numerous groups of caddis flies living at low temperatures in summer 

 (4—6°; 5—8°) or a relatively low temperature in summer (8—12°; 10—16°) in 

 springs, brooks and streams fed by springs or snow, in cold water bodies 

 in high mountains or at high latitudes, and in the open surf littoral of deep 

 cold-water lakes in which the littoral is constantly cooled by the wind, which 

 drives the surface water warmed during the day from the shore to the open 

 lake. 



The stenothermal species which live in brooks and streams fed by 

 springs or snow occupy large areas, from the spring or snow sources to the 

 limit where the summer temperature of the water, together with the increase 

 in depth and strength of the current, prevent the existence of these species, 

 which are adapted to the cold upper reaches of the stream. The upper 

 limit of the water temperature inhabited by a stenothermal species is 

 determined by the daily maximum in the lower zone of distribution of a 

 mountain species. The daily range of the water temperature is clearly 

 marked in shallow water near the coast on clear days with intense 

 insolation; the warming of the water mass mixed by the current is on such 

 days increased by the heated stones projecting from the water near the 

 shore and heating of the bottom of the stream. 



Strictly stenothermal are the Middle Asian mountain genus Himalo - 

 psyche (H.gigantea, Himalopsyche sp. "larva hoplura") from 

 Kirghiz, Dzungarian, Trans -Hi and Talass Ala-Tau and the Fergana Range 

 at an altitude of 1,700— 2,200 m; the larvae live in snow-fed and spring-fed 

 streams with a summer water temperature of 5—9°. Under similar 

 conditions and at a similar altitude we found in summer 1944 larvae of both 

 species in rivers in the Gissar Range: Obi Khil'fa (4.6—8.5° — 17—21 July), 

 107 Mai Khur (8.0-10.1° - 23 July), Sara Dzhou (6-7° - 22-30 May), Mazor Darya 

 (1.5-6.8° - 25-27 May); near the bank of a river at a depth of 20-40 cm, 

 at about 2,300 m near the health resort Khodzha of the Obi-Garm District 

 in August 1944 the daily temperature range in Mazor Darya was as follows: 

 15 August, 08.00-8°; 12.00-12.1°; 16.00-14°; 20.00-10.2°; 16 August, 

 08.00 — 8°. The maximum temperature in the habitats of H.gigantea in 

 Mazor Darya was 14.2° (12 August 1954); larvae of H. gi g ant e a were 

 absent lower in the stream, in the estuary of the Mazor Darya with a water 

 temperature of 18.5° at 17.00 on 9 August 1944.* 



Among the stenothermal species restricted to the mountains of the 

 Caucasus, larvae of Rhyacophila forcipulata and Rh. bacurianica 

 (Lepneva, 1946:330—331; 1962:62) live in the high mountains of the Trialet 

 Range (2,200— 2,300 m) in sources with a summer temperature of 5° in July 

 (l July 1939) and 9° in August (20 August 1953); at 1,700-1,800 m, larvae of 

 the species cited, together with larvae of other species of Rhyacophila, 

 live in the rivulet Bakurianka (issuing from the same sources), forming 

 large populations throughout the river at a markedly higher summer 

 temperature which reached 12° in June (15 June 1939), 10° in July (l July 

 1939), 15.5° (15 July 1953), 17.1° (18 July 1953, at 13.20); in shallow-water 

 arms of the brook, the temperature was 20° on 19 July, 11.30; in August, 

 the daily temperature of water in the brook fluctuates from 17° (3 August 

 1953 at 16.00) to 16° (24 August 1953), falling on some days to 14° (10 August 

 1953). The range of temperature of the cold-water mountain Caucasian 

 species is thus 5—17.1° in summer. 



* According to my observations. 



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