Sphex pensylvanicus, the great black wasp, is a species of digger wasp.[3] It lives across most of North America and grows to a size of 20–35 mm (0.8–1.4 in). The larvae feed on living insects that the females paralyze and carry to the underground nest.
Sphex pensylvanicus is a large, black wasp, significantly larger than their congenerSphex ichneumoneus (the great golden digger wasp).[6] Males are smaller than females, at only 19–28 mm (0.7–1.1 in) long compared with typical female sizes of 25–34 mm (1.0–1.3 in).[2] According to John Bartram, "The sting of this Wasp is painful, but does not swell like others".[7] As well as being larger than S. ichneumoneus, they are also darker, with smoky wings and an entirely black body, where S. ichneumoneus has yellow wings, red legs, and a partly red abdomen.[8]
Adult females of S. pensylvanicus build an underground nest which they provision with various orthopteraninsects,[9] particularly of the genera Microcentrum, Amblycorypha and Scudderia.[6] Prey are stung three times, once in the neck and twice in the thorax, and are paralyzed by the wasp's sting, although they can survive for weeks.[2] The prey are then carried to the nest. While collecting their prey, the females are vulnerable to kleptoparasitism, in which birds, including the house sparrow (Passer domesticus) and the grey catbird (Dumetella carolinensis), steal the prey that the wasp has collected.[9]
The eggs of S. pensylvanicus are 5–6 mm (0.20–0.24 in) long and 1 mm (0.04 in) wide; they are glued to the underside of the prey insect between the first and second pairs of legs.[2] Each of the several chambers in the nest houses a single larva, which consumes 2–6 katydids or grasshoppers.[9] The larval stage lasts 10 days, reaching a pre-pupation size of 30–35 mm (1.2–1.4 in) long by 7–10 mm (0.28–0.39 in) wide.[2]
