The photonic crystal type nanostructures built of chitin, occurring
in the butterfly wing scales of the male individuals
representing the species C. remus and A. metallica were investigated
by electron microscopy and reflectance spectroscopy.
While C. remus has a dorsal metallic blue color arising from a
fully ordered 3D structure and a ventral mat green color produced
by randomly oriented fcc inverse opal photonic crystal
grains, with perfect short range order, but lacking long range
order, the A. metallica has metallic blue color on its dorsal wings
and a very shiny goldish green color on the ventral side. Surprisingly,
both colors of A. metallica are achieved with similar
quasi-ordered layered structures with slightly different structural
parameters. The examination of four different PBG materials
built with the same two components: air and chitin, allowed the
comparison of the efficiency of different structures. The PGB
material found in the ventral scales of A. metallica is the most
efficient reflector from the four investigated ones. It is worth
pointing out that it is not a rigorously ordered structure and it
is based on a moderate refractive index contrast. Such quasiordered
nanostructures, which may be more easily manufactured
than the perfectly ordered 3D nanostructures could prove useful
in various practical applications. The investigation of natural
designs may yield very useful templates for artificial structures