square-headed wasps

Crabronini is a large tribe of square-headed wasps. There are more than 1,500 species in 48 genera worldwide, about 160 species in North America north of Mexico, and at least 34 species in at least 7 genera in Minnesota.

Crabronini are solitary, predatory, stinging wasps. Many nest in a hole in the ground, but some build nests of plant materials and mud. They prey on other insects, including many pest species, and they are therefore considered beneficial to humans. They are not aggressive, but some species can sting if provoked.

Crabronini are small to medium-sized wasps. Adults are 5⁄16″ to ¾″ (8 to 20 mm) in length. Most are black with yellow markings, but some may also have metallic green or blue colors. The body is elongated and slender, with a narrow waist.

The head is large and square, and the compound eyes are large. The inner margins of the compound eyes are straight and converge toward the bottom. The antennae are inserted very low on the face. The plate on the face (clypeus) is covered with silvery hairs, and the hairs extend laterally in a narrow band below each compound eye. This feature has led the tribe to be called by some “mustache wasps”, though that name is not formally applied.

The legs are long relative to their body size.

On the forewing there is only one submarginal cell, and the marginal cell is cut off (truncate) at the end.

Sources

24, 27, 29, 30, 82.

This tribe has no common name. The name of the subfamily Crabroninae is square-headed wasps, and it is adopted here for convenience.

Location: Slinger, Wisconsin