Green-veined white (Pieris napi)
|Size||Wingspan: 4 - 5.2 cm (2)|
Caterpillar length: up to 25 mm (3)
This widespread species is not threatened. It is not listed under any conservation designations (4).
The green-veined white is a familiar common butterfly (4). Despite the English name, the yellowish-green veins on the undersides of the wings are variable in colour, and provide excellent camouflage when this butterfly is at rest amongst leaves (4). In both sexes, the upper surfaces of the wings are yellowish white and the forewings have blackish tips. Males have a central dark spot on the forewings, whereas females have two (2). The caterpillar is well camouflaged with a green body covered with small hairs and fine black dots. Each black spiracle is surrounded by a yellow patch (3).
This common butterfly has a wide range throughout Britain, with the exception of Shetland (4) (3). It is widespread throughout Europe, but is absent from some islands in the Mediterranean. It extends into North Africa and across Asia and is also found in North America (4).
Typically found in damp vegetation where the foodplants occur (4). The foodplants are wild crucifers including garlic mustard (Alliaria petiolata), Hedge mustard (Sisymbrium officinale), water-cress (Rorippa nasturtium-aquaticum), cuckoo flower (Cardamine pratensis) and related species (3). Habitats include woodland margins, damp meadows, hedgerows, moorland and ditches (4).
As the green-veined white feeds on wild crucifers, it is not a pest of cultivated cabbages like some related white butterflies (5).
This is a double-brooded species (3). The first generation of adults emerge in April. The females lay their pale eggs singly on the undersides of leaves of small plants; the first brood females lay their eggs in May, and the caterpillars emerge after one or two weeks (4). The caterpillars feed on leaves for around one month and then pupate whilst attached to the stems of the foodplant (3). After two weeks, the second generation of adults emerge. The eggs of this generation are laid in July or August, and the pupae hibernate through the winter, with the adults emerging the following year (3). In very warm years a third generation may be produced, with the adults flying in September (4).
Although this species is not threatened at present, it has become less numerous in many parts of its British range. This is thought to be caused by the fact that many of its preferred habitats such as lush, damp meadows have been drained or destroyed over the last few decades. Furthermore, this butterfly’s need for damp conditions indicates that it may suffer if climate change causes drier and warmer summers (4).
Conservation action has not been targeted at this widespread species.
For more on this species see:
The Millennium Atlas of Butterflies in Britain and Europe (2001). By Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G. & Jeffcoate, S. Published by Oxford University Press. For more on butterflies and their conservation see the Butterfly Conservation website:
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- Double-brooded: (also known as ‘bivoltine’). Insect life cycle that takes 12 months to be complete, but involves two generations in that time. The first generation adults lay eggs that give rise to those of the second generation. The second generation overwinters either as an egg, larva, pupa or adult.
- Pupae: stage in an insect’s development when huge changes occur, which reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
- Pupate: the process of forming a pupa, the stage in an insect’s development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
- Spiracles: in insects, spiracles are pores on the body where the tubes forming the respiratory system, known as ‘tracheae’, open.
- National Biodiversity Network Species Dictionary (September 2003): http://www.nhm.ac.uk/nbn/
- Still, J. (1996) Collins Wild Guide: butterflies and moths of Britain and Europe. Harper Collins Publishers, London.
- Carter, D. & Hargreaves, B. (1986) A field guide to caterpillars of butterflies and moths in Britain and Europe. William Collins & Sons Ltd, London.
- Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G. & Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
- Buczaki, S. (2002) Fauna Britannica. Hamlyn, London.