NEUROPTERA. 
33 
■ ■ 
The ephemerae are very frequent near waters ; they 
multiply amazingly in fome places ; about Lafs, in 
Carniole, a province in Germany, they are fo nume¬ 
rous in the month of June, that they are ufed as 
manure, and the peafants think lefs than 20 cart loads 
a bad harveft. 
It is thofe fpeeies which live fome days, that fly to 
a tree where they fometimes are employed 24 hours 
in the operation of divefling themfelves of a {lough* 
The ephemerae in the larva and chryfalis flate, 
have fringes of hair, which, when put into motion, 
ferve them as fins. Nothing can be more curious 
than the.plying of thefe little oars in the water. Their 
abdomen is terminated as well as in their date of flies, 
by three threads* Thefe larvae fcoop themfelves out 
dwellings in the banks of rivers, and they are fmall 
tubes made like fiphons, the one fervmg for an en¬ 
trance, the other affording them sn outlet. The 
banks of fome rivers are often full of them. When 
the waters decreafe they dig frefh holes lower down, 
in order to enjoy their element the water. 
The ephemerae of the Rhine appear in the air two 
hours before iun-fet. 
Thefe flies are hatched almoft all at the fame inflan t, 
in fu-ch numbers as to darken the air. 
' The. mofl early of thofe on the Marne and Seine, 
in France, do net begin to fly till two hours after 
tha 
