The large white overwinters as pupa and emerges in late spring. It then lays groups of yellow conical shaped eggs on the undersides of many kinds of wild or cultivated species of the Cruciferae family, with a strong preference for cultivated varieties of Brassica oleracea, such as cabbage and Brussel-sprouts and varieties of B. napus such as oil-seed rape. After a period of 14 days the caterpillars emerge and start feeding in large groups on the host plants. The caterpillars molt as they grow and when fully fed, they seek crevices in sheltered places to pupate.
The caterpillars are hairy and black or dark green with yellow longitudinal and black stripes. They have a length of up to 5 cm and have an enormous appetite. They can very rapidly reduce host plants to veined skeletons and are, therefore, a serious pest in agriculture.