Look closerInsects
How water striders stand on a pond's surface without sinking
When: May to September
Water striders stand on the surface film of eastern Massachusetts ponds on water-repellent, hair-covered legs, denting it into tiny dimples without ever breaking through.
Why this time of year
Calm, warm late-summer water leaves the surface film glassy, so striders, and the round shadows their feet cast on a sunlit bottom, are easy to spot from shore.
How to notice it
- Find a calm patch of pond edge or slow stream and crouch low so you see the surface at an angle.
- Watch how each leg rests in its own tiny dent without sinking.
- Over shallow bottom on a sunny day, look for the small round shadows sliding along beneath each strider.
- Move slowly; they scatter when startled and regroup once you hold still.
Try this with kids: Can you see the dimples where each leg presses the surface?
surface tension is the pull between water molecules that makes the top of the water act like a thin stretchy skin
Safety
- Watch from stable ground at the water's edge; no need to wade.
Sources
- nwf.orgsurface tension plus water-repellent leg hairs let striders stand on the surface; live on ponds, vernal pools, and marshes; found on calm water throughout the continental US
- mdc.mo.govwater-repellent hairs on the legs let them skate; prefer calm water; their feet press small dimples into the surface film that cast round shadows on the bottom; scatter when alarmed
In the guide for May, June, July, August, September