMENOPTERA ACULEATA COXTIXUED- OR ANTS -DIVISION IV. FORMICIDAE B Division IV. Heterogyna or Formicidae— Ants. The segment, or the two segments, behind the propodeum, either small or of irregular form, so that if not throughout of small diameter, the articulation until the segment behind is slender, and there is great mobility. The trochanters undivided. The individuals of each species are usually of three kinds, males, females and workers ; the latter h are no wings, but the males and females (ire usually winged, though the females soon lose the flying organs. They live in communities of various numbers, the majority being workers. The larvae are helpless maggots fed of Aphmnog^i., bar- marked. The abdomen is connected bara (Myrmicides). «, Pro- . . podeum ; b, first abdominal with the propodeum in a peculiar manner, segment forming a scale or one or two segments being detached node : c, second ; rf, third abdominal segment. from the main mass to form a very mobile articulation. This is the most distinctive of the char- acters of ants. The structure and form of these parts varies 132 HYMENOPTERA CHAP. greatly in the family : and the Amblyoponides do not differ in a marked manner from the Scoliidae in ibssorial Hymenoptera. The arrangement of the parts of the mouth is remarkable, and results in leaving the mandibles quite .free and unconnected with the other trophi ; the mouth itself is, except during feeding, closed completely by the lower lip and maxilla assum- ing an ascending vertical direction, while the upper FIG. 54.-Front of head of Dinopon y h d A, Mouth closed ; B, opi-n. and overlaps the lower lip, being closely applied to it ; so that1 in Ponerides the palpi, except the apices of the maxillary pair, are enclosed between the upper and lower lips (Fig. 54, A). In Cryptocerini the palpi are not covered by the closed lips, but are protected by being placed in chinks at the outsides of the parts closing the mouth. The mandibles of ants can thus be used in the freest manner without the other parts of the mouth being opened or even moved. The mandibles close transversely over the rest of the mouth, and when shut are very firmly locked. There are, however, some ants in which the lips remain in the position usual in mandibulate Insects. The antennae, except in the males of some species, have a long basal joint and are abruptly elbowed at its extremity. The eyes and ocelli vary excessively, and may be totally absent or very highly developed in the same species. The winged forms are, however, never blind. The size of the head varies extremely in the same species ; it is frequently very small in the males, and largest in the workers. In some ants the worker-caste consists of large-headed and small- headed individuals ; the former are called soldiers, and it has been supposed that some of them may act the part of superior officers to the others. It should be clearly understood that there is no definite distinction between soldiers and workers; so that in this respect they are widely different from Termites. The complex mass forming the thorax is subject to great change of structure in the same species, according as the indi- viduals are xvinged or wingless. The sutures between the dorsal FORMICIDAE — ANTS 133 (notal) pieces are frequently obliterated in the workers, while they are distinct in the males and females, and the pieces them- selves are also much larger in size in these sexed individuals. The pro-mesothoracic stigma is apparently always distinct ; the meso-metathoracic one is distinct in the male Dorylus, but can scarcely be detected in the winged forms of other ants, owing to its being en- closed within, and covered by, the suture between the two segments : in the workers, however, it is usually quite conspicuous. The posterior part of the thoracic mass, the pro- podeum or median segment, is of considerable size ; no transverse suture between the component pieces of this part can be seen, but its stigma is always very distinct. The Fia ^_0ecodoma cephaMes. South peduncle, Or pedicel, formed by the America. A, Worker major ; B, , ., female after casting the wings. extremely mobile segment or seg- ments at the base of the abdomen (already noticed as form- ing the most conspicuous character of the family), exhibits much FIG. 56. — Stridulating organ of an ant, Myrmica rubra, var. laevinodis. Sagittal section of part of the 6th and 7th post-cephalic segments. (After Janet.) a, a1, muscles ; 6, connecting membrane (corrugated) between 6th and 7th segments : c, 6th seg- ment ; d, its edge or scraper ; e, striate area, or file on 7th segment ; /, posterior part of 7th segment ; g, cells, inside body ; ,h, trachea. variety. Sometimes the first segment bears a plate or shield called a scale (Fig. 53, A, V) ; at other times there are two 134 HYMENOPTERA CHAP. small segments (Fig. 53, B, C, l>, c~) forming nodes or knots, of almost any shape. The articulations between these segments are of the most perfect description. In many ants these parts bear 4 highly developed stridulating organs, and the delicacy and perfection of the articulations allow the parts to be moved either with or without producing stridulation. In the male sex the peduncle and its nodes are much less perfect, and possess comparatively little capacity for movement ; in the male of Dorylus (Figs. 79, A, and 80, /) the single node is only imperfectly formed. The eyes and ocelli of the males are usually more largely developed than they are in the female, though the head is much smaller. The legs of ants are elongate, except in a few forms ; the Cryptocerini and the males of Dorylides being the most conspicuous exceptions. The tarsi are five -jointed, the basal joint being dis- proportionately elongate, so that in use Fro. 57. — Combs and brushes : .• . • /• •, on front leg of an ant, Dino- ^ acts in many species as it it were a ponera grandis (tip of tibia, portion of the tibia, the other four joints 1 .earing the comb-like spur, £ -in in rrl "f and the base of the first joint forming the functional loot. ilie Il'Ollt of the tarsus ; cf. fig. 75). tibiae are furnished with a beautiful A, Inner, B, outer aspect. combing apparatus (Fig. 57) Features of Ant-life. — In order that the reader may realise the nature of ant-life we may briefly recount its more usual and general features. Numerous eggs are produced in a nest by one or more queens, and are taken care of by workers. These eggs hatch and produce helpless maggots, of which great care is taken by the workers. These nurses feed their charges from their own mouths, and keep the helpless creatures in a fitting- state by transporting them to various chambers in conformity with changes of temperature, humidity, and so on. When full grown the maggots change to pupae. In some species the maggots form cocoons for themselves, but in others this is not the case, and the pupae are naked.1 After a brief period of 1 The pupae and cocoons of ants are usually called by the uninstructed, "ants' eggs." In this country they are used as food for pheasants. iv FORMICIDAE ANTS 135 pupal life a metamorphosis into the perfect Insect occurs. The creatures then disclosed may be either winged or wingless ; the wingless are the workers and soldiers — imperfect females — the winged are males or females fully developed. The workers re- main in or near the nest they were produced in, but the winged individuals rise into the air for a nuptial flight, often in great numbers, and couple. When this is accomplished the male speedily dies, but the females cast their wings and are ready to enter on a long life devoted to the production of eggs. From this account it will be gathered that males are only found in the nests for a very short time ; the great communities consist- ing at other periods entirely of the two kinds of females and of young. The imperfect females are themselves in some species of various kinds ; each kind being restricted, more or less com- pletely, to a distinct kind of duty. No Insects are more familiar to us than ants ; in warm countries some of them even invade the habitations of man, or establish their communities in immediate proximity to his dwellings. Their industry and pertinacity have, even in remote ages, attracted the attention and admiration of serious men ; some of whom — we need scarcely mention Solomon as amongst them— have not hesitated to point out these little creatures as worthy of imitation by that most self-complacent of all the species of animals, Homo sapiens. Observation has revealed most remarkable phenomena in the lives of these Insects. Indeed, we can scarcely avoid the conclusion that they have acquired in many respects the art of living together in societies more perfectly than our own species has, and that they have anticipated us in the acquisition of some of the industries and arts that greatly facilitate social life. The lives of individual ants extend over a considerable number of years — in the case of certain species at any rate — so that the competence of the individual may be developed to a considerable extent by exercise ; and one genera- tion may communicate to a younger one by example the arts of living by which it has itself profited. The prolonged life of ants, their existence in the perfect state at all seasons, and the highly social life they lead are facts of the greatest biological importance, and are those that we should expect to be accom- panied by greater and wider competence than is usually exhibited 136 HYMENOPTERA CHAP. by Insects. There can indeed be little doubt that ants are really t a not only the " highest " structurally or mechanically of all Insects, but also the most efficient. There is an American saying to the effect that the ant is the ruler of Brazil. We must add a word of qualification ; the competence of the ant is not like that of man. It is devoted to the welfare of the species rather than to that of the individual, which is, as it were, sacrificed or specialised for the benefit of the community. The distinctions between the sexes in their powers or capacities .are astonishing, and those between the various forms of one sex are also great. The differ- ence between different species is extreme ; we have, in fact, the most imperfect forms of social evolution coexisting, even locally, with the most evolute. These facts render it extremely difficult for us to appreciate the ant ; the limitations of efficiency displayed by the individual being in some cases extreme, while observation seems to elicit contradictory facts. About two thousand species are already known, and it is pretty certain that the number will reach at least five thousand. Before passing to the consideration of a selection from what has been ascertained as to the varieties of form, and of habits of ants we will deal briefly with their habita- tions and polymorphism, reserving some remarks as to their associations with other Insects to the conclusion of this chapter. Nests. — Ants differ greatly from the other Social Hymenoptera in the nature of their habitations. The social bees construct cells of wax crowded together in large numbers, and the wasps do the like with paper ; the eggs and young being placed, each one in a separate cell, the combinations of which form a comb. Ants have, however, a totally different system ; no comb is constructed, and the larvae are not placed in cells, but are kept in masses and are moved about from place to place as the necessities of tempera- ture, air, humidity and other requirements prompt. The habita- tions of ants are in all cases irregular chambers, of which there is often a multiplicity connected by galleries, and they sometimes form a large system extending over a considerable area. Thus the habitations of ants are more like those of the Termites than those of their own allies among the Hymenoptera. They are chiefly remarkable for their great variety, and for the skilful manner in which they are adapted by their little artificers to particular conditions. The most usual form in Europe, is a IV ANTS' HABITATIONS '37 number of subterranean chambers, often under the shelter of a stone, and connected by galleries. It is of course very difficult to trace exactly the details of such a work, because when excavations are made for the purposes of examination, the construction becomes destroyed : it is known, however, that some of these systems extend to a considerable depth in the earth, it is said to as much as nine feet, and it is thought the object of this is to have access to sufficiently moist earth, for ants are most sensitive to variations in the amount of moisture ; a quite dry atmosphere is in the case of many species very speedily fatal. This system of underground labyrinths is sometimes accompanied by above-ground buildings con- sisting of earth more or less firmly cemented together by the ants ; this sort of dwell- ing is inOSt frequently adopted FlG. 58.— Portion of combined nest of For- whell the soil ill which the ' aml Solenopsis fugax (Alter nests are placed is sandy ; it is probable that the earth is in such cases fastened together by means of a cement pro- duced by the salivary glands of the ants, but this has not been determined with certainty ; vaulted galleries or tunnels of this kind are constructed by many species of ants in order to * -liable them to approach desired objects. In South America Camponotus ruftpes and other species that habitually dwell in stumps, in certain districts where they are liable to inundations, build also nests of a different nature on trees for refuge during the floods. In Europe, a little robber-ant, Solenopsis fugax, constructs its dwelling in combination with that of Fn' i/i ir/f f cannot, on account of the small size of the orifices, be entered by the much larger Fur mint. Hence the robber obtains an easy living at the expense of the larger species. The Sauba or Sauva ants of South America (the genus Atta of some, Oecodoma of other authors) appear to be most proficient in the art of sub- Forel.) x |. f, f, Chambers of Formica, recognisable by the coarser shading ; s, s', chambers of the Solenoftsis (with finer shading) ; s", opening in one of the chambers, the entrance to one of the galleries that connects the chambers of the Solenopsis; ic, walls forming the founda- tions of the nest and the limits of the chambers. '38 HYMENOPTERA CHAP. terranean mining. Their systems of tunnels and nests are known to extend through many square yards of earth, and it is said on the authority of Hamlet Clark that one species tunnelled under' the bed of the river Parahyba at a spot where it was as broad as the Thames at London Bridge. A considerable number of ants, instead of mining in the ground, form chambers in wood; these are usually very close to one another, because, the space being limited, galleries cannot be indulged in. Ctimponotus ligniperdus in Europe, and 0. pennsyl- vanicus in North America, work in this way. Our British Lasius fuliginosus lives in decayed wood. Its chambers are said by Forel to consist of a paper-like substance made from small fragments of wood. Cryptocerus burrows in branches. Colobopsis lives in a similar manner, and Forel in- forms us that a worker with a large head is kept stationed within the entrance, its great head acting as a stopper ; when it sees a nest-fellow desirous of entering the nest, this animated and intel- ligent front-door then retreats a little so as to make room for ingress of the friend. Forel has observed that in the tropics of America a large number of species of ants live in the stems of grass. There is also quite a fauna of ants dwelling in hollow thorns, in spines, on trees or bushes, or in dried parts of pithy plants ; and the tropics also furnish a number of species that make nests of delicate paper, or that spin together by means of silk the leaves of trees. One eastern species — Polyrhachis spiniycra — fabricates a gauze-like web of silk, with which it lines a subterranean chamber after the manner of a trap-door spider. Some species of ants appear to lind both food and shelter Kii;. .ri9. — Ant-plant, Hydnophytwn mon- taniim. Java. (After Forel.) iv ANTS 139 entirely on the tree they inhabit, the food being usually sweet stuff secreted by glands of the plant. It is thought that the ants in return are of considerable benefit to the plant by defend- ing it from various small enemies, and this kind of symbiosis has received much attention from naturalists. A very curious con- dition exists in the epiphytic plants of the genera Myrmecodia and Hydnophytum ; these plants form large bulb-like (Fig. 59) excrescences which, when cut into, are found to be divided into chambers quite similar to those frequently made by ants. Though these structures are usually actually inhabited by ants, it appears that they are really produced by the plant independent of the Insects. Variability and Polymorphism of Ants. — Throughout the Hymenoptera there are scattered cases in which one of the sexes appears in dimorphic form. In the social kinds of bees and wasps the female sex exists in two conditions, a reproductive one called queen, and an infertile one called worker, the limits between the two forms seeming in some cases (honey-bee) to be absolute as regards certain structures. This sharp distinction in structure is rare ; while as regards fertility intermediate con- ditions are numerous, and may indeed be induced by changing the social state of a community.1 In ants the phenomena of the kind we are alluding to are very much more complex. There are no solitary ants ; associations are the rule (we shall see there are one or two cases in which the association is with individuals of other species). In correlation with great proclivity to socialism we find an extraordinary increase in the variety of the forms of which species are made up. In addition to the male and female individuals of which the species of Insects usually consist, there are in ants workers of various kinds, and soldiers, all of which are modified infertile females. But in addition to the existence of these castes of infertile females, we find also numerous cases of variability or of dimorphism of the sexual individuals ; and this in both sexes, though more usually in the female. Thus there exists in ants an extraordinary variety in the polymorphism of forms, as shown by the table on p. 141, where several very peculiar conditions are recorded. The complex nature of these phenomena has only recently 1 The parthenogenetic young produced by worker females are invariably of the male sex. 140 HYMENOPTERA CHAP. become known, and as yet has been but little inquired into. The difference between the thoracic structure in the case of the winged rind wingless females of certain species (Fig. 55, and in vol. v. . tiir. .S-'39) is enormous, but in other species this difference appears to be much less. The ordinary distinctions between the queen- female and worker-females appear to be of two kinds; firstly, that the former is winged, the latter wingless ; 1 and secondly, that the former possesses a receptaculum seminis, the latter does not. In a few cases it would seem that the dimorphism of winged ;ind wingless forms is not complete, but that variability exists. Intermediate conditions between the winged and wingless forms are necessarily rare; nevertheless a certain number have already been detected, and specimens of Lasius aliemts have been found with short wings. In rather numerous species some or all of the fertile females depart from the usual state and have no wings ; (a similar condition is seen, it will be recollected, in Mutillides and Thynnides of the neighbouring family Scoliidae). A di- morphism as regards wings also exists in the male sex, though it is only extremely rarely in ants that the males are wingless. Never- less a few species exist of which only wingless males have been found, and a few others in which both winged and wingless individuals of this sex are known to occur. The wingless males of course approach the ordinary workers ( == infertile wingless females) in appearance, but there is not at present any reason for supposing that they show any diminution in their male sexual characters. The distinction between workers and females as based on the existence or non-existence of a receptaculum seminis has only recently become known, and its importance cannot yet be estimated. The adult, sexually capable, though wingless forms, are called ergatoid, because they are similar to workers ('E^ar?;?, a worker).2 1 The student must recollect that the winged female ants cast their wings previously to assuming the social life. The winglessness of these females is a totally different phenomenon from that we here allude to. - See Fun 1, Verh. Ges. deutsch. Xalurf. Ixvi. 1894, 2, pp. 142-147 ; and Emery />'/<>/. ( '< nt i'ii II, I. xiv. 1S<)1, p. 53. The term ergatoid applies to both sexes ; a species with worker-like female is ergatogynous ; with a worker-like male ergatandrous. IV ANTS 141 Table of the Chief Forms of Polymorphism in Ants. 1-9 •v 0 . M g | S ""S ^ ,. £M •— * flj * ^ S S o ° c . Cj s ^ % C +3 rt is o C J O a o H M^ CO ^ ~ Miinaica, Polyrhachis, ~\ etc. "*" Camponotus, Atta,\ Phcidologeton, etc. . J "*" Pheidole, subg. Colo-} bopsis . . . / EC i t o n h a m atu m, "j E. quadriglume, - + + + • + + E. foreli, etc. . Cryptocerus disco- \ ccplmlus, etc. . J + + + Strongylognathus + + + Carebara and Solen- ~j opsis (except S. r + + + geminata) . . | Solenopsis geminata . + + + + f + Formica rufa . + + - excep- ( tionally Ponera punctatissima + + + + Ponera ergatandria . ? + + + Cardiocondyla cmeryi + + + + C. wroughtonii and ) , C. stambuloffi . . j Formicoxentis niti- ~\ - dulus . . . J + + Tomognathus + + + Odontomachus Jtae-} ( . + matodcs . + + ' excep- [ tionally Polyergus . + + + Dorylus, Anomma,} + + Eciton part. . Aenictus . -f- + Leptogenys, Dia-\ , camma . . .j Myrmecocystus mel-} 1 and ligcr, M. mexicanusj "j honey- \_ pots f + f + Ponera eduardi . + + 1 eyes [ large I'Vi-s [obsolete Ancr gates . + + In addition to the above there are apparently cases of females with post-meta- niorphic growth in Dorylides, but these have not yet been the subject of investiga- tion. 14- HYMENOPTERA CHAI'. 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 Attct) —one of the species in which polymorphism is greatest — says1 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 lie doubts it being " the character of the food." There is, however, a considerable 1 Hjdy 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 Lomeclmsa 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 Nature li. 1894, p. 12:.. iv ANTS 143 determined by those " Aulau'en " 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 B'wl. 