COLOURS OF ANIMALS. 



175 



lested ; but if they did not differ in form and colouring 

 from other butterflies, or if they flew so quickly tbat their 

 peculiarities could not be easily noticed, they would be 

 captured, and though not eaten would be maimed or 

 killed. 



As soon as the cause of the peculiarities of these butter- 

 flies was clearly recognised, it was seen that the same ex- 

 planation applied to many other groups of animals. Thus, 

 bees and wasps and other stinging insects are showily 

 and distinctively coloured ; many soft and apparently 

 defenceless beetles, and many gay-coloured moths, were 

 found to be as nauseous as the above-named butterflies ; 

 other beetles, whose hard and glossy coats of mail render 

 them unpalatable to insect-eating birds, are also some- 

 times showily coloured ; and the same rule was found to 

 apply to caterpillars, all the brown and green (or protec- 

 tively coloured species) being greedily eaten by birds, 

 while showy kinds which never hide themselves — like 

 those of the magpie-, mullein-, and burnet-moths — were 

 utterly refused by insectivorous birds, lizards, frogs, and 

 spiders. [Contributions to the Theory of Natural Selec- 

 tion, p. 117.) Some few analogous examples are found 

 among vertebrate animals. I will only mention here a 

 very interesting case not given in my former work. In his 

 delightful book entitled, The Naturalist in Nicaragua, 

 Mr. Belt tells us that there is in that country a frog 

 which is very abundant ; which hops about in the day- 

 time ; which never hides himself ; and which is gorgeously 

 coloured with red and blue. Now frogs are usually 

 green, brown, or earth-coloured ; feed mostly at night ; 

 and are all eaten by snakes and birds. Having full faith 

 in the theory of protective and warning colours, to which 



