Charles Aubrey Ealand, Animal Ingenuity of To-Day, Philadelphia, J.B. Lippincott Company, 1921, pp. 80-82.

Some of the caddis-fly larvae, like those of the tiger-beetle,are flesh-eaters ; they also construct lairs but they live in water and not in the ground. The homes of these water-dwellers are so diverse that we cannot describe them all in detail. Two species cut green leaves into almost rectangular pieces and fasten their edges together, so as to form complete tubular or rectangular mantles, as the case may be. Another common species places short lengths of stick transversa-ely across one another, and fastens them together to form its spiky home. Third constructs a house of small shells, some of which still contain their owners who are carried about wily-nily by the caddis larva. Still another builds a tube of fine sand.
As this list could be continud to considerable lengths, let us mention a little point of interest before describing two of the most extraordinary larval houses to be found amongst these adept house-builders. The caddis larva must needs be something of an engineer, or should we say a physicist, as well as a builder. His home must be light enough to be moved freely from place to place, yet not so light that it will float in water. An examination of a few of these larval cases will show which are absolutely ruined from an architectural point of view.
Beautiful built, in the main, of sticks, or shells, or pebbles, or sand, or whatever material is most favoured by the particular kind of larva, each item in the structure being of approximately the same size as all the others, yet the whole appearance of the case is spoiled by the fact that a large pebble or shell is affixed to one side of the case. These eyesores are not without their uses ; they serve as ballast for the caddis for the caddis home ; they present the little building from flating to the surface of the water.
And now for the more ingenious caddis dwellings. There is one kind of larva which, forsaking the conventional tubular case, builds one of sand exactly like a snail shell in appearance. So close is the ressemblance between the homes of these two quite unrelated creatures that the caddis dwelling for long puzzled naturalist, one of whom actually described it as a new kind of snail. Curiously enough, the home of a minute marine worm closely mimics a snail shell ; the little creature is often found in hundreds attached to the common bladder wrack. …/…