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SEXUAL SELECTION. 
Part IL 
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 wdiich 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. 
