576 



INSECTA ORDER HYMENOPTERA. 



Fig. 55. GALL-FLY 



(Cynips kollari, Hart.). 



Slightly magnified. 



few nervures visible on the fore-wings forming one large cell near the centre. 



The abdomen is short, slightly compressed, and much elevated. A common 



British species is figured. It is hardly necessary to remind 



Gall-Flies our readers that the principal ingredient in ink is obtained 



(GallicolcK). from the galls of a Levantine species of Cynips. Some of our 



own galls are not unlike a cherry, or 

 other fruit ; and there are foreign galls which are much 

 larger and more tempting in appearance ; some of these 

 are called " Apples of Sodom." 



Many of the gall-flies appear at different seasons of 

 the year in two different forms, one in which the sexes 

 are separate, while the other consists exclusively of 

 females, or rather of individuals capable of self-repro- 

 duction. Sometimes one form is winged, and the 

 other apterous and subterranean. It is needless to 

 say that until their habits were discovered, the two 

 broods were regarded as belonging not only to different 

 species, but to distinct genera. Another noteworthy circumstance relative 

 to galls is their extreme liability to attacks of parasites. You may collect a 

 very large quantity of some kinds of galls, and breed hun- 

 Gall- Parasites, dreds of specimens of different species of insects from them, 

 and yet never obtain a specimen of the original gall-maker ; all 

 will be parasites, and not a few will be a small parasitic species of Cynipidce. 



The Entomophaga, or truly parasitic groups of Hymenoptera, include the 

 families Chalcididce, Proctotrypidce, Braconidce, Ichneumonidce and Evaniidce. 

 The female usually pierces the body of the caterpillars, or 

 Parasitic other victims which she attacks, with her ovipositor, and 

 HymeAoptera lodges an egg in each wound. In other cases, the eggs are 

 (Entomophaga). deposited on the eggs or larvae of their victims. Eggs thus 

 attacked never hatch ; but ichneumoned larvae generally 

 attain their full growth, and then die, when the larvae of the parasite, which 

 have been feeding on it all the time, often emerge from it, and form 

 their own cocoons round the dead body of the caterpillar. In other cases, 

 the larva assumes the pupa-state, and the parasites pupate within it, emerg- 

 ing from the pupa-skin instead of the butterfly. 



The Chalcididce are a very extensive family, divided into many sub-families. 

 The antennae are generally 13-jointed, consisting of a long basal joint and a 



series of short ones. The females 

 Family are generally provided with a long 



Chcdcididce. or short ovipositor, which, in the 

 genus Leucospis (Fabr.), is curved 

 over the back. These are among the largest 

 species of the family, and though not British, 

 several species are found in Southern Europe. 

 They are black, with yellow markings, and re- 

 semble small wasps, but may at once be distin- 

 guished from them by the very rudimentary and 

 incomplete neuration of the wings. Leucospis and 

 several other genera among the larger Chalcididce 

 have very thick hind femora, toothed on the under-surface. 



The genus Callimome (Spin.), to which many species which are parasitic in 

 galls, belong, are considerably smaller, rarely measuring more than about 



Fig. 56. Leucospis 

 grandis. Nat. size. 



