IOO The Colours of Animals. 



birds. Again, in another caterpillar, there is an eye- 

 spot on each segment, which mimics the flower of 

 the plant on which it feeds. White spots, in some 

 cases, also resemble the spots of light which pene- 

 trate foliage. In other instances, however, and at 

 any rate in our Elephant Hawk-moth, the eye-spots 

 certainly render the insect more conspicuous. 



8. Now in some cases, this is an advantage, 

 rather than a drawback. Suppose that from the 

 nature of its food, from its being covered with 

 hair, or from any other cause, a small green cater- 

 pillar were very bitter, or disagreeable or dan- 

 gerous as food, still, in the number of small green 

 caterpillars which birds love, it would be continually 

 swallowed by mistake. If, on the other hand, it 

 had a conspicuous and peculiar colour, its evil taste 

 would serve to protect it, because the birds would 

 soon recognise and avoid it, as has been proved ex- 

 perimentally. I have already alluded to a case of 

 this among the Hawk-moths, in a species which, 

 feeding on euphorbia, with its bitter milky juice, 

 is very distasteful to birds, and is thus actually 

 protected by its bold and striking colours. The 

 spots on our Elephant Hawk-moth caterpillar do 

 not admit of this explanation, because the insect is 

 quite good to eat I mean, for birds. We must, 

 therefore, if possible, account for these spots in 

 some other way. There can, I think, be little 

 doubt that Weissmann is right when he suggests 

 that the eye-spots actually protect the caterpillar, 

 by frightening its foes. 



