The forewings are usually pale grey, distinctively marked with a row of three angular black marks. The ground colour, however, is quite variable with pinkish or reddish forms occurring fairly frequently. In the north of Scotland, including Orkney and Shetland, an almost black form occurs (some authorities regard this as a subspecies, "E. g. edda"). The hindwings of the typical forms are white, grey in the darker forms. The wingspan is 32–38 mm. This species flies from the latter half of August to the first half of September and is attracted to light and heather flowers.