Vernon L. Kellogg, « Some water insects »,  The Western Journal of Education, San Francisco, juin 1899, p. 9-10.

Caddice-worms. Firmly attached to stones, especially large ones, in swift parts of the stream, may be found small cases (fig. 36 b) or houses composed of many small pebbles fastened together with silk. In more quiet places in the stream may be found either attached to stones or resting on the bottom, or sometimes floating in the water, elongate cases (fig. 37), an inch to two inches long, made of bits of wood fastened together with silk or bits od spine needles or even grass stems tied cleverly together by silken threads. Or tiny cornucopias (fig. 36 a) composed of sand grains, may be found. All these are the cases of the caddice-worms or case-worms, and the caddice-worm itself may be found snugly concealed in its case. Find and collects as many different kinds of caddices-worms cases as you can ; find cases with the head and fore part of the body of the worm projecting ; find cases moving, i.e., dragged by the slowly walking caddis-worm. Examine a caddis-worm carefully ; note its long, soft, grub-like body ; note thet the head and the front part of the body from which arise the legs, namely, that part of the body which projects from the case, has a strong, hard outer wall. What is the case for ? To protect the soft, defenseless caddis-worm from the many predaceous animals which live in the brook. Why is the head and front part of the body so much harder than the rest of the body ? Can you easily pull  the caddis-worm out of its case ? How does it hold itself so firmly in its cases ? By the pair of strong hooks (legs) which are located on the posterior tip of the body. Note that the front pair of legs (how many pairs are there ?) are longer than one would expect to find on such a worm-like insect ; what is the reason for this condition of the legs ? How does the caddis-worm breathe ?

Not all of the caddis-worms live in cases, and some which make cases do not remains in them all of the time, so that you may sometimes find caddis-worms crawling about on the stones. Some of these home-leaving caddis-worms  make tiny nets are « usually funnel-shaped, opening up-stream and in the center of them there is a portion composed of threadsof silk extending in two directions at right angles to each other, so as to form meshes of surprising regularity. It is as if a spider had stretched a small web in the water

Where the current is swiftest. » The caddis-worms which build theses nets live in rude cases on the under side of stones. The cases are composed of an inner silken tube partly covered with little pebbles.

All these caddis-worms are the young, or larvae, of caddis-flies (fig. 38), moth-like flying insects, with four wings covered with hairs, among which are distribued many flattened scale-like hairs. The antennae are very long and thred-like and the insects may be found fluttering among the foliage or alight upon it, at the brook’s margin.

Collect and put into the schoolroom aquarium a number of those caddis worms (in their cases) which you find in the quiet places of the brook. These many live in the aquarium and an opportunity thus had to observe their habits more closely and also, perhaps, to observe the manner of their transformation into winged adult.