This story appears in the May 2019 issue of National Geographic magazine.
Charles Darwin was fascinated by the spiders that landed on the H.M.S. Beagle nearly two centuries ago. Spiders don’t have wings, yet they alighted on his ship 60 miles offshore. Recent research on flying spider species, however, provides some new clues as to how the Earth’s electric field might help them pull off this aerial feat. They take to the skies in a process called ballooning, in which they position their bodies to catch air, spinning out silk that uses wind—and the electric field—to create lift. They may fly in search of better locations but have little control once airborne.