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. CcntralU. 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 AmUyopone, to certain Mutillides (e.g. Apterogynct) and to the Thyiinides, two divisions of Scoliidae. Emery considers Dory- lidt'.s 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 lni.t 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 ejaculatory 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. Sac. cnt. Bdgique xxxvii. 1893, p. 161 ; the very valuable paper by Emery, in ZooL Jahrb. 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 n/fa, 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 CHAP. 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. pennsylvanicus, 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 Lasiii* (t/ic/ius, unaccompanied by any workers or other assistants. ;tii(l he found at the end of 98 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. cut. France, 1893, p. 467. z Ann. Soc. cat. France, 1893, JJii/L p. cclxiv. JV 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 wras 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 wre shall subsequently see, are formed with ants by numerous other Insects. OecopliyllcL smaragdina, a common ant in Eastern Asia, forms shelters on the leaves of trees by curling the edo;es of leaves t/ O O 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 fur it to form a cocoon with, and the ants utilise the larvae to effect their 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 FIG. 60. — Oecoplrylla smarciyiUna. Worker using a larva for spinning. 148 HYMENOPTERA CHAP. 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. Formic tt ri'ftt, 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 Formicdxenus iv CAMPONOTIDES— SLAVE-MAKING ANTS 149 nilididus lives only with F. rufa. Amongst the most peculiar of its dependants we may mention large beetles of the genera Cetonia and Clytlira, 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 1*700 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. sanguinea is very similar in appearance to its commoner congener F. rufa, and is the only slave-making ant we possess in lUitain. 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 HYMENOPTERA CHAP. 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 off 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. sanguinea. utilises in this way in England are F. fusca, F. cunicularia, and possibly Lasius flatus. Huber and Forel have given graphic accounts of the expeditions of this soldier-ant. In the mixed colonies of F. sanguinea 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 rv/escens, 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 PO////-/V///.S dues 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 Polyergws aet of retreating or making flank move- nifcscens. (After Andre. ) J~, ments when necessary. It 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 with mandibles of a peculiar nature : they are not armed with teeth, iv CAMPONOTIDES SLAVE-MAKING ANTS I 5 I 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 Formica fusca and F.fusca, race auricularia ; after it has routed a colony of one of these species, P. rufescens 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. ru/escens 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 \vorker (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, 7Wy/v///x />/< idus, which some entomologists consider to be merely a variety of 152 IIYMENOPTERA CHAP. the European species, makes slaves of Formica scJiaufussi, 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. AVhen a migration takes place the servitors deport both the males and females of P. hi.cidus. 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 Myrmecocyslus liortideorum and M. mclliger, are mode- rate-sized Insects of subterranean habits, the entrance to the nest of M. 1 1 or tide or u in being placed in a small raised mound. The honey is the product of a small gall found on oak leaves, and is obtained by i- the worker-ants during nocturnal expedi- fooiis, from which they return much dis- v 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 been 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 fond 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. 62.— J/y /•-//. * m ii nn. Honey - pot ant, dorsal view. Flu. 63. — Mi/rmecocystus Lateral view. iv ANTS — CAMPONOTIDES 153 forced by the distention to the posterior part of the body. Lubbock has since described an Australian ant, Melophorus i njiatus, 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. Z. 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 larger 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 pratensis and liberated them at the base of a tree in which was a nest of L. fuliginosus ; these latter, finding them- 154 HYMENOPTERA CHAP. selves thus assaulted and besieged, communicated in some way, information of the fact to the neighbouring colonies, and Forel 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 n/fx 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. Wasmann 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 pratensis 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 IV 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 infhience they attack one another in the most ferocious manner. 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- /'//acltis 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 : has ex- amined 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. argentea covers its small dwelling with little bits of vegetable matter, and a nest of P. rastdla 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. FIG. 64. — Nest of Polyrhachis sp. (After Smith.) HYMENOPTERA CHAP. 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 Cainponotides have no special organ for the production of sound in the position in which one is found in Mvrmicides and Ponerides, yet it is probable that v > t/ x they are able to produce a sound by rubbing together other parts . of the abdomen. FIG. 65. — P<->h/,-/u:i-//i.i JHI, nl ii worker. Singapore. IV ANTS 157 Sub-Fam. 2. Dolichoderides. — Hind //^/y furnished u-ith lut one constriction so that only a single scale or node is formed ; tiling rudiincntari/ ; 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-— fapinoma en-ati- . . . 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 Tn/ii- 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;8 HYMENOPTERA CHAP. 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 1 mrrows 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. Xo 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 M tiller 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. Tbis Insect is thought to protect the plant from the attacks of leaf-cutting ants of the genus Atfn. 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 <>f ahdomcn formed of two in 11- marked nodes (knot-like segments*). Sting present (absent i a Hie Cryptocerini and Attini'). (It should be noted that the 1 See von Iliering, Berlin, cut. Zcitschr. xxxix. 1894, p. 364 ; and Forel, Ann. Soc. cut. /:.•/,/;,{//,•, \\. 1896, p. 170. IV ANTS MYRMTCIDES 159 workers of the genera Eciton and Aenictus of the sub-family Dorylides have, like the Myrmicides, tivo nodes in the 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 : Myrmiciui, 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 , J FIG. 6/. — Pheulologeton labo- are defined are not in all cases fully riosus, large and small applicable to the males. The Crypto- workers> East Iudia- 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, Anergates 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 iu these extraordinary life-histories. it has long lieen known that the little fonmcoxenus mtiduius lives as a guest in the nests of Formica rufa, the wood -ant; and another similar ant, Xtenamma westiuoodi, which shares the same life, FIG. 68.— Formicoxenus mtiduius, male. (After Adlerz. ) Ann. Soc. cut. Belgique, xxxvii. 1893, p. 163. i6o HVMENOPTERA CHAP. 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. westwoodi is really the male of another ant that had till then been called Asemorhoptrum lippulinn. This correc- tion left the workers and females of Formicoxenus nitidulus destitute of a male, but Acllerz 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 Fia.GQ.—Anergatesatratulus. Europe. A. male, with found ill this country, part of hind leg broken off ; B, female, with wings.: C, T, „„..,„ Awernnt^ is female, after casting the wings and becoming a queen. 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 Tetru'inoritnn cawjtitintt, a little ant very like M//n/t!c/ 1, -I in Ins have taken the seeds into the nest they separate the husks and carry them out, depositing them on a heap or kitchen- 1 Until I'crcully this genus was generally known as Atta, but this name is now applied to the leai'-futting ants, that were formerly called Oeeodoma. 2 Foivl, /;,///. Soc. Vaudoise, xxx. pp. 29-30, 1S91. IV ANTS MYRMICIDES 165 midden, formed near by. M'Cook has witnessed and described the process of stripping the seeds. Certain genera — e.g. Aphaenogaster, Plieidole — exhibit great disparity in the forms of the workers, some of which are of size much superior to the others, and possess disproportionately large heads ; these large individuals are found in the same nest as the smaller forms. All the intermediate forms may frequently be found, and at the same time, in the genus Apliaenogaster ; but in Pheidole intermediates are of the utmost rarity. The genus Cremastogaster is remarkable on account of the shape of the hind body and its articulation, which give the abdomen the appearance of being put on upside down. This mode of articulation may allow the Insect to threaten its enemies X A B Fio. 71.' — Oremastogaster tricolor, worker. A, with abdomen extended ; B, uplifted. when they are in front of it ; but it is doubtful whether the Cremastogaster possesses an effective sting. ii. The group ATTINI is distinguished by the presence of a carina near the eye, by the antennae being inserted at a moderate distance from one another, by the clypeus being prolonged back- wards between them ; and by the absence of a sting. The group is not represented in Europe, but in Tropical America the ants belonging to it are amongst the most important of natural objects. The species of the genus Atta (usually styled Oecodomct) are the formidable leaf-cutting ants of America. They occur in enormous colonies in certain places, and will in a short time completely strip a tree of its leaves. As they appear to prefer trees of a useful kind, especially those planted by man, their ravages are often of the most serious nature. The natives, feeling it hopeless to contend with these Insect hordes, only too frequently abandon all attempts to cultivate the trees and vegetables the Insects are fond of. Both Bates and Belt have 1 66 HYMENOPTERA CHAP. given accounts of some points in the economy of these ants. They are amongst the largest of the Formicidae, the females in some cases measuring about two and a half inches across their expanded wings ; the males are much smaller, but are less dis- similar to their partners than is usual among ants. The workers, on the other hand, are so extremely different, that no one would suppose them to he at all related to the males and females (see vol. v. Fig. 339). The mode of operation of these ants is to form paths from their formicary extending for a considerable distance in various directions, so that they have a ready access to any spot in a district of considerable extent ; when a tree or bush is found bearing leaves suitable for their purposes, the worker ants ascend it in large numbers and cut up the leaves by biting out of them pieces similar in size and shape to a small coin ; these pieces are then carried back in the jaws of the ants to their nests ; the ant- paths are therefore constantly traversed by bands of little creatures carrying burdens homewards, or hurrying outwards in search of suitable trees. The formicaries are of considerable size, and are described as consisting of low mounds of bare earth of considerable extent. Bates speaks of as great a circumference as forty yards ; these accumulations of earth have frequently an appearance different from the adjoining soil, owing to their being formed of subsoil brought up from below ; they are kept bare by the ants con- stantly bringing to and depositing on the surface fresh material resulting from their subterranean excavations. The true abodes, beneath the earth, are of greater extent than the mounds them- selves, and extend to a considerable depth ; they consist of chambers connected by galleries. The leaf -cutting ants extend their range to North America, and M'Cook has recently called attention to a case there in which A. fen-ens made an underground route at an average depth of 18 inches, and at an occasional depth oT 0 feet, extending 448 feet entirely beneath the earth, after which it was continued for 185 feet to reach a tree which the ants were engaged in defoliating. This route, extending altogether to a length of more than GOO feet, presented only a very slight deviation from a straight line drawn between the point of departure and the object to be attained. By what sense this ant was enabled IV MYRMICIDES LEAF-CUTTING ANTS I 6/ to make a subterranean tunnel in a straight line to a desired object situated at so great a distance, we know not. The use the leaf-cutting ants make of the enormous amount of material they gather was for long a subject of debate, and has only recently been ascertained by the observations of Moller. After being carried to the nest the pieces of leaves are cut into small fragments by another set of workers and formed into balls, which are packed in various parts of the nest, and amongst which the mycelium of a fungus — Rozites gongylophora — -ramifies. This fungus the ants cultivate in the most skilful manner : they manage to keep it clear from mouldiness and bacterial agents, and to make it produce a modified form of growth in the shape of little white masses, each one formed by an agglomera- tion of swellings of the mycelium. These form the chief food of the colony. Moller ascertained by experiment that the results were due to a true cultivation on the part of the ants : when they were taken away from the nests, the mycelium produced two kinds of conidia instead of the ant-food. Many details of the economy of these leaf-cutting ants are still very imperfectly known. The large-headed forms, called soldiers, have been the subject of contradictory statements ; Bates having concluded from his own observations that they are harmless, while Mr. J. H. Hart assures us that they are very fierce and vindictive, and inflict very serious wounds by biting (the Attini do not sting). We anticipate that the observations of both these naturalists will prove to be substantially correct, and that the differences in habits will be found to be owing to distinctions in the conditions of the community. In connection with this point we may remark that the function of the ex- cessively large heads of certain kinds of soldier-ants is still obscure. In the East Indian Pheidologeton diversus the big- soldiers are quite one hundred times as large as the smaller workers. As these latter bite viciously it would naturally be supposed that their gigantic confreres with enormous heads would be warriors of a most formidable nature ; but, as a matter of fact, the giants are unable to bite even when they try to do so. Aitken has somewhere suggested that these enormous individuals play the part of state elephants ; and we have been informed by Colonel Bingham that the small ants may frequently be seen riding in numbers on their unwieldy fellows. We anticipate 1 68 HYMENOPTERA CHAP. however, that some other function will be found to exist for these forms with enormous heads. An examination of their organs of sense and of voice is very desirable. Details of the modes in which the great communities of the leaf- cutting Attidae are maintained, are still wanting. The females do not, we have been informed by Mr. Hart, possess any considerable powers of aftergrowth, so that there is no reason to suppose them to be unusually prolific. At certain seasons great swarms of winged individuals are produced, and after leaving the nests pair in the manner of our European Myrmica. Possibly the females may, after losing their wings, again enter the large communities. Yon Ihering states that the workers of o o Atta lundi are fertile. iii. The group PSEUDOMYRMIXI includes the genera Pscudo- ini/riiia and Himn, which are by some entomologists treated as but a single genus. The antennae are inserted near together on the front of the head ; there is no carina on the head external to their insertion, and the clypeus does not extend forwards between them. The Insects are usually of elongate form, possess a sting, and have a naked pupa. The group occurs in both hemispheres, but is exclusively exotic, and but little is known of the habits of its members. Forel has recently observed that numerous species live inside dried stems of grass or in hollow twigs, and are beautifully adapted for this mode of life by their elongate form, some of them being as slender as needles. Some interesting observations have been made in Nicaragua by Belt on Pscudo- mynna bicolor and its relations with an acacia-tree, in the thorns of which it lives. The acacia in question is called the bull's-horn thorn, because the branches and trunk are armed with strong curved spines, set in pairs, and much resembling the horns of the quadruped whose name they bear. The ant takes possession of a thorn by boring a small hole near the distal extremity, and forms its nest inside. The leaves of this plant are provided with glands that secrete a honey-like fluid, which it appears forms the chief, if not the sole, subsistence of the ant. I'.elt considers that the presence of the ant is beneficial to the acacia ; he supposes that the ants assume the rights of proprietors, and will not allow caterpillars or leaf-cutting ants to meddle with their property ; the leaves are, he thinks, so preserved to the benefit of the tree. IV ANTS MYRMICIDES 169 Kothney has given some particulars of the habits of Sima rufo-nigra, an ant of this group that appears to be not uncommon FIG. 72. — Sima rufo-nigra and its associates. A, winged female ; B, worker, of the ant ; C, Kliinoijsis ruji- cornis, a fossorial wasp of the sub-family AmjinH- cicles ; D, a spider, Salticus sp. The coloration is ex- tremely similar in all these creatures. near Calcutta, where it lives on the trunks of trees in company with a spider and a wasp that greatly resemble it in form and in colour. The three creatures seem to associate together on amicable terms ; indeed the wasp and the ant occasionally indulge in wrestling matches without doing one another any serious harm. In connection with this fact we may observe that other species of ants have been observed to indulge in sports and feats of agility. S. leviceps, an Australian species of this genus, is furnished with a stridulating file that has the appearance of being constructed so as to produce two very different kinds of Fit;. 73.— stridulating file j of Sima lerlceps. iv. The CRYPTOCERINI are distinguished from other ants by their antennae being inserted at the sides of the head, where they are placed between ridges or in a groove into which they can be withdrawn ; when in some cases they are entirely concealed. These ants assume a great variety of shapes and forms, some of which look almost as if they were the results of an extravagant imagin- ation. The skeleton is usually much harder than it is in other 170 HYMENOPTERA CHAP. ants ; the abdomen consists almost entirely of one very large seg- ment, there being, however, three others visible at its extremity ; these segments can be only slightly protruded, and the ants have 110 power of stinging. They are probably most of them arboreal in their habits. Nearly all of the known forms are exotic. According to the observations of Bates the species of the genus Cryptocerus in the Amazons Valley may frequently be observed in dry open places on low trees and 1 tushes, or running on branches of newly felled trees ; they also visit flowers abund- antly. The species generally are wood-borers, usually perforating the dead branches of trees. C. atmttis has been observed to construct its nests in the dead, suspended branches of woody climbers : a number of neatly drilled holes are all that can he seen pressed first joint of the haul externally ; but, inside, the wood is foot is shown at a and b in P -, c •,-, different positions. freelj perforated with intercommuni- cating galleries. Each community appears to consist of a single female and two kinds of workers ; the latter in some species are quite unlike each other, differing in the form of the head, and in the armature of the thorax and nodes of the peduncle. The species of Cryj>t<«-fi'nx appear to be omnivorous, and are frequently attracted by the excrement of birds. The pupae are not enclosed in a cocoon. In the South of Europe two very minute ants, of the genera /S'/v////////o///.s and k'jri.tritus, belonging to this family, are met with under very large stones partly embedded in the earth. They are of the greatest rarity. Sub-fam. 4. Ponerides. --Hind body elongate,furnished i'-itJi one node at the base, «n i/i-ntt fnjmriti/ •// ir/i there is a .s7 ////// constriction, Rtin///, the in *<• rt <'<1 very near flic front margin of the head. Hind laxly nxniilly elongate anil subcylindricol, with an imperfect l><'ilircl formed by f/ie constriction of tlie Imrk of tlie first segment, but occasionally tin re nee tiro tiodrs in the workers. Distinctions bctn-een tlie hro sexes, mnl between the workers i/ngether 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. 1 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 tlic centre of the cluster and brought out clinging to it many ants holding larvae and pupae." Turning now to the LnhnJuf, question: many American species of this genus have long been known, though all of them iv DORYLIDES WANDERING ANTS I // 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 In.