II. Superfamily NEOCHAETOIDEA Lepneva 

 VII. Family ECNOMIDAE Ulmer* 



Full-grown larva. Length 8.0— 9.5mm. Mandibles moderately long; 

 left mandible without penicillus in the median depression. Labial lobe 

 short, shorter than mandibles, without long ligula; labial palps relatively 

 large and well developed. Nota of all three thoracic segments present. 

 Trochantin long, fused with episternum, with a small spoon-shaped seta; 

 epimeron of prothorax very wide, long in the posterior-angle area, in form 

 of ventrally curved processes. All legs of almost the same length; claws 

 thin, slightly curved, without ventrobasal process. Setae of thorax and legs 

 mainly primary; secondary setae of coxae not numerous. A dense row of 

 thin, long setae forming a spurious lateral line on abdominal segments 2—8. 



Anal legs long; section "a" larger than section "b"; secondary setae 

 of section "b" numerous; claws curved, narrow, with a ventral comb of 

 minute spinules. 



Pupa. Length 5.5— 6.5 mm. Labrum with 5 long setae and a small seta. 

 Apex of mandibles straight, long, pointed, without filiform end. 



Dark setae present on the sides of abdominal segments 6—8. Last 

 abdominal segment moderately long, with short rounded lobes having sparse 

 setae of varying length that form a fan. 



Mode of life and habitats. Slow running water and large clean 

 stagnant water bodies, ponds, reservoirs and lakes. They live on the 

 bottom, on stones, sometimes among vegetation. 



Distribution. Throughout the Soviet Union; everywhere except North 

 America. 



1. Genus Ecnomus McLachlan 



Larvae with the characters of the family. One genus and one species 

 in the USSR. 



1. Ecnomus tenellus Rambur 



414 Klapalek, 1893:119-122, Figure 32.- Ulmer, 1903:121-122, Figure 81; 



1909:231, 297-298, Figures 356,433.- Lestage, 1921:511-514, Figure 171. — 

 Lepneva, 1940:204; 1956:16-20, Figures 2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 

 35, 38,41. 



Full-grown larva. Length 8.0— 9.8 mm; head and pronotum slightly 

 narrower than the following segments; abdominal segment 9 narrow 

 (Figure 586). Head oblong, dorsoventrally compressed. Eyes situated on 

 a white or yellowish area at a distance from the anterior margin; antennae 

 situated near margin of head, near the dorsal articulation of the mandibles. 

 Frontoclypeus (Figure 587) long, broader anteriorly, with distinct lateral 

 indentations; anterior branches of frontal sutures at the end curved; anterior 



4 Considered as Ecnomidae Ulm. without the PseudoneureclepsinaeUlm.; see Ulmer, 1951:111, 123, 135,461, 

 463. 



465 



