Wing deformations during maneuvering flight of the flower chafer, Protaetia cuprea: an overlooked aspect in the ecology and evolution of insect flight

Insect wings are thin, flexible structures that elastically deform during flight as a result of their shape and aerodynamic load. These deformations are believed to be a crucial component of aerodynamic force production. However, very little is known on how wing deformation affects aerial maneuvering or how evolution has shaped insect wings to match their deformability with the flight performance required by the insect’s life style.

To explore these questions we observed wing deformations during free-flight maneuvers of Protaetia cuprea (Coleoptera: Scarabaeidae) using three high-speed video cameras. We measured the position of landmarks on the wings in order to extract and analyze their movements relative to their expected position under a rigid wing assumption. We found that the wings deform substantially in a cyclic pattern within each flapping cycle. We then compared the wing deformation of the left and right wings during maneuvering flight as the insects turned. We found that, while turning, bilateral flapping was asymmetric. The asymmetry between the left and right wings was negatively correlated with asymmetry in wing deformation. The resulting asymmetric wing twist at stroke reversal in highly deformable wings may contribute to the maneuverability of the species. Geometrical morphometric analysis of wing of 12 species within the scarabaeidae show that flower chafers (Cetoniinae) wings have areas of higher flexibility compared to other subfamilies. Thus, our findings suggest that wing deformations are an inseparable and therefore important element of beetle flight in particular, and of insect flight in general.