This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales.
Scales enable development of vivid or indistinct patterns which help the organism protect itself by concealment and camouflage, mimicry and warning.
The 'solid' scales of basal moths are however not as efficient as those of their more advanced relatives as the presence of a lumen adds air layers and increases the insulation value.
[1] Young adults of myrmecophilous Lepidoptera escape from ant's nests by virtue of the deciduous waxy scales with which they are covered when born.
(Forsyth 1992:12) Thomas Eisner tested spiderwebs' effectiveness by dropping various insects onto the webs.
Moths were consistently able to escape, and all left impact spots where scales had stuck to the web.