Charles Ottley Groom Napier, Tommy Try and What he did in Science, New York, D. Appleton & Cie., 1869, p. 243.

Numerous empty cases of the caddis-worm, also, which had attracted to themselves a covering of dead shells consisting of Limnae Planorbis, and other species, together with a few fragments of sticks. During the life of the animal nothing appears but its head and tail; it thus escapes many attacks from fishes and the larvae of water-beetles (Dytiscus) as it drags its soft and fleshy body along the bottom of its native pool. In the following spring, when I found the animals living in their cases, I noticed how some species appeared to prefer stone and shells, and ohers sticks, straws, and vegetable substance.