Butterflies, or members of the Papilionoidea superfamily, use two ultraviolet signals, UV reflectance or absorbance as a communication system. The ultraviolet region is the part of the electromagnetic spectrum between 10 nm and 400 nm in wavelength. Sensitivity to this region provides butterflies several benefits such as nectar guides for nectar, but it also provides a private communication channel unavailable to predators. With this secure line, butterflies are able to facilitate mating behavior and sex recognition.