Roughly 99% of a swallow's diet is flying insects. They gulp down millions of flies, mosquitoes, and agricultural pests, in the course of feeding themselves and their young. The world population of Barn Swallows is estimated to be 190 million. If each ate just 350 insects per day, that would mean more than 65 billion insects consumed in one day. That's a lot of swallows! Here's a video of Barn Swallows feeding their young.
