Charles A. N. Wauton, Troutfisher’s Entomology, An Elementary Treatise on Natural Flies, Londres, The Fishing Gazette, 1930, p. 20.
The larvae have peculiar habits in as much as that they build for themselves houses in which to live and take cover from their ennemies. Making a tube of spun silk, fully open at one end only, they attach to it small particles of stones, sand, or vegetable matter, sometimes one, sometimes the other, and sometimes all three. Some fasten their residences permanently to heavy stones, others leaves them free. The dwellers in fixed abodes come out to feed, but the others drag their cases with them wherever they go, never exposing more than their heads and legs. When danger threaten they hastily withdraw.