About Perizoma didymata (Linnaeus, 1758)
Perizoma didymata (Linnaeus, 1758) has a wingspan of 24–29 mm. The ground colour of its forewings is generally pale or dark grey, with two dark stains located near the forewing apex and costa. Wavy crosslines on the forewings border a darker mid field and a darker marginal field. This species is very variable in colour. Males are considerably darker than females, and this sexual dimorphism is quite striking in some districts. Females are appreciably smaller, have narrower wings than males, and have a much stouter abdomen. Several named aberrations are recognized: ab. ochroleucata Auriv. is unicolorous grey yellow or yellow brown, with no markings other than the light subterminal line. In ab. nigrofasciata Rbl., the ground colour is darkened, and the narrow median band is almost black. ab. nigra Prout has uniform blackish brown wings. In hethlandica Rbl., the male is more or less bright orange brown, while the female is a lighter ochreous brown or fawn colour. The larva of this species is long and slender, a feature that differs it from most other species in the genus Perizoma. It is grey-green with short, dark brushes. This species is distributed across northern and central Europe; further to the south and east, it is only found in the mountain ranges of the Pyrenees, Alps, and Urals.
