Chap. XL] BUTTERFLIES AND MOTHS. 375 



a conflict with another male. Mr. Collingwood, in speak- 

 ing of the frequent battles between the butterflies of Bor- 

 neo, says, " They whirl round each other with the greatest 

 rapidity, and appear to be incited by the greatest ferocity." 

 One case is known of a butterfly, namely, the Ageronia 

 feronia, which, makes a noise like that produced by a 

 toothed wheel passing under a spring-catch, and which 

 could be heard at the distance of several yards. At Rio de 

 Janeiro this sound was noticed by me, only when two 

 were chasing each other in an irregular course, so that it is 

 probably made during the courtship of the sexes ; but I 

 neglected to attend to this point. 2 



Every one has admired the extreme beauty of many 

 butterflies and of some moths ; and we are led to ask, How 

 has this beauty been acquired? Have their colors and 

 diversified patterns simply resulted from the direct action 

 of the physical conditions to which these insects have been 

 exposed, without any benefit being thus derived? Or 

 have successive variations been accumulated and deter- 

 mined either as a protection or for some unknown purpose, 

 or that one sex might be rendered attractive to the other ? 

 And, again, what is the meaning of the colors being wide- 

 ly different in the males and females of certain species, 

 and alike in the two sexes of other species ? Before at- 

 tempting to answer these questions a body of facts must 

 be given. 



With most of our English butterflies, both those which 

 are beautiful, such as the admiral, peacock, and painted 

 lady (Vanessae), and those which are plain-colored, sucb 

 as the meadow-browns (Hipparchia^), the sexes are alike. 

 This is also the case with the magnificent Heliconidse and 



2 See my ' Journal of Researches,' 1845, p. 33. Mr. Doubleday has 

 detected ('Proc. Ent. Soc' March 3, 1845, p. 123) a peculiar mem- 

 branous sac at the base of the front wings, which is probably connected 

 with the production of the sound. 



