Richard Harlan, Medical and physical researches: or Original memoirs in médicine surgery, Philadelphia, Lydia R. Bailey, 1835, p. 436.

The nymph of water-moths, commonly called codbait, cover themselves, by means of gluten, with pieces of wood, straw, small shells, or gravel. It is necessary that they should always be in equilibrium with the water in which they live. To accomplish this purpose, when their habitations are too heavy, they add a piece of wood ; when too light, a bit of gravel.