256 TBESH-WATEK AQUARIA. 



hides its true colour. It then frees itself in a wonderful 

 maimer from this very thin skin, and emerges a beautiful 

 and active fly, with the filaments at the extremity of its body 

 of about double their former length. Numbers of these filmy 

 skins may be seen adhering to trees or weeds upon the water's 

 edge. 



The wings of the perfect Day-fly are so delicate and fragile, 

 that it is almost impossible to preserve the insect in anything 

 approaching a life-like condition without placing it in spirits 

 of some kind. These insects emerge from their pupal 

 envelope generally about sunset. They nearly always appear, 

 when at all, in great numbers ; the males assembling together 

 in crowds, and attracting attention by their curious and 

 graceful up-and-down flight. The swarms of these insects, 

 though frequently very great in this country, are often far 

 greater in the neighbourhood of rivers and canals upon the 

 Continent. Indeed, their numbers there are sometimes so 

 enormous that the bodies of these tiny flies are gathered and 

 used as manure. 



The larvEe and pupse of the Day-flies may be easily kept 

 in confinement, where they may be seen to go through their 

 wonderful metamorphosis. They will live, apparently quite 

 contentedly, in a small aquarium, whether its bottom is covered 

 with mud or not. The best species for the tank is Ephemera 



vulgata, the larvae- (Fig. 

 156) of which is about an 

 inch long. It will fre- 

 quently change its skin, 

 which forms a very in- 

 teresting object under the 

 microscope. It ought to 

 Fig. 156. Larva of Day-ply, Ephemera be always provided with 



VULGATA (ENLARGED). Suitable food, which 



should consist of cyclops, 

 water-fleas {Daphnics), and the like. These httle fresh-water 

 crustaceans may be easily bred .in great numbers for this 

 and similar purposes, directions for which will be given in 

 another chapter. When the time draws near for the pupa 



