Habits of certain Bornean Butterflies. 215 



first, the less favoured are just as certain to be married and 

 leave offspring. 



If one may judge by human analogy, it would seem more 

 probable that the more numerous sex would be the more eager, 

 and it is difficult to see why tlie rare female Brookeana shoukl 

 act in such a leap-year fashion. One would expect the amorous 

 swains to swarm around coy maidens instead of behaving like 

 lepidopterous Josephs. 



In Hestia lynceus and //. leuconoe v. lahuana we have otlier 

 cases in which the female woos the male, and the allied 

 Ideojysis daos I believe does the same. These butterflies fly 

 about in pairs for days together, with a slow flapping flight, 

 the female about a foot above the male. The female follows 

 every turn and movement of the male, keeping a little behind 

 him. In these cases the sexes are alike in decoration, black 

 spots and nervures on a white or transparent ground. Why 

 these females should court the male is a difficult problem to 

 solve, especially as 1 believe there is no great disproportion 

 in the numbers of the sexes. The equality of numbers may 

 be a reason for the sexes being alike in decoration. 



As Darwin has well said, if one sex always preponderated 

 in numbers sexual selection would be easy to understand : 

 " if the males were to the females as two to one, or as three 

 to two, or even in a somewhat lower ratio, the whole aflair 

 would be simple " *. But this is by no means always the 

 case, for though it frequently happens that the male butter- 

 flies are more numerous than the females, and rarely that tlie 

 females exceed the males, there are many cases in which no 

 such disparity is apparent. 



Darwin further makes a valuable distinction between wooing 

 and choosing. The males as a rule woo and the females 

 choose, and probably it is rare for the wooer to be the chooser. 

 In the case of 0. Brookeana^ however, the female was appa- 

 rently both Mooer and ciiooser. Indeed, among butterflies 

 one can ring a number of changes between wooer and chooser, 

 sexes similar and sexes dissimilar, sexes equal and sexes 

 unequal, as in the following illustrations : — 



* ' Descent of Man,' ed. 2, p. 213. 



