Case 22— 2 6 mm long, resembling that of larva; posterior, sievelike 

 membrane as in H. i n t e r p u n c t a t u s, situated some distance from end; 

 both ends covered with plant particles, sometimes sand grains or small 

 stones. 



Mode of life and habitats. Brooks with a moderately i-apid 

 current; open shore of lakes. 



Distribution. Northwestern, western, and northern parts of the 

 European USSR; isolated records from Siberia (Minusinsk area). In 

 addition, Europe. 



3. Halesus digitatus Schrank 



Pictet, 1834:139, Plate VII, Figure 2.- Meyer, 1867:165-166.- Struck, 

 1903:101, 107.- Ulmer, 1903:68; 1903b:205-207, Plate V, Figures 39-41; 

 1909:269, Figure 404.- Dohler, 1914:50.- Lestage, 1921:785, 788-790, 

 793—794.- Martynov, 1926:50.- Moretti, 1934:134-137, Figure 10.— Nielsen, 

 1942:489-497, Figures 118-119.- Hickin, 1949:56-59, Figures 1-12. 



Full-grown larva. Length 17.0—2 0.1 mm. Head light brown, less wide 

 than in Po t a m o phy 1 ax; ratio of width to length 0.86; punctation distinct 

 in some places, darkish brown (Figure 507, A). Frontoclypeus slightly dark 

 laterally in anterior part; a narrow, reddish brown stripe in area of tentorial 

 288 pits and along part of sutures; anterior part with indistinct dots; dots of 

 wedge-shaped pattern large, distinct. Head slightly dark from lateral to 

 epicranial suture to before eye; distinct dots further posteriorly lateral to 

 frontal sutures and along coronal suture; similar dots on sides; ventral 

 surface with groups of indistinct dots near occipital foramen. Gula light 

 (Figure 507, B). 



Labrum brown, with a dark spot behind median pit. Mandibles black; 

 dorsal blade of left miandible with 2 teeth in addition to middle tooth; 

 ventral blade with a large and a small tooth; dorsal blade of right mandible 

 with 3 teeth in addition to middle tooth; ventral blade with a much smaller, 

 blunt tooth; each mandible, therefore, with 5 teeth. =■= 



Pronotum (Figure 508) yellowish; transverse groove in anterior third 

 distinctly dark in middle; posterior submarginal area and part of lateral 

 area also slightly dark. Mesonotum darker than pronotum, brown anteriorly 

 and in middle of posterior part; posterior angles lighter, with dark lines; 

 anterior margin with dark stripe laterally; posterior margin with dark, 

 wide, median part; posterior angles with black margin, lateral margin partly 

 black; punctation as in Figure 508. 



Median sclerites of metathorax grayish brown; lateral sclerites large, 

 lighter, with 1—2 dots anteriorly, with a longitudinal row of dots posteriorly, 

 transverse band formed by dark lines. 



Legs yellowish brown; ratio of length of legs 71:100:93; coxae, femora, 

 and tibiae with dark, distinct punctation. Primary ventral setae of foreleg 

 in form of 2 strong, pointed, light spines of almost the same size; posterior 

 seta thin, dark, situated basal to spines. Ventral setae of mid- and hind 

 legs as in species of Halesus described in preceding paragraphs. 



Not 4 as was stated in earlier descriptions. 



360 



