Fire ant (Fallout 3)

The Fire Ants are a variation of Giant Ants that is even more mutated than the "regular" giant bugs. Their name comes from their ability to literally breathe fire, similarly to the Fire Geckos from the Core Region.

The fire ants were created by Doctor Lesko, a scientist from the Capital Wasteland, and can only be found in that area. He was experimenting to return giant ants to their normal size through genetical manipulation and accidentally created the fire ants.