Chap. XL BUTTERFLIES AND MOTHS. 415 



that the females alone in this latter as in the previous 

 cases originally varied in certain characters ; these cha- 

 racters having been preserved and augmented through 

 ordinary selection for the sake of protection and from 

 the first transmitted to the female offspring alone. 



Bright Colours of Caterpillars. — Whilst reflecting on 

 the beauty of many butterflies, it occurred to me that 

 some caterpillars were splendidly coloured, and as 

 sexual selection could not possibly have here acted, 

 it appeared rash to attribute the beauty of the mature 

 insect to this agency, unless the bright colours of their 

 larvae could be in some manner explained. In the first 

 place it may be observed that the colours of caterpillars 

 do not stand in any close correlation with those of the 

 mature insect. Secondly, their bright colours do not 



the aid of selection to check the variations being inherited by the 

 other sex. No doubt if it could be shewn that the females of very 

 many species had been rendered beautiful through protective miinickry, 

 but that this has never occurred with the males, it would be a serious 

 difficulty. But the number of cases as yet known hardly suffices for a 

 fair judgment. We can see that the males, from having the power of 

 flying more swiftly, and thus escaping danger, would not be so likely 

 as the females to have had their colours modified for the sake of protec- 

 tion ; but this would not in the least have interfered with their receiving 

 protective colours through inheritance from the females. In the second 

 place, it is probable that sexual selection would actually tend to prevent 

 a beautiful male from becoming obscure, for the less brilliant individuals 

 would be less attractive to the females. Supposing that the beauty of 

 the male of any species had been mainly acquired through sexual 

 selection, yet if this beauty likewise served as a protection, the acquisi- 

 tion would have been aided by natural selection. But it would be 

 quite beyond our power to distinguish between the two processes of 

 sexual and ordinary selection. Hence it is not likely that we should 

 be able to adduce cases of the males having been rendered brilliant 

 exclusively through protective mimickry, though this is comparatively 

 easy with the females, which have rarely or never been rendered beau- 

 tiful, as far as we can judge, for the sake of sexual attraction, although 

 they have often received beauty through inheritance from their male 

 parents. 



