Charles McLlvaine, Outdoors, Indoors and Up the Chimney, Phliadelphie, The Sunday School Times Company, 1906, p. 86-88

What seem to be fixed cribs of grass, or tubes of silk, will come to life and move about inthe everlasting search for something to eat. A closer look wil tell that a larva (worm) has put out the forepart of its body from within a silken tube it has spun from its mouth, and is using its legs as if used to it. To protect itself, it has gathered bits of leaves or grass, built them log-cabin wise around its tube, and fastened them together with silk ; or it has built up grains of sand around its tube like the stones of a well-wall cemented them with silk, and lives comfortable safe within. One species covers its case with snail shells. When the snails are alive they hault the caddice-worm about. There is style for you- a worm with its carriage and snails !

Another species fasten pebble to the underside of stones with silken threads.