Understanding the seasonal behaviors of Nearctic hover flies (Diptera: Syrphidae) is a severely understudied, yet enormously significant area of research. The adult stages of most hover fly species are important pollinators for a variety of crop and non-crop plant species while many larvae are crucial biological control agents of soft-bodied pests like aphids. In a recent study using stable isotope analysis (δ2H), Eupeodes americanus was determined to be partially migratory during autumn while a second species, Allograpta obliqua, was perhaps non-migratory. Here we expand on this previous work and examine continental-scale population genomics of these two species to assess long-distance gene flow.