Trogus wasps are parasitoids that lay eggs in swallowtail caterpillars. There are four different Trogus species in the Eastern US and Canada.
Trogus pennator wasps resemble the common red wasp that we know well. Most of us avoid the red wasp. Their stings are painful. The parasitoid wasp, Trogus pennator, doesn’t sting like red wasps sting people. The body is red/orange and the wings are black with a blue sheen. The abdomen is clearly segmented and flatter than a red wasp abdomen. It’s a beautiful wasp.
The adult wasp seeks out caterpillars and lays a single egg in the caterpillar. At the proper time, the egg hatches, and the wasp larva eats the inside of the developing butterfly. This kills the chrysalis.
Once the wasp becomes an adult, it eats a large hole in the side of the chrysalis and emerges, seeking a mate and food. The adult wasp mates and the female is now ready to lay her eggs in more swallowtail caterpillars.