Trichoptera(redirected from Caddis flies)
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(caddis flies), an order of aquatic insects that undergo complete metamorphosis. Caddis flies have two pairs of wings with reduced venation, one pair of filiform antennae, and poorly developed mouth organs. The body and wings are covered with hairs; the coloration is brown or yellowish brown. The body length is 1.5–25 mm, and the wingspread is 5–70 mm. Of the approximately 5,500 species of caddis flies, about 600 are found in the USSR.
Caddis flies have an interesting life cycle. Annular, cylindrical, or discoid gelatinous egg-clutches are deposited on underwater plants and rocks. After hatching, the larvae move about the bottom and soon start feeding and constructing cases or snaring nets. They molt four to six times. The campodeiform larvae of the suborder Annulipalpia have flattened abdomens and deep strangulations between body segments. The majority, mostly predators, live freely without cases; they construct snaring nets (Polycentropus), funnels (Neureclipsis), or chambers (Hydropsyche). The caterpillar-like larvae of the suborder Integ-ripalpia have cylindrical abdomens and superficial strangulations between body segments. They live in cases made from mineral or vegetable particles; the cases are in the form of tubes or, less frequently, little caverns.
Before pupation, the larvae of all species of caddis flies build themselves a case with openings for water circulation. At first the pupa lives in the case, but later it gnaws through the top with its mandibles and swims to the surface. It swims by mean of its second pair of long legs. The pupa finally crawls out of the water and is transformed into the adult fly.
The larvae of caddis flies live in the clear waters of lakes, rivers, and streams. Hence, they serve as indicators of water quality. Adults stay near the water, amid vegetation. The larvae are important as food for whitefish, grayling, European bream, tench, Eurasian perch, ides, and other fishes that feed on benthos.
REFERENCESMartynov, A. V. “Rucheiniki.” In Prakticheskaia entomologiia, fasc. 5. Leningrad, 1924.
Lepneva, S. G. Lichinki i kukolki podotriada kol’chatoshchupikovykh. Moscow-Leningrad, 1964. (Fauna SSSR: Rucheiniki, vol. 2, fasc. 1.)
Lepneva, S. G. Lichinki i kukolki podotriada tsel’noshchupikovykh. Moscow-Leningrad, 1966. (Fauna SSSR: Rucheiniki, vol. 2, fasc. 2.)
Kachalova, O. L. Rucheiniki rek Latvii. Riga, 1972.
O. L. KACHALOVA