Butterfly Colouration

Butterfly Colouration

Butterflies are popular because of their exquisitely coloured and patterned wings . These coloures are produced by pigments ( pigmentary colours), by structures ( structural colors ) or by combination of these two ( combination colours ). The color is usually present in the wing scales or in the underlying epidermal tissue .

Pigmentary colors are produced in three ways: (1) by the insects ‘ own metabolism (2) by sequestering from a plant source and rarely by microbial endosymbionts.
Melanin , the most common pigment imparts the blackish –brown colors. Pterins: leucoptren (white ) , xanthopterin (yellow ) , chrysopterin (orange ) and erythropterin (red ) are pigments found only in the family Pieridae. Flavones are responsible cream or yellow coloures in butterflies . Red and reddish brown are also produced only by pigments.

Structural colours (physical colours ) are produced by the properties of wing scales . These scales have longitudinal ridges or ribs , having thin translucent layers of material set at a constant angle to the plane of the scale . Generally iridescent colors, mostly green and blue are examples of structural colours . White colors in butterflies may also be produced by structural colors.

These two colors may be distinguished by simple test. If butterfly wing is wetted with water, pigmentary colors are not affected but structural colours are dulled owing to the water spoiling the effect of the scale surface .
Combination colors are common in the certain members of Nymphalidae, Pieridae and Papilionidae . In Nymphalidae , melanin pigment is present in the scales and is overlaid by a structural violet –blue color which is visible only when viewed from certain angles . Similarly , some pierid butterflies of the genus Colotis have a red pigment in the scales which is combined with a structural vilot to produce orange pink or shades of magenta. Translucent gold colour of the bird wing ( Troides) butterflies is produced by the pigments and iridescent pinks and greens are due to structural colours.

These butterfly colours have some survival value or adaptive significane . Bright colouration is associated with courtship display and the cryptical coloration on the underside is for protective purpose through camouflage .

Do they have preferences ? : - Butterfly and Flower Association