The roles of body and wing pitching angles in hovering butterflies.

This article focuses on the aerodynamic mechanisms enabling hovering flight in the white cabbage butterfly (Pieris rapae). Using high-speed videography to capture detailed wing and body kinematics, combined with computational fluid dynamics simulations based on the immersed boundary and lattice Boltzmann methods, the study reveals that butterflies generate lift primarily through rapid acceleration and delayed stall mechanisms involving leading-edge vortices (LEVs) and trailing-edge vortices (TEVs). The butterfly maintains a large mean body pitch angle near 90°, balancing forward and vertical forces, with forewings contributing most vertical lift while hindwings mainly stabilize pitching moments despite providing limited lift. These findings clarify the complex wing-body interactions during butterfly hovering and offer insights relevant to bio-inspired flapping-wing robotic design.