This is a photo of a pink glasswing butterfly (Cithaerias merolina) from Peru. The wings of this butterfly are for the most part transparent. However, there is a limited range of viewing angles where the wing membrane reflects iridescent colors, as shown in the photos below. The hair-like structures on the wing are piliform scales. These help the butterfly shed water and may be used for defensive purposes (3).


Detail view.




Approximate Photo Location (Underside)


Magnification: 4X

Field of view: ~1/4” x 3/8” (6.0mm x 9.0mm)

Images in focus stack: 48


Butterflies in the Cithaerias genus can be found in the rainforests of Mexico and Central and South America (1). They typically live in the understory, close to the forest floor (1). (Some photos of them in the field are available here). The wing transparency in these butterflies likely serves as a camouflage, making it harder for predatory birds to track their movements during flight (3). Scientists studying the Greta oto butterfly (a different glasswing) found that the transparency is caused by the light scattering properties of pillar-shaped nanostructures. These forms (which are visible with a scanning electron microscope) are randomly sized and irregularly arranged on the wing (3). Interestingly, a team at MIT has prototyped a coating with the same structure (biomimicry) for solar energy cells, increasing the cells’ efficiency by decreasing the amount of reflected light (4).


1. Penz, C. M., Alexander, L. G., & Devries, P. G. (2014). Revised species definitions and nomenclature of the rose colored Cithaerias butterflies (Lepidoptera, Nymphalidae, Satyrinae). Zootaxa, 3873(5), pp. 541–559. Retrieved from ResearchGate.

2. Smithsonian Tropical Research Institute (STRI). Cithaerias pireta (C. & R. Felder, 1862). Retrieved from the STRI Symbiota Portal.

3. Siddique, R. H., Gomard, G., & Holscher, H. (2015). The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly. Nature Communications, 6(6909). Retrieved from Nature.

4. Matheson, R.  (2015). Biomimetic non-reflective coating for solar cells wins MADMEC. Retrieved from MIT News.

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