98 FLOATING FLIES 



practically instantaneous. You may select any 

 certain area of water, when duns are emerg- 

 ing constantly from every part of a pool, and 

 watch that certain area with the utmost in- 

 tentness; the chances are you will not see a 

 single fly actually upon the water although 

 many do, indeed, emerge from the water un- 

 der observation and fly away. 



In " American Insects " Professor Vernon 

 L. Kellogg, of Leland Stanford University, 

 writes as follows: u At the end of the im- 

 mature life the nymphs rise to the surface, and 

 after floating there a short time suddenly split 

 open the cuticle along the back and after 

 hardly a second's pause expand the delicate 

 wings and fly away. Some nymphs brought 

 into the laboratory from a watering trough at 

 Stanford University emerged one after the 

 other from the aquarium with amazing quick- 

 ness." This from an undoubted authority, 

 with my own experience, comparatively short 

 but to the same end, leads me to believe that 

 rises to the duns on the surface at the time of 

 metamorphosis from the nymph are certainly 

 less frequent than commonly believed and im- 

 plied by dry fly writers; the rise would have to 

 come at such an acutely psychological instant 



