236 ENTOMOLOGY 
lution has been attributed by Darwin and many of his follow- 
ers to sexual selection—a highly debatable subject. Among 
insects, however, no such phenomenon has been found; when- 
ever the two sexes differ in coloration the difference does not 
appear to facilitate the recognition of even one sex by the 
other. 
Evolution of Adaptive Coloration.—Natural selection is 
the only theory of any consequence that explains the highly 
involved phenomena of adaptive coloration. Against such 
vague and unsupported theories as the action of food, climate, 
laws of growth or sexual selection, natural selection alone 
accounts for the multitudinous and intricate correlations of 
color, pattern, form, attitude, movement, place, time, etc., that 
are necessary to the development of a perfect case of protective 
resemblance or mimicry. Natural selection cannot, of course, 
originate colors or any other characters, its action being re- 
stricted to the preservation and accumulation of such advan- 
tageous variations as may arise, from whatever causes. As 
Poulton says, the vast body of facts, utterly meaningless under 
any other theory, become at once intelligible as they fall har- 
moniously into place under the principle of natural selection, 
to which, indeed, they yield the finest kind of support. 
