The Caddis-Worm

Whom shall I lodge in my glass trough, kept always wholesome by the action of the water-weeds? I shall keep Caddis-worms, those insects which clothe themselves with little sticks and other materials. They are among the most ingenious of the self-clothing insects.

The particular species of Caddis-worm I have chosen is found in muddy-bottomed, stagnant pools crammed with small reeds. It is the little grub that carries through the still waters a bundle of tiny fragments fallen from the reeds. Its sheath, a traveling house, is an elaborate piece of work, made of many different materials.

The young worms, the beginners, start with a sort of deep basket in wicker-work, made of small, stiff roots, long steeped and peeled under water. The grub that has made a find of these fibers saws them with its jaws and cuts them into little straight sticks, which it fixes one by one to the edge of its basket, always crosswise. This pile of spikes is a fine protection, but hard to steer through the tangle of water-plants. Sooner or later the worm forsakes it, and builds with round bits of wood, browned by the water, often as wide as a thick straw and a finger’s breadth long, more or less—taking them as chance supplies them.

It does not always use wood, however. If there are plenty of small, dead Pond-snails in the pond, all of the same size, the Caddis-worm makes a splendid patchwork scabbard; with a cluster of slender roots, reduced by rotting to their stiff, straight, woody axis, it manufactures pretty specimens of wicker-work like baskets. With grains of rice, which I gave the grubs in my glass pond as an experiment, they built themselves magnificent towers of ivory. Next to the sheaths of snail-shells, this was the prettiest thing I ever saw the Caddis-worms make.