Edited by Howard A. Stone, Princeton University, Princeton, NJ, and approved October 11, 2019 (received for review June 4, 2019)
We report the honeybee's propulsion at the air-water interface. Honeybees trapped on a water surface use their wings as hydrofoils, which means their wings generate hydrodynamic thrust. The surface wave and flow patterns generated around the bee are the first indication that the wings are used as hydrofoils. Furthermore, the water flow measured under a mechanical wing model showed that both net and oscillatory thrust contribute to their locomotion. Hydrofoiling highlights the versatility of their flapping-wing systems that are capable of generating propulsion with fluids whose densities span 3 orders of magnitude. This discovery inspires an aerial-aquatic hybrid vehicle. Moreover, the findings may have biological implications on the survival of water foragers and preflight locomotion mechanisms.