Ichneumon

Ichneumon, a name applied to the members of a very large family of insects (Ichneumonidae), included in the order Hymenoptera, and notable because the larvae are parasitic in, or sometimes on, other insects. There are several thousand species, represented in all parts of the world, including many minute forms and also some of the largest insects. The long antennæ have many joints; the abdomen is usually joined to the thorax by a narrow waist; the females are provided with ovispositors, which are in some cases very prominent. With these they lay their eggs in the ova, larvae, or adults of other insects, and sometimes also of spiders. The ichneumon embryos develop in the safe and comfortable hiding-place thus afforded, and utilise their hosts as food for a while, but sooner or later, before or oftener after pupation, leave them dead or dying. Sometimes, curiously enough, the ichneumons themselves fall victims to a similar trick played upon them by members of the same or nearly related families. As adults, these insects feed on the juices of flowers. The parasitic habit of the larvae is sometimes of economic importance, since they thus destroy injurious insects. Thus, Microgaster glomeratus and Pimpla instigator are parasitic on the caterpillars of the cabbage butterfly, and Aphidius upon aphides.