WARNING COLORATION. 



151 



of colour thus produced must obviously stand out in greater 

 contrast to the surroundings. This suggestion is particularly 

 applicable to the larva? of many of the Vanessido?; several 

 species of these butterflies lay their eggs upon nettles, and the 

 larva? remain associated together in herds, sometimes entirely 

 defoliating the plants. Now, the caterpillars of the Tortoise- 

 shell and others are greenish-black ; seen singly, their appear- 

 ance is not very striking : indeed, it is almost a case of pro- 

 tective resemblance : the caterpillar, with its hairy or rather 

 spiny coat and greenish-black colour, is not unlike a half- 



ujuBRARY 



Fig. 15. Butt'-tip Moth ami Caterpillar. 



withered and rolled-up leaf of nettle. But a whole battalion 

 of these caterpillars could hardly be passed over by any insect- 

 eating bird; and, like the other instances mentioned, they have 

 been proved to be usually unacceptable to birds, lizards, andfrogs. 

 Some of the experiments made may be fairly criticised r 

 notably those upon the larva of the Elephant Hawk moth. 

 This insect when disturbed retracts the head and distends the 

 anterior end of the body. Two pairs of large eye-like markings 

 are thus brought into great prominence, and suggest the head 

 of a serpent. Dr. Weisniann found that a tame jay ate the 

 larva at once, but that wild sparrows and chaffinches were 

 frightened by it, and would not even approach the trough in 



