caddis fly larvae and other aquatic invertebrates; large larvae of Phryga- 

 nea, Nemotaulius and Limnophilus are given to the nestlings 

 together with their soft cases (Pokrovskaya and Gerd, 1955:96—99). 



Fishermen widely use Trichoptera as bait; in some localities in the 

 European USSR, caddis fly larvae are called "shitik, " which is the name 

 of ancient light boats, the boards of which were tied with bast or leather 

 thongs. Adult Trichoptera are called "lipach" in the Lake Baikal region; 

 they are used to catch graylings and lenoks. 



The larvae of Limnophilus flavicornis and other species build 

 their cases of large detritus particles and cover them with shells of small 

 mollusks, often with the live mollusk inside; these species, therefore, may 

 be beneficial as they help control the carrier of fasioliasis, Galba 

 truncatula. Some caddis fly larvae build their cases entirely from 

 mollusk shells. A larva of Limnophilus flavicornis may use as 

 many as 70 live Galba truncatula for the covering of its case 

 (Bednarz, 1958). 



Trichoptera also cause damage. They shed their pupal exuviae during 

 the nuptial flight; these exuviae float on the water and may clog the filters 

 of municipal water pipes. For example, in Leiningrad in spring 1953, the 

 filters were literally clogged with pupal exuviae of Hydropsyche nevae 

 (E. E. Ruskina). Every year multitudes of this species hatch in the Neva River 

 (near Petrokrepost'). They appeared in especially large numbers on 

 18—22 June 1952; they formed clouds in the town, entering through the windows, 

 settling on food, and formed a thick layer on freshly painted walls and 

 window frames, causing considerable economic damage (according to 

 E. A. Migalina). 



The building of reservoirs and hydroelectric stations provided new 

 favorable habitats for rheophilic species of Hydropsychidae; they settle 

 on the walls of canals, where they build their larval cases, nets and pupal 

 shelters. The larval and pupal structures consist of solidly glued sand 

 grains and small stones; they form incrustations which grow rapidly, 

 narrowing the bed of the canal and often reducing the output of the power 

 stations by 10—20% (Tsuda, 1957; Tsuda and Hiro, 1955). 



We recommend the following measures to prevent large-scale development 

 of Trichoptera in canals: l) periodic scraping of the canal walls; 2) facing 

 the surface of the walls; 3) using electric current to prevent accumulation 

 of larvae; 4) painting the walls with a paint containing cuprous oxide; 

 5) using insecticides. The most effective measure is the use of a paint 

 containing cuprous oxide. 



Multitudes of adult Trichoptera appear in Canada, on the banks of the 

 Niagara River from near its source in Lake Erie and downstream for many 

 tens of kilometers. The mass flight of Trichoptera was extremely intensive 

 in August 1950; it began on the evening of 15 August and continued to 

 179 26 August. The swarms were so dense that over 6,800 specimens were 

 caught with 10 strokes of a net. The predominant species was Hydro - 

 psyche bifida, which formed about 80% of the Trichoptera. The next 

 numerous species were those of Cheumatopsyche, Neureclipsis 

 crepuscularis, Macronema zebratum. The insecticide used for 

 control was a 5%. solution of DDT (Petersen, 1952; Munroe, 1951). 



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