Wing scales. Close-up of the wing of a butterfly, Protboe calidonia, showing its arrangement of wing scales. The structure of the wing is like a roof, with coloured scales corresponding to the overlapping tiles. The scales are attached to the wing membrane by short stalks, which fit into tubular sockets. The colour of the butterfly's wing is determined by pigmentation of the scales and also by diffraction of light off the surface of each scale.