Wingspan 8-10 mm.
Distributed fairly commonly throughout the British Isles, the males of this species are relatively plain greyish brown with indistinct darker mottling. The females are quite different, being smaller with much more distinctive dark grey ground colour with white markings.
It has two generations in most of its range, being on the wing from April to June and from July to September. In northern Scotland however, it is single brooded from June to August.
The larvae mine internally in the blades of various grasses.