which rises in shallow water to 20—27° (Levanidova, 1951:533). N. N. Konakov 

 found in summer 194 6 larvae of Limnophilus rhombicus and 

 Molanna angustata in the fumarole zone of the South Kurile volcanoes, 

 on Kunashir Island, near Tomari [on Sakhalin], in the nonfreezing Lake 

 Honto, with fumaroles opening at the bottom of the lake; the larvae were 

 found on the coarse -gravel littoral (M. angustata in large numbers); 

 both species are widely distributed eurythermal forms (Konakov, 1956:169). 



Eurythermal and stenothermal forms are not uniform ecologically; the 

 groups of species are restricted in temperate latitudes to different thermal 

 ranges in summer; the upper and lower limits of the thermal range in 

 summer are not as important as the duration of the summer maximum, i. e., 

 the average summer temperature. The life conditions of eurythermal forms 

 in temperate and high latitudes in winter (water temperature near 0°) are the 

 same as those of the stenothermal forms. 



The eurythermal forms include species restricted to water bodies with 

 wide yearly fluctuations of water temperature. Such forms are some 

 genera of Polycentropodidae and a number of genera of Hydroptilidae 

 (Annulipalpia) in the USSR; in the Integripalpia, most species of the family 

 Phryganeidae; the tribe Limnophilini and some other groups which live in 

 stagnant and slowly running water belong to this group. 



The inhabitants of large rivers and some inhabitants of the surf zone 

 of lakes, e. g., some species of Hydroptila, Hydropsyche, Cheuma- 

 topsyche, Neureclipsis and Leptocerus are a transitional group 

 between eurythermal and cold-water species. 



109 Light 



Light, an important factor in the life of caddis fly larvae, is especially 

 marked in the first stages of life when the larvae of many phytophilous 

 species show a positive phototaxis. Strong light disturbs the larvae in the 

 later stages, and they move to zones with less illumination, which is 

 characteristic for most adult caddis flies. 



The tendency to avoid strong illumination induces the larvae of many 

 rheophilic species in cold springs and brooks to enter more or less deeply 

 into caves as stygoxens. There are no stygobionts in the order Trichoptera; 

 the status of Wormaldia subterranea described as a sty gobiont is 

 doubtful; the Rumanian specialist of Trichoptera Boto^aneanu considers this 

 species as identical with W. triangulifera, which is a crenobiont widely 

 distributed in springs of Yugoslavia, Rumania, Bulgaria and Italy 

 (Botosaneanu, 1959:37). 



Several species of Stenophylax, Mesophylax and Micropterna 

 were considered as stygophiles which are common in caves in central, 

 western and southern Europe; the group of stygoxens is larger in these 

 water bodies, including a number of common, widely distributed brook 

 species; the following stygophiles of the fauna of Western Europe occur in 

 the USSR: Stenophylax permistus, Micropterna nycterobia, 

 M. testacea and M.sequax; the following stygoxens of Western Europe 

 occur in the fauna of the USSR: Rhyacophila septentrionis, 



100 



