Livingston MacKinnon, The animal’s world, Londres, G.Bell & Sons, 1936, pp. 75-76.

I call it a coat, but perhaps you would rather call it a movable house, for the animal can withdraw completely inside it and shelter from its enemies in the pond: the enemies just see the sand-grains or the little bits of stick and they don’t guess that a living insect is hiding inside, so they go away and leave the caddis alone. If you very gently take a caddis out of its house and put it in a saucer of water with some tiny coloured beads or fragments of colours glass, it will make a new house for itself out of these things. I gave a caddis some red, white and blue beads the other day, and its house looked most patriotic when it was finished!
The house is always shaped like a tube, open at both ends; and, when the caddis
is walking, it’s head and its six legs stick out through the front-door.