Wingspan 50 to 60 mm. The resident populations are quite dark, almost blackish, but the immigrants are usually much paler and greyer.

Grey Arches.

Because of the rarity of this species in our area, your record should be supported by good photographs, and the specimen should be retained until the record has been confirmed by the County Recorder.

Associated with Bog Myrtle, Willows and Birch.

The resident moths fly in July and August; the immigrants generally appearing later, from late August to September.

Although resident in the Scottish Highlands, this species is more often noted as a migrant to the East Coast, especially further north.

Rare in Leicestershire and Rutland.