52 LARVA AND PUPA. 



which it is consequently always full. This cavernous abode 

 serves the double purpose of protecting it from the jaws of its 

 finny foes, and of providing it with a ready supply of that slimy 

 earth on which it is supposed chiefly to subsist.* It has how- 

 ever been suggested that the insect may, after all, only derive 

 nutriment from the decaying vegetable matter mixed with the 

 earth thus swallowed ; but that if, on the contrary, it really feeds 

 on earth, the fact would at once abolish the distinction laid 

 down by Mirbel between the animal and vegetable kingdoms. 



In the above sub-merged, subterranean, sunless and earth- 

 eating existence the streams of life and of its native current 

 glide for four-and-twenty successive moons over the head of 

 our as yet misnamed Ephemera, which, during the latter part 

 of the same period, exchanges the first (or Larva) for the 

 second (or Pupa) state of insect life. It is then that on some 

 fine May morning (or may be evening) it bids adieu for ever 

 to its dark subaqueous dwelling, and rises to the surface, pre- 

 pared to enter on its third estate. 



Having burst from the Pupa skin, which is left behind as 

 the badge and bandage of an inferior and confined condition, 

 it quits, in company with numerous fellows, the water for the 

 air, in the shape, to all appearance, of a perfect fly. As if, 



however, the most fugacious of all insect forms was purposely 





 designed to be also the most elaborately finished, it has still to 



pass through another and fourth stage of development. The 



See Insect Architecture, p. 206. 



