Robert Patterson, Introduction to Zoology for the use of Schools, Londres, Simpkin Marshall, 1846, p. 118.

The larvae of these flies, well known under the name of case-worms, or caddis-worms (Fig. 102), are to be found in every running stream, and almost in every ditch. Their habitation are extremely singular, and differ considerably, both in the materials employed and their external configuration. Some are formed of numerous little pieces of grass ans stems of aquatic plants cut into suitable lengths and placed crossways, forming a rude polygonal figure ; others are constructed of bits of stick, or grains of sand and gravel, cemented together ; and others, again, are composed of fresh-water shells, each containing its own proper inhabitant, « a covering, » as Kirby and Spence remark,, « as singular as if a savage instead of lothing himself with squired-skins, should sew together into a coat the animals themselves. » But, whatever may be the material employed the little builders contrive to make them, of nearly the same specific gravity as the water, so as to be carried without labour.