TRTCHOPTERA. 181 



quiescent. It then resembles the pupae of moths, and 

 while in this state very great changes take place ; as 

 has been already mentioned, the mouth parts become 

 reduced in size, the antennae and wings develop, and 

 the respiratory organs disappear. 



Two instructive species of caddis-flies have been 

 found in streams near Boston.^ One of these makes 

 apparently a tunnel (Fig. 128, enlarged) and attaches it 

 to a stone. The insect, however, economizes material 

 by allowing the stone to serv^e as the lower part of the 

 tunnel. Close to the opening which is towards the 

 current the larva erects a vertical framework and 

 across it stretches a net (see Fig. 128). The food 



Fig. 128. 



brought down by the current is caught in the meshes 

 of the net, and the insect, without wholly leaving the 

 protection of its house, is able to enjoy the meal its 

 ingenuity has secured. Fig. 129 is the case ofahe 

 pupa. The other species, belonging to the genus 

 Plectrocnemia, makes its case of mud. It consists of 

 one or more lateral chambers (Fig. 130), with a tall 



1 See " Description of Two Interesting Houses made by Na- 

 tive Caddis-fly Larvae," Cora H. Clarke, Proc, Bost. Soc. Nat. 

 Hist, Vol. XXII., 1882-83. 



