The current theory, which we owe to Belt, is a prettier one. Certain insects (also certain Batrachians, reptiles, &c.) are unpalatable to the rapacious kinds; it is therefore a direct advantage to these unpalatable 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.