The family Vespertilionidae (excluding Antrozoidae and Tomopeatinae) contains almost one-third of living bat species (Koopman, 1993, 1994). Five subfamilies are currently recognized: Vespertilioninae (27 genera, 180 species), Myotinae (2 genera, 86 species), Miniopterinae (1 genus, 10 species), Murininae (2 genera, 16 species) and Kerivoulinae (1 genus, 22 species) (Koopman, 1993, 19994; Volleth and Heller, 1994; Simmons, 1998; Simmons and Geisler, 1998).

All vespertilionids are insectivorous, and most catch their prey in the air while flying. Some species, however, may glean insects off surfaces or trawl with their hind feet across lakes or streams to catch their food.