Pieris brassicae

Pieris brassicae, called the large white, cabbage butterfly, or cabbage white, belongs to the family Pieridae and is closely related to the small white, Pieris rapae. This butterfly is widespread across Europe, North Africa, and Asia.

It inhabits open spaces like agricultural fields, meadows, and parkland. A strong flier, its British population is regularly boosted by migrants from the continent. The butterfly has established itself in South Africa, and by 1995 it was expected to reach Australia and New Zealand. Reports from the northeastern United States over the past century are questionable, likely due to accidental transport or intentional release, and such introductions risk making it a North American agricultural pest. In 2010, it appeared in Nelson, New Zealand, where it is called the great white butterfly and classified as an unwanted pest. In October 2013, the Department of Conservation offered a $10 reward per captured butterfly; the public turned in 134 in two weeks. Combined with over 263,000 searches in the upper South Island and the release of predatory wasps, the large white was declared eradicated from New Zealand by December 2014.

Eggs are pale yellow, darkening within a day of being laid. Hours before hatching, they turn black and transparent, revealing the larvae inside.

Larvae go through four molts and five instars. First-instar larvae are light yellow with brown heads, soft bodies, and a hairy appearance. After molting, second-instar larvae have tubercles covered in black hair. Third-instar larvae become more active, feed voraciously, and cause significant damage to host plants; they appear more yellow with black dots. Fourth-instar larvae look similar but are larger and feed more. Fifth-instar larvae are cylindrical, robust, and elongated, yellow with bright coloration on the abdomen and thorax, and a grey-and-black head. This stage requires maximum food quality and quantity; otherwise, the larva dies before becoming an adult.

Adult butterflies have white wings with black tips on the forewings. Females also have two black spots on each forewing. The underside is pale greenish, providing camouflage at rest. Black markings are darker in the summer brood. Wingspan averages 5 to 6.5 cm.

In males, the upper side is creamy white. The forewing has black scales sprinkled at the base and along the costa. The apex and termen above vein 2 are broadly black with a smooth inner curve. Occasionally, a small black spot appears in interspace 3. The hindwing is uniform, with black scales at the base and a large black subcostal spot before the apex. The underside of the forewing is white with black scales at the base and along the costa; the apex is light ochraceous brown with a large black spot in interspace 1 and another in interspace 3. The hindwing underside is light ochraceous brown with fine black scales. Antennae are black with white tips; head, thorax, and abdomen are black with white hairs, whitish underneath.

Females resemble males but have more extensive black scaling at the wing bases. The black area on the forewing apex and termen is broader, with a less even inner curve. A large black spot appears in interspace 1 near interspace 3. On the hindwing, the subcostal spot is larger. The underside is similar, but the forewing apex and entire hindwing are light ochraceous yellow, not brown, and the black discal spots on the forewing are larger. Antennae, head, thorax, and abdomen are the same as in males.

Habitat includes large open spaces, farms, and vegetable gardens, where food plants are available. Favored spots are walls, fences, tree trunks, and the food plants themselves. These areas contain wild and cultivated crucifers, oil-seed rape, cabbages, and Brussels sprouts.

The mating system can be polyandrous, but most females mate with only one male.