6o 



growth of aquatic larvoe and postpones the sprouting of 

 aquatic vegetation, if it does not altogether prevent it. 

 All the rivers rising in the West Riding are subject to this 

 influence, and inasmuch as both the aquatic larvae and the 

 vegetation suffer from the low temperature of the spring 

 water, a temperature which is proportionally maintained 

 all the year round, owing to the bare and rocky nature of 

 the bleak gathering grounds, it may be inferred that fish 

 in like manner suffer in common with the meaner life. For 

 these reasons it may be said that we cannot hope to increase 

 the size of trout in the Yorkshire rivers to any great extent, 

 the most obvious requirement being an abundant increase 

 in the food supply, -and to this end a free introduction of 

 aquatic plants and molluscs is recommended. 



The reader who has gone carefully through the descrip- 

 tions of the flies given in this book will have noticed that a 

 large majority of them make no attempt to show careful 

 imitations of the natural insects. It would have been 

 possible in many cases to quote a dozen different dressings 

 for the same fly, varying greatly in detail, but arriving in 

 the end at pretty much the same result, as regards size and 

 colour, for I am decidedly of opinion that those two 

 qualities are of far more importance in an artificial fly 

 for any northern river, than that of shape. " Ephemera " 

 is very strong indeed, that nothing but an exact reproduc- 

 tion of the natural fly can be expected to kill ; yet I suppose 

 he would not have doubted that a drowned and therefore 

 a mis-shapen fly, or an imperfectly hatched fly would be 

 recognised and taken by a hungry trout. In either of these 

 events the shape of the fly is lost, but the size and colour 

 remain. Most old anglers are therefore agreed upon the 

 point that accurate shape may safely be ignored where the 

 size and colour are approximately correct. This being the 

 case, the reason why a hackled fly, made from soft and 



