The Secret Revealed: How Butterflies Stay Dry

Butterfly Wings

Story at-a-glance -

  • Researchers from Boston University and M.I.T. have made an interesting discovery about which surfaces – smooth or bumpy – are more efficient at repelling water.

By Dr. Becker

In case you’ve been lying awake nights wondering how butterflies stay dry, a new study published in the journal Nature1 will have you sleeping like a baby again.

As it turns out, raincoats and other similar items with smooth surfaces intended to repel water don’t do the job as well as things with slightly bumpy surfaces – like butterfly wings.

Butterfly Wings: Raincoats Designed by Nature?

A team of researchers from Boston University and M.I.T. dripped water onto silicon wafers with different textures and filmed the drops as they splashed down. Drops of water that fell onto smooth surfaces formed into tiny Frisbee shapes and then bounced off. But water droplets that fell onto wafers with ridges in them barely skimmed the surface before bouncing away.

The conclusion? Bumpy surfaces force water droplets to bounce away quickly, reducing the amount of time the water contacts the surface. The results explain why the veined wings of Morpho butterflies are so good at staying dry.