SECOND PAY.] FLIES. 21 



is no great variety on this river. We have had lately 

 some warm days, and though it is but the 18th of 

 May, yet I know the May-fly has been out for three 

 or four days, and this is the best period of this destruc- 

 tive season for the fisherman. There are, I observe, 

 many male flies on the high trees, and some females 

 on the alders. 



PHYS. But I see flies already on the water, which 

 seem of various colours, brown and gray, and some 

 very pale, and the trout appear to rise at them 

 eagerly. 



HAL. The fly you see is called by fishermen the 

 alder fly, and appears generally in large quantities 

 before the May-fly. Imitations of this fly, and of 

 the green and the gray drake, of different shades, are 

 the only ones you will need this morning, though I 

 doubt if the last can be much used, as the gray drake 

 is not yet on the water in any quantity. 



PHYS. Pray can you give us any account of these 

 curious little animals ? 



HAL. We ought to draw upon your stores of 

 science for information on these subjects. 



PHYS. I really know nothing of Entomology, but 

 I am desirous of acquiring knowledge. 



HAL. I have made few observations on flies as a 

 philosophical naturalist. What I know I will state 

 at another time. But see, the green drake is descending 



