All parts of the adult are bright white to pale yellow marked with faint buffish fascia.

The species gets its common name from pointed projections on the termen of the hindwing with brownish spots at their base.

It flies at night in June and July [1] and is attracted to light, sometimes in large numbers.

The larva is grey-brown, the colouring arranged in a succession of scarcely noticeable longitudinal lines.

The brown, twig-like larva feeds on a variety of trees and shrubs including elder, hawthorn, honeysuckle and ivy.