Purple Emperor.—His Taste for Carrion.—Wood-pecker.—Blue and Small Copper Butterflies.—Buff-tip Moth.—Moths at Ivy.—Strange-looking Caterpillars.

One hot August day Frank and his faithful follower Jimmy were strolling arm-in-arm along the lanes to call for Dick. Presently they came upon him engaged in no very pleasant occupation. Holding his nose with one hand, with the other he was drawing along a dead dog by means of a long bramble twisted round it. The dog was highly odoriferous, and Frank and Jimmy kept at a distance while they asked him what he was doing that for.

"I saw a purple emperor butterfly flying round the top of one of the oaks in the park. It is impossible to catch it with a net, but I have read that these butterflies have a taste for carrion, and will come down to it; so I just fished about until I found this dead dog, which I mean to lay under the tree as a bait."

"Are you sure it was a purple emperor? They are very rare here," said Frank.

"Oh yes, I saw the purple of its wings shining in the sun, and it was so large, and it flew about the tops of the oaks, and then flew higher still out of sight."

The purple emperor is looked upon as the king of English butterflies. It is a large insect, with wings of dark purple bordered with white, which vary in colour like the material known as shot silk, and in the sunlight gleam most beautifully. The males only have this splendid purple gloss on their wings. The females, though larger in size, have wings of a dull brown. The purple emperor takes its station at the top of the tallest oak and rarely descends to earth. The female is more stay-at-home than the male, and is very rarely caught. The insect would be far oftener seen than caught if it were not for its habit of alighting upon carrion, and collectors take advantage of this low taste, and lie in wait for it, and catch it in the act. The caterpillar is a plump creature, with a tail running to a point, and a pair of horns or tentacles on its head. It is bright green in colour, striped with yellow down each side, and it feeds upon the willow. In the south of England this butterfly is not uncommon, but as you go north it becomes rarer.

Frank and Jimmy accompanied Dick to the park where the oak-trees were, keeping at a respectable distance to windward of him. The carcase was deposited beneath the tree where Dick had seen the purple emperor, and they sat down behind another tree to wait the course of events. Two hours passed away without any sign of the butterfly, but time was no object with the boys, who found it pleasant enough to lie on the cool grass in the shadow of the oaks, and listen to the murmur of woodland sounds. Squirrels and rabbits played about them, and birds fluttered in the trees overhead. The cushat uttered her sleepy moan, and then woke up and flew away on lazy wing to the corn-fields, whence came the sound of the sharpening of scythes. The rattle of the woodpecker tapping the hollow trees was the loudest sound which disturbed the silent, broiling afternoon. The three friends were stretched on the ground talking quietly, and half disposed to doze, every now and then casting glances at the dead dog. Suddenly down a lane of sunlight there fluttered a shimmering purple thing which settled on the carcase, and stayed there, opening and shutting its wings, and sending scintillations of purple light through the green shadows.

"There it is!" said Dick excitedly, and he got hold of his net.

"Don't be in a hurry, Dick; wait until it feels secure and gorges itself a bit," said Frank.

Dick listened to his sound counsel, and waited as patiently as he could for a few minutes, and then he raised his net, and with a single leap reached the spot where the carcase lay, and brought the net down over dog and butterfly together.

"I have got it!" he exclaimed.

"That's right; and you have got a lot of maggots in your net as well, and stirred up the stench most tremendously. Make haste and kill the butterfly and come away, or you will catch a fever," said Jimmy.

The gorgeous insect having been secured in Dick's collecting box, they went off in search of other prey. On a common just beside the wood they found abundance of the beautiful blue butterflies, which shone like flakes of summer sky, and also the small copper butterfly, which rivals the most brightly burnished copper in its sheen. These were playing about in the greatest abundance, the small coppers settling on a blue flower, or a blue butterfly on a red flower, forming most artistic contrasts of colour.

From its throne on the top of a tall nettle, where it sat fanning the air with its black, crimson-barred wings, Dick captured a magnificent red admiral, and shortly after another of the same species. Gorgeous as the upper surface of the wings of this butterfly is, the under side is quite as beautiful in a quieter way, with its delicate tracery of brown and grey.

