Black Hornets in the Grass

About Ground-dwelling Wasps

• There are numerous ground-dwelling wasps digging holes in yard and gardens across the country all summer long. Most are hardly noticed by their human neighbors, and due to their docile nature, they shy away from structures. Unlike wasps that build their nests high in the air, ground-dwelling wasps nest in holes in the ground. The most common black ground-dwelling wasps are solitary, meaning they don't form large collective nests and don't have a queen. If you see them puttering around the lawn, they're probably hunting for food to feed their young or scouting nest sites. These wasps feed on pests such as crickets and grasshoppers, so they're typically considered beneficial insects.

Tarantula Hawk Wasp

• Tarantula hawk wasps (Pepsis spp.) are blue to black wasps that reach about 2 inches in length, with distinctive curled antennae. Their wings are usually brightly colored, appearing in shades of gold, red, orange and mahogany, but some species are less conspicuous with blue-black wings. When these wasps wander around in the grass during the day, they're on the hunt for tarantula dens. Once located, the female wasp stings the tarantula and drags the body to her own den, where she lays a single egg in the tarantula's body. These wasps tend to ignore humans entirely.

Great Black Wasp

• Although most of the slender-waisted digger wasps (Family Sphecidae) are two-toned, one common member of this group, the 1 1/2-inch-long great black wasp (Sphex pensylvanicus), is solid black and bears impressive mandibles that it uses to dig its nest out of soft soil. Males mostly hang around near nectar-bearing flowers and nesting sites, but the females hunt in tall grasses for grasshoppers and katydids, paralyzing them for their young before moving the prey into their nest. Female great black wasps will sting if disturbed, but the far more territorial and much smaller male lacks a stinger.

Grass-Carrying Wasps

• Grass-carrying wasps (Isodontia spp.) are also considered digger wasps, even though they prefer to create nests from dried grass blades inside the tracks of storm windows or in old holes, rather than dig their own nests. The female is frequently seen collecting bits of grass to line her nest during the summer; you may even notice her flying away with grass blades firmly gripped between her legs. Grass-carrying wasps are slightly smaller than their distant cousins the great black wasps, at only 3/4 inch, with smokey brown wings and white hairs emerging from their thoraxes. They hunt crickets for their young and aren't aggressive unless handled roughly.