Abstract
In order to clarify dynamic behaviors of a flying butterfly wings, the authors conducted flight observation experiments by a high-speed camera, measured displacements of a butterfly wings using images captured by the camera and transformed flapping angles from the butterfly's view into lead-lag angles. A butterfly moves its wings not only in upward and downward directions spatially but also anteroposteriorly when it flaps. For bound and towing flights, the butterfly changed flapping angles more greatly than lead-lag angles trying to escape from the towing since its legs and body were bound.
