Abstract
The unknown larva of Rhyacophila osellai Malicky, 1981 is described, and its diagnostic features illustrated. Mature pupae of R. osellai were identified from the male genitalia, and were associated with the larval stage by the metamorphotype method. Because larvae of caddisflies are used in biological monitoring studies, descriptions of unknown larvae are important to improve the knowledge of relationships between larvae and water quality.