Mode of life and habitats. Running water, in the rapid current 

 of small rivulets in the plains. 



Distribution. European USSR, northwest, west and central belt. 

 In addition, northern and Central Europe. 



4. Genus Leiochiton Guinard 



Full-grown larva. Length 3.5— 4.0 mm. Sensilla of antennae slightly 

 shorter than in Oxyethira; seta light, curved inward; the longest seta 

 after seta 9 is seta 15, which is directed obliquely posteriorly; it is thin, 

 hairlike and soft at the end. In addition to the primary anterior -margin 

 seta, the mesonotum bears also a short, yellow, curved seta. 



Distal process of tibia of forelegs with a spatulate, divided chetoid on 

 one side resembling that of Agraylea; the other side with sparse, light 

 hairs; the tibia is the longest segment of midlegs and hind legs; a dorsal 

 spinule absent on the claws. 



Abdomen curved; abdominal segments 1 and 2 much smaller (narrower 

 and lower) than the following segments; there are small, rudimentary 

 tergites near the anterior margin of segments 3—8; claw of anal legs with 

 2 dorsal denticles and 3 additional small hooklike spinules above them. 



Case made of secretion, sac -shaped, with convex sides and anterior and 

 posterior openings of the same size. 



Pupa. Wing sheaths pointed and long. Anterior angles of case with 

 2 attachment disks, each with a stalk; posterior angles of case each with 

 one attachment disk. 



Mode of life and habitats. Stagnant water, in plant thickets; 

 it occurs in large numbers in floodlands in the Volga delta. 



Distribution. European USSR. In addition, Europe. 



1. Leiochiton fagesii Guinard (Oxy eth ir a fagesii 

 Guinard) 



Ulmer, 1909:225, 293. - Lestage, 1921:458-464. 



Full-grown larva (Figure 455). Length 3.5— 4.0 mm. The largest larva 

 of Hydroptilidae in the USSR: the larvae differ from larvae of Oxyethira 

 in the narrow, long thoracic segments, the length of midlegs and hind legs, 

 the characteristic curvature of the abdomen, the relatively narrow first 

 two abdominal segments and the very large segment 4, which is the largest 

 segment of the abdomen. 



Head light yellow, mouthparts only slightly darker; occipital foramen with 

 a narrow brown border; antennae slightly shorter than in species of 

 Oxy e th i r a, with a long, inward-curved seta. Frontoclypeus with 3 dark 

 dots laterally, between the middle and posterior setae; one large dark dot 

 in the middle of the sclerite; the large dark dots with their partly connected 

 margins form a dark bridge in the middle of the sclerite. The most outer 

 anterior-margin seta thin, curved inward; median seta longer and thicker 

 than the others; intermediate seta also long; anterior and posterior frontal 



388 



