Did You See This?

Hopping on Water

Water lily beetles have developed a unique way of walking on water.

The video above reveals the recently-discovered (and weird) way that the water lily beetle, Genus Galerucella, gets across the water between lily pads. It’s decidedly odd. And very cool.

The beetle’s back legs come together, almost as a post, and stick the bug to the water’s surface. Meanwhile, its front legs bounce up and down, propelling it forward. As anyone who’s seen Microcosmos knows, water droplets are big, heavy things in comparison to tiny, near-weightless insects. And the beetle’s rear legs interact with the water’s comparatively solid surface in an interesting way: Should the beetle’s legs want to lift into the air, they can’t, because they’re stuck in the grip of the water. If the beetle starts to sink, its buoyant legs keep it from going under.

Meanwhile: bounce, bounce, bounce, the beetle keeps moving to the next lily pad. As Mechanical Engineering grad student Haripriya Mukundarajan says, the beetle “behaves as if it were on a pogo stick in water.”

The water lily beetle’s secret was discovered by Stanford assistant professor of Bioengineering Manu Prakash, who noticed the odd movement and excitedly brought a couple of beetles home with him. There, he made videos of them pogoing across dinner plates full of water. He was thrilled by the unique way the little bugs were achieving such precision: “Here is an insect that has the capacity to really control its trajectory and locomotion at half a meter per second.”