One of several butterfly species, the caterpillars of which feed on the leaves of members of the cabbage family, particularly as pests on cabbages. Ichneumon flies parasitize the caterpillars, thereby controlling their numbers.

Classification
Cabbage butterflies are in genus Pieris in order Lepidoptera, class Insecta, phylum Arthropoda.

Species
The large white Pieris brassicae is found in Europe and North Africa. The expanded wings measure 7.5 cm/3 in across, and are white with black edgings. The female, which has black spots on the upper surfaces of the wings, lays her yellow eggs in clusters on cabbage leaves. The fully grown caterpillar sometimes measures 4 cm/1.5 in, and will eat twice its own weight of leaf in 24 hours. After it has hung for some time by its tail from a ledge, it changes into a shining pale green chrysalis. The butterfly, which in the case of the autumn brood waits till winter is past before emerging, lives on nectar.

The small white butterfly Pieris rapae, has a wing expansion of about 5 cm/2 in, lays its eggs singly on the underside of vegetable leaves, and produces a velvety caterpillar which devours the hearts, instead of merely the leaves, of cabbages. The chrysalis is brownish-yellow with black spots.

A third species, the green-veined white butterfly Pieris napi, which is similar to the small white, cannot multiply so fast, because both the butterfly and its caterpillar are a favourite food of small birds.