Carl D. Duncan & Gayle Pickwell, The World of Insects, New York, MacGraw-Hill Book Company, 1939, p. 231.

But larval caddis-flies, which live in water and build nets or cases for themselves, would never be mistaken for caterpillars. This business of building cases, or houses, of sticks or pebbles and then dragging the dwelling about wherever the inmate goes is one of the most fascinating activities of water insects. The cases, too, are built in just as many fashions as there are different kinds of caddis-flies. Some have the sticks laid log-cabin fashion ; others lay them like scantlings on a roof ; others sticks pebbles together like the mosaic of a cobblestone chimney. Not all caddis-fly larvae build houses that can be moved. Some stick permanent shelters of pebbles to the sides of large stones, and from the opening in front they build a silken net that seines small foodstuff from the water of the brook.