These wasps are minute, typically 2–4 mm in length, and rarely exceed 8 mm. They often exhibit significant sexual dimorphism, with males and females frequently looking different enough to be mistaken for separate species. Diapriini larvae are internal parasitoids, developing inside the larvae or pupae of their hosts. Their primary hosts are the larvae and pupae of flies (Diptera), including fruit flies, hoverflies, and flesh flies.