Butterfly wing color: A photonic crystal demonstration

•We model the optical response of the wings of the Teinopalpus Imperialis butterfly.•The best matching solution is found by employing a genetic algorithm.•The characterization is performed through band structure calculation and reflection analysis.

We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.