SECOND DAY.] FLIES. 49 



time for fly-fishing, both on account of the cold 

 weather and because there are fewer flies on the water 

 than at any other season. Even in December and 

 January there are a few small gnats or water-flies on 

 the water in the middle of the day, in bright days, 

 or when there is sunshine. These are generally black, 

 and they escape the influence of the frost by the 

 effects of light on their black bodies, and probably by 

 the extreme rapidity of the motions of their fluids, 

 and generally of their organs. They are found only 

 at the surface of the water, where the temperature 

 must be above the freezing point. In February a 

 few double-winged water-flies which swim down the 

 stream are usually found in the middle of the day, — 

 such as the willow -fly ; and the cow-dung-fly is 

 sometimes carried on the water by winds. In March 

 there are several flies found on most rivers. The 

 grannam or green-tail-fly, with a wing like a moth, 

 comes on generally morning and evening, from five 

 till eight o'clock a. m. in mild weather in the end of 

 March and through April. Then there are the blue 

 and the brown, both Ephemerae, which come on, the first 

 in dark days, the second in bright days ; these flies, 

 when well imitated, are very destructive to fish. The 

 first is a small fly with a palish-yellow body, and 

 slender beautiful wings, which rest on the back as it 

 floats down the water. The second, called the cob in 



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