34 



THE COLOUKS OF ANIMALS 



upon the plant. Thus the caterpillar of the Straw 

 Belle {Aspilates gilvaria), feeding upon such plants as 

 yarrow and plantain, coils up the anterior part of its 

 body into a flat spiral, with the head in the centre. 

 Hence the attitude and the whitish colour of the larva 

 produce a very considerable resemblance to a small 

 bleached and empty snail-shell, which 

 would be of no interest to any insect- 

 eater. If the colour of the caterpillar 

 were darker it might be mistaken for 

 a living snail, and it is doubtful how far 

 such a resemblance would be to its ad- 

 vantage, in the case of birds. 



Another larva, that of the Large 

 Emerald Moth {Geometra papilionaria), 

 feeding upon catkin -bearing trees, birch 

 and nut, resembles the catkins rather 

 than the twigs (see fig. 9). It is short 

 and stout, and the manner in which the 

 body-rings succeed each other forcibly 

 suggests the overlapping scales of a cat- 

 kin. Some of the larvae are green and 

 some brown, like catkins of different colours. 



Fig. 9. — 



Protective Kesemblance to bark and lichen in 

 Lepidoptera 



Certain caterpillars belonging to other groups are 

 concealed by their resemblance to the bark of tolerably 



