This family of south-American butterflies (ITHOMIIDAE) has wings that are completely transparent, like panes of stained glass. They also taste bad.
"Greta oto is a brush-footed butterfly, and is a member of the clearwing clade; its wings are transparent. Its most common English name is glasswing, and its Spanish name is "espejitos", which means "little mirrors." Indeed, the tissue between the veins of its wings looks like glass. It is one of the more abundant clearwing species in its home range, which is found in the amazon rainforest (South America) The opaque borders of its wings are dark brown sometimes tinted with red or orange, and its body is dark in color. Its wingspan is between 5.5 and 6 cm.
Adults range from Mexico through Panama and inhabit the rainforest understory and feed on the nectar of a variety of tropical flowers. G. oto prefers to lay its eggs on plants of the tropical nightshade genus Cestrum. The red and purple striped caterpillars feed on these toxic plants and store the alkaloids in their tissues, making them distasteful to predators such as birds. They retain their toxicity in adulthood. The same alkaloids that make them poisonous also are converted into pheromones by the males, which use them to attract females.
G. oto adults also exhibit a number of interesting behaviors, such as long migrations and lekking among males."
"Ithomiines are unpalatable because their adults seek out and sequester pyrrolizidine alkaloids from plants that they visit, especially composit flowers (Asteraceae) and wilted borages (Boraginaceae). The slow-flying adults are Müllerian mimics of each other as well as of many other Lepidoptera. Identification of adult ithomiines relies on hindwing venation and male androconial scales (sex brushes located on the hindwing costa).
The group has repeatedly been proposed as biological indicators of ecological conditions or biological diversity within neotropical forests, but individual sites harbor between 10 and 50 species, for the most part, and beta diversity is often great, even over relatively short distances."
More photos below the cut...
Other glasswings have delicate colors:
A box of ithomiidae at the Butterfly and Insect Museum in La Ceiba, Honduras: