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 the rare female brookeana should 
act in such aleap-year fashion. Onewould expect the amorous 
swains to swarm around coy maidens instead of behaving like 
lepidopterous Josephs. 
In Hestia lynceus and H. leuconoé v. labuana we have other 
cases in which the female woos the male, and the allied 
Ideopsis daos 1 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 I 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 affair 
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 the 
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 O. Brookeana, however, the female was appa- 
rently both wooer and chooser. Indeed, among buttertlies 
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. 218. 
