INSECTS IN THEIR PERFECT STATE. 127 



kinds. In most Lepidoptera the whole growth 

 generally takes place within an hour, often in half 

 that time. In others of that class, a whole day is 

 sometimes occupied in the completion of the wing- 

 growth, as in the case of the Humming-hird Moth, 

 Macroglossa Stellatorum, and some others. 



In the Ephemera, and also in Gnats, the expan- 

 sion may almost be termed sudden — a beautiful 

 provision, so ordered for the purpose of preserving 

 them from the risk they would run during a slower 

 process of wing-growth, as they first enter upon 

 their perfect state upon the surface of the water, 

 where they are not for a moment safe, after they 

 have emerged from the chrysalis, until their wings 

 are perfected. 



The Ephemera; exhibit a peculiarity, previ- 

 ously alluded to, consisting in a kind of moult, 

 almost as sudden as the growth of the wings. 

 No sooner are these insects able to fly, than they 

 nutter to some conveniently situated reed, and 

 there shed a skin or film which encased even the 

 wings, the parts covering which being .furnished 

 with the same coating of minute scales as the 

 surface of the wings themselves ; so that when the 

 insect has, with extraordinary skill, issued from 

 this close-fitting vestment, the skin left behind is 



