The functional morphology of the wings of Odonata

The functional morphology of the wings of Odonata is reviewed in the light of recent detailed work on their structure, taken in conjunction with cinematographic analysis of dragonflies in unimpeded flight. Wing-corrugation, combined with a variety of types of crossvein and of cross-vein/longitudinal vein links, provides resistance to transverse bending while allowing torsion and the development of camber. Controlled torsion, essential to flapping flight, is kept within limits by the pterostigma and by the structure of the leading edge spar, which permits more supination than pronation, so allowing the wing to generate lift on the upstroke and permitting slow, manoeuvrable flight and hovering. Camber and angle of attack are automatically maintained under aerodynamic loading by an array of internal mechanisms including the arculus, the quadrilateral of Zygoptera, the triangle and supratriangle of Anisoptera, and vein-curvature in a variety of broad-winged forms. The slender-based wings of Zygoptera, and their relatively short antenodal spars compared with those of the broader-based Anisoptera, seem to be associated with their generally slower flight.