CHANGING COLOURS OF FLIES. 121 



common yellow shade of June. This, in common 

 with all water flies, gradually assumes a lighter shade, 

 even when exposed to the sun's rays for only an hour. 

 Dull or inclement weather in July produces the July 

 Dun, in which the old and more general olive shade 

 is again visible, commingling with pale yellow. And 

 now, with the declining months, the fish and fisher- 

 man are treated to a repetition of the various shades 

 of the spring, though graduating in the contrary 

 direction, i.e., growing darker as the months pass, 

 instead of lighter. Thus, in August we have the 

 exact shades of May, and in September those of 

 April the state of the weather and the water being 

 similar to that in the corresponding earlier months of 

 the year until we again arrive at the Dull Blue Dun 

 of February in November. 



The whole of the foregoing are the natural progeny 

 of the common red spinner. All the Duns, therefore, 

 that live to maturity become spinners; they are, in 

 consequence, very numerous. In the warmer months 

 this becomes lighter in shade, assuming a golden 

 tint on the body, when it is designated the Golden, 

 instead of the Red Spinner. The limited period 

 usually devoted to the study of the native water flies, 

 which are designed for the sustenance of non- 

 migratory fish, both upon the surface and in the bed 

 of the rivers, has led to erroneous and inaccurate 

 inferences. During an unusually backward and dull 

 season one particular shade of fly will be numerous, 

 often for many weeks, and occasionally even months ; 

 and as no two or three successive years are exactly 



