May to June, but to early August in parts of northern Britain. Rests like a butterfly with wings held closed above the body.

Males fly around conifers in sunshine. Comes to light. Rests with wings held above the body and pressed together like a butterfly. Males vary from yellowish in the south to white in northern England and Scotland, the females varying from orange in the south to brown in the north. Males have feathery antennae.

The larva can be seen from late June to October. They overwinter as pupae on the ground among conifer needles.