Abdominal setae of full-grown larvae of Hydroptilidae markedly 

 reduced compared with the young larva; some of them form setules or are 

 absent in some places. The most prominent setae on the abdomen are the 

 anterior -angle and medioanal surface setae; anterior -angle seta of middle 

 and posterior segments displaced posteriorly and situated close to the 

 surface setae. Intermediate ventral seta of 1st segment always absent. 

 Anterior- angle, dorsal seta of the 9th segment, situated, as in other families, 

 in the posterior angle of the sclerite near the 3 surface setae at the posterior 

 margin; medioanal seta much longer than the others; anterior -margin seta 

 (unlike in the other Annulipalpia) clearly marked, small or moderately long, 

 displaced to the middle of the sclerite or, displaced toward the anal setae 

 as in Orthotrichia. 



Anal legs of the 5th-stage larvae short and forming two hemispherical 

 or broadly conical processes lateral to the large folds surrounding the 

 anus. Sclerite "b" of basal segment has a dorsolateral position; distal 

 part of sclerite differentiated in form of a narrow, slightly curved stripe, 

 which forms a bridge between sclerite "b" and the claw; sclerite "b" with 

 a laterodistal seta and 2 dorsal setae; an apical and a subapical seta; the 

 distodorsal seta and the seta of the bridge are the longest setae of the anal 

 legs; ventral sclerite "c" long, with a very short seta. 



Claws small and short, hooklike; transverse, membranous stripe on inner 

 side of claw broad; claw of full-grown larva directed not ventrally but 

 laterally as in larvae of Integripalpia. Of the 8 setae of the claw (if all 

 are present), there are setae 1 and 4 on the inner side, setae 2 and 5 on the 

 outer side in the basal part near the transverse, membranous stripe or on 

 it; setae 7 and 8 have a characteristic position in the basal part of the 

 claw; setae 6 and 3 are situated dorsally on each side of the claw, in its 

 distal part; setae 2, 3, 7 and 8 are always present; setae 1, 4, 5 and 6 may 

 be absent in some genera (Oxyethira, Orthotrichia, It hy t r i c hi a). 



Three genera have tracheal gills, which consist of three filaments 

 (Hydroptila, Orthotrichia) or one filament (ithytrichia); the gills 

 are situated dorsally on the end of abdominal segment 9 or on the anal legs, 

 near the base of the claw. 



A case is built only by the 5th -stage larvae; the larvae of the first 

 4 stages live without a case. The case is made of secretion (Oxyethira, 

 Orthotrichia), of secretion and algae (A g r a y 1 e a) or of secretion with 

 a covering of minute sand grains or diatoms (Hydroptila). The form 

 of the case differs in the various genera (see pp. 359, 370). 



Young larva. The young larvae of Hydroptilidae have a broad head and 

 a short, narrow abdomen, which tapers gradually posteriorly. Setae which 

 are sometimes longer than the abdomen are present on the head, end of the 

 body and sometimes (A gray lea) also on some other abdominal segments; 

 legs, anal legs and gills (if present) are also relatively long; these 

 characters are especially well marked in the 1st stage. The freshly 

 hatched larva is light, usually green; it gradually assumes the coloration 

 of the full-grown larva from the 2nd stage onward; this is already well 

 marked in the 4th stage; the larva is covered with setae and numerous 

 hairlike setae, which gives it a shaggy appearance. The larvae of 

 Hydroptilidae do not build a case in the first 4 stages, live free and are 

 very mobile and active. 



5724 348 



