54 Adaptive Mimicry. 



surface. Similarly, we are not surprised to hear that the moths 

 which fly in autumn are mainly yellow and brown, those that fly 

 in winter are grey and silvery. The larvae of weevils and beetles 

 are unobserved because they look like the dung of birds, or pellets 

 of earth. There are some little tropical beetles that look like drops 

 of dew, others are so exactly of the colour of the salt marshes on 

 which they are found as only to be distinguishable by their shadow. 

 A Brazilian caterpillar acquires safety by wearing the appeai'ance 

 of a venomous snake. Not to weary you with the many hundreds 

 of similar facts which have now been observed, I will mention but 

 one more. Mr. Stainton was once flinging some dead moths to 

 his turkeys, and found that there was one white moth which each 

 bird in succession seized and then flung out of its mouth, as though 

 it were too nasty to eat. Now, probably this unpleasant taste 

 would protect this moth from all birds, just as the pungency of a 

 great American family of butterflies — the Heliconidae — secures 

 them from all molestation by innmnerable birds. For, of course, 

 turkeys not usually feeding on moths, might not know that this 

 white moth was unpleasant; but the experience of all regular 

 moth-eating birds would long have acquainted them with this fact, 

 and they would be as little likely to- attack this moth as the 

 American birds are to attack any of the Heliconidae. Now it is a 

 curious fact that about the same time when this moth (which is 

 called Psilosoma menthaestri) appears, there appears also another 

 and much rarer moth, the Diaphora mendica, of which the female 

 only is white. Now white, the mrost conspicuous colour, is there- 

 fore obviously for a light flying moth the most dangerous of 

 colours, and we may fairly suppose therefore, that the Psilosoma 

 would run no chance at all with other moths, if it were not 

 protected by its unpleasant taste, which effectually secures it from 

 assault. How, then is the Diaphora safe, which has no unpleasant 

 taste, and which being rare would be soon exterminated .' Is it 

 not fair to believe that it escapes by its protective resemblance to 

 the Psilosoma, and by the defective syllogism which makes birds 

 argue that as the Psilosoma is nasty, all white moths must be 

 nasty, and therefore the Diaphora must be nasty too. 



These special mimicries however, are only parts of a much 

 wider phenomenon, which we may call the protection of colour. 

 Obviously, in a world where there is a desperate and sanguinary 

 struggle for life perpetually going on, — where, as Tennyson says 



" The mayfly is speared by the swallow, the swallow killed by the shrike, 

 And the' whole little world where I live is a world of plunder and prey," — ■ 



it is of essential importance to the very existence of most animals 

 and insects, that they should be able to conceal themselves to a 

 great extent, and to avoid observation under all possible circum- 



