Pupa. Length 2.2— 30.0 mm. Tracheal gills absent; anal appendages 

 absent; if present, they are narrow, with few setae (5—7) or (Stenopsychidae) 

 short and cylindrical, rounded apically, with 29—31 short setae; the pupa is 

 large in this case, with long antennae curled around the posterior end of the 

 body. 



Mode of life and habitats. Microphagous, algophagous, rarely 

 (Rhyacophilidae) predaceous. 



Distribution. Cosmopolitan. 



I. Family RHYACOPHILIDAE Stephens 



Full-grown larva. Larvae vary in size and morphology. Length 

 8.5—30.0 mm. Mandibles without teeth or with a few large teeth. Pronotum 

 sclerotized; meso- and metanotum membranous. Abdomen more or less 

 209 dorsoventrally flattened or almost cylindrical in the middle; gills often 

 absent; if present, they are of varying form. 



Dorsal sclerite of segment 9 relatively large. Section "a" of anal legs 

 absent; sclerites "b" and sometimes also sclerites "c" of some forms have 

 long processes. 



Larvae without case. 



Pupa. Length of pupa 8—20 mm. Labrum short, rounded laterally. 

 Mandibles slightly curved, with 2—3 large or small teeth. Midlegs strong, 

 natatorial, with a row of dense setae on tarsal segments; claws of all legs 

 large, hook-shaped. Anal appendages absent. The pupae are situated in 

 closed, thick, elastic and fluid-filled cocoons which are weakly attached 

 anteriorly and posteriorly to the cavelike case, which is oblong, dome-shaped; 

 it consists of small stones or large sand grains which are connected with 

 strands of tissue; they are attached to the substrate at the margin of the 

 case; there are numerous small openings between the stones through the 

 case wall which ensure a rapid flow of water in the case. 



Mode of life and habitats. The species of the family pre- 

 dominate in small cold or cool brooks and rivulets, from the snowline in the 

 mountains to the plains, where they are usually restricted to hilly landscapes 

 and spring regions; they also live in large turbulent mountain streams; they 

 avoid large rivers in the plains and slowly flowing rivers and rivulets 

 overgrown with plants. 



Distribution. Throughout the USSR, mainly in mountainous regions. 

 They also occur in Europe, Asia, America and Australia. 



Key to Subfamilies 



Full-grown larva 



1 (2). Frontoclypeus of characteristic form, with deep lateral notches in 

 the region of the tentorial pits; the forelegs differ little from the 

 mid- and hind legs in size and form; claws are normally developed; 



gills sometimes present. Widely distributed in the USSR 



1. Rhyacophilinae Ulm. 



2!5 



