HYMENOPTERA | Parasitic Wasps

Gasteruptiidae (Gasteruptid Wasps)

The members of this family of small elongate parasitic wasps are recognisable from their distinctive neck-like propleura, slender subclavate (club-shaped) metasoma, and swollen hind tibia.

The British list includes five species with Gasteruption assectator and Gasteruption jaculator being the most common. Although it would be difficult to accurately identify the male of these species, the females are easily separable by the length of the ovipositor where Gasteruption assectator has a very short ovipositor whilst Gasteruption jaculator is very long.

Gasteruptid wasps were previously regarded as ectoparasitoids, but are now considered to be secondary cleptoparasites of food stored by solitary bees.

Gasteruption jaculator

This species has a black rounded head and elongated thorax, slender abdomen with reddish-orange markings, and swollen hind tibia. The female’s ovipositor is usually very long with a white tip.

When in a resting position, Gasteruption jaculator have a habit of slowly and rhythmically raising and lowering their abdomen. The female uses her long ovipositor to penetrate the bee’s nest and lay an egg on the host larvae. After hatching, the wasp larvae will eat both its host and the food supply that the bee has collected. Adults can grow up to 17mm long, and can normally be seen from May through to September as fresh specimens emerge from the nests of different hosts.

Garston Wood, Cranborne Chase, East Dorset | Aug.21