cad·dis·fly also caddis fly 
(kădĭs-flī′)
(kădĭs-flī′)n.
Any of numerous insects of the order Trichoptera, having long antennae and four wings covered with short hairs, and usually found near lakes and streams. Also called trichopteran.
[Perhaps from obsolete cad (influenced by CADDIS), variant of COD2 (from the tube in which the larva lives).]