of Mr. Wallace s view is confirmed, namely, that certain caterpillars
have been made conspicuous for their own good, so as to be easily
recognised by their enemies, on nearly the same principle that poisons
are sold in coloured bottles by druggists for the good of man. We
cannot, however, at present thus explain the elegant diversity in the
colours of many caterpillars; but any species which had at some former
period acquired a dull, mottled, or striped appearance, either in
imitation of surrounding objects, or from the direct action of climate,
etc., almost certainly would not become uniform in colour, when its
tints were rendered intense and bright; for in order to make a
caterpillar merely conspicuous, there would be no selection in any
definite direction.
A SUMMARY AND CONCLUDING REMARKS ON INSECTS.
Looking back to the several Orders, we see that the sexes often differ
in various characters, the meaning of which is not in the least
understood. The sexes, also, often differ in their organs of sense and
means of locomotion, so that the males may quickly discover and reach
the females. They differ still oftener in the males possessing
diversified contrivances for retaining the females when found. We are,
however, here concerned only in a secondary degree with sexual
differences of these kinds.
In almost all the Orders, the males of some species, even of weak and
delicate kinds, are known to be highly pugnacious; and some few are
furnished with special weapons for fighting with their rivals. But the
law of battle does not prevail nearly so widely with insects as with
the higher animals. Hence it probably arises, that it is in only a few
cases that the males have been rendered larger and stronger than the
females. On the contrary, they are usually smaller, so that they may be
developed within a shorter time, to be ready in large numbers for the
emergence of the females.
In two families of the Homoptera and in three of the Orthoptera, the
males alone possess sound-producing organs in an efficient state. These
are used incessantly during the breeding-season, not only for calling
the females, but apparently for charming or exciting them in rivalry
with other males. No one who admits the agency of selection of any
kind, will, after reading the above discussion, dispute that these
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