Well, it’s not really an ant but a wasp—a wasp in the hymenopteran family Multillidae, also called—for obvious reasons—”velvet ants.” (Ants and wasps are fairly closely related; in fact, ants evolved from early wasps.)
In these wasps the females are wingless and the males winged, and their colors and patterns are aposematic: that is, they are “warning” patterns that tell predators to stay away. Predators presumably learn these patterns readily, for velvet wasps have extremely painful stings.
But isn’t this a cute little girl?
I’m not an expert on this group (or any group of insects save Drosophila), but Wikipedia notes this:
They exhibit extreme sexual dimorphism; the males and females are so different, it is almost impossible to associate the two sexes of a species unless they are captured while mating. In a few species, the male is so much larger than the female, he carries her aloft while mating, which is also seen in the related family Tiphiidae.
Here’s another view, from photo by DrSarahJensen via Flickr:
Velvet ants come in all sorts of striking colors and patterns, presumably aposematic; go here to see some.