Access through your institution Buy or subscribe Aside from its life cycle, the butterfly holds other mysteries too, as anyone knows who has watched a typical flight of this insect over a field of flowers and grass. Butterflies, it once seemed clear to me, are terrible pilots. A butterfly trajectory — a jagged and random jerking through the air — resembles Brownian motion, not the elegant gliding of most birds. And yet, as a biologist friend once pointed out to me, two bu...