The Collaborative International Dictionary of English v.0.48:

Caddice \Cad"dice\, Caddis \Cad"dis\, n. [Prov. E. caddy, cadew;
   cf. G. k["o]der bait.] (Zool.)
   The larva of a caddice fly. These larv[ae] generally live in
   cylindrical cases, open at each end, and covered externally
   with pieces of broken shells, gravel, bits of wood, etc. They
   are a favorite bait with anglers. Called also caddice worm,
   or caddis worm.
   [1913 Webster]