Wingspan c.10-16 mm.
This species can be confused with its close relative, Monopis obviella, and indeed was only separated as a species in the late 19th century. Compared to that species, it is generally less distinctly-marked, with the dorsal streak being darker, and with more speckling on the forewing. However it is best to check the hindwing, which is pale grey in the present species, and dark with a slight purple tinge in M. obviella.
Like many species in the group, the larva feeds on dried animal and vegetable refuse.
It is distributed mainly in the southern half of Britain and in Ireland, and the adults fly between June and October.