INSECTS 



245 



upper surfaces usually exhibit protective resemblance, and 

 not the lower. 



It might be objected that if the exposure of the upper 

 sides in butterflies causes bright conspicuous colours, how 

 can similar exposure cause dull protective colours in moths ? 

 But the exposure is not similar. By exposure I mean the 



FlG. 23. A. Catorala electa, a British moth, wings expanded as in flight. The hind wing is 

 red and black. B. The same with wings closed in the resting position, the brightly 

 coloured hind wings entirely concealed. C. Satyrus seme.le, a British butterfly showing 

 the upper surface of the wings as in flight. D. The same, showing the lower surface 

 of the wings. When the insect settles the fore wing is drawn down behind the hind 

 wing, so as to be entirely concealed. 



kind of light to which the surface is exposed, and I believe 

 that in Lepidoptera the coloration has chiefly been deter- 

 mined by the quality of the light. The upper side of a 

 butterfly's wings in flight is exposed to bright sunshine or to 

 the coloured lights reflected from gay flowers. The upper 



side of the wings 



of a resting 



moth receive dull light in 



