The first of these three groups, INSECTIVORA*, or the FOSSORES Latr., comprises the different families of sand and wood wasps, and corresponds for the most part with the Linnæan genera Sphex and Mutilla, distinguished by having the wings generally developed in both sexes (some of the Mutillidæ excepted), without the existence of individuals of the neuter sex, and which consequently are solitary in their habits. The legs are formed for walking and burrowing only, and are not fitted for collecting pollen, the basal joint of the posterior tarsi not being enlarged; the wings are never folded, the tongue is never thread-like nor lance-shaped, and the body is not clothed with hairs fitted for the transport of pollen.

In general the females excavate cells in the ground, or in posts, &c., in which they deposit, together with their eggs, various larvæ or perfect insects, and sometimes spiders (according to the species), which are destined for the support of their progeny when hatched. Occasionally the insects composing this store are first stung to death, and then buried: but sometimes they are only slightly stung, so that they continue half-alive, to be killed by the larvæ when hatched. These larvæ are white worm-like grubs, destitute of legs, which would be an incumbrance to them in their narrow cells. When full grown

* BIBLIOGR. REFER. TO THE INSECTIVORA OR FOSSORES.

Van der Linden. Obser. sur les Hym. d'Europe de la Fam. Fouisseurs, in Mém. Acad. Sc. et Belles Lettres, Bruxelles 1827, pt. 1., 1829, pt. 2.; and ditto, separately, 1829. 4to.

Shuckard, in Trans. Ent. Soc. vol. i. A few Observ. on Habits of Indigenous Aculeate Hymenoptera. Ditto, vol. ii. p. 68. (Description of n. sp.)- Ditto,

An Essay on the Indigenous Fossorial Hymenoptera, London, 1837. 8vo. Dahlbom. Exercitationes Hymenopterologica.

Rossi, Christius, Jurine, Perty, Spinola, Panzer, Savigny (Egypt), Saint Fargeau (Enc. Méth.).

"habitudes morales" of these tribes, as of primary importance in effecting their distribution (proved by the identical method of forming their cells). Some of the latter (Odyneri) are so closely allied to the sand wasps, that they might with even greater propriety be termed folded-winged Insectivorous Prædones than solitary Diploptera. The economy of the social ants, on the other hand, notwithstanding their sociality, is so different from that of the social wasps, that it may, perhaps, be ultimately questioned, whether it would not be more natural to adopt a classification, founded upon the affinity of the sand wasps and solitary wasps; placing the Scoliida and Mutillidæ at the head of the former, rather than break this affinity by placing the ants between them.

they spin a cocoon, in which they pass the pupa state. The perfect insects are generally very active, and fond of the nectar of flowers, especially those of the Umbelliferæ. They delight in the hottest sunshine, flying and running over sand banks exposed to the mid-day sun, and keeping their wings in continual agitation; their sting is exceedingly powerful, and in the large exotic species a wound from it must be attended with dangerous results.

We are indebted to Saint Fargeau for the notice of an interesting peculiarity in the structure of these insects, indicative, to a certain extent, of their economy, which he has described in the Encyclopédie Méthodique (tom. x.), in a memoir upon the genus Macromeris, in Guérin's Mag. de Zoologie, and in others upon Gorytes and Crabro, in the Annales de la Soc. Ent. de France. Having observed that the species which form their own nests are distinguished by having the anterior legs, and especially the tarsi, furnished with strong spines, and the posterior tibiæ denticulated or spined, he correctly considered the former of these characters as serving for burrowing, and the latter for carrying the prey; and he was thence induced to regard those species which have no spines or ciliæ on the anterior and posterior legs, as incapable of burrowing and provisioning a nest, and consequently as parasites, depositing their eggs in the nests already provisioned by other burrowing Hymenoptera.* It does not, however, appear to have been yet observed at what particular period (with reference to the real inhabitant of the cell) the parasite is hatched; nor whether it merely contents itself with feeding, cuckoo-like, upon the food destined for the supply of its fosterer, which is thus starved to death; or whether, on the contrary, it devours the latter, although, perhaps, it is most natural to suppose that it would do both. An entomologist of our country, who has studied the fossorial Hymenoptera in the true spirit of scientific inquiry - W. E. Shuckard

