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Butterfly Beauty Polarized

May 1 2003

Butterflies may use polarized light as a mating signal, according to a Brief Communication in the May 1 Nature. The brightly coloured iridescent wings of some butterflies, such as Heliconius cydno, are able to polarize the light that bounces off them. Alison Sweeney of Duke University, Durham, North Carolina, and the Smithsonian Tropical Research Institute, Balboa, Panama, and colleagues watched the behaviour of male butterflies from iridescent and non-iridescent species when they were shown the wings of their female counterparts through polarizing or depolarizing filters. Male Heliconius cydno iridescent butterflies approached female wings less often when they no longer appeared to be polarized. In contrast, the filters made no difference to the ardent responses of non-iridescent male Heliconius melpomene butterflies. The team believes that this is the first example of polarized light being used for mate recognition on land. The strategy may have adaptive value for species living in dense forest, where illumination varies greatly both in spectrum and intensity.

“Insect communication: Polarized light as a butterfly mating signal,” Alison Sweeney, Christopher Jiggins & Sönke Johnsen , Nature, May 1, 2003

Abstract © 2003 Nature

Alison Sweeney, Department of Biology, Duke University and Smithsonian Tropical Research Institute, Panama