Maurice Burton, Natural History of Britain, Londres, The Shell & Rainbird Reference Books, 1970, p. 226.
The caddis-larve, often called caddis-woms or stick-worms are of special interest because many of them build portable homes. The are know as « caddis cases » and are usually open-ended tubes composed of various materials such as sand-grains, leaf fragments, twigs and even tiny mollusc shells. The particles are built up on a silken enveloppe which the larva spins round itself before starting to build. The figure shows how neatly the caddis-worm fits the particles together and also how the pattern varies from species to species.