Wingspan 35 to 40 mm. The females of this species are completely wingless (apterous), a feature which is often found in moths which emerge in the winter months. The species shows marked melanism, the black form f. monacharia being commoner than the typical form in certain parts.

It may be found in a wide variety of habitats, often in areas with trees.

The males fly from January to March, searching for the females which have climbed up tree-trunks. They are attracted to light.

The caterpillars feed in late spring on a number of deciduous trees.

Although widespread in Britain it is more common in England and Wales, and scarcer elsewhere. 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)