[ 61 ] VIII. The Anatomy and Development of certain Chalcididse and Ichneumonidse, compared with their special (Economy and Instincts ; with Descriptions of a new Genus and Species of Dee-Parasites. Dy Geokgb Newport, Esq., F.B.S., F.D.S. fyc. Read March 20, 1849. Preliminary observations. A. HE parasitic Hymenoptera include, in their larva state, some of the most imperfectly organized conditions of life to he found in the whole of the Articulata. They leave the ovum delicate, apodal, almost motionless, and entirely incapable of locomotion, and are injured and perish by slight accident, as an abrasion of surface allows the fluids of their bodies to escape quickly and fatally by the wound; and yet these very beings, having passed unhurt through this scarcely other than foetal condition, acquire a perfection of organization, a degree of activity and power, and an acuteness of instinct, fully equal, and perhaps superior to the organic and the functional endowments of other tribes of insects. One section of them, — some of which I shall make the subjects of this paper, — are nourished entirely by suction, and subsist on the fluids of other insects ; and either attached singly to the external surface of the bodies of their victims, or, located internally, between the tissues, they drink up the life-blood prepared for another, without entirely destroying the means of its production. Other species are gregarious and reside in the same cell with their victim ; and while that subsists on vegetable food, — pollen mixed with honey and stored up for it by its parent, — it is attacked on all sides by its insidious enemies, succumbs, and dies as they become nourished. Yet the general form of body, and of the digestive organs, at the earlier periods of growth, is almost precisely the same in most of these de-scriptions of parasite, and the special development of each is regulated by the same laws. They cast their skin at succeeding stages of growth as certainly as do the larvae of Depi-doptera ; but the thrown-off covering is of such extreme tenuity, and is so gradually and almost imperceptibly removed, without interfering with the form or the enlargement of the body, that, hitherto, the deciduation of the tegument of the apodal larvae of Bymeno-ptera has always escaped the observation of naturalists. I have, however, witnessed its repeated occurrence in the genus Paniscus, as I shall show in this paper ; so that these species do not constitute, as was supposed, an exception in this respect to one general law. Much as they resemble each other in external appearance, they do so still more in the structure of their organs of nutrition. The digestive apparatus in the whole of them is at first but a simple, capacious sac or bag, rounded and closed at its larger extremity, with an imperforated intestine proceeding from it, without an anal outlet. It has this form in most of these insects during the earlier periods of the larva state, when the organizing
The Anatomy and Development of certain Chalcididæ and Ichneumonidæ, compared with their special Œconomy and Instincts; with Descriptions of a new Genus and Species of Bee-Parasites
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