THE COLOURS OF ANIMALS AND PLANTS 135 



Insects are of two kinds — those which are extremely 

 difficult to find, and those which are rendered 

 prominent through startling colours and conspicuous 

 attitudes. Warning colours may usually be distin- 

 guished by being conspicuously exposed when the 

 animal is at rest. Crude patterns and startling 

 contrasts in colour are characteristically warning, and 

 these colours and patterns often resemble each other; 

 black combined with white, yellow, or red, are the 

 commonest combinations, and the patterns usually 

 consist of rings, stripes, or spots. 



Other examples are found in the bright colours of 

 some sponges which have been proved to be nauseous 

 to fish ; in the Anemones, Ascidians, and many 

 brightly-coloured Nudibranchs. 



One of the best-known instances is that of the 

 frog found by Mr. Belt in Nicaragua, a small 

 animal, gorgeously coloured with red and blue, which 

 never hides itself; whereas most frogs are coloured 

 green or brown, and hide during the day-time, 

 to avoid being eaten by snakes and birds. Sus- 

 pecting this animal to be uneatable, Mr. Belt 

 offered it to ducks and fowl, all of which refused to 

 touch it, except one young duck, which took the frog 

 in its mouth, but dropped it directly, "and went 

 about jerking its head, as though trying to throw off 

 some unpleasant taste." 



Very numerous examples are found among cater- 

 pillars such as that of the Cinnabar moth, which 

 is coloured black and yellow, and rejected even by a 

 toad. The Magpie-moth caterpillar, which is cream- 

 coloured, with orange and black markings, and 



