The Descent of Man

Every one must have admired the extreme
beauty of many butterflies and of some moths;
and it may be asked, are their colours and diversified
patterns the result of the direct action
of the physical conditions to which these insects
have been exposed, without any benefit
being thus derived? Or have successive variations
been accumulated and determined as a
protection, or for some unknown purpose, or
that one sex may be attractive to the other?
And, again, what is the meaning of the colours
being widely different in the males and females
of certain species, and alike in the two sexes of
other species of the same genus? Before attempting
to answer these questions a body of facts
must be given.
With our beautiful English butterflies, the admiral,
peacock, and painted lady (Vanessae), as
well as many others, the sexes are alike. This is
also the case with the magnificent Heliconidae,
and most of the Danaidae in the tropics. But in