- 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. Miiller. The latter, wrho observed the temporary nests of Eciton liamatum, 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 EC it on- 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- i'i >re, 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 Pscudodictkadia incerf". He thought this might prove to be the female of Eciton- Lubidus ; but his description and figure are imperfect, and do not greatly support his idea of a connection between Eciton and Psc ti dodic tkadia. 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 N 178 HYMENOPTERA CHAP. I 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 Typhlopone 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 Don/lus and of the worker Typhlopone or Anomma. This remained for many years with- out confirmation, but in 1880 Trinien announced the dis- TiG.'iV.—Darylushelcolus. Africa. A, male; covery ill South Africa of ail B, female (Dicthadia) ; C, worker major „ (T>/j>?i/<>,"-) 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 shotild 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 FIG. 80. — Body of male of Dorylus sp. Uelagoa Bay. a, pronotuni ; t>, r, divisions of mtsonotum ; d, nietanotum ; e, propodeum ; ./', first abdominal seg- ment ; (j. //, points of insertion of anterior and pos- terior wings. respects similar to Eciion in luibits, 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. arc ens, 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 lie believes all the supposed species of the genus to be merely varieties of A. burmeisteri. The female of the driver ants is still quite unknown. A Dorylus has been ascertained to be the male of Typlilopone. 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 Typldatta Sin. 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 ants 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 fihognnts. Only the male is known. I 80 HYMENOPTERA CHAP. 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, Labidus = male : ? unknown. J'fii-Hi/ixJirf/iitt/ii/ : female only known, possibly that of Eciton. Cheliomyrmex : workers and soldiers only known. Aenictus = the male, Typlilatt« — worker : unknown. Rliogmus : male ; female unknown. (According to Emery the worker is very small and like Alaopone.} Anomma : only worker known ; male probably a Dorylus. Dorylvs = male ; Dicthadia = 9 : Alaopone and TypJilopone - workers. Sub-Fam. 6. Amblyoponides. — Abdomen destitute of distinct IH'ilirf] ; f/ie articulation between the first and second segments behind the true petiole being broad. "We follow Forel in separating Amblyorjone 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 (Thyimides, e.g.}. Little is known of these \jf) I \. Insects, though they are widely distri- 1 mtecl. A in bli/npone, is found in Australia and Xew Zealand ; the allied genus f, worker. Sfiomafomma has a ^ide distribution, Tasmania. occurring even in Europe. The social life is believed to be imperfect, and the habits subterranean and M'llmtary. 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 tin- fact that a few species of ants are iv INSECTS INHABITING ANTS'-NESTS I 8 I used liy 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 nitis, which so far as is known does them neither sjood nor harm. There are also a considerable number of O 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. X< it- 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 Wasmanu, Berlin 1894. I 82 HYMENOPTERA CHAP. of ;i 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 0 ,, , , FIG. 82. — The beetle, A temeles, soliciting most curious of all the ants- food 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 boucJie. 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 Wasmann attaches great importance. We should, too, notice that some of the inquilines '2 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. Hi. 1896, pp. 411-440. 2 For explanation of tliis term see vol. v. p. 524. CHAPTER V COLEOPTEKA OR BEETLES Order V. Coleoptera. Apparently wingless Insects when at rest, but really with four wings; the elytra, or anterior pair, shell-like, reposing an. the back of the body and fitted together accurately a font/ the middle I// a straight suture; the posterior pair membranous, folded together under the elytra. Mouth with mandibles; lower lip not divided along the middle. Meta- //i/iosis great and very abrupt ; the larra being a grub or maggot, which changes to a • jmpa (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 Yertebrata. 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 Fru. 83. — Under- surface of a beetle, Harpalus caliyinosus ; legs and antenna of one side, and some parts of the mouth removed. A, an- tenna ; B, mandible ; C, labruni ; 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, huccal fissure ; V, plates of ven- tral segments. 1, Prostermim ; 2. prosternal episternum ; 3, pro- sternal epimerou : 4, anterior and middle coxal cavities ; 5, iuflexed side of pronotum; 6, nifsosterimm ; 7, mesosternal episternum ; 8, mesosternal epimeron ; 9, nieta- 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- coiite and Horu.) 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 '-14 I 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 metasteruum 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 Yerhoeff 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. Xaturgcs.}. It should be noticed that in the course of his studies Verhoetf has modified some of his earlier views. 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 teguke 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 (Meloty. 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, Packypus, 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 CHAP. 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 i.eetie, Family sometimes armed with hooks. Cerambycidae (I.Aroniiti ii]><-<-ies, and in them the structure of the antennae characteristic (mske SeM: Mr. (G), viii. No. 1, 1895. 2 Horae Soc. ent. lloss. xiv. 1879, ]>. 15. I92 COLEOPTERA CHAP. they are placed partially in the thorax. The diminution in number takes place in this case by the amalgamation of the first two abdominal with the last thoracic ganglia. Fam. 1. Passalidae. — Lcibrum large, mobile ; mentum deeply cut out in the middle for the accommodation of the liyida ; the lamellae of the anten/nt In-onnlit together by the curling up of the antenna. The elytra entirely cover the dorsal suifuce <>f the abdo- men,. There are four or five hundred species of this family known ; they are usually shining-black, unattractive beetles, of large size, -I- -I FIG. 86.— View of one 7 side of nieso- ami metathorax of a Passalid larva from Borneo showing the stridulating organs. a, b, Portions of the metathorax ; c, coxa of 2nd leg; d, striate or stridulating area thereon ; e, basal part of femur of middle leg ; /', hairs with chitiuous pro- cess at base of each ; g, the diminutive 3rd leg modified for scratching the striated area, x 20. -I and are abundant in the decaying wood of tropical forests. They are quite absent from Europe, and there is only one species in the United States of North America. The larvae are very interesting, from the fact that they appear to have only four legs. This arises from the posterior pair being present only as very short processes, the function of which is to scrape striated areas on the preceding pair of legs and so produce sound. In the specie^ figured (Fig. 86) this short leg is a paw-like structure, bearing several hard digits ; but in other species it is more simple, and without the digits. The perfect Insect has no sound-producing organs, and it is very remarkable therefore to find the larvae v LAMELLICORNIA STAG-BEETLES 193 provided with highly -developed stridulatoiy structures. No auditory organ is known, unless the peculiar spiracles be such. Fam. 2. Lucanidae (Stag-beetles). — Labrum indistinct, fixed ; mentum not excised ; antennae not curled in repose, with but little coadaptation of the terminal joints ; the elytra, entirely cover the dorsal surface of the abdomen. The Stag-beetles are well known on account of the extraordinary development of the mandibles in the male sex, these organs being in some cases nearly as long as the whole of the rest of the Insect, and armed with projections or teeth that give the Insects a most formidable appearance. So far as we have been able to discover, these structures are put to very little use, and in many cases are not capable of being of service even as weapons of offence. The males are usually very much larger than the females, and are remarkable on account of the great variation in the stature of different indi- viduals of the same species ; correlative with these distinctions of individual size we find extreme differences in the development of the head and mandibles. Moreover, the small male specimens exhibit not merely reductions in the size of the mandibles, but also show considerable differences in the form of these parts, due, in some cases, apparently to the fact that only when a certain length of the mandible is attained is there any development of certain of the minor projec- tions : in other cases it is not possible to adopt this view, as the small B mandibles bear as many FIG. 87.-HeadManaprothoraxofformsof the male of projections ES the large a stag-beetle ; Homoeoderns mellyl (Africa). A, forms do, Or even more. Large. B., intermediate, C, small forms. (From a T photograph by ROberthtir.) In each species these variations fall, in the majority of cases, into distinct states, so that entomologists describe them as " forms," the largest developments being called teleodont, the smallest priodont ; the terms mesodont and amphiodont being applied to intermediate states. Leuthner, who has examined many specimens, states that in Odontolabis sinensis, no intermediates between the teleodont and mesodont forms occur, and as the VOL. VI 0 194 COLEOPTERA CHAP. two forms are very different they are liable to be mistaken for distinct species. There are at present between 500 and 600 species of stag- beetles known ; the Indo-Malayan and Austro-Malayan regions being richest in them. Australia possesses many remarkable and aberrant forms. In the Ceratognathini — a group well re- presented in New Zealand as well as in Australia — the structure of the antennae is like that of the Scara- baeidae, rather than of the Luca- nidae. The most aberrant form known is, however, our common Sinodendron cylindricum ; this de- parts in numerous features from other Lucauidae, and instead of the mandibles of the male being FIG. w.— Sinodendron cyiindricum. more largely developed, there is a A, Larva; B, pupa. New Forest. horn on the head ; it is very doubtful whether this Insect should be allowed to remain in the family. Little is known of the habits and development of Lucanidee, except in the case of three or four species that are common in Europe. The common stag-beetle, Lucanus cervus, is our largest British beetle. The larva much resembles that of Melolontlia mdgaris, but attains a larger size, and the anal aperture is placed longitu- dinally instead of transversely ; it lives in decaying wood, or eats the roots of trees without being injurious ; its life in this state lasts about four years ; the pupal, period is passed through rapidly, and the perfect Insect may remain for months underground before it becomes active ; this occurs in June and July. This larva stridulates by scraping certain hard tubercular ridges on the third pair of legs, over a specially adapted rough area at the base of the second pair. The Passalidae and Lucanidae are united by some authorities as a group called Pectinicornia ; the term Lamellicornia being then confined to the Scarabaeidae. The Passalidae appear, how- ever, to be really more nearly allied to the Scarabaeidae than to the Lucanidae. Fam. 3. Scarabaeidae (Chafers'). — The leaflets of the antennae are well coadapted, and are susceptible of separation. The elytra v LAMELLICORNIA — SCARABAEIDAE 195 •usually leave the pygidimii uncovered. The number of visible i'1'ntral segments is usually six, or at the sides seven, not Jive, as in Lucanidae and Passalidae. This is one of the most important families of Insects. About 13,000 species are already known; as some of them are highly remarkable creatures on account of the males being armed with horns, they are figured in many works on natural history. There is great variety of form, and the following five sub-families may be adopted, though authorities are by no means agreed as -to the classification of this extensive family, which, moreover, lie it remarked, is increasing by the dis- covery of about 300 new species every year. Abdominal spiracles plaivd in a line on the connecting membranes, and en- tirely covered by the wing-cases (Laparosticti). Sub-fain. 1. CopRiDES.1 Abdominal spiracles placed almost in a line, but only the basal three on the connecting membranes ; the terminal one usually not covered by the wing-cases. Sub-fain. 2. MELOLONTHIDES. Abdominal spiracles placed in two lines, the basal three on the connecting membranes, the others on the ventral segments (Pleurosticti). The claws of the tarsi unequal. Sub-fam. 3. RUTELIDES. The claws of the tarsi equal ; the front coxae transverse, but little pro- minent in the descending axis. Sub-fam. 4. DYNASTIDES. The claws of the tarsi equal ; the front coxae more prominent, shorter transversely. Sub-fam. 5. CETONIIDES. i. The COPRIDES form an immense group of about 5000 species ; they differ somewhat in habits from other Lamellicorns, inasmucb as most of them live on dung, or decaying animal matter ; the sub-family connects with the Lucanidae, so far as superficial char- acters go, by means of two of its groups, Trogini and Nicagini, the latter being very near to the Ceratognathini in Lucanidae. So little is known as to the morphology and development of these groups that it is not possible to pronounce an opinion as to the validity of this, apparent alliance. Trox stridulates by rubbing two raised lines on the penultimate dorsal segment across two striate ribs on the inner face of the elytra ; Geotrupes, on the other hand, produces an audible sound by rubbing together a file on the posterior coxa and a fine ridge on the contiguous ventral segment. The larva in this genus has a different organ 1 In this sub-family there are numerous forms iu which the elytra cover the pygidium, and in which the number of conspicuous ventral segments is reduced to five or even lour. We use the term Coprides as equivalent to the "Laparosticti" of Lacordaire (Gen. Col. iii. 1856) ; it thus includes the "Comlni" and " Glaphy- rini " of the Cutaloyus Coleopterorum, vol. iv. Munich, 1869. 1 96 COLEOPTERA CHAP. for stridulatiou from the imago ; it is placed on the second and third pairs of legs, the latter pair being much reduced in size. The most interesting division of the Coprides is the group Scarabaeini. Xo member of this group inhabits the British islands, but in Southern Europe, and in still warmer lands, these Insects are well known from the curious habit many of the species have of rolling about balls of dung and earth. The long hind legs are chiefly used for this purpose, and it is on the peculiar structure of these limbs that the group has been established. Many of the stone Scarabaei found in Egyptian tombs represent some kind of Scarabaeini, and it has been said that the ancient Egyptians looked on these Insects as sacred because of their movements. These must certainly appear very strange to those who see them and are unacquainted with their object. It is stated that the dwellers in the vallev of the Xile thought the «. actions of these Insects, when rolling their balls, were typical of the planetary and lunar revolutions : and that the sudden appearance of the beetles after a period of complete absence was emblematic of a future life. Many accounts have been o-iven c. of the habits of members of this group, but according to Fabre all are more or less erroneous ; and he has described the habits and life-history of Scarabaeus sacer (Fig. 89), as observed by him in Southern France. These Insects act the part of scavengers by breaking up and burying the droppings of cattle and other animals. The female Xcarabaeus detaches a portion of the dung and forms it iiito a ball, sometimes as large as the fist : this it rolls along by means of its hind legs, by pushing when necessary with its broad head, or by walking backwards and dragging the ball with its front legs. The strength and patience displayed by the creature in the execution of this task are admirable. Fre- quently the owner of this small spherical property is joined, so Fabre informs us, by a friend, who is usually of the same sex and assists her in pushing along the ball till a suitable place is reached. AVhen this is attained, the owner commences to excavate a chamber for the reception of the ball ; sometimes the false friend takes ad- vantage of the opportunity thus offered and carries off the ball for her own use. Should no disappointment of this sort occur, the Scarabaeus accomplishes the burying of the ball in its subterranean chamber, and accompanies it for the purpose of devouring it ; the feast is continued without intermission till the food is entirely LAMELLICORNIA COPRIDES 197 exhausted, when the *SV"/v//V/< //.< .-^eks a fresh store of provender u> lie treated in a similar manner. According to M. Fabre's account these events occur in the spring of the year, and when the hot weather sets in the ,SVv//w/,arser and more innu- tritions parts are arranged - ts to be reached by the grub only after it has acquired some strength ; lastly, a still more deli- cate and nutritive paste is prepared by the mother tie for a first meal for the newly -hatched grub, by some of the food being submitted to a partial digestion in her organs ; finally, the - _ _ is deposited in the selected spot, and the chamber closed. Certain of the Coprides exhibit, according to Fabre, some extremely exceptional features in their life-histories. The mother, instead of dying after opposition, survives, and sees the growth of her vnung to the perfect state, and then produces another generation. Xo similar case can be pointed out in Insects, except in the Social kinds: but from these the Coprides observed by Fabiv differ pro- foundly, inasmuch as the number of eggs produced by the mother i- extremely small; Copris hispanus, for instance, producing in eaeh of its acts of oviposition only one. two, or three __- FIG. 89. — Scambaeu-s sneer. Portueal. COLEOPTERA CHAP. ii. The MELOLONTHIDES are probably almost as numerous as the Coprides, some 4000 species being already known. The larvae are believed to feed chiefly on roots. Melolontha vulgar is, the common cockchafer, is very abundant in some parts of Europe, and owing to this and to the great damage it causes, has attracted much attention. The memoir by Straus-Durckheim l on its anatomy is one of the classical works of Entomology. This In- sect is so injurious in some parts of France that money is paid by the local authorities for its destruction. M. Eeiset informs us that under this arrangement 867,173,000 perfect cockchafers, and 647,000,000 larvae were destroyed in the Seine-inferieure in the four years from the middle of 1866 to 1870. Unlike the Coprides, the larval life in Melolonthides is prolonged, and that of the imago is of brief duration. In Central Europe the life-cycle of the individual in M. r//A/"/'/x occupies three years, though in dry periods it may be extended to four years. In Scandinavia the time occupied by the development appears to be usually five years. The fertile female enters the ground and deposits its eggs in two or three successive batches of about fifteen each. The eggs swell as the development of the embryo progresses ; the larva emerges about five weeks after the eggs have been deposited, and is of relatively large size. When young the larvae can straighten themselves out and crawl, but when older they lose this power, and when above ground rest helplessly on their sides. In the winter they descend deeply into the earth to protect themselves from frost. The pupa state lasts only a few days, but after the final transformation the perfect Insect may remain motionless for as much as eight months underground before commencing its active life in the air.2 In the perfect state the Insect is sometimes injurious from the large quantity of foliage it destroys. Schiodte 3 considered that these larvae (and those of numerous other Scarabaeidae) stridu- late by rubbing certain projections on the stipes of the maxilla against the under-surface of the mandible. These surfaces appear, however, but little adapted for the purpose of producing sound. iii. The EUTELIDES number about 1500 species : there ;ire many 1 Considerations y/^'/v/A's .