XXIV INTRODUCTION. 



generally also of the Ophioninae. The majority of the Tryphoninae are 

 parasitic upon saw-fly larvae, though the Schizodontes have a predilec- 

 tion for Diptera ; the Prosopi for Micro-lepidoptera, and Orthocentrus for 

 small Coleoptera. Pimplinae prey largely upon xylophagous and other 

 Coleoptera, Aculeate Hymenoptera and, in a few cases, Arachnidae. 

 Many of the Cryptinae are hyper-parasitic, through Braconidae and other 

 Ichneumonidae, including their own sub-family, upon Lepidoptera, but 

 they appear extremely omnivorous, and also attack certain Tenthredinidae, 

 Cynipidae, Coleoptera, Diptera, Neuroptera and s[)iders. Hyper-parasitism 

 is largely practised in this family. The parent insect lays her egg in 

 the body of a parasitic larva already ensconced within a lepidopterous 

 caterpillar, this, hatching, assimilates to itself the juices drawn by the 

 parasite from its host, which, eventually, is destroyed by the parasite, 

 just as the latter is demolished by the hyper-parasite, which alone 

 attains perfection through the dead bodies of both. 



The Ichneumoninae leave but a single egg with each victim ; if two be 

 deposited, one of the ensuing larvae will invariably destroy the other, since 

 the juices of the host are incapable of sustaining both, and were both to 

 live the host would perish before either had attained maturity. It has 

 been ascertained by anatomy that each female possesses from eight to 

 sixteen egg-sacs, each of which is capable of producing at least six eggs. 

 The terebra is conformed, from the very short ones of the Ichneumoninae, 

 which Berthoumieu tells us oviposit tipon the skin, to the tremendous 

 weapons of some of the Pimplinae, which bore with them through at least 

 an inch of solid wood,^ entirely in accordance with the kind of host upon 

 which the insect preys. The position assumed while in the act of egg- 

 laying very considerably varies in different, but is usually identical in the 

 same, species. 



The number of hosts often enumerated in the following pages, under 

 a single parasite, will entirely disprove the ancient theory that each 

 species was confined to one in particular. The only restriction would 

 appear to be the very natural one that the host must be of suitable size to 

 sustain the parasite till the latter be full-fed. Much has been written upon 

 the wonderful instinct of the female in choosing a suitable pabulum for her 

 eggs, and, indeed, there do appear to be a few species which are restricted 

 to a single kind of host, but their number is ever decreasing as more and 

 more species are bred from a larger diversity of victims. A small, and 

 very common Cryptid, Hemiteles areator, has been bred from as many as 

 eighteen different kinds of Lepidoptera (Bombyces, Tortrices and Tineae), 

 ten kinds of Hymenoptera (Tenthredinidae, Ichneumonidae, Braconidae 

 and Cynipidae), several kinds of Coleoptera, one of Diptera and one of 

 Neuroptera. 



The extent of the perfect existence is extremely variable. Many kinds 

 of Ichneumoninae and Cryptinae hibernate in this state, which then lasts 

 from the end of August to, probably, the following May ; others so quickly 

 effect the cycles that as many as two, or even three, generations are com- 



1 E.g., Rhyssa persitasoria. Cj. Proc. Ent. Soc. Meeting, ist April, 1S67 ; lib. cit.. Meeting, 3rd Oct., 

 1900; Bignell, Trans. Devon Assoc, 1898, p. 470; cS:c. I am, however, of opinion tliat this measure is 

 not resorted to when the xylopliagous larva of Sirex, in or upon which the egg is laid, may be reached 

 by intruding the ovipositor along the already excavated galleries. Miss Chawner says (n; lit, 4th 

 January, 1901) that the species is very common in her garden, and she has watched it poking its long 

 ovipositor into the borings of the larvae; Mr. P. C. Adams writes (in lit., 7th December, 1900) also 

 from Lyndhurst, that he has seen the female inserting her terebra as far as possible into holes, in fir 

 posts, but that he does not think it can itself pierce the wood unless it be in a very rotten condition. 



