180 THE COLOURS OF ANIMALS 



conspicuous at these times, when all the tints of nature 

 are sombre and form a background against which the 

 Warning Colours would stand out in startling contrast. 

 Certain species, which are defended in this way, pass 

 the winter in the brightly coloured stage of metamor- 

 phosis ; but they conceal themselves as completely as 

 possible under loose bark or among dead leaves, &c. 

 This is true of the common ladybird, and I have 

 noticed that they begin to hide comparatively early in 

 the autumn, when the insects are rapidly diminishing 

 in numbers, but before the beginning of the cold 

 weather. It is therefore probable that they hide in 

 order to conceal their bright colours and not to escape 

 the cold.- It is also known that ladybirds are eaten 

 by the Green Tree frog in winter, when other insect 

 food is scarce, and also by hungry birds, although 

 they are intensely disliked and are refused (at any rate 

 by the frogs) if other food can be obtained. 



Experimental proof that Insect-eating animals, if 

 hungry, will eat unpalatable species 



This conclusion was tested as completely as pos- 

 sible by offering conspicuous unpalatable insects of 

 many species to animals from which all other food 

 was withheld. Under these circumstances the insects 

 were eaten, although often after many attempts, and 

 evidently with the most intense disgust. 



