This is a widely but thinly distributed species [...] We have a very large number of records, possibly due to the publicity it has received over the years, because of studies in industrial melanism. We cannot think of any other moth which has been the subject of so much research and exposure in the media. One of the earliest species to exhibit the phenomenon of selection for melanism in industrial areas, it exists in three forms in the north east. The jet black form carbonaria is still by far the commonest, particularly on the eastern side [...] whilst types are predominant in the west and north, although carbonaria has been taken in such unlikely places as Upper Teesdale and Cowshill in Upper Weardale. The greyish suffused form insularia is by far the scarcest and is seen only rarely. It is in no way genetically connected with f. carbonaria, but of course is impossible to see when both genes are present together. Since the change over from coal fires to smokeless fuels during the last twenty years, we have seen some change in the incidence of f. carbonaria. Whereas in the 1950's; nothing but f. carbonaria was taken in the Chester-Ie-Street trap, odd singles of the type began to appear in the late 1960's. Both forms appear nowadays in almost equal numbers [...].