The caterpillar of this species may be found in the fens during the greater part of the summer. It turns to a chrysalis in the autumn, and remains in this state throughout the winter, attached to the stems of reeds in the vicinity of its food plants. The perfect
insect is first seen in May, and is more or less abundant from this time to the month of August.
Family—Pieridæ
This family, though known commonly as the 'Whites,' contains four British species that display beautiful tints of bright yellow or orange.
In many respects the Pieridæ resemble the last species. Thus the perfect insects have six fully developed legs; the caterpillars are devoid of bristles or spines; and the chrysalides are attached by means of silky webs at the 'tails,' and strong cords of the same material round the middle.
All the larvæ are also cylindrical or wormlike in shape; and their skins are either quite smooth, or are covered with very short and fine hairs, that sometimes impart a soft, velvety appearance.
The members of this family are remarkable for their partiality for certain of our cultivated plants and trees; and are, in some cases, so abundant and so voracious, that they are exceedingly destructive to certain crops.
The Black-veined White (Aporia Cratægi)
This butterfly may now be regarded as one of our rarities. At one time it was rather abundant in certain localities in England, among which may be mentioned the neighbourhoods of Cardiff and Stroud, also parts of Kent, Sussex, Hampshire, Huntingdonshire, and the Isle of Thanet; but it is to be feared that this species is nearly or quite extinct in this country. It is well, however, not to give up the search for it, and if you happen to be in one of its favoured localities of former days, you might net all the doubtful 'Whites' of large size that arouse your suspicions, liberating them again if, on inspection, they do not answer to the description of the species 'wanted.' This course becomes absolutely necessary, since the Black-veined White is hardly to be distinguished from the Common Large White while on the wing.
If you examine a number of British butterflies you will observe that in nearly all species the wings are bordered by a fringe of hair, more or less distinct. But the case is different with Cratægi. Here they are bordered by a black nervure, without any trace of fringe, thus giving an amount of rigidity to the edges (see [Plate I], fig. 2).