EPHEMERA. 
376 
It seems that the ephemerae only continue to rise 
above the surface about an hour every evening, after 
which time the shower formed by their bodies en- 
tirely ceases, and no more of them are to be seen 
above the river. Notwithstanding the perfect ephe- 
merae are so easdy killed that almost any object they 
touch becomes fatal to them, yet the larvae are so 
tenacious of life, that Swammerdam tells us he even 
pierced one of them with a pin, which, although in 
this manner fastened to a board, lived during the 
whole of the next day. 
The Ephemera vulgata is well known to our an- 
glers by the name of May-fly, and it is frequently 
used as a bait for trout, being a favourite food of 
that fish during the season. 
The little time allotted these insects in their last 
state is employed, by the males, in merely flutter- 
ing above the surface of the water till they drop ; 
they have very little activity, and seem scarcely 
born for any other purpose than to die. The fe- 
males, on the contrary, have got a most important 
duty to fulfil: they have to provide for a future 
generation, and the short period of their existence 
is taken up in depositing their eggs. Two large 
packets of eggs, each containing from three to four 
hundred, are enclosed within the body of every fe- 
male ephemera, from whence they are excluded at 
the same moment, and fall together in one mass 
upon the water. Nature has provided for the sud- 
den alteration, which the loss of so large a quantity 
of eggs at one time might make in the constitution 
