When at rest the wings are gently curled flat over the body. The forewings are greenish-grey with a well-defined yellow stripe along the leading edge. The hindwings are a yellow-straw colour which can be noticed during flight.
Can sometimes be seen basking in the sunshine on tree trunks, walls or posts. Frequently comes to light. They overwinter as small larvae so the caterpillars can be seen from August to the following May.