Moth wing. Coloured scanning electron micrograph (SEM) of scales on a moth. A moth is covered in many tiny scales. The scales are modified hairs, or setae, and are made of chitin, a common substance in insect exoskeletons. The colours of a moth's wings is produced by the diffraction of light by the microscopic structure of these scales. Magnification: x700 when printed at 10 centimetres wide.