Small White, Pieris rapae

Identification

Wingspan, 45mm to 55mm.

Males are white on their upper wings surfaces with grey to black forewing tips and a grey to black spot in the centre of each forewing. The under-side of the forewing is white with a yellow leading edge and wing tip and a grey spot in the middle of the wing. The under-side of the hindwing is yellow with a black dusting.

Females are very similar to the males and differ only in that they have two grey to black spots on each forewing. The markings of the first brood are much paler than those of the second brood.

Behaviour and life history

The Small White is a very active butterfly but is not such a strong flier as the Large White, Pieris brassicae. Consequently, it tends to frequent more sheltered situations out of the wind but like its larger relative it does not live in colonies. Summer numbers can be increased greatly with migrants from the continent. This butterfly over-winters as a chrysalis with the first adult brood appearing from early April onwards. Eggs are laid in May and June with the second brood emerging from mid July onwards. By early October, all the caterpillars from the second brood are turning into chrysalises in which the butterflies hibernate over winter. In good years there may be a third brood. The Small White caterpillars feed on the same food plants as those of the Large White and, like them, they can do very considerable damage top cabbage crops.

Where to look for it

Specimens are likely to be seen anywhere as they roam around looking for breeding sites and mates. They frequent all the open, more sheltered sites in the Citys LNRs and are commonly seen in parks, gardens and lanes.

Distribution and status

Very common and widespread throughout the city.

When to look for it

Adults are in flight most of the year from early April to mid October with only a short break, during late June and early July, between the two main broods.

Similar species

The Small White is separable from the Large White, Pieris brassicae, by is noticeably smaller size. The Green-veined White, Pieris napi, and the female Orange Tip, Anthocharis cardamines, can be easily distinguished from the Small White by their dusky veining and marbled underwing markings respectively.

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