Functional Morphology of Insect Wings

Despite the extensive and long-standing use of wing characters in insect systematics, serious experimental investigations of the functional sense be­ hind insect wing design are virtually confined to the past two decades. Functional discussion in earlier writing is speculative and curiously scarce. Most notably, Rohdendorf attempted to interpret the evolution of wing form in Diptera (115) and insects in general (114) in functional terms, and Edmunds & Traver (52) discussed the ground plan and early evolution of wings with reference to possible changes in flight technique, but these and other workers were hampered by the limited information then available on the movements of wings in flight, and on flapping-flight aerodynamics in general. Studies in both these areas progressed significantly in the 1950s and 1960s through investigations of the flight of tethered insects (95, 119-121, 125), but insect flight and wing morphology remained essentially separate disciplines until the early 1970s, when a coincident series of technical and intellectual developments at last prepared the way for a synthesis. The scanning electron microscope became widely available, allowing a stepwise improvement in detailed morphology. Weis-Fogh (125) and Norberg (104) pioneered high­ speed cinematography of insects flying freely, and hence displaying a far