2 12 MINUTE MARVELS OF NATURE 



S|jecies, its metamorphoses are completed, and 

 the animal leaves the water to become a winged 

 May-fly. Fii,;", 140 shows the larva of a May-fly. 

 It is a mistake to suppose that May-flies only 



Fitj. 140. LaiA'a of Ma>'-tiy 

 X 4 dianunei'S 



appear during- May, as various species arrive at 

 maturity at different periods during the summer 

 months. But the regularit)- of emergence of each 

 species is remarkable, and the phenomenon of the 

 sudden appearance of immense swarms without 

 any warning is a spectacle which familiarity never 

 stales. 



The rise, as it is called, of the flies usuallv takes 



