Agrypnetes crassicornis, which is one of the few species occurring 

 only in water with a high mineralization (e. g., Lake Sevan) or in slightly 

 brackish water. The common freshwater species are absent in the Aral 

 Sea (salinity 9.5— 10.5%o ) and are replaced there by A. crassicornis 

 and the only halobiont caddis fly of the USSR, Oecetis intima, which is 

 known from the Caspian Sea in the region of Mertvyi Kultuk (Bening, 

 1934:194; 1937:172; 1940:95). McLachlan (1887: 154— 155) recorded the 

 larvae of Philanisus plebejus from the coasts of New Zealand and 

 Australia, living among rocks of marine shores in cases built of coral; 

 this species was recently separated as the family Philanisidae (Mosley and 

 Kimmins, 1953:131-132). 



The larvae of Trichoptera are very oxyphilic; they are highly sensitive 

 to the increase of organic matter in water, and they usually inhabit clean 

 water bodies such as springs, mountain streams, large oligotrophic lakes 

 (Lake Baikal, oxygen content 1 . 1 mg O2/ 1, mineral content = 92 mg/ 1; Lake 

 Teletskoe, oxygen content 3.5 mgC»2/l, mineral content = 68 mg/ l) and large 

 rivers in the plains. In eutrophic lakes, ponds, and calm streams overgrown with 

 plant, caddis flies live in places with little natural pollution, and zones with algae 

 with a favorable oxygen regime; they avoid the bottom in these water 

 bodies, which is strongly polluted with organic matter and sapropelic slimy 

 deposits; however, under conditions of natural pollution in regions with 

 algae, or in sandy- slimy regions, the larvae ofAnabolia, Molanna and 

 some species of Limnophilus occur. Kolkvits and Marson consider 

 several species of caddis flies as oligosaprobiotic. Caddis flies avoid 

 polluted water bodies. During a study of the relation between pollution and 

 various groups of aquatic animals in the vicinity of Kharkov, only a few 

 specimens of Orthotrichia tetensii were found in places with a high 

 pollution (Lepneva, 1929:609). 



105 Oxygen 



The high oxyphily of the caddis fly larvae is connected with their ancient 

 occurrence in running water. In the tube- inhabiting Integripalpia, this is 

 expressed by the undulating movements of the abdomen; under experimental 

 conditions, the frequency of these movements increases when the oxygen 

 content decreases; the free -living Annulipalpia do not make such undulating 

 movements in nature, but they make them under experimental conditions 

 in aquaria, and the frequency of the movements also increases in this group 

 with the decrease of oxygen content; the minimum oxygen content at which 

 the activity and movements cease ranges (according to observations on 

 species with different ecological characters) from 0.0 to 4.0mg/l: for 

 Potamophylax stellatus in stagnant water it is 0.7 mg/ 1; for Ana - 

 bolia nervosa in stagnant water 0.0 mg/1 and in running water 0.7 mg/ 1; 

 for Hydropsyche instabilis in stagnant water 3.3 mg/ 1, in running 

 water 0.9 mg/1; for Wormaldia subnigra in stagnant water 4.0 mg/ 1, 

 in running water 0.4mg/l. The species of Annulipalpia thus have a 

 markedly higher tolerance to oxygen deficiency in running water, and their 

 tolerance approaches that of Potamophylax stellatus (integripalpia) 

 in stagnant water. 



96 



