Fourth stage. Length 7—8 mm. Pattern of head and pronotum almost as 

 in full-grown larva; ratio of length of tibia, tarsus and claw of all 3 legs 

 183:100:158, 140:100:126, 133:100:122 (240:100:166, 205:100:147, 154:100: 

 136 in the full-grown larva). 



Pupa. Length 6.0— 8.3 mm. Antennae moniliform at the end, reaching 

 abdominal segment 6 in female pupae, in male pupae end of the body 

 (Figure 634). Anteclypeus (Figure 635) short, separated from labrum by a 

 shallow, distinct fold; labrum small, semicircular; median and intermediate 

 setae of anteclypeus and 2 se^tae of labrum (Figure 635) long, straight, with 

 thin, transparent, sinuous ends; other setae small. Mandibles (Figure 636) 

 sickle -shaped but less long than in PI e c t r o c n e m i a, less curved; base 

 less broad than in PlectrOcnemia; end of the mandibles reaching inner 

 margin of eye when folded; base light yellow on the outer side; blades 

 brown outer setae short. 



With sheaths broad, with rounded ends, reaching beginning of abdominal 

 segment 5. Spurs of midlegs and hind legs of different length; first 

 3 tarsal segments of midlegs dorsoventrally with relatively long, light, dense 

 setae. Presegmental plates present on segments 3—8, postsegmental 

 440 plates on segment 5; number of spinules of male pupae as follows: 

 111:3-4; IV:4-4; V:5-6+ 8-10; VI:8-9; VII:4-5; VIII:3-4. 



Gills filiform, present on segments 2—7; gill of segment 2 with only a 

 dorsal branch; gills of segments 3—4 with a dorsoventral branch; dorsal 

 branch short on segments 5 and 6, absent on segment 7. 



End of body dorsally with two broad, rounded lobes with long, strong, 

 dark or golden brown setae; male pupae ventrally with the sheath of the 

 genital appendages and a broad penis sheath; female pupae with a medio- 

 ventral conical process on segment 8; process blunt and slightly divided 

 at the end. 



Walls of pupal case loose, covered with fine sand grains; ends of case 

 with small filtering sieves of delicate tissue; pupa lying in a sheath of 

 loose grayish tissue. 



Mode of life and habitats. Predacious, building capturing nets; 

 brooks and rivulets with cool water; mainly on stony or sand-stony bottom, 

 also in lakes among stones along the shore. 



Distribution. Northern, western and central regions of the European 

 USSR; south of West Siberia. In addition, Europe, North Africa. 



3. Genus Holocentropus McLachlan 



Full-grown larva. Length 13— 16 mm. Form of body as in Poly- 

 centropus. Head yellowish, slightly broader posteriorly than anteriorly, 

 with a punctate and shaded pattern. Frontoclypeus usually light in the 

 middle. Dorsal stripes present. Gula fused with pregula, broad, slightly 

 longer than in the preceding genera. 



Pronotum with punctate pattern; shaded pattern absent. Midlegs and 

 hind legs longer than forelegs. Tarsi longer on the forelegs than the tibia, 

 of the same length or slightly shorter on midlegs and hind legs; ventro- 

 distal setae of tibia spinelike but less dark, large and projecting as in 



498 



