42 POND LIFE 



Corixa makes its escape. At first they are practically trans- 

 parent, except for their yolk-bag and their eyes. 



Gradually the little creatures become more and more opaque, 

 and darker in colour : their wings appear, and they mature. 



CHAPTER IV 



INSECTS (continued) 



THE may-fly has many admirers. To the fisherman it is the 

 only Diptera worth thinking about, to the naturalist it stands 

 pre-eminently as one of the most beautiful if not the finest 

 fly of our country. But probably it is best known to the 

 majority of people, neither fisherman nor naturalists, as a 

 pathetic example of the seemingly unfairness of nature to 

 some of her children. 



Swammerdam tells that one species, "Palingenia longicauda," 

 lives only for five hours, and that " the flies may be seen in 

 the air for three days together. Those which appear on the 

 first day die the same evening, and the same thing happens 

 on the second and third days." Also that "the eggs are 

 passed into the water, and are there fertilised by the male " (a 

 mildly incorrect statement). He continues "that the eggs 

 hatch into a crowd of minute worms, each with six legs." 

 Certainly, to say the least, very queer creatures. Reaumur is 

 more accurate ; he gives us a vivid picture of a rise of flies in 

 1738. 



Be Geer's observations are more reliable. Taking the 

 trouble to watch may-fly under natural conditions, he saw 

 what everyone may see, if patience allows, the fertilisation of 

 the female, thus totally upsetting the " fishy " theory advanced 

 by Swammerdam. 



The Ephemera are partly pitied without cause, as they are 

 not shorter-lived than the average insect. Let us rather be 

 sorry that so beautiful a creation is seen for so short a time 

 and by so few. 



The adult may-flies, especially those termed by fishermen 

 "drakes" (E. danica and E. vulgata), are some of the most 

 fairy-like little objects to be imagined. 



May-flies have usually two pairs of wings, one pair large, 

 the second pair verylsmall indeed, or totally absent, depending 

 on the species. Like the other members of their family, the 

 venation of the lace wings is most delicate and graceful. The 



