Univoltine but with an extended flight period. Females fly from early May (occasionally as early as late March) to mid October; males from early July to late September.
In Spain, label data referring to ssp. nivalis shows that females and males are active in August (Ortiz-Sanchez & Pauly, 2017).
In Poland, the females emerge in early May, and fly to mid-September, the males are active in August and September. (Pesenko, Banaszak et al., 2000)