310 THE DESCENT OF MAN. 



colored leaf; and in our Englisli orange-tip, the under surface 

 vesembles the flower-head of the wild parsley, on which the 

 butterfly often rests at night." The same reason 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 with bright orange for the same purpose, especially 

 when this character is confined to the males. 



Most Moths rest motionless during the whole or greater part 

 of the day with their wings depressed; and the whole upper 

 surface is often shaded and colored in an admirable manner, as 

 Mr. Wallace has remarked, for escaping detection. The front- 

 wings of the Bombycidae and Noctuidae," when at rest, generally 

 overlap and conceal the hind- wings; so that the latter might be 

 brightly colored without much risk; and they are in fact often 

 thus colored. During flight, moths would often be able to escape 

 from their enemies; nevertheless, as the hind- wings are then 

 fully exposed to view, their bright colors must generally have 

 been acquired at some little risk. But the following fact shows 

 how cautious we ought to be in drawing conclusions on this head. 

 The common Yellow XJnder-wings (Triphsna) 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, in- 

 stead of at the body. For instance, Mr. Weir turned into his 

 aviary a vigorous specimen of Triphasna pronuba, which was in- 

 stantly pursued by a robin; but the bird's attention being caught 

 by the colored wings, the moth was not captured until after 

 about flfty attempts, and small portions of the wings were re- 

 peatedly broken off. He tried the same experiment, in the open 

 air, with a swallow and T. fimbria; but the large size of this 

 moth probably interfered with its capture."^ We are thus remind- 

 ed of a statement made by Mr. Wallace,™ namely, that in the 

 Brazilian forests and Malayan islands, many common and highly- 

 decorated butterfiies are weak flyers, though furnished with a 

 broad expanse of wing; and they "are often captured with pierced 

 "and broken wings, as if they had been seized by birds, from 

 "which they had escaped: if the wings had been much smaller 



i» See the Interesting observations by Mr. T. W. Wood, 'The Student,' 

 Sept. 1868, p. 81. 



" Mr. Wallace in 'Hardwlcke's Science Gossip,' Sept. 1867, p. 193. 



" See also, on this subject, Mr. Weir's paper in 'Transact, Bnt. Soc' 

 1SG9, p. 23. 



" 'Westminster Review.' July 18C7, p. 16. 



