The present work is focused on flow field behavior generated by rigid and flexible rectangular wings undergoing main flapping motion using two dimensional Particle Image Velocimetry (PIV). The experiments have been carried for an asymmetry one degree of freedom main flapping motion of both rigid and flexible low aspect ratio wings at 1 Hz flapping frequency in hovering flight mode (advanced ratio, J = 0) at zero geometric angle of attack, zero wing pitch angle and chord wise based Reynolds number of the order of 104 along the wings spanwise direction at its mid chord to obtain instantaneous flow fields. The improved understanding of effect of wake capture, observation of spanwise flow on the wing, and formation-growth-diffusion of wingtip vortices have been achieved. Effect of wing flexibility on the flow field has been studied by comparing the flow field of both rigid and flexible rectangular wings undergoing main flapping motion. © Springer India 2017.