Two years ago (1909) an experiment was made, under very favourable conditions, to “naturalize” a colony of this fine butterfly at Easton, near Dunmow, in Essex, the property of Lord Warwick. Lord Warwick and Professor Meldola laid down a large number of chrysalids which duly hatched, and, although the surrounding marsh land had been liberally stocked with the food-plant, yet no eggs or larvæ were found after the butterflies had passed their season, nor have any been seen since.
Doubtless the butterfly has many natural enemies, and when we consider the draining, burning, and rush-cutting that go on in these fen lands, it will be apparent that the time cannot be far distant when an effort will need to be made, such as at Wicken, to provide “Cities of Refuge,” for many of our rare and persecuted little friends. I speak for birds, butterflies, flowers and ferns. An educated public taste would do more for them all than any amount of Acts of Parliament.
The Swallow-Tail measures fully 3 inches across the expanded wings; the prevailing tint is a pale primrose yellow, with bars and masses of black, the latter powdered with yellow scales on the fore-wings, and with pale blue on the hind-wings. There are also two red eye spots on the inner angle of the hind-wings near the tails. The under side looks not unlike a washed-out version of the upper, with a little more red on the hind-wings.
The caterpillar, too, is very beautiful, being green in colour, belted with black, and the black is studded with red spots. It thrives well on various members of the carrot family—carrot, parsley, fennel, celery; it has occasionally been found feeding on the common carrot leaves in rural gardens in neighbourhoods where the insect abounds.
The chrysalis, in which form the insect passes through the winter, is hung up in quite the orthodox manner, belted round the back and attached at the tail. If you should find chrysalids in this position during the winter months and wish to remove them, cut away the whole support, and set them up again in your hatching cage, as you found them. Always avoid unnecessary handling of these delicate objects.
There are certainly two, and probably three, broods during a favourable summer, so this butterfly may be captured from May to August. Its headquarters are in the Fen counties of Cambridge and Norfolk, and it is found in many similar localities in fewer numbers.
Black-veined White (Aporia Cratægi), [Plate I.], Fig. 2.—This is one of the rarest of our butterflies, though why it should be so is rather difficult to say. As it feeds upon hawthorn in the larval state the puzzle is all the greater, as a commoner or more widely distributed plant it would be hard to find. It may be also found on blackthorn, cherry, plum, apple, and pear. It is not difficult to distinguish this fine insect from all the other “Whites” on our list. The wings are rather thinly scaled; you can note this by holding the insect up to the light, and looking through the wing with an ordinary pocket-lens. Do the same with its near neighbour, the Large Garden White, and you will see a difference—the Black-Veined White is semi-transparent, while the other is quite dense.
The almost black network of veins is another unmistakable feature, as is the entire absence of a fringe to the wings. Two and a half inches is the average expanse of the extended wings.
