Greta oto is a species of brush-footed butterfly and member of the subfamily Danainae, tribe Ithomiini, and subtribe Godyridina.

It is known by the common name glasswing butterfly for its transparent wings, which allow it to camouflage without extensive coloration.

[1] During the fifth instar stage, the pupa produces a silk pad on the lower surface of leaves through four spinning movements, onto which it attaches.

[6]The adult glasswing butterfly can be identified by its transparent wings with opaque, dark brown borders tinted with red or orange.

[1] They also eat flowers in the Asteraceae and Boraginaceae families and the droppings of insectivorous birds, absorbing amino acids that are later converted to proteins.

Adult butterflies are also toxic due to the males consuming Asteraceae flowers whose nectar contains pyrrolizidine alkaloids.

The glasswing combats predators by consuming toxins through plants of genus Cestrum and family Asteraceae in both the caterpillar and butterfly stages.

The pheromones produced are derived from pyrrolizidine alkaloids that the butterflies obtain through their diet of plants of the family Asteraceae.

[8] These nanopillars, non-periodically arranged on the wing's surface, possess a high aspect ratio (defined as height divided by radius), where the radii are below the wavelengths of the visible light.

Additionally, they feature a random height and width distribution, which is directly responsible for the smooth refractive index gradient and thereby for the broadband and omnidirectional anti-reflection properties.

[11] Additionally, the structure of the nanopillars allows for the wings to have a low roughness factor because of its tiny hair-like microtrichia features.