Diversity in Colour of Flies. 69 



selves undergo ; but because they differ in shades of 

 colour that is not to say that trout cannot distinguish 

 that colour. From this very fact I deduce one very 

 strong argument in favour of their doing so, especially 

 in the case of most of the species of Baetis, such as the 

 Dun Drake, which changes into the Great Red Spinner, 

 &c. This fly is dark when it first comes on the water, 

 and, as the season advances, it also changes to a much 

 lighter hue, but still preserving its original shape a 

 circumstance which does not affect my argument. But 

 in the advanced season, when the light fly is on the water, 

 the dark one is almost totally useless for killing trout. 

 This every experienced Angler in our waters can affirm ; 

 therefore if trout do not distinguish colour, what makes 

 them thus particular or fastidious ? When a certain fly 

 at a certain time of day comes on the water, trout fre- 

 quently all forsake their former favourite and feed upon 

 it. Does caprice seize the whole fry at once ? Or ratheu 

 do they not detect the food designed by nature for them, 

 and arranged doubtless by the All-wise Ruler of the 

 Universe for some wise though to us inscrutable end ? 



May-flies differ considerably in colour according to the 

 gravel in which they are bred. Lead-coloured gravel 

 producing a similar hue in the fly, and bright yellow 

 gravel a corresponding fine yellow-bodied fly. Three or 

 four seasons back I was fishing the May-fly where the 

 water ran over dark-coloured gravel, and I happened to 

 be using a very yellow-bodied fly ; a trout made several 

 runs at it, but never essayed to take it, and I then changed 

 my fly to one of pure stone-colour throughout, and no 

 sooner did he perceive this fly than he took it, and I 

 killed him. On the same day the very opposite of this 

 also occurred, when I was fishing in a bright gravelly 

 stream with a dull-coloured fly, for here again success re- 

 warded a change of fly. These facts clearly proved to me 



