The melanic form of the peppered moth, Biston betularia (Linnaeus, 1758) (Lepidoptera: Geometridae), in Manchester: The end of an era

Biston betularia is the model species for the study of industrial melanism. During the last century a dramatic decline in the carbonaria morph occurred throughout conurbations in the U.K. In this paper we report on changing morph frequencies towards the end of this period and into the 21st century for the Manchester area. Form carbonaria has fallen from 95% to 13.1% and 4.3% respectively in different parts of the conurbation, whereas insularia has increased from 1.5% to 7.5%. The reasons for the decline in one and increase in the other are discussed.