Turquoise Longhorn - Prosopocera lactator
Prosopocera lactator (Coleoptera - Cerambycidae) is an African species of longhorn beetle, displaying elytral scale patterns with greenish-white patches surrounded by light-brown regions.
The greenish-white regions of this beetle are constituted by diminute scales formed by three-dimensional photonic-crystal grains described as a face-centered-cubic array of spheres, connected by short rods, reminiscent of the “ball-and-stick” models used by solid-state chemists to visualize atomic structures.
This type of three-dimensional photonic crystals have been discovered in butterflies and in Coleoptera such as weevils. These well-ordered microstructures are expected to produce iridescence, sometimes with metallic colorations. However, against expectations, in the Turquoise Longhorn this very ordered local structure only produces a desaturated greenish-white coloration, without iridescence.