About Erannis defoliaria (Clerck, 1759)
This species, known scientifically as Erannis defoliaria (Clerck, 1759), shows clear sexual dimorphism. Female Erannis defoliaria are wingless, have a spider-like appearance, and are white or yellow with black patches. They can typically be found on the trunks and stems of their larval host food plants. Males are fully winged, with a wingspan ranging from 40 to 45 mm, and their appearance is highly variable. The ground color of the male's forewing is pale yellow or light yellow ochre, suffused with dark grey. Basal and distal fasciae are dark brown: the basal fascia has a brown cloud bordering its inner side, while the distal fascia has a brown cloud on its outer edge. An additional brown cloud runs along the costa, and two dark brown oblong spots sit in the upper half of the terminal area. The male's hindwing is grey-white with grey suffusion. A grey-black discal spot is present on both the forewing and hindwing. Many significant deviations from this base color pattern exist, some specimens are very dark, and truly melanic forms are common. Similar to the peppered moth, darker forms of Erannis defoliaria are more common in industrial regions. This species occurs across western Europe, ranging from northern Scandinavia south to the Mediterranean, and extends east through the Caucasus, northern Iran, Russia, the Russian Far East, to Ussuri.
