Their body is black and has small yellow spots on the head, thorax and legs.

On each of the second to fourth abdominal segments there is a pair of yellow patches, which usually merge to form bandages.

The females are often found near the nest openings of bees in dead wood or hollow stalks.

An egg is laid anywhere in an unsealed brood cell of bees, filled with pollen and nectar.

The wasp larva hatching from it first sucks out the bee egg and then feeds on the supplies.