An irregular way

Vernon S. Morwood, Wonderful Animals: Working, Domestic and Wild, Their structure, Habits, Homes and Uses, Londres, John Hogg, 1883, p. 57.

The larva makes a curious house for its protection; it is, in fact, a sort of tubular case made up very ingeniously of small stones, shells, fragments of the stems of water-plants, and similar things; these is fastens together by means of a glutinous silk, which also lines the tube. Numbers of these cases may be seen at the bottom of pebbly streams, out of the ends of which the head and feet of the larva may often be seen protruding, and moving about in an irregular way.