Water striders live on the surface of the water, as if it were solid ground. They perform some other magic tricks too.
Water striders are in the Gerridae family of the true bug order of insects. Like shield bugs, they have a piercing mouthpart they use to control and consume their prey, which is usually insects that get stuck in the water.
Why don’t they have to choose between sink or swim? Gerridae have lots of tiny, water-repellent hairs on their legs. By lots, I mean upwards of 2,000 hairs per square millimeter. If a water strider gets dunked by a big wave, the air trapped by these hairs buoys them up again.
Each pair of their legs has a different function. The front legs have claspers mid-way down, like praying mantises, that allow them to catch and hold their prey. The middle legs row a tiny wave of water that propels them, and the back legs steer.
And these insects can scoot … it’s really difficult to approach one without it zooming off, and they can cover a meter in a second. They may be less skittish at meal time; the ones I managed to photograph were eating.
There are water striders in lots of places at Mount Pisgah. They hang out on the shores of the river, particularly under the bridge that leads to the park. I’ve also seen them in seasonal water, and even in puddles on trails. How do they get there? As if walking on water wasn’t enough, they can fly!
Not all water striders have wings, though, and some species have generations with wings and generations without. Which brings me to their second great illusion: There have been very, very few documented sightings of them flying. I found one mention in a text from the 1920s, and one video from a lab experiment. In the lab, the Gerridae took off to escape a predator, but couldn’t have flown very far! In nature, they show up at very remote islands of water, but no one sees them going there. It’s mighty mysterious behavior. Maybe we could learn from their stealth flight skills.
Final fun fact: The Halobates genus of water striders are one of a very small number of insects that live in the ocean.
Stay curious!
See more of Karen’s work here.
Sources:
Annals of Entomological Society of America that mentions witnessing Gerridae flight: tinyurl.com/5fahtya6. Accessed 12/3/21.
Research on jumping and flying Gerridae: https://www.researchgate.net/figure/Predation-escape-strategy-and-behavioural-setups-in-water-striders-a-A-water-strider_fig3_281408433. Accessed 12/3/21.
