42 THE COLOUKS OF ANIMALS 



CHAPTER IV 



PROTECTIVE RESEMBLANCES IN LEPIDOPTERA 

 (continued), DIMORPHISM, ETC. 



General Protective Resemblance and changes of colour 

 corresponding to changes in the surroundings 



ALL the examples hitherto described illustrate Special 

 Protective Resemblance. A good instance of General 

 Resemblance is afforded by the large and common 

 caterpillar of the Privet Hawk Moth (Sphinx ligustri). 

 Although the caterpillar looks so conspicuous, it 

 harmonises very well with its food-plant, and is some- 

 times difficult to find. The purple stripes increase 

 the protection by breaking up the large green surface 

 of the caterpillar into smaller areas. This cater- 

 pillar also affords a good example of a rapid change of 

 colour corresponding to a change of environment. 

 When full grown it descends to the ground and 

 hurries about in search of a spot to bury in, and, 

 being very large and bright green, it would be ex- 

 ceedingly conspicuous against the brown earth if it 

 retained the usual colour. But just before it descends 

 the back begins to turn brown, and becomes finally 



