NEUROPTERA. 233 



These remind one of the cob-houses of our childhood. Fortunately 

 the species that make this style of case live in stagnant water, and 

 may, therefore, be kept alive in aquaria. A case closely resembling 

 in plan but differing in appearance is made of bits of moss. 

 Sometimes leaves are used; these are either fastened so as to form 

 a flat case ; or are arranged in three planes, so as to form a tube, a 

 cross section of which is a triangle. 



Whether stones or wood are used, the material is fastened to- 



ber by silk, which the larva: spin from the mouth in the same 



manner as caterpillars. In some species the case is composed en- 



FIG. 2oi. Case of Caddice-worm. 



tirely of silk. Fig. 201 represents the form of such a case, which is 

 common in Cayuga Lake. 



Before transforming to pupae, the caddice-worms partially close 

 their cases, so as to keep out intruders; but provision is made for 

 the ingress of water for respiration. Thus the owner of the silken 

 case to which reference has just been made, when ready to trans- 

 form, fastens its case to a stem of the grass which grows in the 

 lake, and then closes the entrance to the case with a lid having a 



!ike opening in the centre. The worms making the cases shown 

 in Fig. 199 build a grating in each end of tli 



It would naturally be supposed that the caddice-wonns would 

 the attacks of Ichneumon-flies, living as they do beneath 

 nd within well-built tubes. But this is not so. And curi- 

 ously enough, in certain at least, the parasiti/ed individuals 

 differ from others in fastening their cases by means of a long band, 

 when about to transform, instead of attaching them directly to the 

 supporting object. 



In thr Phry^am-id.T- wo find another group which ditTrrs in su< h important 

 char :n the most nearly < -rts that many rnt f s believe 



it should be classed as a the name Trichopter.i 



' ; ic rndimrnl.iry m<> llh- the adult cad 



flies and the structure of the wings separate them tera, 



and suggest affinities with tl. ptera ; on r hand, the anal legs of 



the larv.-r with hooked claws resemble those of the Sialidx. As ; 



the order Trichop* 

 ime Hagen, McLa< 1 Brauer as among those that share this \ 



