"Cow Killer" Velvet Ant (Dasymutilla occidentalis) -- Female
Like all Velvet Ants this Cow Killer isn't an ant at all. She is a wasp, a flightless, female wasp. (Males have wings and can fly.) Female Cow Killers are in constant motion, scurrying along the ground, presumably searching for bumblebee nests. Once a nest is found, she will dig down into the nest and deposit one egg near the brood chamber. When the egg hatches the larva of the Dasymutilla will enter the bumble bee brood chamber, kill the bee larvae, and feed on them. The Cow Killer larva pupates in the bumble bee brood chamber.
The common name "Cow Killer" is based victim's reports that the sting of the female are painful enough to kill a cow. Like most wasps, the male cannot sting.