Horse Hair Tail Insect
Sat, Jun 20, 2009 at 5:49 PM
These weird looking bugs are hanging around tree stumps, which have many holes in them. I don’t know if these insects made the holes or if they are trying to lay eggs in them, or get at the bugs in the dead stumps. The tail is almost like a strand of horse hair, about 4 inches long. The head, front legs and tentacles are bright yellow. It has a narrow body (black) about 1 1/2 inches in length and the wings are purple in color, 1 inch in length. As you can see in one of the pictures, the tail turns into a light green circular thing and the tail looks like it is rolled up in it. Then it will lose this thing and again have the horse hair like tail again. They also can fly. What the heck are these things?
St. Paul, Minnesota
Good Evening Linda,
You have Giant Ichneumons, Megarhyssa atrata, non-stinging relatives of wasps. Giant Ichnuemons parasitize the larvae of wood boring insects like the Pigeon Horntail. The female Giant Ichneumons locate the grubs deep inside the wood, and then use their stinger-like ovipositor to deposit an egg inside the tunnel inhabited by the larva. When the egg hatches, the larval Giant Ichneumon locates the wood boring larva and parasitizes it. The holes you saw were probably produced when the wood boring larvae emerged as adults, or possibly by the Giant Ichneumon when it emerged.