A plain white species when at rest, although the abdomen, as the name suggests, has a brown tuft of hairs which the female uses to cover the eggs with when they are laid.
The species is distributed mainly around the south and east coasts of England, and in some years can become locally abundant.
The caterpillars are well-known for their urticating hairs; they cause extreme irritation if in contact with human skin. They feed in a communal web on the leaves of hawthorn (
) and blackthorn (