OF HARTING. 375 



of insects, particularly the caterpillars of butterflies 

 and moths, not by openly preying upon them after 

 the manner of carnivorous beetles, dragon-flies and 

 others, but by an indirect mode of proceeding for 

 which their instincts and the structure of their ovi- 

 positors pre-eminently qualify them. The venerable 

 myth handed down to us by naturalists of other days, 

 as a phenomenon in the history of the Egyptian Ich- 

 neumon (Viverra), is scarcely more incredible than the 

 thousands of well ascertained facts in the economy of 

 these flies. Instead of entering the mouths of their 

 victims while the latter are sleeping, they attach one 

 or more eggs to the body of each, sometimes on the 

 skin, sometimes under it, and leave the work of actual 

 destruction to their larvae, which feed on the internal 

 substance of the insects in which, or on which they 

 are hatched. Eggs, larvae, pupae and perfect insects 

 are all more or less subject to the attacks of these 

 parasites, and among the species that oviposit in the 

 former, there are some so very minute that, according 

 to an eminent entomologist who has made this tribe 

 his special study, one butterfly's egg contains sufficient 

 provision for several individuals during the whole 

 period of their existence as larvae. Examples of 

 almost every intermediate size between this micro- 

 scopic form and Rhyssa persuasoria, an insect four 

 inches in length, may be found in these families. 

 Their ovipositors also vary considerably in length in 

 the different species, in those which commit their eggs 

 to naked external feeding larvae, they are very short 

 and scarcely visible beyond the last abdominal seg- 

 ment, while in others which are appropriated to larvae 

 that are concealed in galls, in wood, in artificial cases, 

 or under the bark of trees, the ovipositors are much 

 longer. By what extraordinary faculty the latter are 

 enabled to discover their prey is one of nature's im- 

 penetrable secrets, but that it is by the agency of 

 their antennae, which in the true ichneumons are in 



