Variation in UV light reflected from the wings of Favonius and Quercusia butterflies

The wing colors of eight lycaenid species of the genera Favonius and Quercusia were examined with a spectrophotometer. Four (F. orientalis, F. taxila, F. jezoensis and F. ultramarinus) of five green to blue‐green Favonius species had a double‐peaked pattern, reflecting UV light (345–355 nm) and green light (515–525 nm), whereas F. cognatus reflected only visible green light (539 nm). Thus, the species considered most closely related, F. ultramarinus and F. cognatus, had quite different wing colors in terms of insect vision. Two bluish species had utterly different reflection patterns: F. saphrinus had a single peak in the UV range and Q. fujisana had two peaks, one each in the UV and visible light ranges. The black F. yuasai did not have any peak in the examined range of wavelengths (300–700 nm).