How do butterfly wings look blue, and what produces insect colour?
Insect colour comes from a mix of pigments and, very commonly, microscopic structural mechanisms — the vivid blues, greens and iridescent shifts seen in many butterflies and beetles are usually produced by the physical structure of their scales or exoskeleton rather than by pigment.
Domain: InsectsMechanism: Structural colourMechanism: Biological pigmentMechanism: IridescencePurpose: Mate attractionPurpose: CamouflagePurpose: Warning colourationPurpose: Thermoregulation
There is no blue pigment anywhere in this wing. Microscopic ridges on each scale split and reflect light so that only blue wavelengths reach the eye — the same physical principle behind a hummingbird's gorget or a peacock's tail.
Whole-frame automated colour extraction on this photograph is dominated by the dark background and shadow between the wings, not the wings themselves — these hexes were hand-picked from the wing surface instead."Blue Morpho" by Derkarts, CC BY-SA 3.0, via Wikimedia CommonsLicence details
- Source:
- Wikimedia Commons
- Creator:
- Derkarts
- Licence:
- CC BY-SA 3.0 (also offered under 2.5/2.0/1.0 and GFDL) — free to share and adapt commercially, provided the work is attributed and any adaptation is shared under a compatible licence.
- Reviewed:
- 2026-07-24
How this colour is made
Structural colour
Microscopic physical structures — ridges, layers or particles smaller than the wavelength of light — interfere with light waves so that only certain wavelengths are reflected back. No pigment is involved at all.
Common misconception: A structurally-coloured feather or scale ground into powder loses its colour completely, because grinding destroys the microscopic structure that produced it.
Biological pigment
A molecule in the tissue absorbs some wavelengths of light and reflects others — the reflected wavelengths are the colour seen. Chlorophyll, carotenoids and melanin are the most common examples.
Common misconception: Not every vivid natural colour is a pigment — several of the most striking blues and greens in animals are structural colour instead, which looks similar but works completely differently.
Iridescence
A form of structural colour where the reflected colour visibly shifts as the viewing angle changes, because the interference effect depends on the angle light hits the structure.
Common misconception: Iridescence is often confused with simple metallic shine — the difference is that an iridescent surface changes hue, not just brightness, as you move around it.
Morpho butterflies' vivid blue is produced by microscopic ridged scale structures that reflect blue light through optical interference, not by a blue pigment — the underlying scale pigment is actually brown.
Insects · confidence: high
Many beetles, including jewel beetles, display iridescent colour produced by layered structures in their exoskeleton that reflect specific wavelengths of light depending on viewing angle.
Insects · confidence: high
Some insect colouration, such as the black-and-yellow banding common in wasps and certain bees, functions as warning colouration to deter predators, and is echoed by non-stinging mimic species.
Insects · confidence: high
Dark colouration in some insects, particularly darker-winged butterflies, has been linked to thermoregulation, since darker surfaces absorb more solar heat, though this is not established as the purpose for every dark-coloured species.
Insects · confidence: medium
Established for specific studied species, not confirmed as universal across all dark-winged insects.
Related colour profiles
Practical applications
Related questions
Frequency and rarity claims above are scoped to a specific domain, geography or taxonomic group — none are presented as a single universal ranking. See methodology.