[1] The larvae of these solitary wasps are parasitoids that feed on cockroaches and develop inside the egg-cases, or oothecae, of their hosts.

The head is largely immovable and attaches to the mesosoma on a short neck; with usually 13-segmented antennae that do not differ between males and females.

While they do feed on insects that are considered pests, they rarely attain population sizes sufficient to act as effective biocontrol agents.

As cockroaches are typically more abundant in and around human settlements, Evaniidae are a regular sight in such habitat where many other wasps are absent, and are frequently encountered in buildings looking for prey.

Among these were the more apomorphic and less diverse (but about equally speciose) taxa now placed in the Aulacidae and Gasteruptiidae, which together with ensign wasps make up the superfamily Evanioidea.

Overall, they are successful organisms, existing since the time dinosaurs roamed the Earth with little change in morphology and, presumably, ecology.

The primitive Mesozoic genera Andrenelia, Botsvania, and Praevania are only tentatively identified as Evaniidae at present; the first was once separated as family Andreneliidae.