As there are hundreds of moths that fly by night and sleep by day at seasons when there are perhaps only twenty species of butterflies flying by day and sleeping by night, it is strange that the sleeping moths are not more often found. Some kinds are often disturbed, and are seen. But the great majority are sleeping on the bark of trees, in hedges, in the crevices of pines, oaks and elms, and other rough-skinned timber, and we see them not. Some prefer damp nights with a drizzle of rain to fly in, not the weather which we should choose as inviting us to leave repose. Few like moonlight nights; darkness is their idea of a "fine day" in which to get up and enjoy life, many, like the dreams in Virgil's Hades, being all day high among the leaves of lofty trees, whence they descend at the summons of night, the--
"Filmy shapes
That haunt the dusk, with ermine capes,
And woolly breasts, and beaded eyes,"
The connection between character and bedtime which grew up from association when human life was less complex than now has some counterpart in the world of butterflies and insects. The industrious bees go to bed much earlier than the roving wasps. The latter, which have been out stealing fruit and meat, and foraging on their own individual account, "knock in" at all hours till dark, and may sometimes be seen in a state of disgraceful intoxication, hardly able to find the way in at their own front door. The bees are all asleep by then in their communal dormitory.
It would not be human if some belief had not arisen that the insects that fly by night imitate human thieves and rob those which toil by day. There has always been a tradition that the death's-head moth, the largest of all our moths, does this, and that it creeps into the hives and robs the bees, which are said to be terrified by a squeaking noise made by the gigantic moth, which to a bee must appear as the roc did to its victims. It is said that the bees will close up the sides of the entrance to the hive with wax, so as to make it too small for the moth to creep in. Probably this is a fable, due to the pirate badge which the moth bears on its head. But it is certainly fond of sweet things, and as it is often caught in empty sugar-barrels, it is quite possible that it does come to the hive-door at night and alarm the inmates in its search for honey.
[1] In the illustration it was impossible to photograph butterflies actually sleeping. They show their attitude, but not the degree to which the wings are flattened into a very acute angle.
[CRAYFISH AND TROUT]
About the middle of August, when walking by one of the locks on a disused canal in the Ock Valley, I saw a man engaged in a very artistic mode of catching crayfish. The lock was very old, and the brickwork above water covered with pennywort and crane's-bill growing where the mortar had rotted at the joints. In these same joints below water the crayfish had made holes or homes of some sort, and were sitting at the doors with their claws and feelers just outside, waiting, like Mr. Micawber, for something to turn up. To meet their views the crayfish catcher had cut a long willow withe. From the tapering tip of this he had cut the wood, leaving the bark, which had been carefully slit and the woody tip extracted from it. This pendant of bark he had made into a running noose, and leaning over the bank he worked it over the crayfish's claws and then snared them. It was a neat adaptation of local means to an end; for if you think of it, string would not have answered, because it would not remain rigid, and wire would be too stiff for the job.
Crayfish catching, until lately one of the minor fisheries of the Thames, is now a vanished industry. Ten years ago the banks of the river from Staines to the upper waters at Cricklade were honeycombed with crayfish holes, like sandmartins' nests in a railway cutting. These holes were generally not more than eighteen inches below the normal water line of the river. In winter when the stream was full fresh holes were dug higher up the bank. In summer when the water fell these were deserted. The result was that there were many times more holes than crayfish, and that for hundreds of miles along the Thames and its tributaries these burrows made a perforated border of about three feet deep. The almost complete destruction of the crayfish was due to a disease, which first appeared near Staines, and worked its way up the Thames, with as much method as enteric fever worked its way down the Nile in the Egyptian Campaign after Omdurman. The epidemic is well known in France, where a larger kind of crayfish is reared artificially in ponds, and serves as the material for bisque d'écrevisses, and as the most elegant scarlet garnish for cold and hot dishes of fish in Paris restaurants; but it was new to recent experience of the Thames. Perhaps that is why its effects were so disastrous. The neat little fresh-water lobsters turned almost as red as if they had been boiled, crawled out of their holes, and died. Under some of the most closely perforated banks they lay like a red fringe along the riverside under the water. Near Oxford, and up the Cherwell, Windrush, and other streams they were, before the pestilence, so numerous that making crayfish pots was as much a local industry as making eel-pots, the smaller withes, not much larger than a thick straw, being used for this purpose. Most cottages near