THE ICHNEUMONS, 243 



within the skin of their victim. The egg, in fact, 

 which is supported upon a slender curved footstalk, 

 is attached by this to the surface of the caterpillar 

 destined to become the prey of the included larva ; 

 and this, when hatched, still retains the hinder extre- 

 mity of its body in the egg-shell, whilst with the 

 opposite end it pierces the integuments of its victim, 

 and thus feeds upon his juices. 



In the perfect state these insects are for the most 

 part active, flying lightly about in the neighbourhood 

 of the plants on which they expect to meet with the 

 insects on which their larvae are parasitic, frequently 

 settling on the leaves or twigs, running about and 

 vibrating their antennae. The species which are para- 

 sitic upon wood -boring insects are also to be met 

 with about the stumps of trees and old palings ; they 

 are generally furnished with a very long ovipositor, 

 and they appear to detect the presence of their victim 

 by the agency of their antennas. Their food in this 

 condition, however, is very different from that of 

 their larvae, and consists almost exclusively of the 

 sweet juices which they find in flowers, on which they 

 may frequently be met with. From a statement pub- 

 lished in 1833 by Mr. E. W. Lewis in the Magazine 

 of Natural History (vol. vi.), it would appear, how- 

 ever, that sometimes the perfect insects may prove 

 equally, if not more destructive, than their larvae to 

 the caterpillars. Mr. Lewis calls his paper an ac- 

 count of the " Transactions of a fly with a long tail/' 

 which Mr. Westwood considers to be the Pimpla 

 stercorator. He describes it as frequenting the lilac- 

 bushes in search of the caterpillar of a small moth, 

 which rolls up the leaves of those shrubs to form a 

 shelter for itself from the inclemency of the weather 



M2 



