Beetles are sometimes called “living jewels” in reference to the diverse array of iridescent colours they display. The optical effects are produced by photonic crystals and sophisticated reflectance mechanisms, as these images show.
(Images from Journal of the Royal Society Interface, DOI: 10.1098/rsif.2008.0354.focus; provided by Ainsley Seago)
This picture shows a predatory tiger beetle
Close-up of tiger beetle “skin” – the surface of the wing case.
This electron micrograph of the tiger beetle shows a reflector band (arrow) – where thin layers of tissue with different refractive indices have been laid on top of each other. The spacing of the layers causes different colours to be produced by constructive interference.
Weevils (such as this Pachyrrynchus beetle) have a different method. The scale patches are made of photonic crystals, as seen in the next image…
The three-dimensional crystalline structures in the wing cases of pachyrrynchine weevils are arranged hexagonally, in a similar way to how crystals are arranged in opals.
A beetle from the Amarygminae family
Eupholus, a weevil
Phanaeus, a scarab beetle – considered sacred by the ancient Egyptians
