The characters of specialization are as follows: l) the labium is without 

 palps; it is prolonged in form of a ligula which contains the spinning organ; 

 the function of this organ is to build or repair the tubes, which are very- 

 long in the Psychomyiidae; 2) the trochantin is large, its distal part broad 

 and spoon -shaped; it apparently takes part in food collection together with 

 the labrum, mandibles and broad segments of the forelegs. The anal legs 

 are simple; their claw is small and bent at a right angle. 



The reasons for the separation of the Ecnomidae as an independent family 

 163 are given by Lepneva (1956). This family is related to the Psychomyiidae 

 in the resemblance of their tunnel-shaped tubes; however, the Ecnomidae 

 differ sharply from the Psychomyidae in their predatory mode of life and 

 the morphological characters connected with this. The labrum and the 

 chaetotaxy of the anterior part of the frontoclypeus resemble that of the 

 predators of the higher Polycentropodidae; the structure of the thorax is 

 primitive, i. e., meso- and metathorax are weakly sclerotized; the forelegs 

 are typical raptorial legs with long segments; the chaetotaxy is mostly 

 primary; there are few secondary setae on the coxa; the anal legs are 

 longer than in Psychomyiidae; there are numerous secondary setae. The 

 claw has a different form. The family Ecnomidae is closely related to the 

 Polycentropidae in the larval mode of feeding and some morphological 

 characters, and was at first considered a subfamily of the Polycentropodidae 

 (Ulmer, 1909:228). 



The larvae of Polycentropodidae* of the subfamily Polycentropodinae are 

 predators, which is expressed in their morphology, the structures they build 

 and their mode of life. The tunnel- shaped tube of the ancestors is 

 represented only by its short base; the greater part of the structure consists 

 of various types of traps, bags or funnels for the capture of planktonic and 

 benthonic animals, especially larvae of Chironomidae and other insects. 

 The primitive character uniting these forms with the larvae of the 

 4 previously mentioned families is the simple prognathous head with its 

 primary chaetotaxy; the mandibles are the strong cutting organ of the 

 predator; the long walking legs with their rich secondary chaetotaxy have 

 the raptorial function of the predator; some of the setae form strong, thick, 

 piercing organs; the numerous long setae are sense organs and have the 

 high capacity for orientation which" is necessary when waiting for prey. 

 The anal legs are the longest existing in the Trichoptera; they support 

 the larva when it catches the prey; both parts of section "a" of the anal leg 

 have an abundant secondary chaetotaxy; the claw is long and slightly curved; 

 . the setae are markedly differentiated and some of them are reduced. 



Pupation takes place in a cavelike case built of small stones or sand grains 

 which are usually loosely connected; the cocoon is loose. 



An interesting character of this large family is that a small group of 

 species of Holocentropus and C y rnu s, unlike the other Annulipalpia 

 (except the Hydroptilidae), live in stagnant waters. The wide ecological 

 range of the group in running water is shown by the fact that they live not onb 

 in the rapid brooks and mountain streams typical for the subfamily, but in 

 rivers in the plains and rivulets with dense thickets and also on the calm 

 shores of lakes and in smaller, stagnant water bodies. 



Only the Polycentropodinae are discussed, as this is the only subfamily which has well-studied larvae 

 recorded from the USSR. 



153 



