Wingspan 33 to 38 mm. This subtly-marked species varies less than some of its congeners, but melanic forms do occur in places.

Damper areas around Alder and wooded areas containing Birch.

The adults appear in May and June and are attracted to mercury vapour light. Prior to the use of this trapping method, the species was considered quite rare, as it seldom comes to sugar or flowers.

The larva when young resembles a bird dropping, but when mature is highly distinctive, being black and yellow with a number of club-like hairs. It feeds on a number of different trees, particularly Alder and Birch.

Thinly scattered over most of England and Wales. In a recent survey to determine the status of all macro moths in Britain this species was classified as local.

Fairly frequent but not common in Leicestershire and Rutland. L&R Moth Group status = B (scarce resident or restricted distribution or regular migrant).