Their low mass helps them recover from impacts quickly

Jun 5, 2012 13:12 GMT  ·  By

Their low mass and hydrophobic bodies help mosquitoes withstand mid-flight impacts with raindrops without suffering any structural damage. In a new study conducted using slow-motion cameras, scientists were able to figure out how these factors, and others, interact to spawn this ability.

It is very important to note straight off the bat that most insects are designed to be hydrophobic. This means that their bodies tend to repel water, primarily through small hairs and other nano- or microscale structures on their wings and torsos.

This contributes to increasing the energy required for a drop of water to wet these surfaces. As such, mosquitoes can resist the impact of a drop more than 50 times heavier without experiencing any discomfort. But scientists are quick to point out that there are several other factors that contribute, too.

For starters, the insect has a very strong exoskeleton that displays significant resistance to mechanical stress. Combined with the low weight, this makes the raindrops lose very little momentum when colliding with the flying mosquito. This translates into less splashing.

Though this may seem trivial, splashing is an indicator that more force is transferred between the drop and the surface it's falling on. Comparatively, it could be that a bird experiences more discomfort when flying through rain than a mosquito does, even though birds have hydrophobic wings as well.

Details of the new investigation – which was led by Georgia Institute of Technology assistant professor of mechanical engineering and biology David Hu and his PhD student Andrew Dickerson – appear in the June 4 issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS).

“The most surprising part of this project was seeing the robustness this small flyer has in the rain. If you were to scale up the impact to human size, we would not survive. It would be like standing in the road and getting hit by a car,” Dickerson explains.

The results of the new study could be used for a variety of applications, including improving the safety of micro-airborne vehicles as they fly through rough weather conditions, as well as for figuring out how conditions including malaria are spread by the insects.

“To survive, the mosquito must eventually separate from the front of the drop. The mosquito accomplishes this by using its long legs and wings, whose drag forces act to rotate the mosquito off the point of contact. This is necessary, otherwise the mosquito will be thrown into the ground at the speed of a falling raindrop,” Hu concludes.