•>•///• I'anatomie comparde des animautc articulds, etc., Paris 1828, 4to. xix. and 435 pp., and Atlas of ten (xx.) plates, and 36 pp. - Raspail. Me, n. SIK-. zool. France, vi. 1893, pp. 202-213. :l Ann. soc. ent. /''m/tce, (v.) iv. 1874. p. 39. v LAMELLICORNIA DYNASTIDES CETONIIDES 199 Insects of brilliant metallic colours amongst them, but very little is known as to their life-histories. The larvae are very much like those of Melolonthides. iv. The DYNASTIDES are the smallest division in number of species, there being scarcely 1000 known ; but amongst them we find in the genera Dynastes and Megasoma some of the bniM'st of existing Insects. The horns and projections on the heads and prothoraces of some of the males of these Insects are truly extraordinary, and it does not appear possible to explain their existence by any use they are to their possessors. These structures are but little used for fighting. Baron von Hiigel informs the writer that in Java he has observed large numbers of Xylotrupes gideon; he noticed that the males sometimes carry the females by the aid of their horns ; but this must be an excep- tional case, for the shape of these instruments, in the majority of Dynastides, would not allow of their being put to this use. The development of these horns varies greatly in most of the species, but he did not find that the females exhibited any preference for the highly armed males. The fact that the males are very much larger than the females, and that the armature is usually confined to them, suggests, however, that some sexual reason exists for these remarkable projections. Many Dynastides possess organs of stridu- lation, consisting of lines of sculpture placed so as to form one or two bands on the middle of the propygidium, and brought into play by being rubbed by the extremities of the wing-cases. This apparatus is of a less perfect nature than the structures for the same purpose found in numerous other beetles. "We have no member of this sub-family in Britain, and there are scarcely a dozen in all Europe. Decaying vegetable matter is believed to be the nutriment of Dynastides. The European Oryctes nasicofnis is sometimes found in numbers in spent tan. The growth a::d development of the individual is believed to be but slow. v. The CETONIIDES are renowned for the beauty of their colours and the elegance of their forms; hence they are a favourite group, and about 1600 species have been catalogued. They ;nv specially fond of warm regions, but it is a peculiarity of the sub-family that a large majority of the species are found in the Old World ; South America is inexplicably poor in these Insects, notwithstanding its extensive forests. In this sub-family the mode of night is peculiar ; the elytra do not extend down the 20O COLEOPTERA CHAP. sides of the body, so that, if they are elevated a little, the wings can be protruded. This is the mode of flight adopted by most Cetoniides, but the members of the group Trichiini fly in the usual manner. In Britain we have only four kinds of Cetoniides ; they are called Kose-chafers. The larvae of C.fioricola and some other species live in ants' nests made of vegetable refuse, and it is said that they eat the ants' progeny. Two North American species of Euphoria have similar habits. The group Cremasto- chilini includes numerous peculiar Insects that apparently have still closer relations with ants. Most of them are very aberrant as well as rare forms, and it has been several times observed in N'nrth America that species of Cremastochilus not only live in the nests of the ants, but are forcibly detained therein by the owners, who clearly derive some kind of satisfaction from the companionship of the beetles. The species of the genus Lomap- ft'i-a stridulate in a peculiar manner, by rubbing the edges of the hind femora over a striate area on the ventral segments. Series II. Adephaga or Caraboidea. All tli,- tarsi five-jointed ; antennae filiform, or nearly so; -mouth - l>iirf* //////>/// ilcrelvpi'il, flic outer lolie of tin' nui.'-iUn /n j>u,'ts of the liiliinl palpi il< rt'liipnl ^.s joints of tlie palpi, and in so///' cases approximate at their bases. Alxlunn n n-itli tin' imposed *• 2, A) are usually elon- gate in form and run freely : they may be known by their tarsi ending in two claws, by the exserted, sharp, calliper- like mandibles, by the body ending in two processes (sometimes jointed) and a tube of varying length projecting backwards. The pupae usually have the hind pair of legs so arranged that the tips of the tarsi project behind, beyond the extremity of the Sdiiodte) ; B, imago. A, Larva (after Britain. v ADEPHAGA CARABIDAE 2O5 body. The Carabidae are carnivorous and predaceous both as larvae and perfect Insects ; they attack living Insects, worms, or other small, soft creatures, but do not disdain dead specimens. Some species of Carabus, found in North Africa where snails abound, are specially formed for attacking these molluscs, having the head long and slender so that it can be thrust into the shell of the snail. A few species have been detected eating growing corn, and even the young seeds of some Umbelliferae ; these belong chiefly to the genera Harpalus, Zabrus, and Amara. Some species of the abundant genera Pterostichus and Harpalus, are said to be fond of ripe strawberries. The most anomalous forms of Carabidae are the Pseudomorpliides, a sub-family almost peculiar to Australia, the members of which live under bark, and have but little resemblance to other Carabids owing to their compact forms and continuous outlines. The genus Mormolyce is one of the wonders of the Insect world on account of the extraordinary shape of its members ; the sides of the elytra form large crinkled expansions, and the head is unusually elongate. These Insects live on the underside of fallen trees in the Malay Archipelago and Peninsula ; no reason whatever can be at present assigned for their remarkable shape. There are a considerable number of blind members of this family : some of them live in caverns ; these belong chiefly to the genus Anophthcdmus, species of which have been detected in the caves of the Pyrenees, of Austria, and of North America. It has been shown that the optic nerves and lobes, as well as tin- external organs of vision, are entirely wanting in some of these cave Carabidae ; the tactile setae have, however, a larger develop- ment than usual, and the Insects are as skilful in running as if they possessed eyes. Anophthalmus is closely related to our British genus Trechvs, the species of which are very much given to living in deep crevices in the earth, or under large stones, and have some of them very small eyes. In addition to these cavernicolous Anophthalmus, other blind Carabidae have been discovered during recent years in various parts of the world, where they live under great stones deeply embedded in the earth : these blind lapidicolous Carabidae are of extremely minute size and of most sluggish habits ; the situations in which they are found suggest that many successive generations are probably passed under the same stone. Not a single specimen has ever been found above ground. The minute 206 COLEOPTERA CHAP. Carabids of the genus ACJIKS, that pass a large part of their lives under stones below high-water mark (emerging only when the tide uncovers them), on the borders of the English Channel and elsewhere, are very closely allied to these blind Insects, and have themselves only very small eyes, which, moreover, according to Hammond and Miall, are covered in larger part by a peculiar shield.1 A few Carabidae, of the genera 6V///>/V.s and Orthogonius, are believed to live in the nests of Termites. Savage found the larva of G. sculptilis in the nests of Tcrmes IcHicosus; it has been described by Horn, and is said to bear so great a resem- blance to young queens of the Termites as to have been mistaken for them.2 Mr. Haviland found Rhopalomelus angusticoUis in Termites' nests in South Africa. Peringuey states that it emits a very strong and disagreeable odour. It is probable that it preys on the Termites, and this also is believed to be the habit of the Ceylonese Hdluodes taprobanae. Some species of the Mediterranean genus Siagona stridulate by means of a file on the under surface of the prothorax, rubbed by a striate area, adapted in form, on the anterior femora. A valuable memoir on the classification of this important family is due to the late Dr. (I. H. Horn ; 3 he arranges Carabidae in three sub-families ; we think it necessary to add a fourth for 1. Middle coxal cavities enclosed externally by the junction of the nieso- and nieta-sternum ; neither epimeron nor episternum attaining tin- cavity. Head beneath, "with a deep groove on each side near the eye for the reception of the antennae or a part thereof. Sub-fam. 3. PSEUDOMORPHIDES. Head without antennal grooves. Sub-fam. 2. HARPALIDES. 2. Middle coxal cavities attained on the outside by the tips of the episterna and epimera. Sub-fam. 4. MORMOLYCIDES. 3. Middle coxal cavities attained on the outside by the tips of the epinirm, but not by those of the episterna. Sub-fain. 1. CARABIDES. These four sub-families are of extremely different extent and nature. The Harpalides are the dominant forms, and include upwards of 10,000 known species; while the various tribes into which the sub-family is divided include, as a rule, each many i/ of aquatic Insects, 1895, p. 376. 2 Tr. Anur. cnt. Soc. xv. 1888, p. 18. <>j>. cit. v. 1881, p. 91 ; cf. Sharp, Tr. cut. Soc. London, 1S82, p. 61. ADEPHAGA AMPHIZOIDAE PELOBIIDAE 207 genera ; the Carabides are next in importance, with upwards of 2000 species, but are divided into a comparatively large number of tribes, each of which averages a much smaller number of genera than do the tribes of Harpalides ; Pseudomorphides includes only about 100 species ; and Mormolycides consists of the single genus Mormolycc with three species. Fam. 6. Amphizoidae. — Antennae destitute of pubescence : outer lobe of maxilla not jointed; metasternum with a short transverse impressed line on the middle behind. Hind legs slender, not formed for swimming. This family is limited to the genus Ampliizoa ; the species of which may be briefly de- scribed as lowly organised Carabidae that lead an aquatic life. The geo- graphical distribution is highly remarkable, there being but three species, two of which live in Western Itforth America, the third in Eastern Tibet. The habits of American Am- phizoa are known ; they pass a life of little activity in very cold, rapid streams ; FIG. 93. — Amphizoa lecontei. North America, they do not SWllll, but A, Larva ; B, imago. cling to stones and timber. The larva was recently discovered in Utah by Messrs. Hubbard and Schwarz : : it has the same habits as the perfect Insect, and in general form resembles the larvae of the genus Cardbus ; but it has no terminal tube to the body, the abdomen consisting of eight segments and a pair of short terminal appendages ; the spiracles are obsolete, with the exception of a pair placed near to one another at the termination of the eighth abdominal segment. As regards the mouth this larva is Carabid, as regards the abdomen and stigmata Dytiscid of a primitive type. Fam. 7. Pelobiidae. — Antennae destitute of pubescence : outer lobe of maxilla jointed, metasternum with a short transverse impressed line on the middle behind. Hind legs rather slender, 1 P. ent. Soc. Washington, ii. 1892, p. 341. 208 COLEOPTERA CHAP. formed for swimming, the tarsi longer tlt/m lite tililae. This family is limited to the one genus Pelolnus (Hygrolna of some authors). Like Ani]i}ii~oa, to which it is in several respects analogous, it lias a singular geographical distribution ; there are only four known species, one lives in Britain and the Mediterranean region, one in Chinese Tibet, two in Australia, Pelobivs may be briefly t/ *' described as a Carabid adapted to a considerable extent for living in and swimming about in water ; differing thus from FIG. 94. — Pelobius tardus. Britain. A, Young larva ; B, adult larva ; C, imago. (A ami B alter Scliiodte.) Amphizoa, which has no special adaptation for swimming. The larva of Pelobius is remarkable ; it breathes by means of 1 iranchial filaments on the under surface of the body, the spiracles being present, though those of the abdomen are very minute and the others small. The head is very large, the mandibles are not tube-like, the food being taken after the manner of the Carabidae ; the 8th abdominal segment ends in three long processes ; the small 9th segment is retracted beneath them. The adult 7V/W^Vs inriliix is remarkable for its loud stridulation. The sound is pro- duced by an apparatus described correctly by Charles Darwin:1 1 Descent of Mi in,, i. 1890, p. 338; The views of Landois aud Recker, Arch. f. Naturgesch. Ivii. 1, 1891, p. 101, are erroneous. V ADEPHAGA HALIPLIDAE 209 there is a file on the inside of the wing-cases, and the Insect turns up the tip of the abdomen and scrapes the tile therewith. The Insects are called squeakers in the Covent Garden market, where they are sold. Fam. 8. Haliplidae. — Antennae hire, ten - jointed ; meta- sternum marked l>y a transverse line; posterior coxae 'prolonged as plates, covering a, large part of the lower surface of the abdomen ; the slender, hut clubbed, hind femora move between these plates and the abdomen. The Haliplidae are aquatic, and are all small, not exceeding four or five millimetres in length. The ventral plates are peculiar to the Insects of this family, but their func- tion is not known. The larvae are remarkable on account of the fleshy pro- cesses disposed on their bodies ; but they exhibit considerable variety in this respect ; their man- dibles are grooved so that they suck their prey. In the larva of Haliplus, according to Schiodte, there are eight pairs of abdominal spiracles, but in Cnemidotus (Fig. 95, -r,N , -, , FIG. 95. — Cnemidotus caesus. England. A, Imago ; B), there are 110 spiracles, B, larva, 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 210 COLEOPTERA CHAP. 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 sunmming, not capable of ordinary walking : nieta- 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 wrell on land, and of taking prolonged nights through the air ; (3) the pupa is, so far as known, always terrestrial. The larvae and images 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 swiinming- legs (Fig. 97) are deserving of admiration on account of their mechanical perfection ; this, however, is exhibited in various 1 Src J. Linn. Soc. Zool. xiii. 1876, p. 161. A FIG. 96. — Cybister roesdi ( = laterima,rginalis De G.) Europe. A, Larva (after Sclriudte) ; B, -j. • i i • emarginatus. (After ing. In Britain we have nearly ninety Schiodte). species. Some taxononiists 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 Ritsema 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 t/ 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 no 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 Eiley.1 Little is known as to the food and life-history. Horn states that the eggs are placed on 1 Horn, Tr. Amer. cut. Soc. xv. 1888, p. 23 ; Riley, Insect Life, i. 1S89, p. 300. 22O COLEOPTERA CHAP. the skin of the beaver amongst the densest hair ; the larvae move with a sinuous motion, like those of Staphylinidae. It has been B FIG. 102. — Platypsyllus castoris. 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 mintjandi ; others have supposed that it eats scales of epithelium or hairs of the beaver. Fam. 14. Leptinidae. - - Antennae rather long, eleven-jointed, without club, bet a little thicker at the extremity. Eyes absent or imperfect. Tarsi five- jointed. Elytra quite, covering abdomen. Mentum with the posterior angles spinoiisly 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. — Lent inns testaceus. T i -,c i 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 on 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? 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 burying-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 and 306. 222 COLEOPTERA CHAP. 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 8. 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- plmrus, on decomposing animal matter, but run obscuni. Europe, ''bout to Seek it; hence lacrymosa, many Specimens of SOme J 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. tJwracica in birds' nests containing dead nestlings. 8. atrata and 8. laevigata make war on snails. S. lapponica enters the houses in Lapland and ravages the stores of animal provisions. 8. 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. cinnamomea 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 lie- long to the European and North American regions ; Silphidae being apparently far from numerous in the tropics. Rather more than 100 species are natives of Britain. The family reappears incon- siderable force in New Zealand, and is probably well represented FIG. 104.— A, Larva of (After Schiodte). B, Australia. 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 J)r. 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, I nit with the hind coxae separated, and the facets of the eyes coarser ; the tarsi are five-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. Mastigus 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,, five-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. Tnx oh us, 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 Pln- Insect may be IS at present lonthusnitidus. Britain. (After Schiddte.) « I uite mysterious. The habits B- °^Mf o!?ns> Brit/lil1 > ,C' ^ °f aljd°- 1 . men, of 0. olens \vith stink-vessels. 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. vr Q 226 COLEOPTERA CHAP. 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 Lomecliusa 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 Lonn'di usa, 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. Wasmann 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 clo 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 Lomechusa larvae Wasmann obtained a single imago, and from fifty Ate //teles 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 J'crylcichende Studien «/»r Amfiscngiistc, Xijhoff, 1890; and Tijdschr. cut. xxxiii. 1890, pp. 93, etc. ; T,wl. Ccntralbl. xv. 1895, p. 632. v STAPHYLTNIDAE SPHAERIIDAE TRICHOPTL-.RYGIDAE 22/ the The remarkable Staphylinidae yet discovered are some viviparous species, forming the genera Corotoca and Spiraclitlia, that h;i\i- very swollen abdomens, and live in the nests of Termites in Brazil:1 very little is, however, known about them. A very l;irge 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 hornets by some odour, and they do not seriously attack it. 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 labruni. 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 Staphylinidae in Britain, 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 icith only three visible ventral segments. This family includes only three or four species of In- sects about very convex, and may be found walking on mud. 8. acaroides occurs in our fens. Mr. Matthews considers that they are most nearly allied to Hydrophilidae.2 Fam. 21. Trichopterygidae. — Extremal;/ minute: aiit<:/inic«l joints thicker than middle joints} ; tarsi three-jointed; elytra so'inctinirs covering abdomen, in other cases leaving a variable number of segments exposed; 'icings fringed. Tliis family comprises the smallest Insects ; Nanosella fungi being only y-J-Q- of an inch long, while the largest Trj.choptej.ygid is only yV 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 Insects, •t'-i/h chingnte 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 fonr-jn', ni> <1 . Imt tijtj>i'ii,-i ,ii/if. tiix free ventral segments. Maxillae v.'ith only one lobe. Antfiiiuir 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 Ortlioperus brunnipes was found abundantly by Perris in thatch in France. Mr. Matthews proposes to separate the genus Aphanoceph- alus as a distinct family, Pseudocory- FIG. 107.— A, Larva of Orthoperus lophidae.3 In Corylophidae the brim ill ties (after Perris); B, 0. <'/"- • r. • • ,-, marius, perfect Insect. Britain. wmgs are fringed With long hairs, as is the case in so many small Insects: the species of Aphanoceplialus are rather larger Insects, and the wings are not fringed ; the tarsi are only three-jointed. Monograph, Trichopterygia illustrata, by A. Matthews, London, 1872. 2 For further information refer to Matthews, An Essay on Hydroscapha, London, B \ 1S76, 20 pp. 1 pi. Hist. (5) xix. 1887, p. 115. POLYMORPRA SCAPHIDIIDAE — SYNTELIIDAE 229 Fam. 24. Scaphidiidae. — Front coxae small, conical; prothorax very closely applied to the after-body ; bind coxae transverse, witlcl;/ separated : abdomen with six or seven visible ventral plates ; antennae at the extremity with about Jive joints that become xe/juients exposed. Abdomen with Ji re visible ventral segments ; vo'/A. seven rx«l */>/i//ents, all liard. Front ce.'-<«- strongly transverse, hind coxae widely 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. UQ.—Platysoma depression. Europe, but have well-developed mancli- A, Larva (after Schiodte) ; B, perfect , , i • T insect. oles, the second and third thoracic segments being short, the ninth segment of the abdomen terminal, with two distinctly jointed cerci.2 Histeridae are common in dung, in carcases, decay- ing fungi, etc., and some live under bark — these being, in 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 The family was monographed by the Abbe de Marseul in Ann. Soc. cut. 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. HISTERIDAE PHALACRIDAE — NITIDULIDAE 231 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 covering it; apical joints of antennae rather broader, usually long ; front coxae globular ; posterior coxae contiguous ; abdomen with five visible 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 bicolor. pass the Insects over as having only four- J°illted toi; theh> structure, so far _ as the front two pairs are concerned, being very nearly that of many Fhytophaga. 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 1 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 each with an external prolongation ; tarsi five-jointed, the fourth joint smaller than any of the others ; abdomen with Jive visible plates. These Insects are numerous, about 1600 species being at present known; in many of them the elytra nearly or qiiite 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 "We have about 90 species in Britain ; several forms of 1 SB. Ak. JFien. xxiv. 1857, p. 330. 232 COLEOPTERA CHAP. A the geneva, Meligethes and Epuracn 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 Xalaniim 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 Eape. 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 tforuiiia. lives in FIG. 112.— Pria dulcamarae. fermenting sap, and has four hooks curv- Britain. A, Larva (after ing upwards at the extremity of the body. Ferris) ; B, perfect Insect. .„,"' . /-/ 7 7 7 • ", The curious genus Uybocephalus 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 Pihizophagus has given rise to much discussion ; although now usually placed in Mtidulidae, \vc think it undoubtedly belongs to Cucujidae. Fam. 29. Trogositidae. — Differs from Nitidulidae in the struc- ture of tin' tarsi ; tliese appear f<> lefour- jointed, with tlie third joint similar in size and form to the jircccdi nij ; tliei/ are, however, reaUt/ five-jointed, an eX- fre/rtC/1/ sit oft liana/ joint lici/iif /'/'/'Sent. Hind COXae continuous. The chili of cacli antenna is hilat,-,-all// 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 FIG. \\$.—TemnocMa coerulea. Europe. A, Larva (after larvae in large numbers, and it is pro- p^-ris) •. B, perfect insect, bable that the imagos do the same. The larva of Tcnelroides (better known as Troaoxita} -inauritanica is found in corn and flour, and is said to have sometimes been very 1'oLVMORPHA 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. Xemosomides, 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 ; hind 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 Teneriffe are rich in the genus Tar- [iliius. 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 anophthalma, lives entirely underground and is quite blind, the FIG. 114.