This genus includes five subgenera and 51 species of free-living predators that live in mosses, lichens, leaf litter, bat guano, dung, scarabaeid beetles, nests of mammals and birds, rotting wood, galleries of bark beetles, and under bark (Fain and Camerik, 1994). Two subgenera and two species have been found in nests of bees: Ereynetes (Anereynetes) meliponae Flechtmann, Fain, and Leal, 1985 (ex Melipona scutellaris, Brazil) and Ereynetes (Ereynetes) boharti Hunter and Cross, 1968 (ex Nomia melanderi, USA). They are probably not specific to bees and may come from the outside environment in search of prey (small invertebrates). For example, Ereynetes boharti preys on acarid mites Sancassania boharti normally occurring in nests of bees of the genus Nomia.
Females or nymphs of some species have been found phoretic on dung beetles, flies, and darkwinged fungus gnats (Fain and Camerik, 1994). A few species are permanent associates of hermit crabs (Coenobita).