When a male horsefly (hybomitra hinei wrighti) spies a suitable female, he chases after her, catches her in midair, and they fall to the ground copulating. The behavior is not surprising, but the speed is. Jerry Butler, an entomologist at the University of Florida, once got a male Hybomitra to chase a plastic pellet fired from an air rifle. "Which it caught in midair and dropped," Butler says. From the speed of the pellet, he calculated the fly was going at least 90 miles per hour.
Scientists are far from fully understanding such biomechanical marvels, but in the past few years they have made an excellent start. For one thing, they now have a plausible story for how insect flight evolved. And if they can't quite say how a bug manages to catch a speeding bullet, they at least have an aerodynamic explanation for why it can stay aloft. In both cases, the key insight is this: Insects are not like airplanes.