— crenata. Britain. A, Larva (after optic lobes bei absent. Some Coly- erfect Insect. Ferris) ; B, perfect Insect. the . diidae are more active, and enter burrows of wood-boring Insects to destroy the larvae ((',> 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 Leveille, in Ann. Soc. cnt. France, 1888, p. 429. - For classification, see Sharp, Biol. Ccntr. A mcr. Co7, ii. pt. i. 1894, p. 443. 234 COLEOPTERA CHAP. Fam. 31. Rhysodidae. — Tarsi four-jointed ; mouth-parts covered, l>y the I a rye 'inentum ; front tibiae • notched on the inner cd(i>\ This family consists only of a few species, but is found nc.-irly 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 Aclephaga,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 Rhysodidae, exhibit relations not only with other families of the Coleoptera Polymorpha, but also with most of the great series ; Adephaga, Rhynchophora, Fhytophaga, and Hetero- mera, being each closely approached. Fam. 32. Cucujidae. — Tarsi Jive- or four-jointed, the first joint often short: anteniia.e sometimes r/nlilied, but more often :;(). as well as Leconte and Horn Classification, etc., p. 130. \ POLYMORPHA — CRYPTOPHAGIDAE HELOTIDAE 235 A Fam. 33. Cryptophagidae. — Front and middle coxae very small and deeply embedded; antennae with enlarged terminal joints ; lursi five- jointed, the posterior sometimes in the male only four - jointed; abdomen with five visible ventral segments, capable of in < > r*' at cut, 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, Tclmatophi- lus) are found chiefly on growing plants, especially in flowers. Although the imago of Antherophagus lives in flowers, yet the larva has only been found in the nests of bumble-bees ; there is FIG. ne.—Cryptophagvs 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 ; x this it does by catching hold of the bee with 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 Penis 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 ; five 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 Ferris, Larves. etc.. j>. 75. 236 COLEOPTERA CHAP. There is lint one genns, 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 upper 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-Malayan rr- inn (including Japan) with one species in Eastern Africa, Fam. 35. Thorictidae. — Tarsi five-jointed, none ofthejoinf* hr o«d ; front coxae small, rather prominent, but not at oil fr« /in- verse; fire visible re/itn/J jila/rx, a/I mobile; mctasternn »i very situ rt ; antennae xln>ff,irith a solid dub. This little family, con- sisting of the genus Thorirfnx, 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 pronotmn, or on the under surface of the body on each side of the breast ; AVasmaim thinks that when the beetles are riding about, as above described, the ants have tln-n an opportunity of getting at the patches on the under surface. Fam. 36. Erotylidae.--ram five- jointed, but 'iritJi the fourth -usual/ // very small, the first three mure or less brood a/id i>id>e*ee/// beneath. Antennae xfro//>//f/ clubbed. Front and middle coxal aeetu- "\T/ ) bula round, without angulcw^prolongation FIG. in.-Tritoma Mpustulata. externally; fire risible ventral segments. Erotyiiiiae. Britain. A, Larva This is now a large and important family (after Ferris) ; B, perfect Insect. . ... i • u of about 1800 species, but it is chiefly exotic and tropical, its members haunting the fungoid growths 1 Ritsema, Catalogue of Helota, Xotcs Lcijdcn J/HS. xiii. 1891, p. 223, and xv. 1S93, p. UK). 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 Languriicles (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 Languriicles. Fam. 37. Mycetophagidae. — Tarsi four-joint n], slender, the front fed of the male only three-jointed ; coxae oml, not deeply embedded; abdomen icif/i jin- rentral 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. Jl8. — Litargus bifas- about a dozen species in Britain, and ciatu*. Mycetophagidae. scarcely 100 are described from all the world. The DiphyUid.es, placed by Leconte and Horn in this family, seem to go better in Cryptophagidae. Fam. 38. Coccinellidae (Lady -birds}. — Tarsi apparent!;/ three- jointed ; the jirst two joints pubescent ln/nntli; the third joint consisting really of tivo joints, the small true third joint being inserted near the base of the second joint, the upper surfun- of which is grooved to receive it. Head much concealed l>i/ the thorax. 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 CHAP. and Acari thar are so injurious to cultivated plants. They also eat various other soft-bodied Insects that attack plants. As thev are excessivelv voracious, and are themselves sinid*>myehiden. Leipzig. -"- ". | .Since this work was published, the species known have been multiplied two or three times. 24-O COLEOPTERA CHAP. some forty or fifty species, found chiefly in Europe and North America. We have three in Britain ; one of these, Myeetaea hi /-fa 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 cavities round, not prolonged externally; alxlomen with j! rr innl mobile ventral */i/// tico-jointed, I basal joint and an ch»if/afe claw-bearing joint, but between tin* two tin-re are two very small joints. This family consists only of the American genus Adi/ncrus; nothing is known of POLYMORPHA DERMESTIDAE 241 the life -history of these small Insects. They are of some interest, as this structure of the foot is not found in any other beetles. Fam. 43. Dermestidae. — Tarsi jive-jointed; antennae usually short, with the club frequently very large in proportion, and with the. under side of the thorax hearing 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 small or moderate-sized beetles ; the FlG- 121. — Adimerus setosvs. Adi- „ ,, 1-1 meridae. A, the Insect ; B, one SUrlace, usually Covered With hlie foot more enlarged. Mexico. From hair, forming a pattern, or with BioL Centr- Amer- CoL ij- P*- *• scales. By turns, 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 furniture. The young larva of this species 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 larvae is that of Tiresias serra, which lives amongst cobwebs in VOL. VI R FIG. 122. — Tiresias serra Larva. New Forest. 242 COLEOPTERA CHAP. 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 five-jointed, front coxae not exserted, transverse ; hind coxa shic/di/iif the retracted femur. The ivhole 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 110 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 mentuni, abruptly clubbed antennae, and the head cannot be retracted and concealed. The genus yosw/,'>it/i'i'ii serins 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- ] MX leal 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, dulled ; tarsi four- jointcd; 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 u'ith stout spines ; fi/rsi 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. — Prosternum. distinct in front of the coxae, iixinillil i-lniii'iate, behind forming a process receirnJ into a definite, cavity on the mesosternum ; head retractile, 1 1/ c ///<»///// protected by the prosternum. Tarsi Jive -jointed, term i /ml 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 urii niinatus 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 trachea! tube ; the body is terminated by a process from which there can be protruded bunches of filamentous branchiae. The larvae of Macronychus 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 Psephrm/x 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. — Ta/'si //Vr-/W/// 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. Reticularia hortensis, that are at first pulpy and 246 COLEOPTERA CHAP. afterwards become powder. The larvae of both of our British genera, Sphindus and Aspidipliorus, have been described by Ferris, who considers them allied to the fungivorous Silphidae and Latridiidae. 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 five-jointed, but the first joint very short and imperfectly separated from the second; front coxae prominent, con- tiguous, very little extended transversely ; five 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- FIG. 125.-Apate capudna. ance> the7 have similar habits and larvae. Europe. A, Larva (after The typical Bostiichides are remarkable Ferris) ; B, pt-rt'ect III- n , i • • , n sect. tor 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 u-riyhtii, 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. capudna, 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. Up- wards of 200 species of the family are known. In Britain we have only four small and aberrant forms. Fam. 53. Ptinidae. — Tarsi five-jointed, first joint not reduced in size, often longer than second ; front and middle coxae small, not transversely extended, the former sliglitly prominent; five visible ventral segments; prostenuuii 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." A nobium pan iceum. 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; Anobiutn ($ito- il 1-1 •/>«*) 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 CHAP. in an equally perfect manner, so that no roughness or chink remains, and the creature looks like a little hard seed. Anobium striatuin is a common Insect in houses, and makes little round holes in furniture, which is then said to be " worm-eaten." A. (Xestoln.tnn*) 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 O is standing. The very anomalous genus Ectreplies FIG. 128. — Ectrepkes kingi. J West Australia. (After (Fig. 128) is found ill ants' liests ill Westwood.) Australia. Westwood placed it in Tti- nidae. 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. — Kecen (or even, eiglif) visible ven- tral segments, tlie lasal one not co-adapted in form with the coxae ; tarsi Jive-jointed. Integument softer than usual, the ^orfe of tJie body not accurately co-ad xpti-d. 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-Hies V MALACODERMIDAE FIRE-FLIES — GLOW-WORMS 249 (Ludol(C) 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 Yal Anzasca, which consisted of many hundreds of specimens ; all of those he caught, either on the wing or displaying their lights on the bushes, were 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 and 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 FIG. 129.— Phengodes hieronymi. Cor- doba, South America. (After Haase.) A. Male ; B, female. I, I, Positions of luminous spots ; Is, spiracles. About x 3 at night into lighted apartments. -but the male has elytra and ample wings, and frequently flies 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 Phosphaenus liemipterus 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. cnt. Hal. 1886, p. 406, and Ent. Zeit. Stettin, xliii. 1887, pp. 201-206. Kmrry does not mention the name of the species, but \ve presume it to be the common Italian fire-fly, Luciola italica. 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. noctilma^) ; the luminescence is, however, most marked in the female imago, in which it is concentrated near the extremity of the abdomen ; here there are t\vo 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 no evidence. Considerable difference of opinion has existed as to the luminescence of the eggs of Lampi/ris. 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 Zcitschr. iviss. Zool. xxxvii. 1882, p. 354 ; also Emery, op. cit. xl. 1S84, p. 338. For another theory as to the luminescence, see p. 259. 2 Bull. Soc. Zool. France, xii. 1887, p. 137, postea. v POLYMORPHA — GLOW-WORMS 251 sides of the body, and hence are called, it is said, in Paraguay the railway-beetle. We may refer the reader to Haase's paper1 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 on 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 O O 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. Numerous 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. AVilley recently found in Xew 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 Ceylouese Insect, Dioptoma adamsi Pascoe, is placed in Lampyrides, but can scarcely belong there, as apparently it has but five or six visible ventral segments ; this Insect has two pairs of eyes, a large pair, with coarse facets on 1 Deutsche ent. Zeitsclir. xxxii. 1888, pp. 145-167. - Ent. Mag. xxiv. 1887, p. 148. 252 COLEOPTERA CHAP. the under side of the head, and 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 distinct I;/ co-ailiijit, * ew Forest). w« ;'Tf'5' A, Head ; B, front leg ; C, termination of the body, more mag- immature form, destrOVS Ad'l- • ft -t ** • ft -t 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 1)eef/>-*, v/7/6 soft integu- ments, front and middle coxae exserted, longitudinal in hirxi slender, Jive-jointed ; (t/ife/m/tr *//«/•/, serrate, Imt I'nfli, r Iroad. 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 Lymex'ijlon 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. Sue. cut. France, 1894, p. 7. 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 I'dtlier flimsy integuments, antennae either serrate, filiform, or even made flabellate by long appen- dages ; front coxae elongate, greatly ('.'•sc/'ted ; abdomen ivith jive mobile 1-i'ntral 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 Paruidae and Byrrhidae, that are placed in Clavicornia, than it is to any of the FlG_ 132. __ Hydrocyphou deflexions. ordinary families of Serricornia. It 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, ;ind fragile structure. The few larvae known are of three or four kinds. That of Dascillus 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 < 'yphonides 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 Hydrocyplion (Fig. 132, A) Britain. A, Larva (after Tournier) ; B, imago. 256 COLEOPTERA CHAP. 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 Touriiier, 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 Eucinetas is related to other Dascyllidae ; some authorities indeed place it in Silphidae. Fam. 59. Rhipiceridae.--^?^ fire -jointed, furnished u-ith a robust onychium (a straight chitinons process bearing hairs) between th e claws ; a ntennae of the male bearing long processes, and sometimes consisting of a large manlier of joints. 3fan- 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 dcjcani (Fig. 133, A) is described by Schiodte as hard, cylindrical in form, and peculi- truncate behind, so that FIG. 133. — A, Larva of GaUirhqris dejeani (after Schiiidte) ; B, Rliipicrra mystacina there appear to be Ollly eight male, Australia ; C, under side of its hind •, •, • i • foot. abdominal segments, trie 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 pei'fi /i«/<\ rarely filiform. Front coxae small, spherical. Thorax -usually with 1 Perris, Ann. >SW. ent. France (2) ix. 1851, p. 48. CLICK-BEETLES 257 FIG. 13-1. — Athous rhombeus. New Forest. A, Larva ; B, female imago. J/ i /if? nn riles more or less prolonged backwards; with a prosternal process that can he received in, and usually can move in, a mesosternal cavity. Hind coxa with a plate, above which the femur can lie received. Visible ventral segments 'usually Jive, only the if i- initial 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 o-oing off t/ O O with 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 us to permit its accomplishment. The junction of the prothorax with the after-body involves a large number of pieces which an- 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. Naturgesch. xlviii. 1, 1882, p. 371. VOL. VI S 258 COLEOPTERA CHAP. 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- sterual 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-worms " 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 Myriapods (see Vol. Y. p. 29) 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 Xew "\Vorld, with the exception that there may possibly be luminous species, allied to the American forms, in the Fiji Islands and the New Hebrides. In the tropics of America the Pyrophorits, or Cucujos, form one of the most remarkable of the natural phenomena. v ELATERIDAE 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. noctiliicus is one of the most abundant and largest of the Pyroplnirux, and possesses 011 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 011 Glow- worms. He considers that the light is produced by the reactions of two special substances, luciferase and luciferine. Lucifernse 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 Elateridea hnniueux," Bull. Soc. Zool. France, xi. 1SS6 ; also Lemons dc I'/ii/xin/tii/i'i' iji'ngralc, Paris. 1898, and C.R. Ac. Sci. cxxiii. 1S96, p. 653. 260 COLEOPTERA CHAP. 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. Labrum concealed ; antennae somewhat distant from the eyes, their insertion narrowing the front EUCXEMIDES. Labnuu visible, free; antennae arising near the eyes under the frontal margin ..... ELATERIDES. Lalirum transverse, connate with the front. Ventral segments six ; claws simple ; tibial spurs well developed. ( 'EBRIOXIDES. 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, 1 >ut are highly remarkable, inasmuch as it is FIG. 135. -Larva of Forna.c difficult to lilld any mouth-opeiling n. sp. Hawaii. A, Upper side; B, under side: s *, in some of them, and they have no legs. Ei^ore Srjd \ g The other divisions possess very few species under side of terminal seg- compared with Elaterides. Iii Britain ment ; a. anus. i •> • • p T-II 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 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, t/ic second, the others mobile. Tarsi five-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) gigantea 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 metal. The dorsal plates of the abdo- 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 FIG. 136. — A, Larva of Euchroma (joliath (after Schiodte) ; B, imago of MdanopMla decostiyma. Europe. 262 COLEOPTERA CHAP. bark of trees and bushes, or in roots thereof; some inhabit the stems 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 Etlion dwell in galls on various plants. Buprestid larvae axe 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, tJiOse 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 live. Several of the families of the series are of doubtful validity ; indeed beyond that of Tenebrioiiidae 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 o o */ 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 the 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 AVestwood (Mod. Classif. i. 1839, p. 229), and figured as probably Buprestis atttximf". is doubtless a Passalid. V HETEROMERA 263 3 1 h-h mditor. Europe, etc. A, Larva (meal-worm); B, pupa (after Schiodte) ; c, imago. Fam. 62. Tenebrionidae. — Front coxae short, not projecting from the cavities, enclosed InhimJ. Feet destitute of lobed joints. Clmcs smooth. This is one of the largest families of Coleoptera, about 10,000 species being already known. A very large portion of the Tenebrionidae are entirely terrestrial, wings suitable for flight being absent, and the elytra frequently more or less soldered. Such forms are described in systematic works as apterous. Unfortunately no comprehensive study has ever been made of the wings or their rudiments in these " apterous forms." It is prob- able that the wings, or their rudiments or vestiges, always exist, but in various degrees of development according to the species, and that they are never A y used by the great majority of the terrestrial forms. Man v of the Flc- 137-— , „ ,. m . . . .. wood - feeding Tenebrionidae, and the genera usually placed at the end of the family, possess wings well adapted for flight. The apterous forms are chiefly ground -beetles, living in dry places ; they are very numerous in Africa, California, and North Mexico. Their colour is nearly always black, and this is probably of some physiological importance ; the integuments are thick and hard, and if the wing-cases are taken off, it will be found that they are usually more or less yellow on the inner face, even when jet-black externally ; the external skeleton is very closely fitted together, the parts that are covered consisting of very delicate membrane ; the transition between the hard and the membranous portions of the external skeleton is remarkably abrupt. These ground-Tenebrionidae form a very interesting study, though, on account of their unattractive appearance, they have not received the attention they deserve. Many of the Tenebrionidae, notwithstanding their dark 1 Casey has examined the wings in the genus Blapstinus (an "apterous" genus), and found that the wings are extremely varied in development, according to the species ; in no case, however, did they appear to be capable of giving more than a laboured and feeble flight. — Ann. Neio York Ac. v. 1890, p. 416. In Eleodcs, though the meso- and meta-notum are formed of delicate membrane, the wings exist as minute flaps, requiring some examination for their detection. 