J.G. Wood, The fresh and salt water aquarium, Londres, G. Routledge, circa 1873, p. 137-138.
In the accompanying illustration may be seen specimens of cases which have been selected from a large collection. Fig .a is made of little bits of stone, while fig. a exhibits two specimens of the curved sand cases which have arready been mentioned. Fig.e is a peculiarly good specimen of a case which is formed of bits of grass-stems cut to measure, and ingeniously set spirally, so as to leave a tubular aperture in the centre, in which the little architect lives. At fig. b is another case, made of fragments of decayed wood ; and at d is a singularly ingenious one, made of scraps of grass arranged cross wise over each other. When first found, the grass was stil, green, but in proces of time it became dry withered, and almost colourless. A somewhat similar specimen is seen at fig. 5 on Plate XI. But the grass is mixted up with other materials, and is not so regularly arranged.
At fig. f is an example of a kind of Caddis-case that os often found and which is composed of small shells, mostly belonging to the genus Plonorbis. Two other examples may be seen on Plate XI., figs. 6 and 7. In making these cases, the Caddis-worm is by no means particular as to the shells, and is just as likely to use those which have living occupants as those which the little molluscs have died.
The young aquarium-keeper is strongly advised to procure some caddis-worms, and to watch them at work. They are most interesting creatures, and well repay the trouble of examination. If they are quietly ejected from their homes, and supplied with fresh materials, they will soon set to work to build fresh habitations, and by a judicious regulation of the supply of material, they can be forced to build cases of all sorts of substances, and to do so in such a manner as to produce a kind of pattern. Brilliant substances, such as fragments of coral, coloured glass, and sands, china, shells, straws, and so forth, have been supplied to the Caddis-worms, and have been used in the formation of their new homes.