Engineers have continuously observed scales growing and assembling on a butterfly wing for the first time as the developing insect transforms inside its chrysalis.

Now, MIT engineers have captured the intricate choreography of butterfly scales forming during metamorphosis. The team has for the first time continuously observed the wing scales growing and assembling as a developing butterfly transforms inside its chrysalis.

With some minor surgery and a clever imaging approach, the researchers were able to watch wing scales form in specimens of Vanessa cardui, commonly known as the Painted Lady butterfly. They observed that, as a wing forms, cells on its surface line up in orderly rows as they grow. These cells quickly differentiate into alternating «cover» and «ground» scales, producing an overlapping shingle-like pattern. As they reach their full size, the scales sprout thin ridges along their length — tiny corrugated features that control the insect’s color and help it to shed rain and moisture.

The team’s study, published in the Proceedings of the National Academy of Sciences, offers the most detailed look yet at the budding architecture of butterfly scales. The new visualizations also could serve as a blueprint for designing new functional materials, such as iridescent windows and waterproof textiles.

«Butterfly wings control many of their attributes by precisely forming the structural architecture of their wing scales,» says lead author Anthony McDougal, a research assistant in MIT’s Department of Mechanical Engineering. «This strategy might be used, for example, to give both color and self-cleaning properties to automobiles and buildings. Now we can learn from butterflies’ structural control of these complex, micro-nanostructured materials.»

McDougal’s co-authors at MIT include postdoc Sungsam Kang, research scientist Zahid Yaqoob, professor of mechanical engineering and biological engineering Peter So, and associate professor of mechanical engineering Mathias Kolle.

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Materials provided by Massachusetts Institute of Technology. Original written by Jennifer Chu. Note: Content may be edited for style and length.