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Why Do Butterflies Have Bright Colours?

peacock butterfly

Have you ever stopped to admire the colours of a butterfly’s wings? From the Adonis blue’s brilliant blue to the five-bar swordtail’s bright greens, these delicate creatures display an astonishing range of hues and patterns. But have you ever wondered why butterflies have such bright colours?

Why Do Butterflies Have Bright Colours?

Butterflies have bright colours for various reasons, including attracting mates, deterring predators, and regulating body temperature. Some species use bright colours to signal that they are toxic or unpalatable to predators, while others use them to blend in with their surroundings.

The colours of a butterfly’s wings are produced by pigments, structural colouration, or iridescence and often serve multiple functions. Understanding the science behind butterfly colouration can help us appreciate the beauty and complexity of these fascinating creatures.

The Science Behind The Colours

Butterflies display a wide range of colours and patterns on their wings, which are produced by a combination of different biological mechanisms. These mechanisms include pigments, structural colouration, and iridescence.


Pigments are molecules that absorb specific wavelengths of light and reflect others, producing a particular colour. Butterflies use two types of pigments to create their colours: melanins and carotenoids. Melanins are dark colours, such as black, brown, and orange. Carotenoids are responsible for producing bright yellow, orange, and red colours.

Structural Colouration

Structural colouration is produced by the physical structure of the butterfly’s wings rather than by pigments. Some butterflies’ wings have tiny scales arranged in a way that reflects light in a specific way, producing a particular colour. This structural colouration is often iridescent, meaning that the colour changes depending on the angle of the light.


Iridescence is a type of structural colouration that produces a shimmering effect as the angle of the light changes. It is caused by how light waves interact with the microscopic structures on the surface of the butterfly’s wings. These structures reflect and refract the light to produce the iridescent effect.

Five Colourful Butterflies

Cairns Birdwing

birdwing butterfly

Latin name: Ornithoptera euphorion

The male cairns birdwing is a colourful butterfly with golds, blues and greens contrasting nicely against its blacks. The female is mainly black and white with a little yellow. They live in the rainforests of north-eastern Australia from Cooktown to Mackay. They are the largest butterfly in Australia, with a wingspan of 18 cm (7 in).

Crimson Rose

crimson rose butterfly

Latin name: Pachliopta hector

The crimson rose is a large swallowtail butterfly. Both sexes have a similar pattern, but the females have duller colours. The crimson rose is black with two white bands on its forewings, with the hindwings having two rows of bright crimson blotches. They are the closest butterflies to being pink.

They are native to India and Sri Lanka, living in both the jungle and open country. They can breed 6 – 7 times a year and go from an egg into a butterfly in only 39 – 47 days.

European Peacock

peacock butterfly

Latin name: Aglais io

The peacock butterfly has blue, red and brownish wings, with each wing having a large colourful eyespot. The eyespot is a defence mechanism against predators. The underside of the wings is almost black, resembling a dried-up dead leaf. They live right across Eurasia and have a wingspan of 6.5 – 7 cm (2.5 – 2.8 in).

Adonis Blue

adonis blue butterfly

Latin name: Polyommatus bellargus

Male Adonis blues are intense sky-blue or turquoise with thin black lines stretching out to the white border along the tips of their wings. Females are commonly brown and white with one row of orange spots, but some can be blue. They have a wingspan of 3 cm (1.2 in) and are native to Eurasia.

Five Bar Swordtail

five bar swordtail
Dipanjali Biswas, CC BY-SA 4.0, via Wikimedia Commons

Latin name: Graphium antiphates

The upper side of their wings is white-creamish, with black strips extending inwards. They have yellow markings in between the black strips. They have black stripes on the underside but are more colourful with greens, yellows and oranges. They have two long sword-like tails. They live in the south and southeast Asia and have a wingspan of 8 – 9 cm (3.1 – 3.5 in).

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