The Green–veined White Butterfly, Pieris napi
The Green-veined White Butterfly, Pieris napi, is common throughout most of the British Isles, Europe, North America and parts of Africa and Asia.
The butterfly shows a preference for damp habitat but is one of the most widespread ‘white’ butterflies and commonly seen in both open countryside and gardens.
In good summers there may be three generations in the south of the UK.
The caterpillars feed on a variety of crucifers.
The Green-veined White butterfly has a max wingspan of c 50mm.
Both male and females have black wing tips and veining of varying intensity according to the generation.
The dark veining, the black triangles at the wing tips and the heavily veined yellowy underside of the hindwings are useful identification features.
The female has two prominent black spots in the centre of the forewing and in the first generation the veining is more pronounced than that of the males.
The male is generally less well marked with a single black spot which may be faint or missing in the first brood.
Other ‘white’ butterflies family Pieridae –
Other butterflies can be seen on the Butterfly galleries
The Green-veined White Butterfly caterpillar, Pieris napi
The caterpillars of the Green-veined White Butterfly are fully grown in 3-4 weeks and about 25mm long. The body is green with short, white hairs and yellow ringed spiracles.
A close inspection is necessary to identify the caterpillars of the Green-veined Butterfly from those of the Small White Butterfly – yellow ringed spiracles and lack of a yellow dorsal stripe being useful identification features.
Life cycle of the Green-veined White Butterfly
The butterflies are double brooded, sometimes with a third in the south, with the first eggs laid in early Spring.
Numbers of later generations butterflies may be boosted by continental migrants.
The female lays up to 60 eggs singly, mainly on the underside of leaves of the larval foodplant. The pale, yellow, conical shaped eggs are heavily ribbed and despite only being 1 mm long are fairly easy to spot on fresh green leaves.
The eggs hatch within about a week when the caterpillars are less than 2 mm long and pale yellow, becoming progressively greener with each moult.
Larval foodplants of the Green-veined White Butterfly
The caterpillars feed on a wide range of crucifers including some cultivated vegetables found in gardens and the open countryside.
In the wild larval plants include garlic mustard, hedge mustard, watercress, lady’s smock, charlock, and wild cabbage.
In gardens the butterflies lay eggs on crucifers in the Brassica family as well as Nasturtiums and Wall flowers.
The caterpillar secures its claspers to a silk pad before weaving a silken girdle around its body.
The colour of the formed chrysalis depends on its surroundings but is commonly green or brown, paler when fresh.
Early broods emerge within 14 – 20 days, with the latest broods over wintering as a chrysalis.
For those wishing to learn how to rear butterflies then the Green-veined White is a good species to start with.
The simplest way is to watch out for a female depositing her eggs and then pick the leaves with the eggs attached and place them in a rearing container.
The caterpillars hatch within about a week and are easy to rear on wild and cultivated crucifers
After 20-30 days the fully grown caterpillars will pupate either on the sides/top of the cage or on a plant stem.
Vegetable feeding damage of the Green-veined White butterfly caterpillar
Unlike the caterpillars of the Small White and Large White Butterflies, the Green-veined White is not considered a major pest of vegetables.
The damage caused when the caterpillars are small appears as small round holes in the leaf of the plant.
As the caterpillar grows the holes become larger but rarely are whole leaves damaged.
Black frass and holes in leaves are signs that an almost fully grown caterpillar is on the underside of a leaf.
How to protect the vegetables from the Green-veined White Butterfly caterpillars
The simple and most environmentally friendly solution is to prevent eggs being laid by covering the vegetables with a net having a maximum mesh size of 25 mm.
Care should be taken to ensure the netting does not rest on the vegetables as the butterfly will deposit her eggs through the mesh.
A more labour intensive way is to search out and scrape off the eggs and pick off the caterpillars.
Recommended Butterfly Books – Pocket Guide to the Butterflies of Great Britain and Ireland – Richard Lewington.
The Cornwall Butterfly Atlas – Watcher, Worth and Spalding
The Complete Guide to British butterflies – Margaret Brooks and Charles Knight.
Collins Butterfly Guide of Britain and Europe – Tolman and Lewington.