4i8 



THE INSECT WORLD. 



provided with two or three long silky hairs. Their name indicates 

 the short duration of their existence. They appear in great numbers 

 at certain seasons of the year. Their hatching takes place at sunset ; 

 they have coupled and laid their eggs by sunrise next day, and have 

 ceased to live ; so that the banks of rivers, of ponds, of lakes, are 

 strewed with their bodies. Their number 

 is sometimes so considerable that, according 

 to Reaumur, the soil seems as if it were 

 covered with snow, and they are gathered 

 up for manure. The common Ephemera, 

 or May-Fly {Ephemera vulgato,, Fig. 390), 

 is of a brown colour, banded with yellow, 

 and the wings smoky, with brown spots. 

 These insects are remarkable for their 

 elegant flight ; they are continually rising 

 and falling. When they move their wings 

 they rise ; but if their wings, though spread 

 out, remain motionless, as also the silky 

 hairs which form their tail, they fall again. 

 They may be seen in myriads in places 

 where there is much water. 



We have said that the Ephemerce live 

 only for a few hours. This is the general 

 rule ; but their existence can be prolonged 

 for ten or fifteen days by preventing their 

 copulation. If, however, the duration of 

 the life of these insects is so short when 

 they have reached the perfect state, and 

 when the conformation of the mouth pre- 

 vents them from taking any nourishment, 

 their larva state is of very long continuance. 

 Swammerdam says, in his curious Memoir, entitled " Vita Ephemeri," 

 it is not less than three years. 



The females lay their eggs in one single mass, and let them fall 

 into the water, in the form of a packet. The larvae which come out 

 of them are very active, and swim with great ease ; but generally 

 conceal themselves under the pebbles at the bottom. The sides of 

 their abdomen are provided with gills, very much fringed, which serve 

 them, not only for breathing the air uiider the water in the same way 

 that fish do, but also for swimming. The larvas have, at the extremity 

 of their body, two or three hairs, like the perfect insect. They hollow 

 out galleries in the beds of rivers and ponds, and live on small insects. 



Fig. 390. 

 Ephemera vulgata, imago. 



