their enemies that they are unpalatable. In other cases in which the
sexes resemble each other and are both brilliant, especially when the
colours are arranged for display, we may conclude that they have been
gained by the male sex as an attraction, and have been transferred to
the female. We are more especially led to this conclusion whenever the
same type of coloration prevails throughout a whole group, and we find
that the males of some species differ widely in colour from the
females, whilst others differ slightly or not at all with intermediate
gradations connecting these extreme states.
In the same manner as bright colours have often been partially
transferred from the males to the females, so it has been with the
extraordinary horns of many Lamellicorn and some other beetles. So
again, the sound-producing organs proper to the males of the Homoptera
and Orthoptera have generally been transferred in a rudimentary, or
even in a nearly perfect condition, to the females; yet not
sufficiently perfect to be of any use. It is also an interesting fact,
as bearing on sexual selection, that the stridulating organs of certain
male Orthoptera are not fully developed until the last moult; and that
the colours of certain male dragon-flies are not fully developed until
some little time after their emergence from the pupal state, and when
they are ready to breed.
Sexual selection implies that the more attractive individuals are
preferred by the opposite sex; and as with insects, when the sexes
differ, it is the male which, with some rare exceptions, is the more
ornamented, and departs more from the type to which the species
belongs; and as it is the male which searches eagerly for the female,
we must suppose that the females habitually or occasionally prefer the
more beautiful males, and that these have thus acquired their beauty.
That the females in most or all the Orders would have the power of
rejecting any particular male, is probable from the many singular
contrivances possessed by the males, such as great jaws, adhesive
cushions, spines, elongated legs, etc., for seizing the female; for
these contrivances show that there is some difficulty in the act, so
that her concurrence would seem necessary. Judging from what we know of
the perceptive powers and affections of various insects, there is no
antecedent improbability in sexual selection having come largely into
play; but we have as yet no direct evidence on this head, and some
facts are opposed to the belief. Nevertheless, when we see many males
359