Revnivykh, 1937:267-273). The important role of Trichoptera in the food of 

 the Amur sturgeon (Acipenser schrencki) has been known for a long 

 time; large numbers of caddis flies, mayflies, stoneflies and Diptera cover 

 the stones and tree stumps; these insects have obtained the popular name 

 of "sturgeon food" on the Amur (Soldatov, 1914-1915:238-239). In the 

 Zoological Institute collections, there is a sample of about 200 specimens 

 of large larvae of Aethaloptera rossica obtained in 1912 by 

 Soldatov from the stomach of a sturgeon from the Amur. The rich food 

 supply on the bottom of the large rivers of Russia can be inferred in summer 

 from the multitudes of adult mayflies and caddis flies seen taking wing 

 (see p. 168). 



Trichoptera abundantly inhabit the stony bottom of the littoral of large 

 oligotrophic lakes and clean cold-water mountain brooks and rivulets; they 

 are, therefore, a constant part of the food of Thymallidae and Salmonidae. 

 Salmo trutta morpha fario, the Amu Darya trout (S. trutta 

 oxianus) and Thymallus thymallus feed on larvae and adults of 

 Trichoptera and other insects. These fish jump out of the water to catch 

 the adults or collect them from the water surface when they hatch or lay 

 eggs. In the rivers of the Kola Peninsula, e. g., the Mesna River 

 (Svetovidov, 193 6:234) the European grayling frequently feeds on Trichoptera 

 (relative frequency = 25%); the same was observed in the Narva River 

 (Arnold, 1912:56-57). In Lake Teletskoe, Trichoptera constitute 48.8% of 

 the food of Thymallus a r c t i c u s, the stomach of which is sometimes 

 filled with larvae of Dicosmoecus palatus; this species swallows 

 the larvae together with their massive cases (Solomonovskaya, unpublished 

 data; Lepneva, 1949:111). In the Yenisei and its tributaries, to 44% of the 

 food of the Siberian grayling consists in some localities of Trichoptera, 

 including species of Hydropsyche, Leptoceridae and Limnophilidae 

 (isachenko, 1916:32— 47; Romano va, 194 8:1 86). Thymallus arcticus 

 baicalensis and Th. arcticus baicalensis infrasubsp. brevi- 

 pennis feed also on Trichoptera which are found in large numbers on 

 stones in the open littoral of the lake (Kozhov, 1934:119, 123—125; Berg, 

 1948:426; Svetovidov, 1931:72). Th. arcticus grubei constantly feeds 

 on Trichoptera, which constitute 0.8-— 27.3% of its food; in the Amur, this 

 species feeds on larvae of the species of Rhyacophila, H-y d ropsyche 

 neyae, Macronema radiatum, Goer a sp. and Leptoceridae 

 (Klyuchareva, 1952:368-370). 



Trichoptera are an important part of the food of many whitefish. In the 

 Ukhta lakes of Karelia (Upper, Middle and Lower Kuito) Trichoptera are 

 often predominant in the food of Coregonus lavaretus karelicus. 

 Young specimens weighing 0.2— 0.6 kg (3—4 years old) feed mainly on small 

 larvae of Leptoceridae (Oecetis lacustris, Leptocerus cinereus); 

 as many as 192 specimens have been found in a stomach; the solid cases 

 of Oecetis pass through the intestine of fish almost intact. Large white- 

 fish, 5—12 years old and weighing 0.6—1.4 kg feed on large larvae; they 

 prefer Phryganeidae (Ph ry gane a st r i at a, Ag r y pn i a obsoleta), 

 which they swallow together with their cases covered with plant fragments 

 (which become much changed in the intestine of the fish); one often finds 

 176 more than 50 large larvae (sometimes even 295 specimens) in the stomach 

 of 1 fish. Whitefish rarely swallow larvae of A. pagetana and Molanna 

 angustata; the thin wings of the case of Molanna are destroyed in the 



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