Peppered Moth (Biston betularia)
The Peppered Moth usually is a white moth with numerous black dots and patches. But the amount of black is extremely variable and many animals are melanistic, or putting it in simple words: almost entirely black. In some areas and at certain times the black form (called Biston betularia forma carbonaria) are more common than the 'peppered' form. The fat, hairy body sometimes causes problems identifying this species, for it doesn't really look like a typical Geometer. When melanistic animals appear they can easily be mistaken for melanistic Oak Beauties. Luckily these fly earlier and the two species are hardly ever appearing together. The wingspan of the Peppered Moth matches its colours in variability, ranging from 45 to 62 mm!
The caterpillar looks like a twig and is also extremely variable in colour: reddish brown, dark brown, greenish brown or entirely green. Usually there is a dark line running all over the back and there are two bumps on the 8th segment. The head is brown. The caterpillars are active from July to September. They feed by night and sit, stretched out like a twig, motionless during the day. This makes them very hard to find. In autumn they descent from the foodplant to pupate underground. The Peppered Moth overwinters as a pupa. The larvae may be some 6 cm long once fullgrown. It feeds on numerous trees and shrubs. In our garden found on Buddleja.
The Peppered Moth only flies by night, but comes to light readily. There is only one generation a year, but it is on the wing for a long period of time: from April to August. Most numerous in June and July, though. It prefers woodland, hedgerows, parks and gardens, including those in towns and cities. Very common in England, Wales and Ireland, widespread but local in Scotland, the Hebrides and Orkney. Also very common, often numerous on the continent.
The theory of melanistic forms appearing in industrial areas derives from this species. The use of coal in the 19th and first half of the 20th century has been offered as an explanation. Nowadays this theory has been abandoned, but you still come across it in many books and on many sites.