Nanoscale glitches let flowers make a blue blur that bees can see
Imperfectly spaced petal ridges weaken iridescence — but that’s all good
BLUE HALO Bees can easily learn to recognize a bluish tinge called a blue halo created by sloppy nanoscale structures (located in the dark center circle, and seen at right) on such flowers as Ursinia speciosa.
E. Moyroud et al/Nature 2017