264 COLEOPTERA CHAP. colours, are diurnal in habits, and some of them run with extreme velocity in places so bare and desert that the means of existence of the Insects is a mystery. Most of the Tenebrionidae, however, shun the light. The food is usually vegetable matter, and it is apparently preferred in a very dry state. Mr. Gahan has recently recorded that in Praogena the under surface of the head has the gular region striate for stridulating purposes. This is the only instance known of a voice -organ in this situation, and moreover is the only case in all the Tenebrionidae in which any sound-producing organ has been discovered. The larvae exhibit but little variety, they are elongate and cylindrical, with harder integument than is usual in Coleopterous larvae ; they have six thoracic legs, and at the under side of the posterior extremity the anus serves as a very short pseudopod. The resemblance of these larvae to those of Elateridae is considerable : but though the body is terminated by one or two small processes, these never attain the complexity of the terminal segment of Elateridae. The common meal-worm— i.e. the larva of Tenebrio molitor — is a very characteristic example of the group. The pupae are remarkable on account of peculiar projections, of varied and irregular form, that exist on the sides of the abdominal segments. Britain is very poor in these Insects ; our list of them scarcely attains the number of thirty species. Fam. 63. Cistelidae. — Claws comb-like. The very obscure beetles forming this family are only separated from Tenebrionidae on account of their pectinate claws. About 500 species of Cis- telidae are recorded ; the early instars, so far as known, do not differ from those of Tenebrionidae ; the larvae are believed to live on dead wood. Fam. 64. Lagriidae. — Anterior coxal cavities dosed, tips of the front coxae free, claws smooth, penultimate joint of the tarti broader, j>t>l>rxecnt beneath. This family has very little to dis- tinguish it from Tenebrionidae, and the group Heterotarsini appears to connect the two. It is a small family of about 200 species, widely distributed, and represented in Britain by one species, Lai/fia hirta. The early instars are similar to those of the Tenebrionidae, except that the larva is less retiring in its habits and wanders about on foliage: it is of broader form than that of most of the Tenebrionidae. The pupa has long projections at the sides of the abdominal segments. HETEROMERA 265 Fam. 65. Othniidae. — Only about ten species are known of this dubious family. They are small Insects with weak integument, and are said by Leconte and Horn to be distinguished from " degraded Tenebrionidae " by the more mobile abdominal seg- ments, the hind-margins of which are semi -membranous. The antennae are of the clubbed shape, characteristic of " Clavicornia," but this also occurs in numerous undoubted Tenebrionidae. Species of Otlinius have been found in Japan and Borneo, as well as in North America. Nothing is known as to their metamorphoses. Fam. 66. ^Egialitidae. — All the coxae very ividely separated ; mi co-adaptation Between the sides of the abdomen and the edges of the wing-cases ; five ventral segments and tip of a sixth visible. Two minute and rare Insects from North-West America constitute this family. It is distinguished from Pythidae by the minute front coxae, widely separated, completely closed in, and deeply embedded in the prosternum. Fam. 67. Monommidae.--This is a small family of less than 100 species, the members of which have the details of their external structure much modified, permitting the Insect to pack itself up in repose in a very perfect manner. * They are of small size and oval form ; and are absent from Europe and the Anti- podes. Nothing appears to be known as to the metamorphosis. Fam. 68. Nilionidae. — Broad, circular Heteromera, of moderate size, with the front coxae but little separated, and the anterior acetabula closed, though having the appearance of being open in consequence of the tips of the epimera being free. The infle,<-«/ portion of the wing-cases remarkably broad. A small family of less than fifty species, found on fungi, chiefly in South America. The metamorphoses are not known. It is of very doubtful validity. Fam. 69. Melandryidae. — Head not constricted, behind the eyes ; anterior acetabula not closed ; claws smooth. Prothorax broad behind. These are loosely -fitted- together Insects, of moderate or small size, frequenting dry wood or fungi. About 200 species are known, found chiefly in temperate regions. The few described larvae are rather varied in their details and cannot be generalised at present. The characters of the members of this family require fresh investigation. Fam. 70. Pythidae. — Distinguished from Melandryidae by the 266 COLEOPTERA CHAP. prothorax being narrow behind. This is a small family of about 100 species, found in temperate regions in connection with timber. The species of Iihi/msum/s have the head prolonged in front of the antennae so as to form a beak. The larva of Pytho x melanura is common on our V HETEROMERA MORDELLIDAE 267 FIG. 138. — Asdera cnernlea. A, Larva ; B, pupa (after Scbiudte) ; C, imago. Cambridge. coasts, where its larva lives in timber cast up by the sea, or brought down by Hoods, and it is able to resist immersion by the tide. It is remarkable from the possession of five pairs of dorsal false feet on the anterior segments, and two pairs on the ventral aspect. In Asdera caerv.lea there are six dorsal and three ventral pairs of these re- markable pseudopods. "We have six species of Oedemeridae in Britain, including Asdera as well as Naccrilcs. Fam. 74. Mordellidae (incl. Rhipiphoridae). — Head peculiarly formed, vertex lobcd or ridged behind, so that in extension it looses on the front edge of the pvo- notum ; capable of great inflection and then covering the pro sternum ; hind coxae with laminae forming a sharp edge behind, frequently very large. This family is a very distinct one, though it exhibits great variety. Lacordaire has pointed out that Rmpiphoridae cannot at present be satisfactorily distinguished from Mordellidae. Leconte and Horn separate the two by the fact that the sides of the prothorax form a sharp edge in Mordellidae, but not in Khipiphoridae. A better character would perhaps be found by a study of the head, but as this would clearly result in a radical change in the composition of the two families it is preferable to treat them at present as only sub-families : if placed on a similar basis to the preceding families, the group would however form, not two, but several families. Besides the unusual shape of the head (Fig. 130, D) the ventral region of the body is remarkably formed, being very convex, and in many Mordellides terminating in a strong spinous process (Fig. 139, C). The elytra are, in several Ehipiphorids, of the groups Myoditini and Rhipidiini, reduced to a very small size, and the wings are not folded. The Mordellidae are remarkable for their activity; in the perfect state they usually frequent flowers, and fly and run with extreme rapidity. Mordellides are amongst the most numerous and abundant of the European Coleoptera, and in Britain the Anas-oini swarm on the flowers of bushes and Umbelliferae. The 268 COLEOPTERA CHAP. life-histories appear to be singularly varied : hut unfortunately they are incompletely known. The larvae of some of the Mordellids have been found in the stems of plants, and derive their nutriment therefrom. This is said by Schwarz to be undoubtedly the case with Moi'flcUistcna floridensis. Coquillett has found the larvae of J/ i>nx1iil«l«. in plant-stems under circumstances that render it highly probable that they were feeding on a Lepidopterous larva contained in the stems ; and Osborn found a similar larva that was pretty certainly a Mordellist$na, and fed voraciously on Dipterous larvae in the steins of a plant. The little that is known as to the meta- FIG. IW.—Mordelli- stenn tJi'i'iilensis. America. (After Pdley.) A, Larva ; B. pupa ; C, imago ; D, outline of de- tached head of im- ago of M. fin in iln, to show the ueck. morphoses of Mordclla and Anuspis shows that they live in old wood, but does not make clear the nature of their food. Although it has been ascertained that the Ehipiphorides exhibit instances of remarkable metamorphosis, their life- histories are still very imperfectly known. Dr. Chapman has ascertained some particulars as to Metoecus paradoxns, which has long been known to prey in the larval state on the larvae of the common social wasps.1 The eggs are apparently not deposited in the nests of the wasps, but in old wood. The young larva is a triungulin, similar to that of the Cantharidae, we shall sub- sequently describe. It is not known how it makes its way to the was] is' nests, but it is possible that when a wasp visits some old wood haunted by these larvae, some of them may attach themselves to it and be carried to the wasps' nests. When 1 Ann. Nat. Jlisf. (4) vi. 1870, p. 314 ; and Ent. Mudlata, a genus allied to Metoecus, has been discovered by Chobaut to have a similar life-history, except that it attacks a solitary wasp of the genus Odynerus? An old record to the effect that a second species of Emenadia, E. bimaculata, lives in the stalks of Eryngium campestre, on the pith, is now thought to be erroneous. Fabre has found the larvae and pupae of another Ehipiphorid in the cells of a bee, Halictus sexcinctus. The most remarkable of the Bhipiphorids, from the point of view of its habits, is certainly Symlius blattarum, which is now treated as the same as an Insect previously described by Thunberg from specimens found in amber and called Ripidius pectinicornis. This species is parasitic in cockroaches : the male and female are very different, the former being an active winged Insect, while the female is worm-like, differing but little from the larva, and never leaving the body of the cockroach. It is to be regretted that the life-history is not better known. The species has been found on board ship in vessels coining from India ; the male has been met with in several European countries, but the female is excessively rare. Fam. 75. Cantharidae or Meloidae (Blister-beetles, Oil -beetles'). —Head with an abrupt neck ; elytra and sides of the abdomen witli - out any coadaptation ; each claw of the feet with a long ^y^"'"'/"/" r/o.sv/// Applied beneath it. This distinct family consists of Heteromera with soft integument, and is remarkable for the fact that many of its members contain a substance that when extracted 1 Mitt. Schu-eiz. cut. Ges. iv. 1876, p. 556. - Ann. Soc. ent. France, Ix. 1891, p. 447. 2/O COLEOPTERA CHAP. and applied to the human skin, possesses the power of raising blisters. The life-history is highly remarkable, the most complex forms of hyper-metamorphosis being exhibited. The species now known amount to about 1500; there can be no difficulty in recognising a member of the family by the above characters, except that in a very few cases each claw bears a projecting tooth, instead of an elongate appendage parallel with itself. The penultimate tarsal joint is scarcely ever broader than the pi'e- ceding ; the colour and style of markings are extremely varied. There are two very distinct sub - families, Cantharides and Meloides ; the former are winged Insects, and are frequently found on flowers or foliage. The Meloides are wingless, and consequently terrestrial ; they have a very short metasternum, so that the middle coxae touch the hind ; and they also have very peculiar wing-cases, one of the two overlapping the other at the base ; in a few Meloids the wing - cases are merely rudiments. The post-embryonic development of these Insects is amongst the most remarkable of modern entomological discoveries. The first steps were made by Newport in 185 1,1 and the subject has since been greatly advanced by Fabre, Eiley, and others. .Is an example of these peculiar histories, we may cite Eiley's account- of Epicauta vittata (Fig. 140), a blister-beetle living at the expense of North American locusts of the genus Calop- /' /ins. The locust lays its eggs underground, in masses sur- rounded by an irregular capsule, and the Epicauta deposits its eggs in spots frequented by the locust, but not in special proximity to the eggs thereof. In a few days the eggs of the blister-beetle hatch, giving rise to little larvae uf the kind called triungulin (Fig. 140, A), because each leg is terminated by three tarsal spines or claws. In warm, sunny weather these triungulins become very active ; they run about on the surface of the ground exploring all its cracks, penetrating various spots and burrowing, till an egg-pod of the locust is met with : into Ih is the triungulin at once eats its way, and commences to devour an egg. Should two or more Iriungulins enter the same egg-pod, battles occur till only one is left. After a few days passed in "On the Natural History, Anatomy, and Development of the Oil-Beetle, Meloe, ' Tr. LI mi. ,S'oe. xx. 1851, p. 297 ; ami xxi. 18.13, p. 167. Rep. U.S. ent. Commission, i. L878, p. 297. HETEROMERA CANTIIARIDAE 271 devouring a couple of eggs, the triungulin sheds its skin and appears as a different larva (Fig. 140, B), with soft skin, short legs, small eyes, and different form and proportions ; a second moult takes place after about a week, Lut is not accompanied by any very great change of form, thong] i the larva is now curved, less active, and in form like a larva of Scarabaeidae ; when another moult occurs the fourth instar appears as a still more helpless form of larva (Fig. 140, D), which increases rapidly in size, and when full grown leaves the remains of the egg-pod FIG. 140. — Hypermetamorphosis of Epicauta vittata. North America. (After Riley.) A, Young larva or triungulin ; B, Caraboid iustar or second larva ; C, coarctate larva, or instar between the Scarabaeoid and Scolytoid larva ; D, Scarabaeoid larva, from which the Scolytoid, or sixth, instar differs but little ; E, pupa ; F, imago. it has been living on, and forms a small cavity near by ; here it lies on one side motionless, but gradually contracting, till the skin separates and is pushed down to the end of the body, dis- closing a completely helpless creature that has been variously called a semi-pupa, pseudo-pupa, or coarctate larva (Fig. 140, C) ; in this state the winter is passed. In spring the skin of the coarctate larva bursts, and there crawls out of it a sixth instar which resembles the fourth (Fig. 140, D), except in the somewhat n-durrd si/c and greater whiteness. It is worthy of remark that the skin it has deserted retains its original form almost intact. In this sixth instar the larva is rather active and burrows about. 272 COLEOPTERA CHAP. but does not take food, and in the course of a few days again moults and discloses the true pupa (Fig. 140, E). As usual in Coleoptera this instar lasts but a short time, and in five or six days the perfect beetle appears (Fig. 140, F). It is extremely difficult to frame any explanation of this complex development ; there are, it will be noticed, no less than five stages interposed between the first larval instar and the pupal instar, and the creature assumes in the penultimate one a quasi-pupal state, to again quit it for a return to a previous state. It is possible to look on the triungulin and the pupal instars as special adaptations to external conditions ; but it is not possible to account for the intermediate instars in this way, and we must look on them as necessitated by the physiological processes going on internally. Nothing, how- ever, is known as to these. It may be well to mention that, after describing and figuring (lac. cit.} this series of instars, Eiley changed his views as to their nomenclature.1 The following summary of the metamorphosis, to which we have added the two nomenclatures of Eiley — the original one, when different from the amended one, being given in square brackets — may therefore be useful, viz. — Egg ; 1, triungulin-larva — moult ; 2, Caraboid larva [second larva, Caraboid stage] — moult ; 3, Scarabaeoid larva [second larva, Scarabaeoid stage] — moult; 4, Scarabaeoid laiva [second larva, ultimate stage] (large amount of food and much growth) — moult; 5, coarctate larva [pseudo-pupa, or semi pupa] ; 6, Scolytoid larva [third larva] (active, but little or no food taken) —moult ; 7, pupa — moult ; 8, perfect Insect. M. Fabre has succeeded in elucidating the history of Sitaris Immeralis, a Cantharid that lives at the expense of bees of the genus Anthophora? The eggs of the Sitaris are deposited in the earth in close proximity to the entrances to the bees' nests, about August. They are very numerous, a single female pro- ducing, it is believed, upwards of 2000 eggs. In about a month - towards the end of September — they hatch, producing a tiny triungulin of black colour ; the larvae do not, however, move away, but, without taking any food, hibernate in a heap, remaining in this state till the following April or May, when they become active. Although they are close to the abodes of the bees they do not enter them, but seek to attach themselves 1 Amer. Nat. xvii. 1883, p. 790. • For illustration of this metamorphosis, see Vol. Y. p. 159 of this work. CANTHARIDAE 2/3 to any haiiy object that may come near them, and thus a certain number of them get on to the bodies of the AntTio-phora and are carried to its nest. They attach themselves with equal readiness to any other hairy Insect, and it is probable that very large numbers perish in consequence of attaching themselves to the wrong Insects. The bee in question is a species that nests in the ground and forms cells, in each of which it places honey and lays an egg, finally closing the receptacle. It is worthy of remark that in the case of the Anthophora observed by M. Fabre, the male appears about a month before the female, and it is probable that the vast majority of the predatory larvae attach themselves to the male, but afterwards seize a favourable opportunity, transfer themselves to the female, and so get carried to the cells of the bee. When she deposits an egg on the honey, the triungulin glides from the body of the bee on to the egg, and remains perched thereon as on a raft, floating on the honey, and is then shut in by the bee closing the cell. This remarkable act of slipping on to the egg cannot be actually witnessed, but the experiments and observations of the French naturalist leave little room for doubt as to the matter really happening in the way described. The egg of the bee forms the first nutriment of the tiny triungulin, which spends about eight days in consuming its contents ; never quitting it, because contact with the surrounding honey is death to the little creature, which is entirely unfitted for living thereon. After this the triungulin undergoes a moult and appears as a very different creature, being now a sort of vesicle with the spiracles placed near the upper part ;. so that it is admirably fitted for floating on the honey (Vol. V. Fig. 86, 10). In about forty days, that is, towards the middle of July, the honey is consumed, and the vesicular larva after a few days of repose changes to a pseudo-pupa (11 of the fig. cited) within the larval skin. After remaining in this state for about a month, some of the specimens go through the subsequent changes, and appear as perfect Insects in August or September. The majority delay this subsequent metamorphosis till the follow- ing spring, wintering as pseudo-pupae and continuing the series of changes in June of the following year ; at that time the pseudo- pupa returns to a larval form (12 of the fig. cited), differing com- paratively little from the second instar. The skin, though detached, is again not shed, so that this ultimate larva is enclosed in two vor, vi T 2/4 COLEOPTERA CHAP. dead skins ; in this curious envelope it turns round, and in a couple of days, having thus reversed its position, becomes lethargic and changes to the true pupa, and in about a month subsequent to this appears as a perfect Insect, at about the same time of the year as it would have done had only one year, instead of two, been occupied by its metamorphosis. M. Fabre employs the term, third larva, for the instar designated by Riley Scolytoid larva, but this is clearly an inconvenient mode of naming the instar. Sitaris humeralis is now very rare in Britain, but it seems formerly to have been more common, and it is not improbable that its triungulin may have been the " Pediculus meliUae," that was believed by Kirby to be a sort of bee-louse. Some species of the genus Mdoe are still common in Britain, and the Insects maybe seen with heavy distended abdomen grazing on herbage in the spring. The females are enormously prolific, a single one producing, it is believed, about 10,000 eggs. Meloe is also dependent on Antlwpliora, and its life-history seems 011 the whole to be similar to that of Sitaris ; the eggs are, however, not necessarily deposited in the neighbourhood of the bees' nests, and the triungulins distribute themselves on all sorts of un- suitable Insects, so that it is possible that not more than one in a thousand succeeds in getting access to the Antliopliora nest. It would be supposed that it would be a much better course for these bee-frequenting triungulins to act like those of E^ncauta, and hunt for the prey they are to live on ; but it must be remembered that they cannot live on honey ; the one tiny egg is their object, and this apparently can only be reached by the method indicated by Fabre. The history of these Insects certainly forms a most remarkably instructive chapter in the department of animal instinct, and it is a matter for surprise that it should not yet have attracted the attention of comparative psychologists. The series of actions, to be performed once and once only in a lifetime by an uniiistructed, inexperienced atom, is such that we should a 2]r'iori have denounced it as an impossible means of existence, were it not shown that it is constantly successful. It is no wonder that the female Jfeloe produces 5000 times more eggs than are necessary to continue the species without diminu- tion in the number of its individuals, for the first and most important act in the complex series of this life - history is accomplished by an extremely indiscriminating instinct; the HETEROMERA 275 newly hatched 3Moe has to get on to the body of the female of one species of bee ; but it has no discrimination whatever of the kind of object it requires, and as a matter of fact, passes with surprising rapidity on to any hairy object that touches it ; hence an enormous majority of the young are wasted by getting on to all sorts of other Insects ; these larvae have been found in numbers on hairy Coleoptera as well as on flies and bees of wrong kinds ; the writer has ascertained by experiment that a camel's- hair brush is as eagerly seized, and passed on to, by the young Mdoe as a living Insect is. The histories of several other Cantharids have been more or less completely discovered. Fabre has found the larva of Germ-milt/, schaefferi attacking the stores of provisions laid up by a fossorial wasp of the genus Tacliytes, and consisting of Orthoptera of the family Mantidae. The student who wishes for further information may refer to M. Beauregard's work on this family.1 Some half-dozen species of the genus Ceplialoon found in Siberia, Japan, and North America, have, by some authorities, been separated as the family Cephaloidae. Nothing is known as to the metamorphosis of these rare beetles ; and at present it is not necessary to distinguish them from Cantharidse. Fam. 76. Trictenotomidae. — Large Heteromera, with powerful free projecting mandibles ; the antennae long, but with the termi mil three joints short, with angular projections on one side. This family includes only two genera and seven or eight species. They are very remarkable Insects ; Autocrates aenea being three inches long. The family is of considerable interest, as it seems to have no affinity with any other Coleoptera. The appearance of the species somewhat reminds one of Lucanidae, or Prionides ; but Trictenotomidae have even less relation to those beetles th;in they have to the members of the Heteromerous series. The Trictenotomidae appear to be found only in the primitive forests of the Indian and Indo-Malayan regions. Nothing is known as to their life-histories. 