402 SEXUAL SELECTION. [Part II. 



females alone in this latter as in the previous cases origi- 

 nally varied in certain characters ; these characters hav- 

 ing been preserved and augmented through ordinary se- 

 lection for the sake of protection, an 1 from the first trans- 

 mitted to the female offspring alone. 



Bright Colors of Caterpillars. — While reflecting on 

 the beauty of many butterflies, it occurred to me that 

 some caterpillars were splendidly colored, 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 colors of their larvae could be in 

 some manner explained. In the first place, it may be ob- 

 served that the colors of caterpillars do not stand in any 

 close correlation with those of the mature insect. Sec- 

 ondly, their bright colors do not serve in any ordinary 

 manner as a protection. As an instance of this, Mr. Bates 

 informs me that the most conspicuous caterpillar which he 

 ever beheld (that of a Sphinx) lived on the large green 

 leaves of a tree on the open llanos of South America; it 

 was about four inches in length, transversely banded with 

 black and yellow, and with its head, legs, and tail of a 

 bright red. Hence it caught the eye of any man who 



heritance 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 attrac- 

 tive 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 acquisition would have been aided 

 by natural selection. But it would be quite beyond our power to dis- 

 tinguish 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 mimicry, 

 though this is comparatively easy with the females, which have rarely or 

 never been rendered beautiful, as far as we can judge, for the sake of 

 sexual attraction, although they have often received beauty through in- 

 heritance from their male parents. 



