416 SEXUAL SELECTION. Part II. 



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 passed by at the 

 distance of many yards, and no doubt of every passing 

 bird. 



I then applied to Mr. Wallace, who has an innate 

 genius for solving difficulties. After some consideration 

 he replied : " Most caterpillars require protection, as 

 " may be inferred from some kinds being furnished 

 " with spines or irritating hairs, and from many being 

 " coloured green like the leaves on which they feed, 

 '•' or curiously like the twigs of the trees on which they 

 " live." I may add as another instance of protection, 

 that there is a caterpillar of a moth, as I am informed 

 by Mr. J. Mansel Weale, which lives on the mimosas in 

 South Africa, and fabricates for itself a case, quite un- 

 distinguishable from the surrounding thorns. From 

 such considerations Mr. Wallace thought it probable 

 that conspicuously-coloured caterpillars were protected 

 by having a nauseous taste ; but as their skin is ex- 

 tremely tender, and as their intestines readily protrude 

 from a wound, a slight peck from the beak of a bird 

 would be as fatal to them as if they had been devoured. 

 Hence, as Mr. Wallace remarks, " distastefulness alone 

 " would be insufficient to protect a caterpillar unless 

 " some outward sign indicated to its would-be destroyer 

 " that its prey was a disgusting morsel." Under these 

 circumstances it would be highly advantageous to a 

 caterpillar to be instantaneously and certainly recog- 

 nised as unpalatable by all birds and other animals. 



