8. Genus Oecet is McLachlan 



Full-grown larva. Length 8 — 14 mm. Head wide; sensilla of antenna 

 shorter than in preceding genera; adfrontal and lateral, light stripes 

 absent; gula small, dark, fused with large, lateral sclerites; gular suture 

 absent. 



Labrum wide, with small, deep, median indentation; dorsal sclerite with 

 numerous, small, secondary setae. Mandibles flat, knife -like; ventral 

 blade undeveloped. Maxillary palps thin, long; middle segment formed by 

 fusion of second and third segment, much longer than the other two segnaents. 

 Galea thin, long, fused with palpifer and with first 3 segments of the palp, 

 adjacent to palp at end. 



Pronotum and mesonotum sclerotized; mesonotum narrower posteriorly. 

 Hind tibiae undivided, claw of mid- and hind legs with rudimentary, basal 

 seta in some species. 

 499 Gills single. Lateral line on segments 3—7. Tergite of segment 9 pale, 

 weakly sclerotized or absent; several secondary setae, in addition to the 

 primary setae on the tergite or on its site in some species. Claw of anal 

 legs with 2, sometimes 3—4 dorsal denticles. 



Case made of fine sand grains or of plant fragments, conical, slightly 

 curved in some species. 



Pupa. Length 8 — 12 mm. Antennae of male pupae coiled about 4 times 

 around the body. Labrum with teat-shaped, median process and numerous, 

 small, secondary setae, in addition to primary setae. Mandibles curved in 

 the middle; blade coarsely serrated basally. 



Wing sheaths reaching to segments 6 — 7. Natatorial rows of setae present 

 on mid-tarsi and partly on fore tarsi. Gills absent. Lateral line on 

 segments 3 — 8. 



Dorsal processes of abdominal segment 9 large, with 3—4 or more (to 20) 

 strong setae. Anal rods large, long, tapering, apical part much smaller 

 than basal part. 



Mode of life and habitats. Mainly stagnant and slowly running, 

 large or small water bodies, littoral and sublittoral of lakes; some species 

 occur in brackish water. 



Distribution. European and Asiatic parts of the USSR. Cosmopolitan. 



Key to Species 

 Full-grown larva 



1 (6). Basal seta of claw of mid- and hind legs normal or almost normal, 



in form of a short, thin, light spine; case made of plant fragments. 



2 (5). Claw of mid- and hind legs with pointed, basal spine; ventral side 



of case not flattened. 



3 (4). Head pattern variegated, consisting of numerous, large, brown dots; 



case rough, made of transversely arranged plant fragments of 

 different form 4. O.furva Ramb. (p. 637). 



4 (3). Head pattern with less numerous dots; case smooth, made of uniform 



rectangular fragments in regular spirals 



5. Oecetis sp. 1 (Lake Kurgal'dzhin) (p. 643) 



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