‘Blue halo’ brings bees to flowers

An “aura” invisible to the human eye surrounds some flower petals and acts as a signal for bees, scientists say. The flowers create the effect, dubbed a “blue halo”, using microscopic ridges to scatter light.

In tests, artificial surfaces designed to replicate the halo attracted foraging bumblebees searching for nectar.

The light-manipulating magic is due to the messy nature of the petal nanostructures, which consist of ridges and grooves varying greatly in height, width and spacing.

Professor Beverley Glover, director of Cambridge University’s botanic garden, said: “We had always assumed that the disorder we saw in our petal surfaces was just an accidental by-product of life – that flowers couldn’t do any better. It came as a real surprise to discover that the disorder itself is what generates the important optical signal that allows bees to find the flowers more effectively.”