THE ICHNEUMON FLIES 



( Super-family Ichneumonoidea.) 



Until quite recently this great group comprising what are 

 popularly known as the Ichneumon flies* was considered by 

 entomologists to form but a single family — the ichneumonidae, 

 but Ashmead has justly decided that the group is of super-family 

 rank, and in a recent paper has carefully worked out the genera 

 of the world, recognizing no less than 1,140 distinct genera, very 

 many of which inhabit the United States. The species of the 

 Ichneumonoidea are without exception parasitic upon other in- 

 sects, and for the most part upon insects which are injurious to 

 vegetation. Caterpillars are especially subject to the attacks 

 of the Ichneumon flies. In his paper upon the Hymenopterous 

 parasites of North American butterflies, published as a chapter in 

 Mr. Scudder's great work "The Butterflies of the Eastern United 

 States and Canada," the writer has described a large number of 

 Ichneumon flies which lay their eggs in butterfly larvas, and 

 which issue as adults either from the caterpillars or from the 

 chrysalids. One of the most frequent disappointments met with 

 by collectors of butterflies in trying to rear to the adult condition 

 the larva of some interesting or rare species is the ultimate 

 realization of the fact that some Ichneumon fly has laid her eggs 

 in the rare specimen before it was captured. Not only do larvae 

 of butterflies and moths suffer from the attacks of members of 

 this group, but also beetle and fly larvae and more rarely the 

 larvae of other orders. They are on the whole distinctly bene- 

 ficial insects, and as will be shown in the detailed life history 

 which follows, they may be responsible for the absolute saving 

 of great damage to the shade trees of our cities as well as to agri- 

 cultural crops by their widespread destruction of injurious insects. 



* Both the scientific and the popular names of this group were derived from 

 the name of the so-called Egyptian Ichneumon or Pharaoh's rat, which devours 

 the eggs and young of the crocodile and was held sacred by the ancient Egyptians. 

 The applicability of this title to the group under consideration is due to the 

 parasitic habits of the Ichneumon flies. 



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