Which butterfly is known for having transparent wings with dark borders?

The butterfly known for transparent wings with dark borders is the glasswing butterfly, Greta oto.

Greta oto is a brush-footed butterfly native to Central and South America. Much of each wing lacks the dense colored scales typical of butterflies, allowing light to pass through and creating its characteristic glasslike appearance. Dark brown margins and reddish or orange markings outline the transparent areas.

The butterfly’s transparency helps make its outline less conspicuous in forest habitats. Its wings are not literally made of glass: the effect results from specialized wing structure and the sparse distribution of scales. The species is often called the glasswing or glasswing butterfly in English.

Adult glasswings feed on nectar, while males also obtain chemicals from certain plants that can be converted into courtship pheromones. The species is sometimes confused with other clearwing butterflies, but Greta oto is the specific glasswing named in this answer.