species to be distinguishable from all the persecuted, and the more
conspicuous and well-known they are, the less likely are they to be
mistaken by birds, insectivorous mammals, &c., for eatable kinds and
caught or injured. Hence we find that many such species have acquired
for their protection very brilliant or strongly-contrasted
colours--warning colours--which insect-eaters come to know.

The firefly, a soft-bodied, slow-flying insect, is easily caught and
injured, but it is not fit for food, and, therefore, says the theory,
lest it should be injured or killed by mistake, it has a fiery spark to
warn enemies---birds, bats, and rapacious insects--that it is uneatable.

The theory of warning colours is an excellent one, but it has been
pushed too far. We have seen that one of the most common fireflies is
diurnal in habits, or, at any rate, that it performs all the important
business of its life by day, when it has neither bright colour nor light
to warn its bird enemies; and out of every hundred species of
insect-eating birds at least ninety-nine are diurnal. Raptorial insects,
as I have said, feed freely on fireflies, so that the supposed warning
is not for them, and it would be hard to believe that the magnificent
display made by luminous insects is useful only in preventing accidental
injuries to them from a few crepuscular bats and goatsuckers. And to
believe even this we should first have to assume that bats and
goatsuckers are differently constituted from all other creatures; for in
other animals--insects, birds, and mammalians--the appearance of fire by
night seems to confuse and frighten, but it certainly cannot be said to
_warn,_ in the sense in which that word is used when we speak of the
brilliant colours of some butterflies, or even of the gestures of some
venomous snakes, and of the sounds they emit.