18 June 1999
Vol 284, Issue 5422

About The Cover

Cover image expansion

COVER A fruit fly tethered to a fine steel wire demonstrates the large stroke amplitude (160 degrees) and high stroke frequency (200 hertz) typical of small insects. Conventional steady-state aerodynamic theory fails to explain how insects generate enough force to remain airborne. Studies using robotic models of flapping wings have begun to uncover the unsteady mechanisms that insects use to fly and maneuver. See page 1954 [Image: Michael Springer/Gamma Liaison]