Nano-scale features on butterfly wing scales interact with specific wavelengths of visible light (photonic bandgap material) to produce bright colors as observed by the human eye. This structure, for example, removes certain wavelengths from the white light that hits it (mainly blue, 472nm) so that the color, when observed by the human eye, appears orange.
I hope you found this poor dead butterfly and didnt intentionally kill him/her for testing. Animals are better than humans.