One question concerned wingless hymenopterans (bees, wasps, and ants). The question, in particular, concerned evolutionary aspects of Cow Killers. As commonly occurs, I had no idea. So I’ve spent some time learning about Cow Killers in the last few days.
So, why ask about them at a native bee talk? Easy.
Turns out the females are parasitoid Wasps without wings who chew their way through the nests of ground-nesting solitary bees and bumble bees and lay their eggs in bee pupa growing in the nests. When the eggs of the Cow Killer wasps hatch, they eat the bee pupa. Yum.
Let’s get some of the biology facts down. First, Cow Killers are members of the Hymenoptera, but they are definitely NOT bees. They are not ants, either. They are actually predatory Wasps in the Mutillidae family. Cow Killers (also known as Velvet Ants) are known by their scientific name, Dasymutilla occidentalis. There are other species of Dasymutilla found in Texas too. According to Texas A&M University Extension, Texas is also home to the Thistledown (or Gray Velvet) Ant. These little predatory wasps really do look like solitary bees!
The female Cow Killer doesn’t have wings (further adding to the identification confusion), but the male does. The female also has a very long stinger which she uses like a “multi-purpose stun-gun/venom injection apparatus” according to Dr. Eric Grissell in his indespensible book, Bees, Wasps and Ants: The Indespensable Role of Hymenoptera in Gardens. The male doesn’t have a stinger. The general scientific opinion seems to be that the sting of a Cow Killer is really bad–but probably not bad enough to bring down a cow!
I found a nice little article (here) that will give you a bit more detail on Cow Killers (Velvet Ants).
And here's a video from Youtube that shows a Velvet Ant (Cow Killer) searching for native bee nests on the ground. The video also gives a nice talk about Cow Killers.
Watch out for these little girls when you are out in the wilds. This is one lady you do not want to pick up!
Originally published 11/17/10