I was lucky to spy this gorgeous, large wasp on a cool cloudy day—low temperatures slowed it down. Normally, these predators are in constant motion, and near impossible to photograph.
That’s because Ichneumon genus wasps lay their eggs on the larvae of other insects like moths or beetles, and are always on the lookout, stalking. Ichneumon comes from a Latin word that means “tracker,” because the females track their prey with amazing precision.
This wasp is a female Therion circumflexum. Males have entirely yellow faces. Many Ichneumon females have incredibly long ovipositors (egg-layers), often longer than their entire body. This one’s is much more modest. Note: It’s not a stinger. These wasps aren’t defensive of a colony, like yellow jackets.
If you imagine a paper wasp in flight, you probably picture it with the rearmost legs hanging down. It’s the same with these larger wasps, and it gives them a strange, upright look as they survey the foliage for caterpillars. There’s a link to a nice picture below.
The Ichneumon genus is one of the largest in the insect world. The number of species is always edging up as scientists sort them out. Right now, there are about 60,000 known species in the world, and 5,000 in North America. BugGuide says “any identification based solely on comparing images should be treated as suspect,” because there are so many look-alikes, but I’m confident on this photograph, because Therion circumflexum is the only local Therion species.
See more of Karen’s work here.
Image of a Therion in flight by Carlo Galliani: https://pbase.com/carlogalliani/image/167544530. Accessed 5/17/22.
BugLady on Therion wasps: https://uwm.edu/field-station/therion-wasp/. Accessed 5/17/22.
BugGuide’s summary of the species: https://bugguide.net/node/view/1984740. Accessed 5/17/22.