THE TROUT STREAM 23 



hears it in the north of England. In the case of 

 the north, and also of the three most western 

 counties referred to in this book, it is usually attri- 

 buted to unseasonable weather. The insect is 

 there all right, but simply has not hatched — such is 

 the belief. The chalk stream angler, on the other 

 hand, is often found lamenting that the fly is 

 disappearing. He attributes it to the lowering 

 of the springs of the river, to injudicious weed 

 cutting, and to tampering over much with the 

 water after the method of some very zealous 

 keepers. 



Pollution, a correspondent assures me, has had 

 much to do with lessening the number of natural 

 flies on the lower Colne of Middlesex ; only the 

 " more hardy species," he writes, " having escaped." 

 The fly has diminished for some reason or reasons 

 in various waters ; but is the evil quite so wide- 

 spread and growing as some would have us believe } 

 I ask the question because I have more than once 

 heard anglers, and good ones too, complaining that 

 there has been no fly out on a day when I have 

 noticed, at a different part of the stream perhaps, 

 a good number of insects of different species, flat- 

 winged as well as upright. The story is certainly 

 not a new one, and some who have not read that 

 entertaining little book may be surprised to learn 

 that Sir Humphry Davy in his Sabnonia, pub- 

 lished close upon seventy years ago, discusses it. 

 " It appears to me that since I have been a fisher- 

 man, which is now the best part of half a century, 

 I have observed in some rivers where I have been 

 accustomed to fish habitually, a diminution of the 

 number of flies." But curiously enough Sir Humphry 

 did not notice this diminution in the case of the 



