Large White, Pieris brassicae

Identification

Wingspan, 60mm to 70mm

Males have a pure white set of upper wings with a black tip to each forewing and a small black blotch half way on the leading edge of the hind wing. The under-side of the forewing is white with the greyish wingtips. The under-side of the hind wings is pale yellow with a grey dusting.

Females are very similar to the males but, in addition, they have two prominent black spots on the upper side of each forewing and black streak running along the inner half of the lower margin of the forewing.

Behaviour and life history

The Large White is a strong, if erratic flier, which appears to roam wherever it pleases since it does not form colonies. Mid summer numbers are often boosted by large migrations from the continent. Large Whites over-winter as a chrysalis with the first adult brood appearing towards the end of April or beginning of May. Eggs are laid in May and June, with the caterpillars feeding from late May until the middle of July. A few weeks are then spent as a chrysalis before the second adult brood emerges towards the end of July and into August. Eggs from the second brood are laid from early August onwards, and their caterpillars hibernate as chrysalises above ground in sheltered locations from late September onwards. There can be a third brood in good years. Larval food plants include cabbage (hence they, together with Small Whites, Pieris rapae, areoften collectively known as Cabbage Whites) but they will feed on most plants in the cabbage family (Brassicaceae) and are also partial to garden Nasturtiums (Trapaeolum spp.).

Where to look for it

Anywhere, but particularly along hedgerows, in allotments and gardens.

Distribution and status

Very common and widespread throughout Plymouth.

When to look for it

Adults are most often to be seen on the wing during May and August.

Similar species

Size alone should be sufficient to separate this species from the other white butterflies. Green-veined Whites, Pieris napi, are immediately separable by the dusky veins of their underwings, as are female Orange Tips, Anthocharis cardamines, with their darkly marbled underwings. The dark wing tips of the Small White, Pieris rapae, which barely extend down along the outer edge of the forewing, should be sufficient to separate it from more extensive markings of the Large White.

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