AppearanceThe sexes differ in size but are similar in colour. The forewings are orange brown with three narrow yellow fascia with two dark discal spots between the inner two fascia. Sometimes these occur, but weaker, on the rear wings. The apex of the forewing is hook shaped, giving the species its name. The hindwings are lighter orange, again with three yellow fascia. Usually two broods are produced each year, the adults flying in May and June and again in August . Second-generation moths are much smaller and slightly lighter coloured than those of the first. They are very similar to ''Watsonalla cultraria'' which also has a yellowish-brown colour. Two black twin points on the front wings are the clearest differentiator. The species sometimes flies during the day but usually flies at night and is attracted to light.
The larva is brown with yellow markings and shows the typical drepanid shape with a tapered tail. It usually feeds on oak but has also been recorded on alder, beech and birch. The species overwinters as a pupa.
NamingThe species was first described by Johann Siegfried Hufnagel in 1767.
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