How the Butterfly Builds Green: A New Piece Falls into Place

Butterflies have fascinated MBL Director Nipam Patel since he was a kid in Texas, found a dead swallowtail in his yard and, after reading a “How and Why of Butterflies and Moths” book, figured out how to mount it. He was soon catching the charismatic insects with a homemade net, building a collection of colorful specimens from the desert around his house and from his family’s travels in Europe, India and Africa.

Many of Patel’s spectacular butterflies were on display at his Falmouth Forum talk on Sept. 26, “The Amazing Life of Butterflies” (if you missed it, the video is here.) Patel shared many stories – some inspiring, funny, or provocative -  to show how different butterflies use coloring and patterning for crucial life strategies, from courtship to hiding from predators.

“Butterflies offer incredible insight into biology and nature and the diversity out there in the world … And why it’s so important to go out there and really examine nature,” he said.

Patel also touched on one scientific focus he’s chosen for his lab: How butterflies make the vibrant greens and blues that dazzle in their wings. Unlike other wing colors, which the butterfly makes by filling wing scales with pigments, blue and green are often “structural colors” that are created by light interacting with the scales. Patel’s lab wants to know: How does the butterfly (during the pupa stage) build the thin nanostructures on the wing that will manipulate light to create blue and green?

Recently, his lab took part in a study that adds a piece to the puzzle. With scientists at Murdoch University in Australia, they discovered an additional stage of growth during wing development that had not been known before. The study was published in Proceedings of the National Academy of Sciences.

“These remarkable gyroid structures [in the wing scales] have evolved at least three different times to create green color in a few butterfly species. The recent paper shows that the gyroids in Parides sesostris, the Emerald-patched Cattleheart butterfly, appear to be assembled very differently than described for another group of previously studied butterflies,” Patel said. Read more about the new study.