Sternotomis callais

The scales on the African longhorn beetle exhibit a brilliant green color due to a photonic crystal-like periodic cuticle network, and the three-dimensional network of the cuticle was found to be modelled appropriately by the I-WP photonic crystal.^[2] Although described mathematically in 1970, this is the first time this kind of photonic crystal structure has been observed in nature. ^[3]

The I-WP-type minimal surface was mathematically found by Schoen in 1970, was named "I-graph-Wrapped Package graph surface" because it reminded Schoen of the arrangement of string on a simply wrapped package.^[4] The wavelength range of the green color corresponds to the frequency of the photonic band gap.^[2]