Answer by
jsmith (2067)
Without much of a description, I'm going to guess you are describing what are referred to as "cow killers" or red velvet ants. Their scientific name is Dasymutilla occidentalis. Interestingly, they aren't actually ants but are of the family Mutillidae which include several different flightless wasps. The cow killer moniker arises from the legend of their painful sting.