They are typically mimics of bees or stinging wasps, often black with yellow, red, or white markings, sometimes metallic, with a robust mesosoma and very strong sculpturing.

The hind femora are often greatly enlarged, with a row of teeth or serrations along the lower margin as in Chalcididae.

The female ovipositor is sometimes short, but if not, it is recurved and lies along the dorsal side of the metasoma, a unique feature.

Leucospis pinna, which parasitizes the orchid bee Eulaema meriana, is known to have multiple adults emerging from a single brood cell of the host.

[3] Leucospids are rarely encountered except in areas where their hosts are abundant; in the United States, the best-known species is Leucospis affinis, which parasitizes leafcutter bees.