off topic query

[Kenelm Philip]

	The 'powdery stuff on the wings' of butterflies and moths consists
of tiny scales (try looking at them with a microscope). The colors of the
scales are produced in two ways:

1. Chemicals within the scales that absorb various wavelengths of light.

2. Diffraction gratings on the walls of the scales--producing so-called
'structural colors', which may alter depending on the viewing (and lighting)
angle.

							Ken Philip
fnkwp at aurora.alaska.edu