The adult's wingspan is 40–48 mm. The wings of this species are whitish-grey or -yellowish, though they have a buff or grey appearance from a distance, as they are heavily speckled with brown or black dots. Running over the fore- and hindwings in a semicircle are the two blackish bands commonly found in Ennominae, but they are broken and somewhat indistinct in this species. A tell-tale characteristic is a single bulge in the forewing part
of the outer blackish bands. Melanic forms (e.g. rebeli) sometimes occur. The sexes can be distinguished by their antennae, which are strongly feathered in the male, but almost smooth in the female. See similar species (below) This moth inhabits woodland, gardens and similar habitat. Either one or two generations occur each year, depending on locality. The adults are on the wing during summer – e.g. June to September on the British Isles, while in the more
continental climate of Austria they are rarely seen anymore in late August. They fly at night and are attracted to light. The caterpillar larva is reddish-brown and feeds on a variety of trees and shrubs, but – despite its name – rarely or never on willows (Salix). The species overwinters as a small larva. As evidenced by the species distribution, it does not seem to tolerate severe and dry winters very well.
