How Do Mosquitoes Walk on Water?

Until recently, it had been unclear how mosquitoes could walk on water. Researchers have measured the supporting force of mosquitoes’ legs, and found that a single leg can support 23 times the mosquito’s body weight. This is significantly stronger than other water-walking insects.

The tarsus, the bottommost part of a mosquito’s leg, carries the bulk of its weight. The tarsus is a long, flexible section that lies almost horizontally on the water surface. It is covered with hydrophobic scales, which repel water molecules, and also forms a stable air cushion at the leg/water interface. The distal portion of the tarsus also assists with the take-off from the water surface.

The water-repellent nanostructure may also help provide stability when the mosquitoes land on water. However, the researchers found that only 12.5% of the total supporting force came from the protective wax and scales.

According to the researchers, the most significant factors in the mosquito’s ability to walk on water are the angle of contact between the legs and the water surface and the length of contact. The researchers determined that the supporting force of a mosquito’s leg was strongest when the leg was parallel to the water surface. This is because mosquitoes can use their legs to adjust the angle of contact.

Researchers also found that the length of contact between the leg and the water surface could be adjusted. This allows mosquitoes to walk on water without sinking. This is possible because water molecules at the water surface are more attracted to each other than those in other materials.