the river had one or two of these pots, which were baited on summer nights and laid in the bottom of the stream near the crayfish holes. It must be supposed that they only use them by day, and come out by night, just as lobsters do, to roam about and seek food on a larger scale than that which they seize as it floats past their holes by day. That time of more or less enforced idleness the crayfish used to spend in looking out of their holes with their claws hanging just over the edge ready to seize and haul in anything nice that floated by. Their appetite by night was such that no form of animal food came amiss to them. The "pots" were baited with most unpleasant dainties, but nasty as these were they were not so unsavoury as the food which the crayfish found for themselves and thoroughly enjoyed, such as dead water-rats and dead fish, worms, snails, and larvae. They were always hungry, and one of the simplest ways of catching them was to push into their holes a gloved finger, which the creature always seized with its claw and tried to drag further in. The crayfish, who, like the lobster, looked on it as a point of honour never to let go, was then jerked out into a basket. They rather liked the neighbourhood of towns and villages because plenty of dirty refuse was thrown into the water. In the canalised stream which runs into Oxford city itself there were numbers, which not only burrowed in the bank, but made homes in all the chinks of stone and brick river walls, and sides of locks, and in the wood of the weiring, where they sat ensconced as snugly as crickets round a brick farmhouse kitchen fireplace. They were regularly caught by the families of the riverine population of boatmen, bargees, and waterside labourers, and sold in the Oxford market. A dish of crayfish, as scarlet as coral, was not unfrequently seen at a College luncheon. Possibly the recovery from the epidemic may be rapid, and the small boys of Medley and Mill Street may earn their sixpence a dozen as delightfully as they used to. Young crayfish, when hatched from the egg, are almost exactly like their parents. The female nurses and protects them, carrying them attached to its underside in clinging crowds. They grow very fast, and this makes it necessary for the youthful crayfish to "moult" or shed their shells eight times in their first twelvemonth of life, as the shell is rigid and does not grow with the body. The constant secretion of the lime necessary to make these shells is so exhausting to the youthful crayfish that only a small number ever grow up. In America, where a large freshwater crayfish nearly a foot long is found, its burrowing habits are a serious nuisance, especially in the dykes of the Mississippi. In those streams from which these interesting little creatures have entirely disappeared it might be worth while to introduce the large Continental crayfish. As it is bred artificially, there would be no difficulty in obtaining a supply, and it would be a useful substitute for the small native kind.
Sea crayfish, which grow to a very large size, are not much esteemed in this country. They are not so well flavoured as their cousin the lobster. But as river crayfish of a superior kind can be cultivated, and are reared for the table abroad, it might be worth while to pay some attention to what has been done in the United States to replenish by artificial breeding the stock of lobsters now somewhat depleted by the great "canning" industry. The method of obtaining the young lobsters is different from that employed to rear trout from ova. The female lobsters carry all their eggs fastened to hair-fringed fans or "swimmerets" under their tails, the eggs being glued to these hairs by a kind of gum which instantly hardens when it touches the water. For some ten months the female lobster carries the eggs in this way, aerating them all the time with the movement of the swimmerets. When they are caught in the lobster-pots in the months of June and July, the eggs are taken to the hatchery, and the ova are detached. As they are already fertilised, they are put into hatching jars, where in due course they become young lobsters, or rather lobster larvae, for the lobster does not start in life quite so much developed as does the infant crayfish. It is about one-third of an inch long, has no large claws, and swims naturally on the surface of the water, instead of lurking at the bottom as it does when it has come to lobster's estate. It seems to be compelled to rise to the surface, for sunlight, or any bright illumination, always brings swarms of lobsterlings to the top of the jars in which they are hatched. In the sea this impulse towards the light stands them in good stead, for in the surface-waters they find themselves surrounded by the countless atoms of animal life, or potential life, the eggs and young of smaller sea beasts. The young lobster is furiously hungry and voracious, because, like the young crayfish, it has to change not only its shell but the lining of its stomach five times in eighteen days. Unfortunately, in the hatching jars there is no such store of natural food as in the sea. The result is that the young lobsters have to eat each other, which they do with a cheerful mind, if they are not at once liberated. When they have reached their fifth month they go to the bottom and "settle down" in the literal sense to the serious life of lobsters.