Horatio Gordon Hutchinson, A fellowship of anglers Longmans, Londres, Green & Co., 1925, p. 92-95.
What is remarkable about this tiny larva of a few days from the egg, as seen through the microscope, is that it has already, baby as it is, formed itself its swaddling clothes, has already made its caddis, it is as wise now as ite ver will be all through its long life, and it lives for more than a twelve month. How long did it take man, after he had begun to be worthy of that distinctive title of Homo Sapiens, to learn to build himself a house ? We do not know. Nor even now will a human baby, left to his own devices, build himself a house or a suit of clothes at the age of three days, or fore three years. But a caperer baby will. It is true that the human baby will have, before they both come to an end, the better of him. For the human will learn, and the caperer will not-that is, in part the difference between the reasonning and the purely instinctive animal- but the caperer baby is far better fitted at the outside with weapons and will and wisdom to face his world than the human child. It is the natural condition of the caperer to be an orphan : both father and mother are dead before his birth, and he knows nothing of them. He has to fight with his own hand from the start.
I have written of the inability of the human child at three-whether three days or thre years- to build either house or suit of clothes, because caddis insects, the tribe to which the caperer belongs, may be said to do either the one or the other. There are species which make to themselves a case in which they move about, carrying it with them, as a snail his shell, so that a person who does not know the ways of aquatic things, looking at a clear pond, or an aquarium, may be a trifle startled, and may think that the foundations of his round world are becoming a little insecure, as he sees what look like a small longitudinal section of the floor of the pond beginning to move about.
This is the caddis, a case compounded of an envelope, spun about itself by the larva of one or the other of the caddis-flies, and strengthened with any trifles of woodwork or masonry, vegetable matter or mineral, which may be lying about handy for working in with it-a kind of reinforced concrete. The creature’s head and shoulders, with some legs action it moves itself about, taking the case with it. The case, because of this mosaic of little pebbles and the like, looks exactly like the floor on which it rests, and so, when it moves, creates the illusion of the floor’s moving in small sections. It looks quite uncanny. But the value to the larva of this caddis is manifest ; the caddis protects the inmate, both the making him so inconspicuous that only his movement reveals the case when it is lying among the precisely similar debris on the bottom, and it is also a stony and strong integument which is a sufficient shield from animals that are not big enough to swallow it whole. Even so, it may be somewhat hard of digestion, though we do find, by post-mortem examination of trout, small pebbles and grit inside them which probably come from the greedy habit of gulping down caddis and all for the sake of the larva within, as though a man should swallow oyster shell and all for the succulent bivalve’s sake.
A travelling caddis, thus used and worm, is to be regarded rather as a suit of clothes than a house. It has frequent additions tacked to it, as the inmate outgrows it, but otherwise its inhabitant does not quit it. There is another use of a caddis, however, and it is this that our friend the caperer makes- its use as a house from which the occupant goes forth on his lawful occasions, to get his meals, and so on, and returns to it when these are plished. That sort of caddis is a fixed residence its foundation secured by attachments to a relatively large stone.
And even as the baby caperer was wise, so soon as ever he came forth from the egg, and set immediately to work to make just that sort of home for himself that fits his need best, so, too, he shows a wisdom no less remarkable at the final stage of his larval life when he is full grown and is about to pass into the pupal sleep.