Eastern velvet ant (female)

The Eastern Velvet Ant is the largest of the velvet ant species in the United States, attaining an approximate length of ¾ of an inch (1.9 cm). Adults display aposematic coloration, consisting of black overall coloring with an orange-red pattern on the dorsal surface of the thorax and abdomen. They are covered in dense velvet-like hair.

Females are capable of a extremely painful sting, hence the name "cow killer." They seek out the chambers of ground-nesting bumble bees and other members of Hymenoptera, where they deposit an egg onto a host larva. The egg quickly hatches into a white legless grub, which consumes the host and goes through several larval stages prior to pupa formation. Unlike the females, males have dark, transparent wings and no sting. (information from Wikipedia)