Wingspan c. 9mm
Occupying damp habitats such as fens and river banks, this species is to be found locally in a number of localities ranging from southern England to Wales, as well as parts of Ireland and the Western Isles in Scotland.
It is similar in appearance to other Cosmopterix species, but has a much more distinct large metallic patch at the base of the forewing.
The larvae feed on a number of grasses (Poaceae), mining the blades and forming an irregular gallery.
Adult moths occur from late May to August.