'Blue Halo' effect: Flowers create optical illusion to attract bumblebees, says study

An atypical study led by a group of researchers from the Botanical Gardens at the University of Cambridge suggests that there are certain kinds of flowers which create ethereal halos of blue light to attract bees. They project those halos in order to generate a rather unusual optical illusion and these halos are not visible to humans in most cases.

While an earlier study suggests that blue flowers like hydrangeas and delphiniums are high in nectar and are easy to attract bumblebees on their own, the latest invention directs something different altogether.

"The exciting thing is that it is a new optical trick – we didn’t know that flowers could use disorder to generate a specific color, and that is quite clever," senior author Beverly Glover, director of the Botanical Gardens at the University of Cambridge was quoted while talking about the same.

The latest invention, published in the journal Nature had gone through a series of laboratory experiments where bumblebees were drawn to synthetic flowers designed to generate the same kind of ultraviolet rings.

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"The effect occurs in the ultraviolet part of the optical spectrum that we cannot see," said co-author Ullrich Steiner, a researcher at the Adolphe Merkle Institute in Fribourg, Switzerland.

"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," stated Beverly Glover.

"But the disorder we see in petal nanostructure appears to have been harnessed by evolution and ends up aiding floral communication with bees," Glover added further.

Previous studies have proved that bees usually search for nectar-giving plants and are attracted to odours, but take most of their cues from colours and petal shapes.

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Moreover, there are reports that bees are especially sensitive to the band of colours on the light spectrum where blue graduates into the ultraviolet.