Wingspan 40 to 50 mm. This is the largest of the 'emeralds'.

It inhabits woods, heaths and moors.

Flies at night in June and July, when it is easily attracted by light.

The caterpillar is brown at first, but after overwintering becomes green with brownish 'warts', and feeds mainly on birch.

Fairly frequent throughout most of Britain. In a recent survey to determine the status of all macro moths in Britain this species was classified as common.

Fairly common in Leicestershire and Rutland. L&R Moth Group status = A (common and resident).