Cabbage moth caterpillars often bore right into the hearts of cabbage, caulifower, mustard, broccoli, brussel sprout, Chinese cabbage, radish, turnip, celery, beets and watercress  making them unfit for the table. Only a small part of a vegetable may actually be eaten by one of these caterpillars, but their frass (droppings) accumulate in the central part of the plant on which they develop and that part of the plant may soon start to decay. Host plants also include several ornamentals, such as wallflower, candytuft, stocks and alyssum.  The moths are on the wing in May and June and the caterpillars are active in June and July. Larvae which reach maturity pupate in the soil under the host plants.