Abstract below

Raphaël Clément

Institut de Biologie du Développement de Marseille,
Aix-Marseille Université

Mechanics of wing deployment in insects

During their final transformation from larva to adult, flies emerge from their cocoon (the “pupal case”) and deploy their wings within minutes. Wings expand from a compact folded structure into a planar and rigid wing blade that allows the insect to fly. We showed that deployment is enabled by an increase of internal pressure, and by the subsequent flow of blood-like fluid (hemolymph) into the deployable wing structure. We first characterized the unfolding kinematics at the organ scale. Using a combination of imaging techniques, we found that wings not only unfold the macroscopic folds but also expand, which involves an expansion of cell surface area and the unwrinkling of microscopic cuticle wrinkles. We complemented these morphological observations with mechanical characterization of the wing and scaling analyses. The coupling between geometry and nonlinear constitutive mechanics reveals an operating point for deployment, predicting both the working pressure and the timescale of deployment. This work combines morphometric, kinematic, and mechanical analyses to gain insight into a largely overlooked phenomenon: how insects deploy their wings. It also shows how hydraulic forces can drive fast, large scale reconfiguration of entire organs in animal morphogenesis.