184 NATURAL HISTORY: 
firft: flight at'the fun, die before that luminary rifes 
again. Some have only the lite of an honr; others” 
exift but half an hour. | 
The ephemera, before they fly, have been in fome 
manner fifies-: And, what is very remarkable, they 
have been obferved to remain as long as one; two and 
three years, in their larva and chryfalid ftates. Both 
the larva and-chryfalis have fmall fringes of hair” on 
each fide; which, when moved in the water, ferve 
them as fins. The. plying of thefe little oars is ex- 
ceedingly curious. ‘Lhe larva make their refidence 
by perforating, or making holes in the banks of riv- 
ers ; and, when the water falls, or decreafes, they 
make other holes lower, in order to have ready ac- 
cefs to their favourite element. Flames attract them, 
fo as to caufe them to forma thoufand circles round 
fuch a light, with an amazing regularity. One fin- 
gle female will lay feven or eight eggs, which fink to 
the bottom of the water, where they are depotited. 
The larva which they produce, conftruct habitations 
to fthelter them from every danger. The flies. hav- 
ing propagated, immediately die in heaps.— Fifher- 
men confider thefe multitudes of deftroyed infects. as 
manna for the fith. .We.can,.therefore, perceive, 
that even this infect, which cannot, for its very fhort 
exiftence, be of much fervice during life, is, by the 
wifdom of the Creator, fo calculated, as to be ot ef, . 
fential fervice, even in its departed ftate- ” e 
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