Wingspan c.10 mm.
Members of the Glyphipterix family can be rather similar in appearance, but forsterella has a noticeable white or silvery dot in the black apical patch of the forewing, which differentiates it from its congeners.
The species is distributed locally throughout much of Britain, occupying suitable habitats where the foodplants are found.
The larvae feed from August to April on various sedges (Carex), including fox sedge (C. vulpina), apparently on the seeds.
The diurnal adult moths fly in May and June and feed on the flowers of the foodplants.