The little architect

A. Ackerman, First Book of Natural History, New York, Cady & Burgess, 1848, p. 221-222.

A very interesting class of grubs live under water, where they construct for themselves moveable habitations of sand, stones, shells, wood, and leaves, which are skillfully joined and cemented together. They are know to fisherman by the name of caddis-worms, and to naturalists as the larvae of a species of four-winged flies. One of these grubs forms a case of pieces of reed, grass, straw, or wood, cut into convenient lengths, which are carefully joined and cemented together; and to finish the case more completely, a broad piece longer than the rest is frequently added to shade the door-way over head so that it may not be seen from above.

One of the most singular instances of their skill appears in the structures, of which small stones are the principal material. They make a tube, the hole being about the size of the hollow of a wheat straw, and equally smooth and uniform. Although this tube is formed of small stones full of angles and irregular surfaces, yet the little architects, by patiently examining them and turning them round on every side, never fail to make the inside perfectly smooth. The under surface is also made smooth and flat, without any projecting angles, which might impede its progress when dragged along the bottom of a brook.