238 DARWmiSlVr CHAP. 



animals, while, in the immense majority of cases, the con- 

 sjaicuous, hairy, or brightly coloured larvte have been rejected 

 by some or all of them. In some instances the inedibility of 

 the larvae extends to the perfect insect, but not in others. In 

 the former cases the perfect insect is usually adorned with 

 conspicuous colours, as the burnet and ragwort moths ; but 

 in the case of the buff-tip, the moth resembles a broken piece 

 of rotten stick, yet it is partly inedible, being refused by 

 lizards. It is, however, very doubtful Avhether these are its 

 chief enemies, and its protective form and colour may be 

 needed against insectivorous birds or mammals. 



Mr. Samuel H. Scudder, Avho has largely bred North 

 American butterflies, has found so many of the eggs and larvae 

 destroyed by hymenopterous and dipterous parasites that he 

 thinks at least nine-tenths, perhaps a greater proportion, never 

 reach maturity. Yet he has never found any evidence that 

 such parasites attack either the egg or the larva of the inedible 

 Danais archippus, so that in this case the insect is distasteful 

 to its most dangerous foes in all the stages of its existence, 

 a fact which serves to explain its great abundance and its 

 extension over almost the whole world. ^ 



One case has been found of a jDrotectively coloured larva, 

 — one, moreover, which in all its habits shows that it 

 trusts to concealment to escape its enemies — which was yet 

 always rejected by lizards after they had seized it, evidently 

 under the impression that from its colour it would be 

 eatable. This is the caterpillar of the very common moth 

 Mania typica ; and Mr. Poulton thinks that, in this case, the 

 unpleasant taste is an incidental result of some jDhysiological 

 processes in the organism, and is itself a merely useless 

 character. It is evident that the insect would not conceal 

 itself so carefully as it does if it had not some enemies, and 

 these are probably birds or small mammals, as its food-plants 

 are said to be dock and willow-herb, not suggestive of places 

 frecjuented by lizards ; and it has been found by experiment 

 that lizards and birds have not always the same likes and 

 dislikes. The case is interesting, because it shows that 

 nauseous fluids sometimes occur sporadically, and may thus be 

 intensified by natural selection when required for the purpose 



' Nature, vol. iii. ]). 147. 



