Head of larva slightly dorsoventrally compressed, widest in the middle; 

 some setae almost 4 times as long as the width of the head; mandibles 

 shorter and broader than in the full-grown larva, with more numerous and 

 pointed distal denticles on both mandibles. 

 319 The dorsal sclerites of all 3 thoracic segments (not only of last 



2 segments, as in the full-grown larva) do not reach the anterior margin 

 but leave a membranous stripe at the anterior margin. Anterior -angle 



seta longer than the others in the 1st stage, secondary anterior -margin setae 

 begin to appear in the 2nd stage; setae of series M appear on the pronotum 

 in the 2nd stage; these setae are short, but they are almost as long as the 

 anterior -angle seta in the 4th stage; together with the secondary anterior- 

 angle setae, curved, yellow, anterior-margin setae of series m also appear 

 in the 3rd stage. 



The pleurites are not fully developed in the young stages; the horn of the 

 trochantin is still absent in the 4th stage in some genera (A gray lea, 

 Hy d r opt i la, Oxy e t h i r a); this hornlike process appears in Ortho- 

 t r i c hia and Ithytrichia in the 3rd stage but reaches its full 

 development only in the full-grown larva. 



Legs of the young larvae relatively longer than in the full-grown larvae; 

 the forelegs, which are not used in construction, differ little from the other 

 legs; basal process of femur absent, distal process of tibia weakly marked; 

 some setae relatively longer, other setae relatively shorter than in the 

 full-grown larva; the differentiated and specialized setae of the young larva 

 are much smaller than those of the full-grown larva. Claws of legs thin, 

 sometimes very long, without basoventral seta. 



Abdominal segments 1—8 of young larvae of some genera with tergites 

 which are not always distinct; they are as wide as the segment but much 

 shorter; posterior margin of tergite situated at the posterior margin of the 

 segment; the segment remains membranous anteriorly; the tergite of the 

 first abdominal segment of Oxyethira is very small, divided into 



3 tergites, one median and 2 lateral, which bear an anterior -angle seta; 

 segments 2—8 have not only tergites but also small rounded pleural sclerites 

 with 2 lateral setae. The sclerites bear the 5 dorsal setae, which are well 

 developed in the young larva; anterior-angle and medioanal seta among the 

 longest setae of the body; the posterior lateral setae may also be very long; 

 abdominal segment 9 much more sclerotized (sometimes completely or al- 

 most completely) so that only a small median stripe and a stripe near the 

 posterior margin remain membranous ventrally; these membranous areas 

 are also sometimes absent and the sclerite of segment 9 becomes ring- 

 shaped (ithytrichia). 



Unlike in the full-grown larvae, the anal legs of the young larvae ot 

 Hydroptilidae are long, with a cylindrical section "b" which is well 

 developed in some genera; this section is sclerotized on the dorsal side, 

 on the sides and partly on the ventral side; the distal part of the sclerite is 

 differentiated in form of a bridge and is a narrow, small plate situated 

 between sclerite "b" and the basal margin of the claw; sclerite "b" with 

 3 setae, 2 distal setae (dorsal and lateral seta), which are, together with the 

 seta of the bridge of some forms, some of the longest setae of the body; 

 subapical seta of sclerite "b" shorter and thinner. Claw long and thin, 

 slightly curved, with a narrow, transverse, membranous stripe; setae as in 



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