The four-spotted moth is mainly single-brooded (4), but often produces a second brood within its more southerly colonies (6). Adults fly in sunshine and at night from mid-May to mid- August, but the precise time of emergence depends on the climate (2). Eggs are deposited singly on the stems or flower buds of the foodplant during June. Caterpillars can be found at night on the foodplant in July and August, and occasionally later in the year. The overwintering stage is the pupa (2), which develops in September under the ground protected by a tough cocoon (4).