130 THE MEANING OF EVOLUTION 



that, in very many of the butterflies and moths, the 

 attractive coloration is chiefly displayed when they are 

 moving actively about; and when they alight and 

 their enemies can the more easily capture them, they 

 conceal their brilliant colorings. Most butterflies are 

 very brilliant on the upper surface of the wings and 

 very much duller on the under surface. Hence in 

 flight they show their colorings exquisitely, but when 

 they alight, and are thus more likely to be captured, 

 they fold the brilliant surfaces together in an upright 

 position. In this way not only is the dull side of the 

 wings placed outward, but the wings themselves are 

 placed edgewise to the sky, and it is from this direc- 

 tion that their enemies, the birds, are most likely to see 

 them. Once upon the wing these creatures display 

 their beauty with much greater safety because they 

 can escape the birds very readily by use of their ex- 

 ceedingly jerky flight. The butterfly's motion is as 

 irregular as any we have except the bat's. This ec- 

 centricity is one great element in their safety, and 

 makes it less dangerous for them to display their at- 

 tractive colorations. 



One very large group of the night-flying moths 

 have been named the "underwings," because of the 

 fact that their hind wings are very much more bril- 

 liant than the front, and in lighting they fold the dull 

 pair back over the bright, completely concealing them. 



