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Ichneumon Flies — Part 1

(Super-family Ichneumonoidea.)

Until quite recently this great group comprising what are popularly known as the Ichneumon flies* (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.) 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 insects, 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 larvae, 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 beneficial 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 agricultural crops by their widespread destruction of injurious insects.

Life History of an Ichneumon Fly

(Pimpla inquisitor, Say.)