Peppered Moth {Biston betularia} showing a comparison of the melanic form f. carbonaria next to the typical paler form on dark soot-covered bark. The melanic form has long been cited by genetic studies as an example of industural melanism. Sooty deposits on trees and other surfaces meant that the darker form was better camouflaged and more successful in industrial areas of Northern England. In recent decades air quality has imporved to the extent that the melanic form is declining in these areas and is now less frequently encountered than the typical form. Peak District National Park, Derbyshire, UK. July.