34-2 THE COMMON EPHEMERA OR DAY-FLY. 



with two holes, the one serving for an entrance, and 

 the other as an outlet ; and these are so numerous 

 that the banks of some rivers are observed to be full 

 of them. When the waters decrease, they dig fresh 

 holes lower down. The flies are hatched nearlv all 

 at the same instant, in such numbers as even to 

 darken the air. 



The females, by the help of the threads of their 

 tails, and the flapping of their wings, support them- 

 selves on the surface of the water, and, in an almost 

 upright position, drop their eggs in little clusters 

 into the water *. A single insect will lay some- 

 times seven or eight hundred. 



The mouth of the perfect insect has no jaws, but 

 is furnished with four very short thread-shaped feel- 

 ers. The antennae are short and thread-shaped ± 

 and, above the eyes, there are two or three large 

 stemmata. The wings are erect (the lower ones 

 much the shortest) and the tail is terminated by 

 long hairs or bristles. 



THE COMMON EPHEMERA OR DAY-FLY f. 



M. de Reaumur has described very accurately the 



metamorphosis of one species, which, except in the 



time of the year w T hen it is produced, and the dura- 



- f its fly state, seems very much to resemble the 



pie sent species, and is most probably only a variety. 



the nineteenth of August, 1738, he waited for 



fter sut-set on the bank of the Seine, to 



nscct. 213. t Ephemera vulgata. Linn. 



