The Horse Guard Wasp (Stictia carolina) is a type of so called sand wasps widespread in eastern North America. The species is named for the behavior of its females, which hover around horses to catch horse flies. These rather large wasps may treat us humans in a similar manner – as fly lures.
The wasps nest in the sand, sometimes in dense colonies with sometimes thousands of other wasps. A female may take anywhere from 30 to 60 flies as food to provision each one of her nests. Nests are simple burrows up to 15 cm deep, with a single enlarged chamber at the bottom. An egg is laid in the empty chamber, and the female wasp brings back paralyzed flies until the chamber is full, at which point she closes the nest and begins another.
Here a little video about horse guard wasps: