Electron microscopy and spectroscopical studies on the coloured patches on the wing of a butterfly, Graphium sarpedon (Lepidoptera: Papillionidae) with reference to their photobiological and electrical properties.

The surface ultra-structural features of the coloured patches on the wing of a butterfly Graphium sarpedon have been studied with the help of scanning electron microscopy. Comparisons have been made between the dark brown area and the light green patches of the wing. A diffraction grating pattern with 15 lines per micron 2 with a uniform spacing of about 1 micron is present in the light green patches. A slightly coarser grating is present on the dark brown area, which constitutes the major portion of the wing. Sensilla chaetica was found on both the light green and dark brown area. A special type of sensilla trichodea with a big socket and some elongated projections were localized only on the light green patches. This region of the wing also contains some spherical structures with a diameter of 0.5 to 0.6 micron. The infra-red spectroscopy has revealed some differences in the nature and position of the peaks in the low-energy region in the dark brown area and the light green patches. The atomic absorption spectroscopy also shows qualitative as well as quantitative differences in the inorganic set up of the two regions. The electron spin resonance spectroscopy reveals the presence of a peak in the dark brown region only, indicating the presence of free radical in it. The differences observed in the ultra-structural and spectroscopical features, and also in the inorganic components of the two regions, are discussed in relation to their physical and physiological properties.