PDF - Wallace Online

v COLOURS OF ANIMALS 351showy colours and slow flight. It isgood for them to beseen and recognised, for then they are never molested ;butifthey did not differ in form and colouring from otherbutterflies, or if they flew so quickly that their peculiaritiescould not be easily noticed, they would be captured, andthough not eaten would be maimed or killed.As soon as the cause of the peculiarities of these butterflieswas clearly recognised, it was seen that the same explanationapplied to many other groups of animals. Thus, bees andwasps and other stinging insects are showily and distinctivelycoloured ; many soft and apparently defenceless beetles, andmany gay-coloured moths, were found to be as nauseous as theabove-named butterflies ;other beetles, whose hard and glossycoats of mail render them unpalatable to insect-eating birds,are also sometimes showily coloured ;and the same rule wasfound to apply to caterpillars, all the brown and green (orprotectively coloured species) being greedily eaten by birds,while showy kinds which never hide themselves like thoseof the magpie-, mullein-, and burnet-moths were utterlyrefused by insectivorous birds, lizards, frogs, and spiders(p. 84). Some few analogous examples are found amongvertebrate animals. I will only mention here a very interestingcase not given in my former work. In his delightfulbook, entitled The Naturalist in Nicaragua, Mr. Belt tells usthat 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, feedmostly at night, and are all eaten by snakes and birds.Having full faith in the theory of protective and warningcolours, to which he had himself contributed some valuablefacts and observations, Mr. Belt felt convinced that this frogmust be uneatable. He therefore took one home, and threwit to his ducks and fowls ;but all refused to touch it exceptone young duck, which took the frog in its mouth, butdropped it directly, and went about jerking its head as iftrying to get rid of something nasty. Here the uneatablenessof the frog was predicted from its colours and habits, and wecan have no more convincing proof of the truth of a theorythan such previsions.