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 1s 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. 
