Polyblastus wahlbergi

Forewing length about 7 mm. The thorax and body of this species is dark blackish, but the legs show quite a lot of yellow. The wings have a dark stigma.

Various habitats including hedgerows and well wooded areas.

May to October and may be attracted to light.

Polyblastus wahlbergi is an ectoparasitoid of sawfly larvae. A few genera of the subfamily Tryphoninae habitually carry an egg at the base of the ovipositor but Polyblastus is the only genus that carries a whole bunch of eggs. Each egg has a stalk, which is secured within the ovipositor, so when the host is parasitized the stalk passes down the ovipositor and is anchored in the cuticle of the host. The eggs, when they are carried externally, are ready to hatch very quickly, which seems to be an adaptation to enable the parasitoid larva to begin feeding quickly and avoid being sloughed off when the host starts its final moult.

The species is relatively common and seems to come to light fairly regularly.

Status in Leicestershire and Rutland unknown.