Small to medium-sized wasps. Cuticle brightly metallic-coloured, which may be purple, blue, green and red. There are three visible gastral segments. Their hosts belong to the vespid subfamily Eumeninae and Apoid family Crabronidae. The hosts nest in the ground, in cavities in wood and in mud cells attached to a firm structure such as a wall. The female enters the host's nest and lays an egg in each available cell. On hatching, the larva usually eats the egg or young larva of the host, before the food store (cleptoparasitic life history). In some species the larva feeds only on the larva of the host and eventually kills it (parasitoid life history). Adults can adopt a rolled-up defensive posture when threatened. Nationally: 4 genera with c.18 species.