—Design of a flapping mechanism for flapping wing micro air vehicles (FWMAV) is presented based on a mathematical model of insect thorax. This model also includes an aerodynamic model of flapping wings. Using experiments on dynamically scaled wings and numerical optimization, the mechanism is tuned for peak aerodynamic performance. The thorax model is used to understand the mechanics of the biological flapping mechanism and reveals the significance of rotational stiffness and inertia distribution in flapping wings. Experiments conducted on the actual thorax based mechanism validate theoretical findings and also show significant lift generation capability.