Nerve-winged Insects; Scorpion-flies; Caddis-flies 243 



stock found that it had perfect use of its wings, although they were so recently 

 expanded. The time required for the insect to expand its wings and take 

 its first flight was scarcely more than one second; certainly less than two. 

 As such caddis-flies normally emerge from rapidly flowing streams which 

 dash over rocks, it is evident that if much time were required for the wings 

 to become fit for use, as is the case with most other insects,' the wave succeed- 

 ing that which swept one from the water would sweep it back again and 

 destroy it. 



Fig. 335. Fig. 336. 



Fig. 335. — Fishing-net of caddis-worm in stream. (After Comstock.) 

 Fig. 336.— GoHio/u«//H5 dispcclus. (Xller Ncedham; enlarged.) 



The adult caddis-flies are practically unknown to general students. 

 They are mostly obscurely colored, rather small, moth-like creatures, that 

 limit their flying to short, uncertain excursions along the stream or pond 

 shore, and spend long hours of resting in the close foliage of the bank. 

 So far as observed the flies take no food, although in all the specimens I 

 have examined there are fairly well-developed mouth-parts fitted for lap- 

 ping up liquids. They probably do not live long, and certainly do not live 



Fig. 357. — TricBtwdes ignilit. (After Needham; enlarged.) 



excitingly. In the Colorado mountains numerous small species occur, 

 some w'th beautiful snow-white wings and delicate blue-green bodies (Setodes) ; 

 other black-winged, brown-bodied kinds (Mystacides) ; and other light- 

 brown winged species (Hydropsyche) in great abundance, but usually the 

 adults are comparatively solitary and inconspicuous. They probably fly 



