100 CHRYSANTHEMUMS. 
narrow at the head, and gradually widening at the tail. As 
soon as they are fully fed they attach themselves to a leaf, 
Active wasp-like flies which hover over plants and deposit their egg^s amid colomes 
of greenflies. Their larvae when hatched devour the greenflies voraciously. Fig. 1, 
Scaevajbalteata ; 2, its larva or grub ; 3, its pupa or chrys^s ; 4. Scaeva Pyrastri ; 5, 
its larva or grub ; 6. its pupa or chrysalis ; 7. Scaeva Ribesii. 
enter into the pupal stage, and finally emerge as perfect flies 
in a very few days. 
Ichneumon Fly (Pimpla instigator). — There are several 
kinds of Ichneumon flies, but all are alike in their general 
Friendly Ichneumon Flies. 
The flies alight on the bodies of caterpillars, pierce them and lay eggs therein. The 
grubs in due course feed on the caterpillars and destroy them. A, insect flying; B, 
insect at rest. 
habits. They vary in size from an inch long to that of a midge. 
All have more or less slender bodies furnished with an 
ovipositor similar to the sting in the wasp. These insects 
alight on the bodies of caterpillars, pierce them with their 
ovipositor, and then deposit an egg, which, in due course, 
