Oemopteryx glacialis

Oemopteryx glacialis (Barnston, 1848) Notes Oemopteryx glacialis is commonly known as the Canadian Willowfly (Stark et al. 2012). This species is common in large rivers, ranging from Quebec west though the Laurentian Great Lakes region to Minnesota, south to New York and Connecticut, and with a disjunct distribution southward to West Virginia (Stewart 2000, DeWalt et al. 2024, Verdone et al. 2025). In Quebec, this species exhibits a univoltine-fast life cycle with direct hatching of eggs, larval diapause during summer and early autumn months, and emergence of adults occurring in April (Harper et al. 1991 a). In New York, adults are active from early March through mid-April (Fig. 22). Reported elevations for this species in the state range from 30-502 m asl (Fig. 23) with a widespread distribution in larger rivers north of the Mohawk River Valley (Fig. 24 a).