Dye flow visualization analysis of the leading edge vortex (LEV) in hawkmoth, locust forewing and locust hindwing models reveal a dual vortex system with a minor vortex travelling along the leading edge of the wing at a zero angle relative to the leading edge and a primary vortex traveling from wing base to wing tip at a non zero angle relative to the leading edge (θ). The overall trends for all planforms are as follows: As angle of attack (α) increases, detachment point (r/R) decreases and θ, ellipse size, distance between leading edge and vortex centre (x) and the height of the vortex centre above the wing surface (y) all increase. As Reynolds number increases, r/R and θ decrease. With a change in axial flow (offset condition), r/R decreases and the θ, ellipse size, x and y all increase.