The brown-tailed moth is better known as a caterpillar, with nasty barbed hairs. People can get skin irritations should they come in contact with the caterpillar. In the autumn, the caterpillars are very small and not dangerous. They make a communal cocoon in sea buckthorn bushes before the winter begins, where they spend the cold months. In the spring, they emerge from the cocoon where they grow into large caterpillars. By the end of June, they pupate and a pure white downy moth emerges towards the end of July. The females have a tuft of brown hairs at their hind end.