* St. Fargeau (Hist. Nat. Hym. p. 6.) draws a very proper distinction between those parasites which, like the cuckoo, realise the true sense of the word parasite, and those which prey upon or in the bodies of other insects, as the Ichneumonidæ, &c. which are often also called parasites. St. Fargeau proposes to call them "Carnassiers." This term does not, however, sufficiently indicate them as living within the intestines of the victim, upon which they are exercising their cannibal propensities. Latreille had indicated this diversity by calling a tribe of parasite bees Cucullina; but, as St. Fargeau observes, the term parasite is the proper name for such species, sanctioned by well-known and immemorial use. The Ichneumonidæ have been called "Cuckoo-flies" by some English writers, (and in p. 82. I have adopted this expression), but it is not sufficiently precise.

has disproved a portion of St. Fargeau's theory, by observing, that although the sand burrowers have spined legs, others which are destitute of spines burrow in wood.* (Trans. Ent. Soc. vol. i.) The reason for this appears to me obvious: the sand burrowers have need of powerful brushes to enable them to make their way through the fine loose particles of sand, whilst the wood burrowers must have recourse to their strong, broad, and multidentate mandibles.† Mr. Shuckard has further objected to the supposed use of the spines of the hind legs for carrying the prey, regarding them as applicable to the formation of the cells, or for the closing of its mouth; in support of which latter opinion he has given an instance in which he had captured one of these insects with the hind tibiæ thickly coated with clay. It is to be observed, however, that in those Aculeate Hymenoptera whose proceedings have been observed, the materials for closing the cells are carried by the jaws. I have also published a memoir still further limiting the theory of Messrs. St. Fargeau and Shuckard (in the Annales Soc. Ent. de France for 1836), having observed the rare British species Miscophus bicolor at Coombe Wood, and a species of Pompilus on the Drachenfels, both of which are destitute of spines on the fore legs, in the act of burrowing in the sand; and having further noticed a female of Pompilus petiolatus, which has simple fore legs, engaged in carrying her prey by the help of her jaws and fore legs, and not by the help of the hind legs. Cerceris læta, on the other hand (whose proceedings I have described in the Trans. Ent. Soc. vol. i. p. 203.), although furnished with strong posterior tibial denticulations, carries its prey with its four fore-legs, the hind legs alone being extended.

* St Fargeau himself appears indeed to have been aware of the limitation necessary to be thus imposed on his theory, for in his memoir on Crabro he speaks of the presence or absence of spines on the anterior tarsi, indicating that these insects “travaillent dans la terre ou dans la bois." (Ann. Soc. France, 1834, p. 692.)

†The variation in the form of the mandibles is not, however, conclusive as to the differences in economy; for in several of the Crabronidæ, which are distinctly woodborers, the mandibles, as observed by Mr. Shuckard, "are merely bidentate at their apex. May not this disparity arise from the different nature of the wood they are instinctively led to form their nests in? for I have always found that the insects with this shaped mandible make their cells in subputrescent and soft woods, chiefly decaying willows." (Essay Foss. Hym. p. 12.)

The theory of St. Fargeau ought moreover to apply to the solitary wasps, Odyneri, &c., which are truly fossorial, as well as to the Fossores; and yet the females of Odynerus have simple tarsi, but are not parasites, provisioning their own nests. (See my notice of the habits of Odynerus Antilope, Trans. Ent. Soc. vol. i. p. 78.)

