downward-directed tubes which are made of very small sand grains; the 

 small stones of the case are connected with numerous small ventilation 

 holes. 



The cases of Agape tus are spacious; the larva can freely turn in 

 them from side to side, sticking its head out either of the anterior or 

 posterior end. Case of full-grown larva 8 mm long. 



Young larva. There are seven larval stages. The length of the body 

 and the width of the head of the larvae in the different stages are given in 

 Table 2 (after Nielsen). 



TABLE 2 



Stage 



Length (mm) 



Width of head (mm) 



1st 



0.8-1.2 

 1.2-1.64 

 1.31-2.19 

 1.75-2.32 

 2.18-3.42 

 2.52-4.30 

 3.76-6.25 



0.13 



2nd 



0.15 



3rd 



0.17 



4th 



0.21 



5th 



0.27 



6th 



0.35 



7th 



0.43-0.48 







The larvae of the 1st stage (Figure 381 ) is slender, as in the species 

 of Rhyacophila; the broad abdomen characteristic for the older stages 

 is absent; setae relatively long; form and setae of head, mandibles, foreleg, 

 abdominal segment 9 and anal legs shown in Figures 382—385. 



The body of the larva of the 2nd stage and its primary setae remain 

 slender; sclerites of head, pronotum, segment 9 and anal legs become 

 brownish. The sclerites become slightly darker in the 3rd stage. The 

 form of the larva in the 4th, 5th and 6th stages becomes gradually similar to 

 the form characteristic for the full-grown larva, and the sclerites become 

 chestnut brown; setae of head and anal legs are still moderately long in the 

 4th and 5th stage. 



The increase of the number of secondary setae of the thorax is given in 

 Table 3 (after Nielsen). 



TABLE 3 



,315 



Setae 



Stage 



1st 



2nd 



3rd 



4th 



5th 



6th 



7th 



Anterior-angle and 



anterior- margin setae. . 

 Surface setae 



1 

 4 







6-10 



4 







12-17 

 7-8 



1 



17-24 

 10-12 



2 



24-26 

 12-14 



2-3 



26-31 

 13-17 



3-4 



28-32 

 16—17 



Lateral setae (in the 

 middle of the lateral 



4-5 



A small, secondary seta appears near the primary anterior-angle seta 

 of meso- and metathorax from the 3rd stage onward. 



342 



