Plagues of locusts are the stuff of nightmares. The largest swarms have been known to number in the trillions, and can consume whole countrysides in mere hours.
One of the largest recorded locust plagues in North American history, Albert's swarm, occurred in 1875. It was named after physician Albert Child, who measured the size of the swarm to be 198,000 square miles — roughly the size of California. The swarm may have consisted of as many as 12.5 trillion insects, which, if true, would make it the largest concentration of animals ever recorded.