The caterpillar relies on a combination of
its extraordinary shape with disruptive coloration to disguise the fact that
it is a caterpillar. It feeds on willow, alder, apple or hawthorn from August
to early October. When it has finished eating it drops to the ground and makes
a flimsy cocoon amongst the ground litter. It stays in the cocoon, as a diapausing
caterpillar, throughout the winter, transforming to a pupa in the spring. The
adult moth wraps its wings around its body into a tight cylinder and is barely
to be distinguished from a fragment of broken stick.