CADDIS-FLY and CADDIS-WORM, the name given to insects with a superficial resemblance to moths and referred to the order Trichoptera (q.v.) in allusion to the hairy covering of the body and wings. Caddis-flies occur in the neighbourhood of fresh water in which they lay their eggs, and their larvae (caddis worms) are aquatic. These larvae provide themselves with shelters (caddis-cases) made of particles of sand, sticks, leaves, etc., held together with silk which is secreted by the insects for that purpose. Should other materials be lacking, they will make their cases of glass beads. Thus concealed they crawl about seeking their food which is mainly of a vegetable nature. Before turning to the pupa the larva closes the orifice of the case against in truders, and the pupa when mature, after biting its way out, rises to the surface of the water to allow of the emergence of the per fect insect.