~ 

 LtUll. 



58 DRY-FLY FISHING 



compared with that of their aquatic existence. 

 The egg soon hatches into a larva which, according 

 to its species, may burrow in mud, crawl or creep 



among stones, swim from one 

 shelter to another. All larvae 

 alike prey upon minute or- 

 ganisms, until for each the 

 appointed time arrives for its 

 transformation. The period 

 required for the full develop- 

 ment of the larva varies, and 

 it may be delayed by unto- 

 ward weather conditions or 

 hastened by favourable cir- 

 cumstances ; but, when it 

 passes, the larva reaches the 

 air, in some cases by ascend- 

 ing to the surface of the waters, in others by moving 

 towards the bank. 



Species which adopt the latter method afford the 

 angler the best opportunities for observing the 

 emergence of the winged insect. By turning over 

 a few stones close to the edge of the stream, he will 

 soon be rewarded by finding on the underside of 

 one of them a larva or nymph on the point of under- 

 going its metamorphosis. He will know when 

 to prosecute the search by noticing fully developed 

 flies resting along the margin of the stream. The 

 large Evening Olive, a conspicuous fly on the 

 Tweed in July, is one species which is easy to 

 observe, coming as it does to the gravelly shores 

 for the purpose, and spending quite a long time in 

 the process, of extricating itself from the nymphal 

 envelope. Some, which rise direct to the surface, 



