The height of chitinous ridges alone produces the entire structural colour palette

TL;DR

This study shows that the height of chitinous ridges alone can produce the full spectrum of butterfly wing colours, using a novel method to isolate the contribution of specific nanostructure features.

Contribution

It introduces a new methodology to reproduce and analyze the role of individual nanostructure features in butterfly wing coloration.

Findings

Chitinous ridge height alone determines butterfly wing colour palette.

Reproduced ridges can replicate the entire colour spectrum of butterfly wings.

Complex structures may be unnecessary for colour production when multifunctionality is not required.

Abstract

The colourful wings of butterflies result from the interaction between light and the intricate chitinous nanostructures on butterflies' scales. This study demonstrates that just by reproducing the chitinous ridges present in butterfly scales (i.e., without any other secondary structure), the entire colour palette is achieved. This result was achieved using a new methodology based on the controlled reproduction of parts of the biological structure of complex chitinous systems using their native chemistry, enabling the isolation of different features' contributions. Here we isolate the contribution of the ridges and their variations as producing and modulating colour hue. The results suggest that complicated butterfly scales may be non-ideal solutions for producing colour when multifunctionality is not considered.