1 Les Inscctcs Vesicants, Paris 1890, 554 pp. Parts of this work were pre- viously published in J. de I'Anat. Phys., xxi. xxii. xxiii. 1886 and 1SS7. 2/6 COLEOPTERA CHAP. Series V. Phytophaga. Tarsi apparently four-jointed, the three basal joints usually densely set with cushion -like pubescence beneath; the third joint different in form, being divided into two lobes, or grooved on its upper surface so as to allow of tit e fourth joint being inserted near its base instead of at its extremity. Head not forming a definite prolonged beak ; its labrum visible, the palpi rarely (and even then not con^letcly} occluded in the mouth. This great series of beetles includes something like 35,000 species. It approaches, like all the other series, the Polymorpha, especially the family Erotylidae placed therein, Imt in the great majority of cases there is no difficulty in recognising its members. The tarsi have never the Heteromerous formula, the head is not constructed like that of Ehyuchophora, nor the mouth and feet like those of Adephaga ; the antennae are different from those of the Lamellicorns. The tarsi are really five-jointed, for careful inspection shows that the long claw-joint has at its extreme base a small nodule, which is undoubtedly the fourth joint (Fig. 142, B). In speaking of the joints it is, however, customary not to refer to this small and functionally useless joint at all, and to call the claw-joint the fourth ; when the little joint is referred to it may be called the true fourth joint, Nearly the whole of the enormous number of species of this series are directly dependent on the vegetable kingdom for their nutriment ; they are therefore well styled Phytophaga. This term is, however, restricted by some systematists to the family we have called Chrysomelidae. Although there is enormous variety in this series, three families only can be at all naturally distinguished, and this with difficulty. Of these the Bruchidae are seed -feeders, the Chrysomelidae, as a rule, leaf- feeders, the Cerambycidae wood and stem-feeders. The number of exceptions to this rule is but small, though certain Cerambycidae and certain Chrysomelidae live on roots. Fam. 77. Bruchidae. — Prosternum extremely short ; in front perpendicular; behind the coxae, forming merely a transverse lamina with pointed extremity. Hind femora more or less PHYTOPHAGA — BRUCHIDAE 2/7 thickened. This comparatively small family includes about 70 0 species of small, unattractive beetles. The larvae live in seeds ; hence some of the species are liable to be transported by means of commerce ; some of them do considerable injury ; peas and beans being specially subject to their attacks. They are able to complete their growth with a very small amount of nutriment, some of them consuming only a portion a little larger than themselves of a bean or pea. The larvae are fat maggots without legs, but Riley has discovered that the young larvae of Bruclius pisi and B. fabae have, when first hatched, three pairs of legs which are subsequently lost. They also have peculiar FIG. \±\.—Bn>clivs pisi or pea-weevil. A, Young larva ; B.protlioracie spin- ous process ; C, post-embr yonic leg, greatly magni- fied. ; D, pea-pod, with tracks of entry ; E, portion of pod, with egg, and the ' subse- quently formed track, magnified ; F, imago. (After Riley.) spinous processes on the pronotum. Both of these characteristics may be correlative with the transient differences in the activities of the larva, for the little creature is not at first located in the pea, but mines a gallery in the pod, in which it moves about, subsequently entering the pea and losing its legs. There is a good deal of difference in these respects between the two species — B. pisi and B. fabae — examined by Riley, and as but little is known of the life-histories of other Bruchidae it is probable that still greater variety prevails. Heeger has found that Bruclius lentis sometimes requires two seeds to enable it to complete its growth ; it is, notwithstanding its legless state when half-grown, able to migrate by dropping to the earth, and dragging itself along by its mandibles till it conies to another pod into which it bites its way. The family has, until recently, been placed in the Rhyncho- 2/0 COLEOPTERA CHAP. phorous series, with which it has, however, no direct connection. On the other hand, it is so closely connected with Chrysomelidae that it is not possible to indicate good characters to distinguish the two at present. The Australian genus Carpophagus, and the large South American species of Garydborus appear to be quite indistinguishable as families, though Lacordaire and Chapuis placed one in Bruchidae, the other in Chrysomelidae. The definition we have given applies, therefore, to the majority of the family, but not to the aberrant forms just mentioned. The European genus Urodon appears to belong to Anthribidae, not to Bruchidae. The family Bruchidae is called Mylabridae by some. Fam. 78. Chrysomelidae. — Antennae moderately long ; eyes moderately I// rt/r, usu filly not at all surrounding the insertion of tlir antennae; upper surface usually bare, frequently brightly coloured a ml shining. This enormous family comprises about 18,000 species of beetles, in which the form and details of structure are very varied. No satisfactory character for distinguishing 5 Chrysomelidae from Cerambycidae has ^e^ ^een disco vered, although the two families are certainly distinct and natural. Most of the Chrysomelidae live on foliage ; few of them are more than half an inch long, whereas the Cerambycidae are wood - feeders and usually of more elongate form and larger size. The potato beetle, or Colorado beetle, that occasioned so much destruction in North America some thirty years ago,and the introduction of which into Europe was anticipated with much dread, is a good example of the Chrysomelidae. The turnip flea, a tiny hopping beetle, is FIG. [4-2. — Doryphoru decent- J i in fit ta, the potato beetle, among the smallest forms of the family. rSndTi. \InS a»d is » member of another very exten- joint ; •!, true fourth joint ; sive subdivision of Chrysomelidae, viz. [>, so-called fourth joint. TT it- • i TU -r»i i Halticides. The term Phytophaga is by many naturalists limited to Chrysomelidae, the Cerambycidae being excluded. The classification of the family is but little advanced, but the enormous number of species of Chrysomelidae are placed in four divisions, viz. :— v PHYTOPHAGA CHRYSOMELIDAE . 279 Prothorax much narrower at the base than the elytra, and usually with- out side-margins (raised edges). Sub-fain. 1. EUPODA ; with three divisions, Sagrides, Donaciides, Criocerides. The basal ventral plates of the abdominal segments are somewhat shorter in tlie middle than at the sides, the fourth one being often invisible in the middle, while the fifth is very large. Sub-fam. 2. CAMPTOSOJIES ; with six divisions, Megascelides, Megalopides, Clythrides,.Cryptocephalides, Chlamydes, Sphaerocarides. In the other two groups there is no great disparity between the fourth and fifth ventral plates. Prothorax not greatly narrower at the base than the elytra, and usually with distinct edges at the outsides. Sub-fam. 3. CYCLICA ; with four divi- sions, Lainprosomides, Eumolpides, Chrysomelides, Galerucides. Front of the head bent downwards or inflexed, so that the mouth is on the lower aspect. Antennae inserted close together on the most anterior I'-ul of the head, so that they are more forward than the mouth. Sub-fam. 4. CRYPTOSTOMES ; with two divisions Hispides, Cassidides. In the other three divisions the mouth is placed as usual, but the insertion '////'n/(). x. Paris. 1874, p. 15. 280 COLEOPTERA CHAP. inside the stems of Dioscorea batatas, in swellings ; the group Sagrides, to which it belongs, is a very anomalous one. i. EUPODA. The beetles of the genus Donacia are of special interest. They form, with the genus Haemonia, a peculiar group, wrell represented in Europe, and also in our own country. They are all connected with aquatic plants, the species of Haemonia living entirely under water, while the Donacia, live in the imago-state an aerial life ; though many of them enter the water with great readiness, and, it is said, are able to take wing from the surface. The larvae live 011 the roots of aquatic plants, and derive not only nutriment but air therefrom ; they pass several months as pupae (or as resting larvae waiting for pupation), under water in cocoons which they construct, and which, incredible as it may seem, are filled with air, not water. Exact details as to the construction of these cocoons are wanting. It was formerly absurdly supposed that the larva swelled itself out to the size of the cocoon it was about to make, and so served as a mould, subsequently con- tracting. The observations of Schmidt-Schwedt l make it, however, more probable that the plant itself furnishes the air which, under pressure of the water (so he supposes), fills the cocoon ; the larva wounds the root, piercing to an air-vessel and then constructs the cocoon on this spot, leaving to the last moment an orifice, according to Schmidt, as an exit for the water. The larva uses a similar artifice for obtaining air; it has no gills, but is pro- vided near the extremity of the body with two sharp chitinous processes which it drives into the root of the plant till it penetrates an air-vessel. Schmidt thinks the processes serve as conduits to conduct the air to the tracheae, but Dewitz thinks the air enters the larva in a more normal manner, by means of a stigma placed at the base of the piercing process. A similar larva exists in Haemonia ; which genus is additionally interesting from the fact that the imago lives entirely submerged. It is not known how it breathes. This genus is the only member of the Chrysomelidae that does not possess the structure of the feet that is characteristic of the Phytophaga. The late Professor Babington about sixty years ago found H. curtisi at Cley on the Norfolk coast on submerged Potamoycton pectinatus, but it has not been met with there for a great many years. The larvae of Criocerides are of two kinds, in one of which the 1 JJ.Tliti. ent. Zdt. 1887, i>. o25, and 1889, p. 299. PHYTOPHAGA CHRYSOMELIDAE 281 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 Lcma 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. merdiyera, 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- latiug 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 tine 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- FIG. 143. — Crioceris asparagi. A, Eggs in position on stem of asparagus ; B, one egg much enlarged ; C, young larva. Cambridge. 282 COLEOPTERA CHAP. quently enlarges it by additions from its own body. The beautiful Insects of the genus Cryptocephalus, 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 Khynchophora. 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 Cerambycida?. 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. Hi spa 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. Lie'/jc, x. 1855, p. 260. PHYTOPIiAGA CHRVSOMELIDAE 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, and 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, alw;iy- makes use of two leaves, and of two opposed leaves. A know- ledge of the habits of some of the larger of the exotic Hispicles would be of much interest. FIG. 144. — Pupa of C ass id id beetle (? AspidomorjiJi" s p.). 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 they cannot be considered merely incidental. In several species this covering-matter is like lichen. This is the case with Dolichotoma jxil iinn-tnii, the larva of which has, in place of the usual fork, a more complex appendage on the hack 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 Aspidomorplia — 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 gkins 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. trtstts 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 arc 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, FIG. 1-45.— Nest of intes- and make an even surface ; but the outside finally-made filaments fij fc d fc j somewhat busllV under winch the larva ' of Poi-j>Jii/ri(yj>i.-i trintis 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 2><>fpJn/fitsj>is--P. palmarum- -lasts been recorded as PHYTOPHAGA CERAMBYCIDAE 285 forming similar nests on a species of Thrinax in St. Domingo. Candeze says l that when it lias 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 oblong, not much, curved in outline at the sides; surface very frequent! '// ren- dered dull by a very minute hairiness, which often forms a /»///*/•// ; antennae usually long, and their insertion much embraced by ///*' 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, w^hitish 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- O O bycidae and those of Buprestidae, and when the thorax of a Lougicorn larva is unusually broad, e.g. Asiynomus, this similarity is very pronounced. 1 Mem. Soc. LUge, xvi. 1861, p. 387. 1H! 286 COLEOPTERA CHAT. 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 popidnea 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-primer in Xorth America. The parent beetle lays an eiro' near the axilla of a leaf-stalk or small stem, and the oo 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 pa-bulum and as a shelter, within which the metamorphosis is completed. The species of the American genus Oncideres are called girdlers, 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 O O 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. Recent 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. TVaterhouse had for some years a Longicorn larva under observation, feeding in this way in the wood of a boot-tree ; ~ 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. 1S90, p. 689. - Xot a growing tree, but the instrument used for stretching boots. 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 J has noticed that species of the genus Odontocera resemble various Hymenoptera, one species being called 0. braconoides; he also observed that these Hymenoptera - like Longicorus, instead of withdrawing their underwings under the elytra as beetles generally dn. vibrate them rapidly like Hyn;en- "ptera. A large number of Loiigicnrn- ,-tridulate loudly by rubbing a ridge inside the pronotum on a highly specialised, striate >urf;i<-e 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- o o o */ velupcd, while in some species the margin of the elytra and b:;se of the femora are also well adapted for the purpose of sound- production, and in a few species of the genus there are al.-» 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 ; prothorax 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-fain. 2. CERAMBYCIDK-. 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 "ii the inner side. Sub-fam. 3. LAMIIDES. 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 Mn<'ruJ?n, Bonn, 184(5. The first in- cludes an extensive philosophical discussion ; the second is a valuable collection of observation-. v KHYNCHOPHORA 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 Rhynchophora, 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 Rhynchophora. Some authorities treat the Platypides as a distinct family. Some of the members of the group Tomicides also bore into the wood. Recent 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 wooded 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, ili/'cctly continuing the long axis of the body, often so thick as to form an elongate head ; antennae not elbou-ed. The Brenthidae form a family of about 800 species, remarkable for the excessive 1 Bull. U.S. Dcp. Agric. ent. New series, No. 7, 1897. 2 Penis, Ann. Sci. Nat. (2) xiv. 1840. p. 89, pi. iii. 296 COLEOPTERA length and sleuderness of some of its forms, and for the s extreme difference in the sexes that frequently exists. It well represented in the tropics only, and very little is known as to the natural history and development. These beetles are stated to lie 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- d;iceous, and enter the burrows of wood-boring Insects to search fiG. 150. — JSupsalis mmuta. Aorth America. A, Larva ; B. pupa ; c, for larvae as prey : they are female imago; D, head of male. (After veiy much modified ill 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 .#///> W/.s 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 ;in 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 BRENTHIDAE 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.'2 The males of some species tight ; they do not, however, wound their opponent, but merely frighten him away. In Eupscdis 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, Lasiorhynchus barlini/'iiis, 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 Rhynchophora 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. AVest- 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. '• 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 Brcntltus anchorage* — 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 Xew Caledonia. The former is believed to live in the stems of Euphorbia canariensis ; Canary islands, a Xew Zealand species has _ ITT 1 •*• 151. — A'jtiic,/ed ; head of the male scarcely prolonged, hut that of the female fur ming a definite rostrum.; maxillae and ligula entirely covered l>y the mention-. 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).--Jfa£e 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. •n-Hliunt 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 Fio. 152. — 1'i-iifi'rliiiinx /eciiiifei. 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 triungulin (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. 153. — Sexes of Strep- siptera. A, Male of Stylops dalii (after Cur- tis) ; B, female of Xenos rossii (after von Siebold). B A 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 on 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.) AVhen 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. ;oo STREPSIPTERA CHAP. male emerging very soon after the host has become an active winged Insect, while the female undergoes no further change of position, but 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 Xtylops 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 ATery different from ^////n/is 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- FIG. 154.— Young larva ever, that they vary much according to the of Stulops on a Lee's- -11 T 155._porti0n of early stages of 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 Xenos rossii. (After YOU Siebold.) A, Small male larva ; B, small female larva ; C, full-grown 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 Styloi>s shown in Fig. 154.) 1 Yon Siebold, Arch. Naturgcs. ix. 1843, pp. 137-161. Xassonoff's recent paper is in Russian, but so far as we can gather (cf. Zool. Centralbl. i. 1894, p. 766), it does not add greatly to the data furnished by von Siebold. 3O2 STREPSIPTERA CHAP. 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. Yon Siebold apparently entertained no doubt as to the part of the female that is extruded being the anterior extremity ; indeed lie called it a cephalothorax. 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, Andrenu, are concealed under ground ; and in the case of the wasps, Pulistes, 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 Ent. Meddcl. v. 1890. j>. 14S, and <>c. Dunske Selsk. 1896,, p. 67. -' i- Soc. cut. lluss. xiv. 1879, p. 14. STYLO PS 303 metamorphosis. They have been observed in several species of Homoptera ; and the writer has a large Pentatomicl bug of the genus Collided, which bears a female Strepslpteron apparently of large size. This bug 1 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 Nassonofif think parthenogenesis occurs in Strepsiptera, but there appear to be no facts FlG> i56.-Abdpmen of a wasp (Polistes heb- to warrant this supposition. Von Siebold rams) with a strep- speaks of the phenomena of Strepsipterous gg^ ^^ reproduction as paedogenesis, or pseudo- dorsal plates of the j • i -,-, wasp's abdomen being paedogenesis, but we must agree with removed. «, Project Meinert that they cannot be so classed. tion of Pai-t of the mi i f c • i- f parasite ; b, line in- Ihe males of Strepsiptera live for only a dicating the position very short time, and are very difficult of of the removen the body frequent!!/ lllore °r less like lair: nervures moderate in number, at the prripJiery of one winy not exceeding fifteen, but little irregular ; eross- nervules not more than four, there being usually only one or two closed cells on each wing, 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 bod// ; the larva with large or moderate head and strong mandibles. Pupa with the apt>i'inl,iges usu«U tj nd pressed and cemented to the body so that it presents « mnre 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. Nemognatlut. VI 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, FIG. 157. — Metamorphosis of a Lepidopteron (Rhegmatophila alpinct, Notodontidae). (After Poujade, Ann. Soc. cnt. 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, male moth in repose ; G, female moth iu 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 Lepidopteron may be a pupa. In other Orders of VOL. VI X 306 LEPIDOPTERA CHAP. Insects it would appear that the tendency of the higher forms is to shorten the pupal period, and when much time has to he 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 (Ephestia, Jcuehniella, 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 Lepidopteroii 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 pleswppus. (After Scudcler.) «, Base of antenna ; b, pronotum ; b", scutum of mesothorax ; c, clypeus ; ex, coxa ; d, scutellum ; d1, scutellum of metathorax ; e, post-scutellum ( = base of phragma) ; em, epimerou ; ep, episternum ; /, scutum of metathorax ; m, basal part of pro- boscis ( = maxilla); o, eye; p, labial palp; /•, mesosteruum ; s, prothoracic spiracle ; t, tegula ; tr, trocliauter ; 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, Castnici) 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.' 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 Bornbyces and Fsychidae ; 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 labruni is a very short, 1 Kellogg, Kansas Quarterly, ii. 1893, p. 51, plate II. 308 LEPIDOPTERA CHAP. 