As its name suggests, the adult green-veined white butterfly has white/creamy coloured wings with prominent greenish-grey veins particularly on the underside of the hind wings. The forewings have one or more dark spots on the upper side – the female usually two and the male just the one. Both have darker tips to the forewings. When the wings are closed, the underside of the wings appears yellowish.

Behaviour

This butterfly typically has two broods, the first, when adults emerge in late April, the second (which is always stronger than the first), with paler markings emerging in early July. In really good years, the second brood may emerge in late June and give rise to a third brood. More commonly, the caterpillar from the second brood forms a chrysalis in September and over-winters. In northern Scotland, there is only one brood which peaks between May and August. Newly emerged adult males frequently congregate on mud or other surfaces which are rich in nutrients.

The female typically lays its eggs on plants such as water cress, lady’s smock, garlic mustard, hedge mustard. The green-veined white, unlike some of its cousins, such as the small white, is not guilty of being a pest to cultivated cabbages; its caterpillars feed on other members of the cruciferae plant family.

It may be confused with the small white butterfly, which doesn’t have the greenish-grey veins and which is more likely to be found in gardens than the green-veined white. The small white has a really strong directional flight pattern, whilst green-veined butterflies tend to have a more delicate, gentle flutter.

Size

• Wingspan: 40-52mm
• Lifespan: three weeks (as adult butterfly)

Status

Common and widespread; of no concern

Distribution

The green-veined white is widespread throughout the British Isles, but is absent, or very rare, on the Shetland Isles and the highest peaks of the Scottish Highlands. This butterfly prefers damp locations, such as ditches, river banks, moorland and woodland edges. Sightings in parks and gardens are less numerous. It is probably the most widely spread butterfly in South West Scotland and also common on the Western Isles.

When to see

The butterfly of the green-veined white can be seen between April and late September. In South West Scotland, adults can be found anytime from April through to early October with the first brood peaking in May to mid June and the second brood in late July to August.

Facts

• The so-called green veins on the underside of the adults are, in fact, an illusion, created by a subtle combination of yellow and black scales bordering the veins.
• There are two sub species of green-veined white found in Scotland; the Pieris napi thomsoni which generally speaking has more yellow colour on the under wings and is a little smaller, and the Pieris napi Britannica which generally has more intense dark markings and a bright yellow underside to the hind wing.
• When a male mates, he injects a chemical, methyl salicylate along with their sperm. The smell of this compound repels other males, thus ensuring the first male’s paternity of the eggs.