The Diapriidae are a family of insects belonging to the order Hymenoptera. These tiny wasps have an average length of 2-4 mm and never exceed 8 mm. They are typically parasitoids on the larvae and pupae of a wide range of insects, especially flies; a few are hyperparasitoids (e.g., Ismarus, which parasitizes Dryinidae, which are themselves parasites of leafhoppers). The about 2,300 described species in 150 genera are divided into four subfamilies, and the group has a global distribution.
Diapriids show considerable diversity of form, with aptery (lack of wings) fairly common, sometimes in both sexes. Nearly all species exhibit noticeable sexual dimorphism, with males and females often mistaken for separate species. The wings, when present, show characteristically reduced venation, with the greatest reduction in the subfamilies Ambositrinae and Diapriinae.