John W.M. Bush is an applied mathematician at MIT, where he studies how insects stand, paddle, jump and jitter along the surface of water, via what he calls "interfacial biolocomotion." As this video compilation illustrates, the movements and mechanisms at work are surprisingly complex, and captivating to watch.
FYFD explains some of what we're seeing:
Waxy, hydrophobic coatings typically make such insects’ points of contact (feet, legs, etc.) water-repellent, and their light weight can be supported by surface tension. Navigating the interface between air and water is more complicated, though, and these creatures have evolved several mechanisms to help. Some, like water striders, use appendages they insert below the surface for propulsion. At 0:49 in the montage above, you can see flow visualization of the vortices generated by a stroke. Other insects release a chemical in their wake that lowers the local surface tension and drives them away via the Marangoni effect
T0 be clear: this isn't floating. These are different mechanisms entirely. To read more about them, visit Bush's website or read this quick explainer featured in Physics Today.
[Via the always-excellent Fuck Yeah Fluid Dynamics]