Butterfly of month - Green-veined White

When most people talk about white butterflies, they visualise the Large and Small Whites, whose caterpillars ravage their carefully grown cabbages. The Green-veined White
is rather different. The females are likely to favour any Nasturtium in your garden for laying their eggs
and you may find the green caterpillars munching the leaves.

Butterflies emerging from their chrysalides in May and flying around the Blackwater Valley may have laid their eggs singly on a wide range of wild food plants such as Watercress, Lady’s Smock, Garlic Mustard and Hedge Mustard. The resulting caterpillars will have pupated in
June or early July and it is from
these chrysalides that you will
see the August butterflies.You can easily distinguish Green-veined Whites from Large and Small Whites when at rest by their especially attractive underwings on which every vein is accentuated by a dusting of dark scales. The veins have a slightly greenish tinge, hence the name Green-veined White.

The butterflies may be seen anywhere in the Blackwater Valley, although they prefer moist, sheltered places and are more likely to be flying in damp grassland and woodland rides. Populations of several thousands are recorded in Britain in a good year, but the drought of 1976 was very devastating for this species. So far this year, I have not seen any, but, as the August brood is normally much more numerous than the spring brood, I hope that we will see reasonable numbers this summer.

Watch out for their courtship rituals! Male Green-veined Whites usually emerge a few days before the females and patrol back and forth with a rather weak zig-zag type of flight. When one eventually finds a female perched nearby, it showers her with what could be called a ‘love dust’ which gives off a lemon verbena aroma so potent that evens humans can smell it. They may fly back and forth before she accepts his advances by landing and folding her wings. During mating, the female is smeared with an anti-aphrodisiac to deter other males from courting her. If you see a female settled with wings open and her abdomen held upright at 90°, she is trying to deter any further suitors.

From eggs laid in August, the caterpillars will emerge after a week or two. They grow rapidly and, after moulting four times, they pupate after about four weeks. Chrysalides, strangely, can vary in colour. Some are green and some are brown. They are often attached to plants, but may be found in sheds or summerhouses attached by their tail-hooks and silken girdles.

Peter Martin

Peter Martin is the author of Blackwater Valley Butterflies a handy A5-sized full-colour guide giving details about all the 32 different butterfly species that you are likely to come across in the Valley.                                                       More details >>>

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