Wingspan 18-22 mm.
Formerly only known from the birch woods of the Scottish Highlands, this species has now been found several times in the south of England. It's possible that these records are the result of migrants and the species is now becoming established in the south.
The adult illustrated from Hampshire was the first record for that county, found at a lighted window in January 2003.
The adults generally emerge from September and overwinter, being found through to April. The larvae feed between spun leaves of birch (Betula).