There are perhaps 60,000 to 100,000 species of Ichneumon wasps (Hymenoptera: Ichneumonidae) throughout the world, and these abundant insects can be found almost anywhere. One night last week I noticed this individual resting on an interior wall of my garage.
Female Ichneumon wasps often feature prominent and formidable-looking ovipositors, yet most are incapable of breaking human skin to deliver stings. Instead they use these long, narrow, egg-laying organs to deposit their eggs near, on, or inside other insects. Once their larvae hatch they’re parasitoids of their hosts, consuming and ultimately killing them. Since many of their host insects are pests to humans and our crops, Ichneumon wasps are great biological control agents and are highly beneficial to us.
The innumerable species of these wasps vary considerably in size, shape, and coloration. In general they’re long and slender, some combination of brown and black with perhaps some yellow, and they have very long antennae. Another interesting feature that sets them apart is the typical “horse head” pattern in the veins of their forewings. Over the years I’ve written about three other species (1, 2, 3) and they bear little resemblance to each other except for these features.