<p>Seasonal timing of life stages often co-evolves with other ecological traits. Among temperate Lepidoptera, moths flying in early spring or late autumn have been suggested to share a suite of correlated traits – including female flightlessness, spring-feeding larvae, woody host plants, and forest habitats – collectively described as the “winter moth syndrome”. Using a newly available complete phylogeny of northern European Geometridae, we applied phylogenetic comparative methods to reveal the ecological correlates of female flightlessness and, more generally, “winter flight”. Further, we aimed to identify traits that predispose lineages to the evolution of such phenotypes. Our analyses confirm that adult phenology is the strongest predictor of female flightlessness, whereas other traits show weaker or inconsistent associations once phylogeny is accounted for. Sister clades of flightless taxa were significantly more likely to have spring-feeding larvae and, in younger lineages, to have larger body sizes and adult activity shifted towards colder months, suggesting that phenology is among the key preconditions for the loss of flight. We propose that the key adaptive shift underlying the evolution of winter flight and female flightlessness is the abandonment of selective oviposition, with wing reduction evolving secondarily in response to predation and abiotic conditions characteristic of the extreme timing of adult flight. Nevertheless, while the traits facilitating the evolution of female flightlessness in winter moths appear reasonably well understood, evaluating various selective pressures potentially responsible for this evolutionary shift per se still remains a challenge.</p>