314 THE DESCENT OF MAN. 



in S. Brazil, show an unmistakable preference for certa'in colors 

 over others: he observed that they very often visited the brill- 

 iant red flowers of five or six genera of plants, but never the 

 white or yellow flowering species of the same and other genera, 

 growing in the same garden; and I have received other accounts 

 to the same effect. As I hear from Mr. Doubleday, the common 

 white butterfly often flies down to a bit of paper on the ground, 

 no doubt mistaking it for one of its own species. Mr. Colling- 

 wood^ in speaking of the dilficulty in collecting certain butter- 

 flies in the Malay Archipelago, states that "a dead specimen pinned 

 "upon a conspicuous twig will often arrest an insect of the 

 "same species in its headlong flight, and bring it down within 

 "easy reach of the net, especially if it be of the opposite sex." 



The courtship of butterflies is, as before remarked, a pro- 

 longed affair. The males sometimes fight together in rivalry; and 

 many may be seen pursuing or crowding round the same female. 

 Unless, then, the females prefer one male to another, the pairing 

 must be left to mere chance, and this does not appear probable. 

 If, on the other hand, the females habitually, or even occasionally, 

 prefer the' more beautiful males, the colors of the latter will 

 have been rendered brighter by degrees, and will have been 

 transmitted to both sexes or to one sex, according to the law 

 of inheritance which has prevailed. The process of sexual selec- 

 tion will have been much facilitated, if the conclusion can be 

 trusted, arrived at from various kinds of evidence in the supple- 

 ment to the ninth chapter; namely, that the males of many 

 Lepidoptera, at least in the imago state, greatly exceed the 

 females in number. 



Some facts, however, are opposed to the belief that female 

 butterflies prefer the more beautiful males; thus, as I have 

 been assured by several collectors, fresh females may frequently 

 be seen paired v/ith battered, faded, or dingy males; but this is 

 a circumstance which could hardly fail often to follow from the 

 males emerging from their cocoons earlier than the females. 

 With moths of the family of the Bombycid®, the sexes pair im- 

 mediately after assuming the imago state; for they cannot feed, 

 owing to the rudimentary condition of their mouths. The females, 

 as several entomologists have remarked to me, lie in an almost 

 torpid state, and appear not to evince the least choice in regard 

 to their partners. This is the case with the common silk-moth 

 (B. mori), as I have been told by some continental and English 

 breeders. Dr. Wallace, who has had great experience in breeding 

 Bombyx cynthia, is convinced that the females evince no choice 

 or preference. He has kept above 300 of these moths together, 

 and has often found the most vigorous females mated with 



=2 'Eambles o£ a Naturalist in the Chinese Seas,' 1868, p. 182. 



