PEPPERED MOTH

(Biston betularia), a European moth of the family Geometridae (order Lepidoptera), having speckled black-and-white wings. It is of significance in exemplifying natural selection through industrial melanism. The peppered moth had originally been white-coloured, but a dark (melanic) form of the peppered moth, first noticed in Manchester, Eng., in 1848, had outnumbered the usual light-coloured moth by 99 to 1 by 1898. The explanation of this phenomenon is that the dark moth, which originally was a chance mutation, was rendered less conspicuous to bird predators than the light moth against tree trunks which had become covered with black soot owing to the air pollution caused by nearby industries. The difference is genetic and of interest as a striking example of rapid evolutionary change in a localized area.