Most species are brightly coloured with yellow and black patterning and about 2 cm long.

They have characteristically enlarged femurs on the hind leg, with the lower margin toothed.

The wings have a longitudinal fold and the long ovipositor is bent over their backs above the abdomen or metasoma.

They are parasitic on wasps and solitary bees that construct cells and provision food for their offspring.

The genus Micrapion from South Africa is very closely related, and phylogenetic studies suggest merging of the two genera.