The aerodynamic force and flow structure of a wing performing an unsteady motion at small Reynolds number (Re=4000) is calculated by solving Navier-Stokes equations. Numerical Simulations were done in order to investigate the role of vortex formation in the force-generation of a low aspect ratio insect wing, with a free end condition, starting from rest. The study was done with a simplified case of hovering flight, where the wing starts impulsively in still air and moves with a constant azimuth velocity after achieving a certain maximum velocity. Relative importance of various acceleration rates were initially comprehended and were compared with motion similar to a fixed wing aircraft. At Re=4000 and flow conditions, the stall -absence mechanism was noted with a high CL valve till 8.0 chord length of travel. The velocity field of the leading edge vortices (LEVs) was plotted in chordwise planes at 25, 50 and 75% span. Chordwise results show a spanwise pressure gradient within the LEVs. This pressure gradient is responsible for spanwise flow moving through the core of the LEV, directed towards from the tip, which gives them a helical cone-like structure.