Large (up to 50mm long) black and yellow hairy caterpillars causing defoliation of large parts of host trees. It is found on oak, hornbeam, lime, cherry, birch and many other deciduous trees and shrubs. Small trees or shrubs can be completely defoliated.
The caterpillars are present from July to October and when fully grown enter the soil to pupate. After overwintering as a pupae the adult moths emerge from late May to July.