I'HKYGANEIDjE, OR CADDICE-FLIES. 



155 



with which their wings, as well as their bodies, are beset. In 

 this character, as also in the arrangement of the nerves of the 

 wings, they bear a strong resemblance to the Lepidoptera. 



682. These Insects are chiefly remarkable on account of the 

 habits of the larvae, which are well known under the name of Cad- 

 dice-worms. These reside in cylindrical cases, open at each end, 

 to which they attach various matters, as bits of stick, weeds, 

 pebbles, or even small living shells, by the assistance of silken 

 threads, which they spin from the mouth. These cases they bear 



about with them ; protruding 

 the three first segments, with 

 their legs, when they creep 

 forwards ; and withdrawing 

 these upon the slightest alarm. 

 They are never known to 

 quit these cases of their own 

 accord. Different species ap- 

 pear to prefer different mate- 

 rials for the construction of 

 their cases; but they have 

 the power of employing almost 

 any which fall in their way, 

 when there is a deficiency of those usually preferred. The 

 food of some of the larvae is vegetable ; but others prey upon 

 small aquatic larvae, such as those of the Neuroptera. When 

 about to assume the pupa state, the larvae fix their cases to some 

 solid substances beneath the water, and close the two extremities 

 with a kind of grating, that admits of the passage of water 

 through the tube, which is necessary for respiration. A short 

 time before they are to assume their perfect form, they make 

 their way out, by means of the pair of hooked jaws, with which 

 they are then furnished, and swim about with great activity by 

 means of the two hind legs, crawling occasionally upon the four 

 first. In order to throw off their pupa-case, the larger species 

 crawl up plants out of the water ; but the smaller ones merely 

 come to the surface, and there undergo their transformation, 

 using their old envelope as a boat, out of which they rise to 



FIG. 380. PHRVGANEA GRANDIS A, Larva in 



its case ; n, grating ; c, Imago. 



