The Black-veined White has a wingspan of 51 to 70 mm (2.0 to 2.8 in). The upper side of both fore and hind wings is a translucent white boldly veined with black. The underside is similar in the male but the female has brown veining. This butterfly can be told from other members of the white butterfly genus Pieris by its distinctive veined wings.
The flight time of the Black-veined White is between April and July. The adults are quite social and their abundance varies greatly from year to year. The eggs are laid on the foodplant, usually a member of the rose family Rosaceae and often a tree in the genus Prunus such as the rowan (Prunus padus) or the bird cherry (Prunus padus), the hawthorns (Crataegus spp.) or the apple (Malus domestica). The eggs are yellow at first, darkening with age, and are laid in groups of 30 to 100. They take about three weeks to hatch. The caterpillars are greenish-grey with transverse banding and tend to remain in a group with a communal larval web. The caterpillars overwinter communally in a webbing tent with entwined leaves. Caterpillars feed close together on the leaves of the foodplant at first, before dispersing in the later developmental stages to other parts of the tree. The pupa is creamy-white, marked with black, attached by a silken girdle to a twig. The pupal stage lasts about three weeks.
Butterfly in Tuscany