382 SEXUAL SELECTION. [Part II. 



power which compels us to believe that the lower surfaces 

 have here been colored for the sake of protection, leads us 

 to deny that the wings have been tipped, especially when 

 this character is confined to the males, with bright orange 

 for the same purpose. 



Turning now to Moths : most of these rest motionless 

 with their wings depressed during the whole or greater 

 part of the day ; and the upper surfaces of their wings 

 are often shaded and colored in an admirable manner, as 

 Mr. Wallace has remarked, for escaping detection. With 

 most of the BombycidaB and Noctuida3* 7 when at rest, the 

 front-wings overlap and conceal the hind- wings ; so that 

 the latter might be brightly colored without much risk ; 

 and they are thus colored in many species of both families. 

 During the act of flight, moths would often be able to es- 

 cape from their enemies ; nevertheless, as the hind- wings 

 are then fully exposed to view, their bright colors must 

 generally have been acquired at the cost of some little 

 risk. But the following fact shows us how cautious we 

 ought to be in drawing conclusions on this head. The 

 common yellow under-wings (Triphaena) often fly about 

 during the day or early evening, and are then conspicuous 

 from the color of their hind-wings. It would naturally 

 be thought that this would be a source of danger ; but 

 Mr. J. Jenner Weir believes that it actually serves them 

 as a means of escape, for birds strike at these brightly- 

 colored and fragile. surfaces, instead of at the body. For 

 instance, Mr. Weir turned into his aviary a vigorous spe- 

 cimen of Triphaena pronuba, which was instantly pur- 

 sued by a robin ; but, the bird's attention being caught 

 by the colored wings; the moth was not captured until 

 after about fifty attempts, and small portions of the wings 

 were repeatedly broken off. He tried the same experi- 



7 Mr. Wallace in c Hardwicke's Science Gossip,' Sept. 1867, p. 193. 



