58 TREATISE ON FLY-FISHING. 



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 sun- 

 shine. 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 on the surface of the water, where the temper- 

 ature 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, and in April, the blue and 

 browns come on the first in dark days the se- 

 cond in bright. These lay their eggs in the water, 

 which produce larvae that remain in the state of 

 worms, feeding and breathing in the water, till 



