20 -THE ORDERS OF INSECTS. 



black on the back, and measuring about half an inch in length. 

 Its gregarious larvae soon strip the gooseberry and currant bushes 

 of their leaves, when they once get a footing in a garden. 



The Gall Flies (Cyntpidce) are very small four-winged flies, 

 which deposit their eggs in a somewhat similar manner under 

 the cuticle of plants, and more especially on the oak. The 

 puncture gives rise to an excrescence in which the larva lives 

 and grows. These larvae, however, are greatly infested with 

 parasites, and you may sometimes rear several different species 

 of small parasitic Hymenoptera from a gall, without the real 

 owner being one of the party. 



The Ichneumonida are a very large group of parasitic insects. 

 Many of them puncture the bodies of caterpillars, and deposit 

 an egg in each wound. The ichneumon larvae, when hatched, 

 devour the caterpillar alive, until it is full grown, or assumes 

 the pupa state, when the larvae quit the body of their victim, 



\ 



Ichneumon Fly (Plmpla Turlonellce), Magnified. 



frequently forming their cocoons around it. The Ichneumon 

 Flies are often gaily coloured, with black and yellow mark- 

 ings. They are slender, elegantly formed insects, with long 

 antennae, and often a long ovipositor, which is sometimes formed 

 of two or three filaments. There are several groups of Hymen- 

 optera besides the Ichneumons proper which are parasites. 

 Among these are the smallest of all, the Proctotrupidtz^ or egg- 

 parasites, to which we have already alluded. 



