Insects are impressive natural flyers. They fly with high agility and maneuverability by flapping their wings. Emulating their flight capability and flight mechanisms may provide a good start in the design of a micro air vehicle (MAV). In this paper, wing flappers are designed and developed with reference to the blueprint of the flight thorax of insects. The developed wing flappers consist of a thoracic frame structure as a flapping mechanism and a vibration motor as a driver. The bio-inspired thorax design is evaluated and its performances are compared with those of the flapping wing insects. The initial prototype demonstrates that the wing flappers are comparable to the insects in terms of the wingbeat frequency and body mass. The initial wing flappers can flaps at a flapping angle of 30°. In addition, simplified analytic model of the wing flappers are derived to optimized the design. Upon redesigned, an improved wing flappers can flaps at a large flapping angle of 75°.