How do bugs walk on water? See for yourself
- Meghan McMahon
- Aug 29
- 2 min read
If you’ve visited a river or a lake recently, you might have seen some insects in the water. If you took a second look, you might have noticed that some bugs sit on the water. How does that happen?!
These bugs are water striders. As their name suggests, they stride, or glide, across the water. They are able to do this because, for starters, their light weight is evenly spread out.
We can try to float on the water with our legs and arms spread out, but we still sink a little. People are much heavier than water striders! And finally, there are forces we can’t see keeping the strider on the water.
Water is made of molecules that want to stick to the neighboring molecules next to, above and below them. For the water molecules at the surface, there’s nothing on top, just air. So those top molecules have a greater connection to the molecules next to and below them. That causes a thin membrane on the top of the water. We call this surface tension.
Water striders are so light that the force pushing the insect up is greater than gravity pulling it down.
Let’s create our own water strider to explore this.
Materials
Paper straws
Scissors
A bowl or cup
Water
Pom poms (optional)
Googly eyes (optional)
Glue
Instructions
To start, take two paper straws and cut them in half. You will need three of the four halves. Make sure they’re even!
Next, make a wide X with two of the straw pieces. Glue them in the middle of the X shape. Pinch the middle of the X.
Then glue the final straw piece in the middle of the X. These are the feet for your water strider, so it should look like an insect — three legs on each side.
After all the “legs” have dried, hold the middle section and bend all the legs together, so the water strider doesn’t sit flat.
Time for the feet. Pinch and bend the very end of the straws to give your water strider some feet. This will help it balance on the water. Make sure all feet are evenly touching the surface you’re working on.
If you want to give your strider a little personality, consider adding a pom-pom and some googly eyes.
Test out your water strider. Place it on top of your bowl of water. If we did this correctly, the straw insect will rest on top of the water with no legs poking through!
Try different materials — plastic straws, pipe cleaners, Popsicle sticks. What else is light enough to not break the surface tension? And don’t forget to keep an eye out for live water striders when exploring outside!
