Wingspan c. 10mm.
This species was unknown from Britain until 1996 when it was found in Dorset and then in Hampshire the following year.
It differs from other British Cosmopterix species by the very narrow white lines in the basal half of the wing, a small dark spot in the inner silver fascia, and the longitudinal streak which extends from the orange patch to the tip of the wing.
Feeding on common reed (Phragmites australis), the larvae create distinctive mines in the leaf blades.
Adult moths fly from late June to October.