Fig. 5. Strokes A and B generate almost the same amount of force. The only difference occurs near the end of the stroke when the wing reverses its pitch. In A the leading edge remains the same, and in B it switches. The wing pitching in stroke A can be facilitated by wing inertia and aerodynamic torque as the wing decelerates (Berman and Wang, 2007; Bergou et al., 2007).