42 THE COLOURS OF ANIMALS 



CHAPTEB IV 



PBOTECTIVE BE SEMBLANCES IN LEPIDOPTEBA 

 {continued), DIMOBPHISM, ETC, 



General Protective Resemblance and changes of colour 

 corresponding to changes in the surroundings 



All the examples hitherto described illustrate Special 

 Protective Eesemblance. A good instance of General 

 Eesemblance 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 



