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Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterflies of Britain & Europe
 
Green-veined White
Pieris napi LINNAEUS, 1758
Family - PIERIDAE
subfamily - PIERINAE
Tribe - PIERINI
 
 introduction | habitats | lifecycle | adult behaviour
 
Green-veined White Pieris napi, 2nd brood female, Stockbridge Down, Hampshire, England
 
Introduction
 
This is a widespread and common species occurring throughout Europe, temperate Asia, and at high altitudes in the Atlas mountains of north Africa. It also occurs in North America, where it is known as the Mustard White.
 
When seen in flight it can be confused with the Small White Pieris rapae, but while the Green-veined White has a lazy flight, usually fairly close to the ground, the Small White has a stronger and more directional flight pattern, and appears brighter and more conspicuous.
 
It can more easily be confused with the female Orange tip Anthocharis cardamines, which flies in similar habitats, but the differences are immediately apparent once the insect has settled - the Orange tip having a very distinctive mottled green and white underside quite unlike that of the present species.
 
The underside hindwing ground colour varies between the broods - being creamy in the spring brood, and white in the summer brood. There is also a degree of variation in the intensity of the grey markings on the upperside, which suffuse across the wings in some individuals, but are almost absent in others.
 
I have sometimes come across individuals that were very much smaller than average, for example at Noar Hill, Hampshire, in August 2004, and again at Stockbridge Down on 14th July 2007 I found singletons each no larger than a Chalkhill Blue.
 
Green-veined White Pieris napi, 2nd brood male, Hampshire, England
 
Habitats
 
The Green-veined White is found throughout Britain, with the exception of the Shetland Isles. It occurs in damp sunny and sheltered situations such as woodland rides, glades, riverbanks, ditches and dykes bordering hedgerows, and wet meadows.
 
Although it can sometimes be seen flying in open habitats such as grassland and heaths, it generally prefers to stay close to it's breeding sites.
 
Lifecycle
 
There are normally 2 generations in Britain, emerging in May-June and in early August, but there is occasionally a partial third brood which emerges in late September. The second brood is always the more numerous. At high altitudes and in the far north of Britain there may be just a single brood, emerging in June.
 
The pale straw-coloured eggs are laid singly on the undersides of leaves of various crucifers, including cuckoo flower Cardamine pratensis, garlic mustard Alliaria petiolata, hedge mustard Sisymbrium officinale and water cress Nasturtium officinale. The butterflies usually prefer to oviposit on smaller plants, growing in damp sunlit situations, often along the edges of woodland ditches and paths.
 
The caterpillar feeds solitarily during daylight, and is a dark slightly bluish green colour, with yellow spiracles. They can be found in June and again in August.
 
The chrysalis is difficult to find. It has various colour forms ranging from pale green to straw coloured, and is attached vertically with a silken girdle to living or dead stems in the vicinity of the foodplants. The summer brood pupae emerge after about 2 weeks, while those of the 2nd brood hibernate from October to March.
 
Green-veined White Pieris napi, 1st brood male, Hampshire, England
 
Adult behaviour

 

The butterflies have a weak fluttering flight, pausing regularly to nectar at low growing flowers including bugle, dandelion, cuckoo flower and herb robert in spring, while in summer they favour thistles and hemp agrimony.

 

In hazy conditions they bask on low foliage, with wings held slightly apart, so that the warmth of the sunlight is reflected onto the dark thorax, enabling the butterflies to gain energy rapidly. This "reflectance basking" is a habit featured also by Small Whites, Large Whites and Orange tips.

 

In late May 2008 I watched a female Green-veined White for several minutes while she searched for places to lay her eggs. Every 4 or 5 seconds she would alight momentarily on a leaf, "tasting" it using the olfactory sensors on her feet to check whether or not it was the correct foodplant for her future offspring. Surprisingly she tested ivy, bracken and oak leaves ( all very different visually from the crucifers she needed to locate ), a fact that would appear to indicate that sight plays little or no role in selecting plants for egg-laying.

 
                                                       
Almost every British and European species of butterfly is declining rapidly in numbers, due in most cases to loss or degradation of habitats.
 
You can help to reverse the decline by supporting conservation organisations which purchase and manage habitats as nature reserves, and which lobby government at local, national and international levels, often very successfully, to bring about changes in farming, forestry and urban development policies.
 
Please contact the conservation organisations for advice on how you can help protect British and European butterflies and their habitats. You may be able to offer practical help e.g. by monitoring butterfly populations or helping to manage nature reserves. Donations to these organisations enable them to employ ecologists and biologists. Even if you are unable to provide such help, merely having your name on the membership list can be a powerful tool for conservation organisations wishing to demonstrate the levels of support they have for their policies.

 

 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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