Trichacis is a genus of parasitoid wasps in the family Platygastridae.

Members of this genus have a tuft of setae on the mesoscutellum and transverse striae or rugulae above the antennae.

They are parasitoids of Cecidomyiidae, although the hosts of most species remain unknown.

[1] The genus has been revised for the Nearctic,[2] Neotropics,[3] and Europe.

[1] These 66 species belong to the genus Trichacis: