TREES AND SHRUBS 



easily mistaken for any other species. Its body, head, and thorax are leaf- 

 green : its eyes golden-green, large and conspicuous; and its wings wide, 

 thin, gauzy, and glossed with changing hues of green and pink. It flies 

 chiefly at night, and in the daytime may be seen at rest, with the wings 

 pressed against the sides of the body. It possesses an evil odour, which 

 attaches itself strongly to the finger that crushes it. The larva is extremely 

 predacious, feeding voraciously on the aphides, covering itself with the emptied 

 bodies of its victims as a protection. It pupates in a cocoon of extremely 

 tough silk. The eggs are deposited on leaves, each being fixed to the end 

 of a slender stalk about I in. long. They are pure white, and bear a re- 

 semblance to the capsules of certain mosses. 



The Ichneumon Flies, of which there are probably over 2000 species in 

 England, are of inestimable benefit to man, their chief function in the 

 economy of nature being the maintenance of a balance amongst the various 

 insect tribes. They are parasitic insects, belonging to the Order Hymenoptera, 

 being provided with four wings, and the female being furnished with a sharp 

 ovipositor. Many of them puncture the bodies of caterpillars, depositing an 

 egg in each wound. The larvas, when hatched, devour the caterpillar alive, 

 feeding on the soft but less vital parts of the host, and when full-grown 

 quit the body of their victim, frequently forming their cocoons around it. 

 Almost every species of caterpillar, grub, aphis, or other form of insect 

 life, has one or more parasites which keep it in check. One of the species 

 most frequently seen at work is Microgaster glomeratus, which lays from 

 thirty to sixty eggs in a single caterpillar of the Large Cabbage White 

 Butterfly. When about to pupate, the larvas gnaw their Avay out, and 

 each spins a yellow silken cocoon, generally beside the empty skin of the 

 caterpillar or upon its surface. 



The Chalcidkke are a family of Ichneumons, for the most part exceed- 

 ingly small, and many being parasitic upon other parasites. Some deposit 

 their eggs in various galls, where they feed upon the rightful inhabitants. 

 Others work havoc among the aphides. 



The Proctotrupida?, a family of minute Ichneumons, comprise some of 



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