Red Velvet Ant (Cow killer) (female)

The exoskeleton of all velvet ants is unusually tough (to the point that some entomologists have reported difficulty piercing them with steel pins when attempting to mount them for display in cabinets). This characteristic allows them to successfully invade the nests of their prey and also helps them retain moisture. Like related families in the Vespoidea, males have wings but females uniformly are wingless. 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.
In mutillids, as in all Hymenoptera, only the female is capable of inflicting a sting because the stinger itself is a modified female organ called an ovipositor; female mutillids have unusually long and maneuverable stingers. In both sexes, a structure called a stridulitrum on the metasoma is used to produce a squeaking or chirping sound when alarmed. Both sexes of mutillids also bear hair-lined grooves on the side of the metasoma called felt lines. Only one other vespoid family, the Bradynobaenidae, has felt lines, but the females have a distinct pronotum and an elongated ant-like petiole.