Glossosoma boltoni, Plectrocnemia conspers a, Hydro- 

 psyche pellucidula.* 



The Trichoptera of caves in the USSR have been little studied; Steno - 

 phylax permistus from an adult insect was recorded as being found 

 in caves in the Crimea (Pliginskii, 1927:175). The larvae of the stygoxen 

 Plectrocnemia sp. have been found in caves in Transcaucasia 

 (Lepneva, 1940:83, Figure 2).** 



Current and soil 



As shown by the Russian name of Trichoptera ["rucheiniki" = inhabitants 

 of streams], the larvae of Trichoptera are adapted to life in running water; 

 different types and ecological groups of caddis flies occur in all types of 

 running water, from slowly trickling sources to turbulent mountain streams, 

 from calm brooks overgrown with vegetation to large rivers in the plains. 

 It could be stated that in a large river which is hypsometrically and 

 hydrographically diversified, the larvae of caddis flies occur throughout the 

 whole network of the river system, in the sources, brooks or snow streams 

 of the upper reaches and also in calm and small tributaries and in the large 

 main stream in the plains; they also occur in the floodland of the river. 

 The further from the origin of the current and nearer the regions of erosion 

 and of water accumulation, the more the character of the stream changes, 

 and with it, the ecological composition of the fauna of caddis flies, which is 

 adapted to life in such different conditions of running water. The speed of 

 the current in the habitats of different species of rheophilous larvae varies 

 greatly; the current may be so slow as to be hardly noticeable, as in a 

 110 trickling source or an arm of a steppe brook where it may run less than 

 1 cm/secj or it may be a turbulent stream with a force of 2— 3 m/ sec. 



The relation of a rheophilous bottom organism to the current is closely 

 connected with its relation to the soil of its biotope. 



To retain a steady position in the current of a stream, the caddis fly 

 larva must attach itself to an immobile substrate. This is achieved by the 

 development of adaptations which enable these insects which live as 

 lithorheophiles on the bottom to fulfil their principal biological functions: 

 feeding, respiration, growth, molting, construction of cases and pupation. 



The most stable ground (often the only ground in mountain streams) 

 on which the larvae can settle are stones; the specificity of the life of 

 caddis fly larvae in rapid streams is most marked in the fauna of stones. 

 The adaptations to life on stones in running water are mainly intended to 

 resist the force of the stream and are a complex of morphological and 

 physiological characters which enable the larvae to exploit the current for 

 other purposes, e. g., to collect food. The respiration of oxyphilous larvae 

 is best satisfied in the current and on stony ground. 



Details on the aquatic fauna of caves in Europe are given in the following publications: Ulmer, 1920; 

 Radovanovic, 1932; Moretti, 1936; Murgoci, Marcoci, 1955; Botosaneanu, 1959. 



These were possibly larvae of Plectrocnemia latissima Mart, (which is widely distributed in 

 illuminated water bodies in the Caucasus) which changed their coloration and other characters in the caves. 



101 



