C

      Delicate step gives mosquitoes strength to walk on water.

   It's not a magical power. Mosquitoes can walk on water because of the angle at which their legs touch its surface.

   A mosquito's leg is strong enough to bear up to 23 times its total body weight, which is one reason why it can walk on water so effortlessly. This is far greater than the leg strength of other water-walking insects like water striders(水黾), whose legs have been more carefully studied.

   Jian-Lin Liu of the China University of Petroleum in Qingdao and his colleagues thought a mosquito's advantage might also come from the protective wax and microscopic scales(鳞片) coating its legs. They removed these layers(层) and measured the change in the leg's load-bearing capacity(承重能力), but found that the layers were responsible for less than 12.5 percent of the overall supporting force.

   The main player turned out to be the angle between the leg and the water surface. The supporting force was strongest when the leg was nearly parallel to the surface. Any angle greater than 62 degrees would make the mosquito fall through the surface.

The researchers believe that mosquitoes can adjust this angle during landing and take-off to ensure they remain on the water's surface. This ability is very important because many species land on fresh or still water to lay their eggs in it.

    The work could inspire insect-like robots and waterproof materials, the team says.