This paper investigates the unsteady aerodynamic features of wing-body-vortex interactions in three-dimensional insects" flapping motions under forward flight condition. Since the flow field around the blowfly exhibits characteristics of low-Reynolds number flow, the three-dimensional unsteady incompressible Navier-Stokes equations are employed as the governing equations. In this paper, detailed numerical simulations of four types of wings are carried out under various body angles. From the results, the wing-body interactions have a non-negligible effect on the qualitative and quantitative aerodynamic characteristics.