The black-veined white (Aporia crataegi (Linnaeus, 1758)).

This is the most abundant and omnipresent (and, besides, most simply coloured) butterfly almost everywhere in the forest zone and woody mountains of South Siberia. Almost every year these butterflies appear in immense quantities and fly throughout June, forming incredible congregations on wet ground and swarming at flowering plants. I also often observed these butterflies flying, separately from each other, not in swarms, in the same direction for days but don't know the reason for it. Their main foodplant is the bird cherry (Padus avium), and also Spiraea media, Crataegus sanguinea and other arboreal Rosaceae, in Yakutia, Amurland and Transbaikalia also Vaccinium uliginosum. The larvae live gregareously; they hibernate on silken winter nests on the foodplant branches. Being so abundant, they often almost defoliate small bird cherry trees, the pupae densely covering thick branches at 1-3 m above the ground. These butterflies copulate mostly when they are teneral, just having hatched from the pupae, which are placed usually close to each other. At the same time, most frequently observed and conspicupus element of sexual behaviour of these butterflies is female rejection to male attemnts to mate them, when a pair acquire a very expressive posture with the female widely spreading wings and lifting the abdomen, while male sits above it, moves the wing vigorously and hits the female's abdomen with its own. It looks like an antropomorphic mimic of human sexual intercourse, while in fact the already mated and inreceptive female just lifts its abdomen and spread its wing to prevent genitalic contact. is Thanks to such an expressive behaviour, many females loose most scales from their fore wings which appear almost transparent and look dark. Besides, hind wings of these butterflies are often brightly coloured (red or yellow) with flower pollen. There are very few fruit trees in Siberia and, besides, they are not suffer from this species, which almost does not seem to cause any substantial harm even for adult trees of its main foodplant bird cherry. But almost all local population traditionally beleive these are large whites (Pieris brassice, in Russian "kapustnitsa", i.e. "a cabbager") which eat their cabbage. In fact P. brassice penetrated into West Siberia only about 35 (first recorded by Y.P. Korshunov) and become abundant about 20 years ago, the cabbage suffering mostly from Pieris rapae.

The Berd' River right bank at the village Legostaevo, Iskitim District, Novosibirsk Region, West Siberia, Russia. 13th of June 1994.