Pieris Rapae - Life Cycle

Life Cycle

In Britain, it has two flight periods, April–May and July–August, but is continuously-brooded in North America, being one of the first butterflies to emerge from the chrysalis in spring, flying until hard freeze in the fall.

Its caterpillars can be a pest on cultivated cabbages, kale, radish, broccoli, and horseradish but it will readily lay eggs on wild members of the cabbage family such as Charlock (Sinapis arvensis) and Hedge mustard (Sisybrium officinale). The eggs are laid singularly on foodplant leaves. It has been suggested that isothiocyanate compounds in the family Brassicaceae may have been evolved to reduce herbivory by caterpillars of the Small White.

Traditionally known in the United States as the Imported Cabbage Worm, now more commonly the Cabbage White, the caterpillars are green and well camouflaged. Caterpillars rest on the undersides of the leaves, thus making them less visible to predators. Unlike the Large White, they are not distasteful to predators like birds. Like many other "White" butterflies, they hibernate as a pupa. It is also one of the most cold-hardy of the non-hibernating butterflies, occasionally seen emerging during mid-winter mild spells in cities as far north as Washington D.C.

Like its close relative the Large White this is a strong flyer and the British population is increased by continental immigrants in most years. Adults are diurnal and fly throughout the day except for early morning and evening, although there is occasional activity during the later part of the night it ceases as dawn breaks.

• Egg

• Caterpillar

• Pupa

• Copulating pair