BUTTERFLY AESTHETICS. 157 



Let me note, too, just in passing, that 

 while the upper half of the butterfly's wing is 

 generally beautiful in colour, so as to attract 

 his fastidious mate, the under half, displayed 

 while he is at rest, is almost always dull, and 

 often resembles the plant upon which he 

 habitually alights. The first set of colours is 

 obviously due to sexual selection, and has for 

 its object the making an effective courtship ; 

 but the second set is obviously due to natural 

 selection, and has been produced by the fact 

 that all those insects whose bright colours 

 show through too vividly when they are at 

 rest fall a prey to birds or other enemies, 

 leaving only the best protected to continue 

 the life of the species. 



But sight is not the only important sense 

 to the butterfly. He is largely moved and 

 guided by smell as well. Both bees and 

 butterflies seem largely to select the flowers 

 they visit by means of smell, though colour 

 also aids them greatly. When we remember 

 that in ants scent alone does duty instead of 



