244 EVOLUTION AND GENETICS 



brightly colored underwings which are conspicuous during flight 

 (Fig. 147). Their other colors are dull. When the insect flies, its 

 bright colors attract attention, but when it settles again thej'- are 

 so suddenly concealed that it seems to disappear, and it is very 

 difficult to determine its exact location. Another effect of these 



bright parts is that they are 

 hkely to be seized by a bird 

 if it overtakes the insect in 

 flight, so that the insect 

 escapes with no more injury 

 than a torn wing. 



Sexual Colors. Sexual 

 colors are again complex. 

 Many birds have brilliant 

 colors in the male sex, and 

 dull in the female. To what 

 extent the colors are attrac- 

 tive to the female, we cannot 

 say. It is almost certain 

 that they afford some degree 

 of protection to the nesting 

 birds, since marauders would 

 be more easily attracted to 

 the conspicuous male than to 

 the brooding female. We can 

 judge no better the value of 

 sexual coloration than by 

 Beebe's story of the tinamou 

 (Crypturus variegatus), in 

 which sexual behaviour is 

 completely reversed. In this 

 species the male raises the 

 young, and the female does 

 Fig. 148. — Larva of a geometric! moth, the courting. Through song 

 resting extended from a twig (From ^^^ ^^ ^^^ ^^^ display 



Woodruff, after Jordan and Kellogg.) , , , i i 



of such color as she possessed, 



he observed one of these birds carrying on her courtship in the 

 jungle of British Guiana. The bright colors are usually con- 

 cealed beneath the rudimentary tail, and then the bird blends 

 wonderfully into its jungle background. 



