Purple martins are known to eat at least 79 species of insects including dragonflies, flies, bees, moths, and butterflies. However, I would be willing to guess you did not know they also dine on fire ants.
It seems purple martins target mating male and queen fire ants. One group of researchers studying the feeding habits of purple martins found fire ants were captured during 32 percent of the birds foraging trips. The ants accounted for 31 percent of the insects taken. In addition, fire ants comprised 27 percent of the biomass consumed by the birds and their young.
Based on these data, the scientists estimated purple martins consume some 1.7 billion fire ants annually across the United States.