The feeding habits of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats have been documented for their summer grounds, but little is known about their feeding habits while en route during migration. We analyzed stomach contents of L. cinereus and L. noctivagans collected at a wind-turbine facility in southwestern Alberta to gain insight into the feeding behavior of migrating bats. We addressed four questions: (1) Do L. cinereus and L. noctivagans feed while en route? (2) On what prey types do each species feed? (3) Do diets differ between species? (4) Do diets differ between age classes within each species? We found that both species fed while migrating and that their diets were similar to those found in their summer grounds, with the exception that L. cinereus consumed a considerable number of water boatmen (Hemiptera; Corixidae). Diets differed between species and age groups within species.