With a view to illustrate this subject more completely than has hitherto been done, I have given in fig. 80. a series of illustrations of the structure of the anterior and posterior legs of various species, whose economy has been discovered, and which it will be seen vary very considerably inter se, so as to have led Saint Fargeau to adopt the theory above noticed. I have also added figures of the mandibles of the different species in question, although the precise share which these organs take in the economy of the several insects has not been clearly noticed: the figures marked t 1 represent the anterior tibia and tarsus, t 3 the posterior tibia, and m the mandible Fig. 80. 1. represents these details in Crabro cephalotes, a wood-boring species; and in which the anterior tarsi are but very slightly armed with short thin spines: the hind tibiæ are very strong and rough, with short thick spines. Fig. 80. 2. represents the same parts in Pemphredon unicolor, also a wood boring species, having the anterior tarsi very slightly spined, but furnished on one side with long curved hairs; the hind tibiæ have only four minute spines on the margin. Fig. 80. 3. are from Gorytes mystaceus; the fore legs being still less spined, and the hind tibiæ quite simple. This species I have selected, as being that which led Saint Fargeau to establish his theory, considering it a parasite. It is, however, as Mr. Shuckard and myself have discovered, a predatory species; and that gentleman states that he has seen it enter a sand bank with its prey. Mellinus arvensis (fig. 80. 4.) has stronger and longer spines to the fore tarsi, and the hind tibia has a marginal row of short spines. This is common in sandy districts, its prey consisting of Diptera; but it has not been observed to burrow, unless indeed Réaumur's figure, subsequently noticed, be intended for it. Fig. 80. 5. represents a more decidedly fossorial

species, Gorytes 4-fasciatus Fab., at least judging from the armature of the legs; but its economy has not been observed. Fig. 80. 6. exhibit the legs of Miscophus bicolor, observed by me to burrow in sand; the fore legs are, however, very sparingly armed with short simple spines, and the hind tibiæ nearly simple; and fig. 80. 7. are details of Cerceris arenaria, a true sand burrower; having the fore legs very strongly ciliated, and the hind tibiæ armed with many short strong spines. Other figures, illustrating the fossorial structure of the legs, will be found under the family Sphegida; in which also will be found the details of Ceropales maculata, a species having perfectly simple legs, and regarded as a parasite.

Although there is much general similarity in the habits of the truly fossorial species, there is considerrble diversity in the details of their proceedings: thus, whilst Oxybelus conveys its prey by means of its hind legs, Pompilus and Ammophila walk backwards, dragging it with their mandibles. "Astata, Tachytes, Psen, Crabro, Mellinus, and Cerceris, fly bodily and directly forward with it in their mandibles, assisted by their fore-legs." (Shuckard, l. c.) From my own observations, each species appears ordinarily to confine itself to its own particular prey. Instances are on record, however, in which considerable diversity in the prey of the same species has been observed: this probably arose from the female not being able to discover her legitimate prey; thus Serville and Saint Fargeau state that Bembex rostrata indifferently collects the species of Eristalis, Stratiomys, and the larger Muscidæ ; but it may be regarded as the ordinary rule, that each species confines itself to its peculiar prey: thus, numbers of the same species of fly or larva are found in the same cell, although this must sometimes be a matter of difficulty; as, in the case recorded by Réaumur (tom. vi. p. 272.), where numbers of individuals of a species of Anthrax, "plus rares qu'aucune des [mouches] précédentes," were found" dans d'autres trous;" and in other cases mentioned to me by the Senator Van Heyden, of Frankfort, and M. Audouin, in which numbers of the very rare Ogcodes gibbosus had been thus stored up by one of these insects for its young.* The prey is, moreover, very various, comprising insects of nearly every order; the Coleoptera†, * Réaumur also figures (tom. vi. pl. 27.) cells separately filled with numbers of specimens of a Chironomus? Tetanocera? and Thereva?

+ Mr. Shuckard states that he knows only one instance in which a Coleopterous insect is subject to the attacks of these Fossores; namely, Strophosomus, one of the Curculionidæ, preyed upon by Cerceris arenaria. Lixus Ascanii, and several other Curculionidæ, are preyed upon by several other species of Cerceris. (See infrà.)