Grow a few plants of several different coloured varieties - a red 'Polestar', deep pink and white, 'Painted Lady' and a pure white 'White Lady'.

For instance, in Costa Rica, the two most closely related species are white or yellow, which prefer to mate with those of their own color.

It's a Small Tortoiseshell - probably just hatched this morning.

The researchers will continue to study the role of genes in both color and mate choice - which could send the populations diverging forever into new species.

Blotchy eyes with hundreds of minute lenses guide the butterfly to nectar-bearing flowers whose colors give off ultraviolet rays visible to the insect but not to humans.