Aerial predator–prey interactions may impact populations of many terrestrial species. Here, we use altitude loggers to study aerial foraging in a native insectivore, the purple martin ( Progne subis ), in the southern USA. Purple martins fed primarily on mating queens and males of the invasive red imported fire ant ( Solenopsis invicta ), and doubled their foraging efficiency by doing so. Across the USA, purple martins likely eat billions of fire ant queens each year, potentially impacting the spread of this species. Alternatively, predation on fire ants may help sustain populations of purple martins and other aerial insectivores.