Question

Why are some insects able to walk on water?

Answer 1

It is not simply the water-air surface tension that allows the insect to walk on water. It is the combination of the legs not being wetted and the surface tension. The legs of water striders are hydrophobic. Water molecules are strongly attracted to one another.

Answer 2

Some insects have waxy feet's/pads which sticks to the tiny molecules present on the surface of water.Sometimes this coating of wax is present in their body as well.Example: Pond skater.This insect is able to walk on the surface of water.Water has a see through film on its top layer which is created by surface tension.That means molecules of water are more likely to cling to other molecules of water than to something else.The surface tension of insect's body is much less than water and hence water tends to bond itself rather than wetting the insect's feet and unless the insect is too heavy,it can remain on top of water surface.