Representatives of six butterfly species, flying freely in the field or in simulated field conditions, were filmed with a high-speed ciné camera and subjected to kinematic and morphometric analysis. This is the first detailed investigation on an insect performing the varied patterns of ‘natural’ flight. Kinematic parameters in representative sequences of selected flight modes were calculated and compared, and wing shapes were characterized using aspect ratio and non-dimensional moment parameters.
The analyses and field observations of these and other butterflies suggest possible correlations between flight performance and wing shape. The behaviour of individual species conforms reasonably well with crude predictions based on aspect ratio, wing loading and wing inertia.
The homology of veins and other wing characters in Heteroptera is reviewed in the light of palaeontology and new functional studies. A cladogram is given for the higher taxa of Hemiptera. It is probable that the vannus is an autapomorphy of AuchenorrhynchaSHeteropteroidea; that the leading edge vein of heteropteran fore-and hindwings is C+Sc; that Rs cannot be distinguished from R; that the hamus is part of M; that the glochis is a secondary structure. The difficulty of defining a vein is stressed. The functional significance of the hemielytron, cuneal fracture and longitudinal flexion lines is discussed. A preliminary ground-plan for Heteroptera wings is presented.
A high degree of automation of the wingstroke in the Heteroptera has resulted in the simplification of the axillae and associated musculature. The functions of the indirect, asynchronous flight muscles are summarised from previous investigations and original work. Functions are suggested for the tonic muscles but await confirmation by electrophysiological research.
The deformations seen in heteropteran wings can be explained in terms of muscularly generated and aerodynamic forces. Unsteady aerodynamic benefits of such deformations, though unproven, may be of primary importance. Torsion, camber change and transverse flexion are all candidates for the generation of unsteady effects. The ‘near clap and peel’ seen at pronation has been described in other insects by Ellington (1984a), and it seems likely that it serves the same purpose in Heteroptera.
Heteroptera, like many other insects, show wing‐tip flexion. Among several possible functions, inertial stress reduction is shown to be important.
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