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 cajn. A, Seen from front : B, from front and below. «, Clypeus ; b, labrum ; c, epipharynx ; d, mandibular area ; d', prominence beneath mandibular area ; e, one side of haustellum or pro- boscis ; f, 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 Erioceplmla, a genus that was not dis- tinguished by him from Micropteryx and was therefore termed " niedere Micropterygiuen," 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. Zcitschr. 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. cnt. Soc. London, 1893, p. 263. vi MOUTH-PARTS 309 articulation — on each side of the labrum ; and even this pro- jection is usually absent. Meinert recognised these projections as mandibles in Smerinthus popttli, 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 Sphingidae. 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 Jfcpialus 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 Amcr. Natural, xxix. 1895, p. 637. It should be recollected that many Lepidoptera do not possess any proboscis. 310 LEPIDOPTERA CHAP. 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 oviposition 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. Zdtschr. Natunv. 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 Miiller'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 dorsum. 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-scuturn, and a 1 Amer. Natiiral. xiv. 1880, p. 313. - 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. Sd. 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. Zcitschr. Xaturw. xv. 1882, p. 151. 3 See Cholodkovsky, Zool. Anz. ix. p. 615 ; Haase, t.c. p. 711 ;. also Riley, P. cut. Soc. Washington, ii. 1892, p. 310. 3 I 2 LEPIDOPTERA CHAP. 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 inesothorax 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 inesothorax, 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 inesothorax 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 I 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 mesonotum 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, Noctuidae, etc, the true structure of the metanotum is further concealed by the back of the mesoscutelluni reposing on, and covering it. Difference of opinion exists as to the thoracic SPIRACLES ; there is one conspicuous enough in the membrane behind the pronotum, 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 describes l 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 Peytoureaiv 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. Set. Paris, cxviii. 1894, p. 360 ; and his Thesis, Bordeaux, 1895. 3 C.R. Ac. Set. Paris, cxviii. 1894, p. 542. LEPIDOPTERA CHAP. 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 come together when closed, and may lie 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, and that the scaphium is the tenth ventral Thus, according view, the ninth FIG. 160. — Acherontia (ifr<~is. The termination of ini'in'Inux ,5, after Staudinger and Schatz). A, front, B, hind wing. I. — c, costal ; sc, subcostal ; •//(, median ; In. Ifi, lr, 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 uervure ; 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, upper, 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 nervules ; 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 a, I), 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 B inner marginal, and on the wng + 2 or 3 inner marginal. hind In genus FIG. 162. — Wing - nervuration of Castnia. Undersides of, A, front, B, hind wings, la, lb, Ic, Irf, Inner marginal nervnres ; 2, lower branch of median ; 8, subcostal of hind wing ; 1'2, subcostal of front wing; e, "stalk" of 8 and 9 ; _/", frenuluni ; r, retinaculum ; s, shoulder ; ij, articulation of the aberrant moths of the Castnia the nervuration is unusually complex and irregular (Fig. 162), and an analogous condition occurs in our common Goat - moth (Cossus ligniperda). In Jfi-jiinliis and Micropteryx (the jugate moths of Comstock) the hind wings are less dissimilar in nervuration from the front wings than they are in other Lepidoptera.1 Internal Anatomy. ~ — The alimentary canal extends as a long, • 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, L'.Il. Ac. Paris, xxxiv. 1852, p. 718; Scudder, JJi/tf. Xi'/r England, i. 1SS9, p. 47 ; Minot and Bur^rss. Fourth Jtcj>. I'. S. Entmn. 1885, p. 53. 320 LEPIDOPTERA CHAP. 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 Mai- pi ghian 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 j>/r.ri/>i>its. (After Scudder. ) The portion to the left of the vertical line more magnified. I. II. Ill, thoracic segments ; 1-9, abdominal segments ; «, antenna ; «, anus ; ac, aortal chamber ; agl, etc., abdominal ganglia ; agl1, agl~, accessory glands ; an, aorta ; br. brain ; c, colon ; cp, copnlatory pouch ; ex1, ex-, cjc3, coxae ; _/>. food-reservoir ; g1, suboesophageal ganglion ; h, dorsal vessel ; i, intestine ; I in, area filled by wing muscles ; Lor, ovary, or egg-tubes of left side ; mi-, Malpighian tube (the two others of the right side cut away, except small por- tions) ; ni.c, maxilla ; u, oviduct ; uo, its orifice ; oe, oesophagus ; ov.c, end of left ovary ; />, labial palp ; j/h, pharynx ; r.ov, terminal jiarts of right ovarian tubes, turned to one side, after the tubes have been cut away ; &•. 238. worm-like creature — in old English 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 jjive rise to the les;s of the imago. The number o o o 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. LEPIDOPTERA CHAP. 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 4- d:j. z i FIG. 165. — A, Section of male caterpillar of Anosia plcxippus — muscular and traclieal 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 ; if-ff, ganglia of ventral chain ; h, head ; /, intestine ; iti.r, Malpighian tube ; n.c, nerve-cord of ventral chain ; ue, oesophagus ; «, spinneret ; s.o.g, infra-oesophageal ganglion ; nt, stomach ; s.i; 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 -j.) 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. 1 66, g} 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 Lyounet's famous work, Trait£ anatomique de la c/teitilh' qui range Ic lois de saule, La Have, 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 ^/. <-- / */ the first eight abdominal segments ; . FIG. 166. — Front view of head of there are no true stigmata on the a caterpillar, with the jaws second and third thoracic segments. Partially opened, a Labrum ; o, mandible ; c, antenna ; tf, though traces Of their rudiments Ol' ocelli ; e, maxilla ; /, lingua ; g, vestiges are sometimes visible. sphmeret ; 7'' 1:ihial pal1'- 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 — (Lymaiitriidae of modern authors) — the caterpillars are said to be of different colours in the two sexes. Most of what is known on this point has 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 yamamai and others, even this is exceeded. They 1 See Plateau, Bull. Ac. Belgique, xv. 1888, p. 28 ; in reference to structure of ocelli, Blanc, Tete du Bombyx mori . . . 1891, pp. 163, etc. ; and Landois in Zcitsehr. wiss. Zool. xvi. 1866, p. 27-. - Entvrickelungsgeschicfite der Schmetterlinge, Cassel, 1815. 3 Tr. Linn. Soc. London, Zool. 2nd Ser., v. 1890, pp. 147, 148. 326 LEPIDOPTERA CHAP. grow with remarkable rapidity, being in the young silk-worm only 3 mm. long, in the adult 22 mm. The increase in weight is still more remarkable ; when the silk-worm is thirty-one days old, the sericteria weigh only 3 mgr., but when the age is fifty days their weight has increased to 541 mgr., being then | of the whole weight of the body. In the pupa they undergo a gradual atrophy, and in the moth they are, according to Helm, no longer to be found, though earlier authors were of a contrary opinion.1 Ac- cording to Joseph," the silk-vessels begin to develop at an ex- tremely early age of the embryo, and are very different in their nature from the salivary glands, the former being derivatives of the external integument (ectoderm), while the salivary glands belong to the alimentary system. This view is to some extent con- firmed by the observations of Gilson as to the different manner in which these two sets of glands discharge their functions. The chief feature in the anatomy of the larva is the great size of the stomach. There is a very short oesophagus and crop ; the latter becomes enlarged, spreading out so as to form the stomach, a great sac occupying the larger part of the body-cavity (Fig. 165). On the hinder end of this sac the Malpighian tubes open ; they are similar in their disposition to those of the imago ; behind the stomach the canal expands into two successive, short dilatations, the first called an intestine, the second a rectum ; they are connected by very short isthmuses. The dorsal vessel is a simple, slender tube, extending from the eighth abdominal segment to the head. The main nervous system consists of supra- and infra -oesophageal ganglia, a small frontal ganglion, and a ventral chain of eleven ganglia, three thoracic and eight abdominal, the last of these latter being double. The sexual organs are quite rudimentary, and the passages connected with them very incompletely developed. Pupa. — The pupa, which is one of the most remarkable of the instars of an Insect's life, attains its highest development in Lepidoptera. The Lepidopterous pupa is frequently called a " chry- salis," a term originally ;ippli»'d t<> certain metallic butterfly pupae. The Lepidopterous pupa differs from that of other Insects in the fact that its outer skin forms a bard shell, all the appendages of 1 For information as to the structure and function of the silk-vessels, refer to Ifrhn, Zci/sc/tr. -wiss. Zuol. xxvi. 1876, p. 434 ; and Gilson, La Cellule, vi. 1800, p. 116. - Jahresbcr. Schlcsisch. Gcs. Iviii. 1881, p. 116. VI PUPA 327 the body being glued together by an exudation so as to form a single continuous outer skin. This form of perfect pupa is called " pupa obtecta." The obtected pupa is exhibited in various stages of perfection in the Lepidoptera ; the maximum of perfection is attained by the pupae of such butterflies as are exposed without protection or concealment ; on the other hand, we find in various small moths conditions of the pupa that do not differ in any marked manner from the pupae of Insects of other Orders. Moreover, certain Coleoptera and Diptera exhibit obtected pupae of a more or less perfect kind. Hence the pupa obtecta is to be considered as a perfected condition that exists more frequently in the Lepidoptera than in other Orders. The pupa has no orifices to the alimentary canal or sexual FIG. 167.— Section of female pupa of Anosia plexippus, 3-4 days old. I, pro-, II, meso-, III, meta-thorax ; 1-9, abdominal s e g- ments ; a, anten- na(?) ; ac, aortal chamber ; ay1 - . . , opening of the imagination; tr, acic segments might be looked trachea. B, posterior wing-rudiment for- rt^ ^{\[ j^g 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 ; i, pedi- twQ thoracic segments ill Lepi- cel ; tr, trachea. (After Goniu.) dopterous larvae). Gonm has examined the wing-rudiments in the caterpillar, a few days old, of 1 Latter, Tr. cut. Soc. London, 1895, p. 399. vi DEVELOPMENT - WINGS - NERVURES 329 Pier is 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 Fig. 169. This fact was known a a to the older entomologists, and gave sti 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 p" p.-" Goilill's Observations that it is not FIG. 169.— Anterior parts of a cater- by a process of evagination, but by Pillar of p- brassieae, the body- . ' wall having beeii dissected oft, destruction Ot the hypodermiS lying immediately before pupation. outside the wing. However this may a\ a'> Anterior and posterior wings ; st 7, first spiracle ; p, p , be, it is Well kllOWll 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. 1VO, 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. Vaudoise, xxx. 1894, No. 115. 330 LEPIDOPTERA CHAP. trachea, and also a " wing-rib " and blood-cells. He remarks that even in nervures, perfectly formed as to their chitinous parts, either wing-rib or trachea or both may be absent.1 Schaffer 2 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 B FIG. 170. — Structure of wing of imago. A, Transverse section of basal portion of wing [of Vanessa ?] containing a nervure : <; cuticle ; ft; wing-rib ; //, wall of nervure (" Grunilmembran ") ; //, hypodermis ; p, connecting columns : r, lumen of nervure ; B, section of a rib ; b, one of the chitinous pro- jections ; sir, central rod. (After Schafl'er.) Fiu. 171. — Scales of male Lepidoptera. A, Scale from upper surface of Eccres /• 179. — insertion of scales. true scales may be found on the wings of certain Lepidoptera that baar both hairs and scales, e.g. Ithomia. It has been calculated that there are a million and a half of scales on the wings of an individual of the genus Moiylio. 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 wring, 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 l 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 androconial 1 Amer. Natural., xxvii. 1893, p. 1018. 332 LEPIDOPTERA CHAP. structures is sometimes ornamental. As a rule, however, the •' brands " of male Lepidoptera detract from their beauty to our eyes. FIG. 173. — A, section of part of wing showing the complex androconia of Thanaos tages, 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 ; /, posterior covering scales ; g, lumen of the costal nervure : B, a portion of the costal area flattened out and seen from above ; lettering as before : C, section of audroconium 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 VI WING-DEVELOPMENT ao, 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 Corn- stock and JSTeedharn,1 that in some Insects the " peritracheal spaces " that mark out the position of the future nervures are destitute of tracheae. Gonin 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 Aincr. Natural., xxxii. 1898. p. 256. - Zeitschr. u-iss. Zool. viii. 1857, p. 326. 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 Gouin.) LEPIDOPTERA CHAP. 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 unites ; 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 IsTewbigin suggests that the organic pigments used in scale -coloration will be found to be of two "i;L B FIG. 175.— Early condition of scales and nervures. (After Semper.) A, Section of portion of \viug of pupa of N//////M: /li/n/xtr/ ; n, basal membrane with trachea beneath it ; c, scale-forming cell ; . 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 CHAP. and P. marcellus. It is uncertain how 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 marcellus ; 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. 1'oulton has shown * 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 Tnuts. cut. SOL: London, 1892, p. 293, etc. vt 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 knowrn, 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, wrho 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 ; 2 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. '• Trans. Linn, Soc. xxiii. 1862, p. 507. VOL. VI 338 LEPIDOPTERA CHAP. 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." 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." 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 Animal Coloration, London, 1892. An account of the subject with numerous illus- trations has been given by Haase, " Untersuchungen iiber die Mimicry," Bill. ZonJ. 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. Sue. 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 Stctt. cut. Zdt. li. 1891, p. 264 ; and Ivi. 1895, p. 234. 340 LEPIDOPTERA CHAP. 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, Pier is bras- siaif ; '_', >'///.!• infernalis ; 3, Hetstiu ill en (sub-family Dan- aicle.s) ; 4, Eudamus proteus, ami 5, Lii/HH-lini-i'x tinnnas (Hesperiidae). (Alter Bchatz and Sc mliler.) 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 Pvr;ilidac, 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 uuscu'iitilir. Series 1. Rhopalocera 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. 7/r/rrwrm or Cloths. — Antennae various in form, only rarely knobbed at the tip, and in such cases a frenulum present. In the large majority a riviiulimi is present, and the costal nervure of the hind-wing is either but little a relied at the base (as in Fig. KM. 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 Rhopalocera. vi BUTTERFLIES 34! It may be inferred from these definitions that the distinc- tion between the two snb-Orders is neither sharply defined nor of great importance. The club of the antenna of the Rhopalocera exhibits considerable variety in form (Fig. 17G).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, Fam. 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 empodiuui in connection with them. Fam. PIERIDAE. 1 For an account of the antenna of butterflies, see Jordan, J\~oi: Zool. v. 1898, pp. 37-1-415. 2 Haase first proposed the name Netrocera (Deutsclie cut. Zeit. Lcp. iv. 1891, p. 1) for Hesperiidae, as a division distinct from all other butterflies ; Karsch replaced the name in the following year by Grypoceva, because Netrocera is the name of a genus. 342 LEPIDOPTERA CHAP. 3. The front legs are like the other pairs ; their tibiae however possess pads ; the claws are large, not bifid, and there is no empodium ; the metanotum is completely exposed at the base of the abdomen. Fam. PAPILIONIDAE. 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. Fam. HESPERIIDAE. The relations between the families Erycinidae, 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 ' Eurales." It is however difficult to go so far and no farther : for the relations between both divisions of Eurales and the Nymphalidae are considerable. "NVe shall subsequently find that the genus Libytliea 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 Nyinphalo-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 Hesj>eriids, such as Tlianaos, be compared with one of the lower Papilionidae, such as Parnassius, very little approximation can be perceived. vi 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 Rhopalocera 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, \vhile 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 but one joint, '• The literature of butterflies has become extremely extensive. The following works contain information as to general questions : 1, Scudder's Butterflies of Neio England, a beautifully illustrated work completed in 1889, and replete with interesting discussions. 2, Staudinger, Schatz and Rober, Exotischc Tag/alter, in three folio volumes (Fiirth, 1884-1887), with illustrations of exotic butterflies and a detailed sketch of their characters. 3, Enzio Renter, "Tiber die Palpen der Rhopaloceren," in Acta Soc. Sci. Fenn. xxii. 1896, treating fully of classifica- tion and phylogeny. 344 LEriDOPTERA CHAP. though in the female there are usually five hut without any claws. Pupa xiixjii'iided l>y the tail so as to hang down freely. AVe include in this family several sub -families treated by some taxonomists as families ; in this respect we follow Bates, whose arrangement l 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 Apatura in New Forest. A, Lateral, B, M ^ j j dorsal aspect ; C, enlarged view of cremaster ° with the suspensory hook ; D, one hook still Various parts of the body, more enlarged. -r, IT j -i ,-1 It is believed that the I term chrysalid was first suggested by these golden pupae. 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 (Pig. 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-margin 1 Journal of Entomology, i. 1862, p. 218 : for early instars of South American Nymphalidae sue JM tiller, Zoo 1. Jahrl. Syst. i. 1886, p. 117. vi RHOPALOCERA DANAIDES 345 (submedian) nervure, with a short fork at the base. Cell of hind i/'iug dosed. Front foot of the female ending in a corrugate knob. Caterpillars smooth, provided with a feio long fie shy 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, Or. (unfortunately also called Anosia menippe, Hb., and Danais archippus or even I). 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, Asdepias. 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 Danaides 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. 2 P. Zoul. Soc. London, 1883, p. 205. 3 Finn, J. Asiat. Soc. Bengal, Ixvi. 1896, p. 528 ; Ixvii. 1897, p. 213. 346 LEPIDOPTERA CHAP. Sub-Fam. 2. Ithomiides. — Differs from. Danaides ly the female front foot having a true, though somewhat abbreviate fi'/'sus. The caterpiUcrs 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 Itunci and Lycorea do not belong here but to Danaides. Godman and Salvin treat it as a group of the Danaid 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 Hy in i a if is are remarkable for the small area of their wings, which bear remarkably few scales, these ornaments being in many cases FIG. 1/S. — Itfiomia pusio. Brazil. 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 subcostal 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 Dismorpliia (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 Dism»r/>// ia coloured like thrmst-hrs. They arc 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 — 1THOMIIDES SATYRIDES 347 they are very wary when the wasp is near, and rise off their 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 pressed tor/ether, 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 bijid. Pupa generally suspended by the cretnastcr, 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 Erelria of the highlands and mountains belonging to it. Most of these Insects have but feeble powers of flight, 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 twTo 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, Hipparchia semelc, 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 a perpendicular position, head upwards, amongst the grass. 1 Trans. Linn. Soc. xxiii, 1862, p. 495. 348 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 Haetcm, 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 ;is a sub-family, or even as a family, Elymniidae, 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 50 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 ?r/////, the discocellular ncrrulc Icing absent (Fig. 1 6 1, II. B). Caterpillars smooth or spiny, with the extremity of the u<>