Water-Walking Bugs: How Do They Do That?

During a recent field trip to Chatfield’s Hole in East Hampton, students from were treated to some great wildlife watching that included bullfrogs, painted turtles, a green heron, a broad-winged hawk and a double-crested cormorant. One of the creatures that really caught our attention was an insect called a water strider. It’s also known as water skimmer, pond skater and even Jesus bug because of its ability to – well, you guessed it – walk on water.

Typically, I become motivated to brush up on my naturalist skills by students’ questions in the field. This time, many of those questions revolved around the mystery of how water striders walk on water. So, to the field guides and Internet I went! Here’s what I found out:

I was surprised to learn that there are more than 1,500 species of water striders worldwide. The ones we frequently see on calm waters of ponds, gliding and hopping quite gracefully across the surface of the water, are common water striders, Gerris remigis. For years, their rather biblical mode of locomotion was poorly understood among the scientific community. However, research conducted by scientists at the Chinese Academy of Sciences and mathematicians from Massachusetts Institute of Technology (MIT) has shed light on this mystery. 

Microscopic images of a water strider’s long legs showed layers of extremely thin hairs that trap air and repel water, much like duck feathers, but so much more effective that scientists call them “superhydrophobic.” This adaptation, combined with the water strider’s very light weight, allow a them to stay on the surface of the water.

But how do they glide and hop across the water?

At MIT, researchers used advanced video technology to film water striders on the move. A closer look revealed a slight dimpling on the surface of the water made by their long, thin, hairy legs. Water striders apply just enough pressure to the surface of the water behind their back legs to make a slight valley, but not enough to break through the surface tension of the water. The valley then bounces back (sort of like a trampoline) and propels the insect forward.

Trampoline jumping, superhydrophobic bugs? I can’t wait to share this with students!

Anita C. Wright is an environmental educator with Group for the East End. She earned her B.A. from Tufts University and her M.S. in Environmental Education from Antioch New England Graduate School. In the fall of 1998, she joined Group for the East End as an Environmental Educator. Prior to working at the Group, she spent 5 years as an Outdoor Educator and Assistant Program Director for Boston University Sargent Center in New Hampshire where she taught environmental education and led high ropes courses, rock climbing and wilderness trips.