The mammal-nest beetles (Leptinidae) are a very small family, closely related to the rove beetles. The representatives of this family live in the nests or ectoparasitic in the fur of small mammals (mostly rodents, e.g. beavers, shrews and moles). The feed on scurfs or on other insects or acarids. In Germany only two species occur, Leptinus testaceus (on small rodents) and Platypsyllus castoris (on beavers). Both species are eye-less and are with their flattened body well-adapted to the life in the fur of their host. The family comprises four genera with palearctic, nearctic or holoarctic distribution.