Glasswing butterfly is the common name for Greta Oto, a butterfly found from southern Texas to northern Chile. The glasswing butterfly gets its name from its transparent wings, used as a form of protection from predators. The butterflies blend in with their surroundings, instead of employing camouflage through extensive coloration. Glasswing butterflies transition through the four life stages of butterflies, living primarily on nightshade plants. Following the egg, larval, and pupa stage, the butterfly emerges with a dark brown body and transparent wings bordered with orange and black coloration.
Scientists at the Marine Biological Laboratory (MBL) in Massachusetts wanted to solve the mystery surrounding the development of transparency in glasswing butterflies. Transparency is not common among the order, Lepidoptera, butterflies and moths.
Extensive study has been done on the scales and coloration used by butterflies for camouflage. Many species of butterflies employ structures that interact with light and produce a variety of colors. These scales have special cuticles, packed with transparent nanostructures. Butterflies color their scales using pigments, primarily melanin-producing browns and blacks. Yet no significant studies into transparency in butterflies existed.
The study was led by PhD candidate Aaron Pomerantz, whose interest in transparent butterfly wings was sparked by field research in Peru. Aaron noticed these butterflies flitting around the rainforest and wanted to understand how glasswing butterflies created their wings.
MBL Director Nipam Patel, donated specimens from his personal collection to the study. The study was run by students from the MBL Embryology course that began imaging the specimens with a variety of microscopes. Electron and confocal microscopes were used to examine the glasswing butterfly wings. The researchers found that transparent areas consisted of clear, wing membranes with spaced apart, bristle-like scales. The orange and black rims contained the same clear, wing membrane, but this membrane was covered in flat scales. Scientists believe that if water-repellant scales were completely absent from the transparent wing sections, rain would cause the butterfly’s wings to stick together.
Additionally, the slightly bumpy and waxy wing surface of nanostructures allows light to gradually shift over the wings. This results in a 2% or less reflection of light and prevented glare in even the brightest of sunlight. Researchers tested the bump and waxy wing surface effectiveness, by scraping off the waxy layer. They found that the glasswing’s transparent wings now reflected 4-5% of light.
If humans are able to replicate and create nanostructures that can reflect light in the same way, the applications are nearly endless. Nanotechnology is still in its infancy, humans are years away from realizing the full potential of innovation nanotechnology can produce.
Military applications are the most obvious, as the United States military is always working to improve its stealth technology. Using reflective technology for vehicles, bombers, planes, and even soldiers would change the face of intelligence gathering and war. Commercial applications could apply to any situation in which visual minimization of a product would be desirable.
While human technology may not be able to replicate transparency anytime soon, improving reflective technology would allow for the reduction in the visual footprint of human structures. One day buildings, utilities, and more could be cloaked. Outdoorsmen would also benefit from improved stealth for their clothing and equipment.