The Eastern Velvet Ant (aka: "Cow Killer") is not an ant at all, though it looks like a hairy one. It is actually a wasp and the female has a severely ferocious sting that is rumored to be strong enough to kill cattle. It is extremely painful and this insect should not be handled.
Males have wings and look more like a typical wasp though they still retain some hairs on their body. Females do not have wings, but they can and do sting. The Eastern Velvet Ant is a solitary wasp meaning they do not congregate in nests with hundreds of others of their kind. They are also parasitic to bumble bees.
Females lay eggs in a bumble bee's hive. Once the wasp's eggs hatch, theses larvae eat the larvae of the bumble bee. Adults drink nectar.
Cow Killers can be found in fields, meadows, sandy areas and the edges of forests. They are typically most active at dusk or during the night. Though the female looks like an ant, her warning coloration and ferocious sting are enough defensive adaptations to keep most predators (and curious animals) at bay.