782 



A HISTORY OF 



every kind of fresh-water fish. It is in vain 

 that these little animals form galleries at the 

 bottom of the river, from whence they seldom 

 remove ; many kinds of fish break in upon 

 their retreats, and thin their numbers. For 

 this reason fishermen are careful to provide 

 themselves with these insects, as the most 

 grateful bait ; and thus turn the fish's rapacity 

 to its own destruction. 



But though the usual date of those flies is 

 two or three hours at farthest, there are som.e 

 kinds that live several days; and one kind in 



particular, after quitting the water, has 

 another case or skin to get rid of. These 

 are often seen in the fields and woods, distant 

 from the water; but they are more frequent- 

 ly found in its vicinity. They are often tound 

 sticking upon walls and trees ; and frequent- 

 ly with the head downwards, without chang- 

 ing place, or having any sensible motion. 

 They are then waiting for the moment when 

 they shall be divested of their last incommo- 

 dious garment, which sometimes does not 

 happen for two or three days together. 



