MAY BUTTERFLIES.
RETURNING warmth brings to life again, one after another, the creatures which have dozed in some natural chimney-corner through the dead season. In the month of May there are two distinct generations of butterflies abroad, one newly freed from the chrysalis, the other a spectacular flash-in-the-pan composed of insects saved over from the disastrous end of the summer before. A few, certainly, are awakened prematurely by a genial day nearer the outset of the year—I have caught a drowsy yellow Brimstone on the border of a Chiltern beechwood so early as the first of February and seen a Lesser Tortoiseshell fluttering in the draughty, sunless streets of Eton during the third week in March. But it is in early May that these hibernated butterflies are to be seen in numbers, and when these Rip Van Winkles die at last, towards the end of the month, none appear to take their places. There will be no more Peacocks, no more Tortoiseshells, no more Brimstones till the new stock is ready about the beginning of August.
It cannot. be said that the butterflies which have cheated death through the winter by the device of imi- tating him look so splendid as the August generation. They have often a faded, almost decrepit appearance, like specimens from a museum come to life again. They are utilitarian creatures, preserved simply for the purpose of laying the eggs out of which the next brood will spring ; when their work is done they retire decently from the scene.
It is in May also that the largest and noblest of English species is first seen on the wing—the majestic Swallowtail. It was not always simply an inhabitant of the East Anglian marshes, but used to be seen in Sussex and even along the Thames. The corpulent caterpillars were found year after year " in osier beds in Battersea Fields," which have long ago been drained and sophisticated into the shape of a metropolitan park. There is no logical reason why it. should not be common with us even now, since it includes among its food-plants the ordinary carrot and the common fennel, and is to be found in the most unex- pected places all over the Continent. I have actually seen it dancing up and down above the very edge of the cliffs near the Fishermen's. Church on the bill above Dieppe, not sixty miles from the opposing cliffs of Beachy Head across the Channel. For such an insect that is not more than a couple of hours' flight With a fair wind ;: certainly it would make the crossing on its yellow-and- black fantastically angular wings more rapidly and with less discomfort than the passengers on a cross-channel steamer.
There is a strong temptation to believe that the Swallow- tail could be successfully reintroduced in parts of the south of England. At any rate, I have an ambition sometime to put the matter to the test by buying up an ample supply of chrysalids and allowing them to hatch out in Amberley Wildbrooks, between Arundel and Pulborough. Formerly, if Norfolk felt inclined to boast about its Swallowtails, Sussex did not need to take second place, but now they have all been exterminated in Sussex and left Norfolk the monopoly. The experiment, of course, might fail. In fact, an enthusiast who once released hundreds of specimens near Matlock, was quite unsuccessful in the venture. But then Matlock seems a most outlandish place to choose for the introduction of a fenland butterfly ; Pulborough, we know, was suitable eighty years ago.
Since the Swallowtail is the largest British butterfly, and one of the most handsome, its re-establishment in the south would be a great achievement. But it would be extremely unpopular with some of the more fanatical entomologists. They make it an article of faith to dis- countenance and oppose any deliberate human interfer- ence with nature, and they refuse to make any distinction between reviving an ancient member of the fauna which has fallen on bad times and importing some destructive novelty from America. The introduction of alien species is certainly a perilous practice and ought to be forbidden, but replacing a variety destroyed by the action of man is quite a different matter.
One does not look for scent in a caterpillar, but the Swallowtail in its larval state has a very strong smell, which has been compared to that of a pineapple and enables it to be located in rank grass. Near the Rhine I have seen Swallowtails flitting among the thistles on bare, dry, sandy soil hundreds of yards from the river ; the real question on which everything depends is whether it is simply the British race which prefers to confine itself to the marshes, or whether the climate or some other outside cause is responsible.
It is a tantalizing thing that England, having only sixty butterflies compared with two hundred in France, should suffer an added handicap in that the most mag- nificent kinds, which are common across the Channel, are comparative rarities here. The glorious Purple Emperor, which has a habit of soaring above oak-forests and a notorious weakness for a feast of putrefying stoats, and the rich, velvety Camberwell Beauty, are two principal ornaments of the British list which I have only succeeded in finding abroad. Camberwells, in fact, have often not been seen at all in England for two or three seasons running, and they were never more than rarities.
Of the really well-known butterflies the most typical of May is the Orange-tip. In some years it has appeared considerably earlier ; in the phenomenal Orange-tip season of 1920 it appeared near Tunbridge Wells before March was out, and by mid-April there were plenty. But normally, its career as a butterfly coincides almost exactly with the month of. May. Only the male has the brilliant characteristic orange wing-tips, yet it seems in a country walk as if three out of every four of them display it. Clearly the females are in a minority.
The beautiful little Green Hairstreak, another May butterfly, is one of the most.perfect examples of protective colouring to be found with us. On the upper surface, with the wings open, it is all green ; suddenly it shuts up and is turned into a frail fragment of brown, inconspicu- ous to the point of invisibility. That is the colour-scheme which Mr. Richard Kearton found the best when he made a reversible suit and cap, green one side and brown the other; to wear for nature photography. This diminutive butterfly is not at all difficult to approach, but exceedingly elusive to follow ; its sudden disappearances often frustrate the keenest eye. Yet it is not very common,- and in some parts absolutely unknown. It cannot be said that protective coloration has made many fortune's among our British butterflies. Of the commonest kinds almost all—the Large and Small Cabbage Whites and the Green-veined, the Tortoiseshell, Red •Admiral, Common Blue, and others—cannot by any stretch of the imagina- tion be called protectively coloured. The Meadow'Brown certainly is, and the Peacock may be admitted because it generally shows the sober underside of its wings to the world when at rest. But most of the dingy skulking kinds are repaid for their timidity by being scarce. In fact the real rarities, the prizes of butterfly-hunting, are with a few brilliant exceptions a very poor set compared with the commonest sorts. The butterfly is a revolt against the drabness of the caterpillar, and the more brilliant it is the more- it normally flourishes under the working of that great unexpounded law of nature and humanitythe law of the Survival of the Brazenest.
E. M. N.
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