any of a group of wasps in the subfamily Bembicinae (family Crabronidae, order Hymenoptera) that are solitary, stout-bodied insects about 2 to 2.5 cm (about 0.8 to 1 inch) long.

The horse-guard (Bembix carolina) of the southern United States often hunts for flies around horses. It is about 2.5 cm in length and is black with yellow or yellowish green markings. Microbembex monodonta is found along the seashore. Many sand wasps are black with white, yellow, or green markings. A distinguishing character is their elongated triangular labrum (upper lip), which makes them appear to have a beak. Their nests are sand burrows, many of which are often clustered together. The larvae feed mainly on other insects caught by the parents.