'Chap. XI. 
BUTTERFLIES AND MOTHS. 
403 
Islands, males are frequently found which closely 
resemble the females. In a future chapter I shall have 
occasion to shew that the beautiful eye-like spots or 
ocelli, so common on the wings of many Lepidoptera, 
are eminently variable. 
On the whole, although many serious objections may 
be urged, it seems probable that most of the species of 
Lepidoptera which are brilliantly coloured, owe their 
colours to sexual selection, excepting in certain cases, 
presently to be mentioned, in which conspicuous colours 
are beneficial as a protection. From the ardour of the 
male throughout the animal kingdom, he is generally 
willing to accept any female ; and it is the female which 
usually exerts a choice. Hence if sexual selection has 
here acted, the male, when the sexes differ, ought to be 
the most brilliantly coloured ; and this undoubtedly is 
the ordinary rule. When the sexes are brilliantly co- 
loured and resemble each other, the characters acquired 
ky the males appear to have been transmitted to both 
sexes. But will this explanation of the similarity and 
dissimilarity in colour between the sexes suffice ? | 
The males and females of the same species of butterfly 
are known 20 in several cases to inhabit different stations, 
the former commonly basking in the sunshine, the latter 
haunting gloomy forests. It is therefore possible that 
different conditions of life may have acted directly on 
the two sexes ; but this is not probable , 21 as in the adult 
state they are exposed during a very short period to 
different conditions ; and the larvae of both are ex- 
posed to the same conditions. Mr. Wallace believes 
20 H. W. Bates, ‘The Naturalist on the Amazons/ vol. ii. 1863, 
p. 228. A. R. Wallace, in 4 Transact. Linn. Soc.’ vol. xxy. 1865, p. 10. 
21 On this whole subject see ‘ The Variation of Animals and Plants 
under Domestication,’ vol. ii. 1868, chap, xxiii. 
2 D 2 
