Velvet ant ("cow killer")
Sometimes names can be misleading. Velvet ants are not ants—they are actually wasps, and even though females can inflict an extremely painful sting, they don’t actually kill cows (as far as we know). The individual in the photo is a female. We are sure of this because only females have a sting, and male velvet ants have wings!
Velvet ants are solitary (meaning they don’t live together in a nest like honey bees or yellowjackets), and they are parasitoids (a type of parasite that kills its host), but don’t worry, they do not parasitize people! Female velvet ants search for underground insect nests (usually the nests of other solitary wasps or bees), and if they can avoid or defeat any guards, they find a cell containing a larva or pupa of the host. An egg is deposited on the unlucky insect, and the velvet ant larva hatches and eventually devours the defenseless victim!
If you would like to see photos of some of the other velvet ants (some species are truly spectacular), visit www.bugguide.net and search for “Mutillidae” (which is the family name for this group of wasps).