You cannot hope to see this splendid butterfly on the wing unless you visit its haunts during its season--May to August; but the pupae may be purchased for a few pence each from most of the entomological dealers; and if you obtain a few of these and watch them closely, you may be fortunate enough to see the perfect insect emerge from its case, and witness the gradual expansion of its beautiful wings. The pupa (Plate VIII, fig. 7) itself is a most beautiful object. Its colour is a pale green, and it is fixed to its support by the tail, and further secured by a very strong silk band. The larva (Plate VIII, fig. 1), too, is exceedingly beautiful. Its ground colour is a lovely green, and twelve velvety black rings mark the divisions between the segments. Between these are also black bars, all spotted with bright orange except the one on the second segment. A remarkable feature of this larva is the possession of a forked, Y-shaped 'horn,' that is projected from the back, just behind the head, when the creature is alarmed. If it is gently pressed or irritated in any way, this horn is thrust out just as if it were an important weapon of defence. And perhaps it is, for it is the source of a powerful odour of fennel--one of the food plants of the caterpillar--that may possibly prove objectionable to some of its numerous enemies. The food plants of _Machaon_ are the milk parsley or hog's fennel (_Peucedanum palustre_), cow-parsnip (_Heracleum sphondylium_), and the wild angelica (_Angelica sylvestris_); but in confinement it will also partake of rue and carrot leaves. 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--PIERIDAE 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 _Pieridae_ 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 larvae 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 Crataegi_)