Butterflies Can See Ultraviolet

Many butterflies have light-sensitive receptors tuned to ultraviolet, and some species distinguish a broad range of colors, including red and violet. The Japanese yellow swallowtail, *Papilio xuthus*, for example, has been described as having eight types of spectral receptor. But visual systems differ among species: not every butterfly has the same receptor set or sees color in the same way. The illustration is AI-generated and only schematically suggests UV patterns that humans cannot see.