While Dick was setting the butterfly in his box, Frank leaned against the trunk of an oak-tree, and as he did so he caught sight of a moth which was resting upon it. It was a large thick-bodied moth, and Dick on being appealed to said it must be a buff-tip moth, from the large patches of pale buff colour at the ends of its wings. Frank said,—

"I should not have seen that moth if my face had not almost touched it. Its colour suits the tree-trunk so admirably that it looks just like a piece of the rough bark. I suppose it knows that, and rests on the oak-tree for safety."

"Yes," said Dick; "I have read that many moths and butterflies are so like the substances on which they rest by day, that they can scarcely be distinguished from them, and of course there must be a meaning in it. The lappet-moth looks exactly like two or three oak-leaves stuck together, and its wings are folded in a peculiar manner, so as to keep up the delusion. There are caterpillars too which can stiffen themselves and stand out on end, so as to look like sticks."

"It is the same with birds'-eggs," said Frank. "Those which are laid on the ground without any attempt at concealment are of such a colour that you can hardly see them. For instance, take a partridge or pheasant. How like their eggs are in colour to the dead leaves of the ditch where they nest. The same with the lapwings, and all the plover tribe. Coots and water-hens' eggs are so like their nests, that at a little distance you cannot tell whether there are eggs in or not."

"I wonder," said Dick, "if birds take any pleasure in the prettiness of their eggs. If so (and I don't see why they shouldn't), there is a reason why birds which build in bushes and branches of trees should have pretty coloured eggs, as they have, and why birds which build in dark holes should have white or light-coloured eggs, otherwise they would not see them at all."

"That is a very ingenious theory, Dick, and it may have something of truth in it," answered Frank.

That night was a still, warm night, and the moths were out in abundance. As soon as it became dark they all went out with a dark lantern to hunt them, and they were very successful. As they were returning home they passed by an old wall covered with huge masses of ivy. Dick going close to it said,

"Do look here. There are hundreds of tiny sparkles. What can they be? Why, they are the eyes of moths. The ivy is covered with the moths, feeding on the flowers. Look how their eyes gleam." And truly it was a marvellous sight. When they turned the light of their lantern on them they saw that the moths were busy with a curious silent activity, flying from flower to flower, sipping their sweets.

"There are so many that I hardly know how to set about catching them," said Dick. "Many of these must be rare and many common."

"Sweep the face of the ivy all over with your net as rapidly as you can, and keep them in your net until we get home, and then we can kill and pick out all that you want," counselled Frank.

Dick followed his advice, and with a dozen rapid sweeps of his net he seemed to have filled it. Closing the net by turning the gauze over the ring, they walked quickly back to the boat-house, and carefully closing the door and window, they opened the net and let them all out into the room, and then caught them singly. In a couple of hours they found that they had secured about fifty specimens, comprising twenty different species.

During the summer a strange creature which fed on the potato plants had much frightened the country people, who thought it a sign of a coming plague. It was a large caterpillar, of a lemon-yellow colour, with seven slanting violet stripes on each side and a horn on its tail. The people in the neighbourhood of Hickling, knowing that Frank and his companions were fond of collecting such things, brought some to them, and by this means they became possessed of more than thirty specimens. They were the larvÆ of the death's-head moth, the largest of all our British moths. It is remarkable not only for its size, but for two other things, each of which is very curious. On its thorax it has a perfect delineation in white of a skull, or death's head, with a pair of cross-bones below it. In addition to this singular mark, it—and it alone of all our moths and butterflies—has the power of making a squeaking noise, which it does when it is touched or annoyed. How it makes this noise no one seems to know. At least there are so many conflicting opinions that the matter may be said to be still in doubt.

The boys fed the larvÆ on potato-leaves put in a box in which there was placed about six inches of earth. When the larvÆ had finished their eating, they dived into this earth and turned into the pupÆ state. In the autumn the perfect moths came out, but only about half of the number reached the final stage. The others died in the pupÆ state. However, Dick had plenty of specimens for his cabinet and for exchange.