Can butterflies have transparent wings?
The Great Oto species in America and Argentina do have such wings. This effect is achieved with the presence of special nanostructures in the tissues of the wings which greatly reduce reflective capability. Coupled with low light scattering and almost no absorption, the light just passes through the wings, creating transparency. The veins and the outline of the wing are still visible.
Their caterpillars are unique, having either red or purple striped coloring
In Spain, such butterflies are called "little mirrors".