The Physics of Mosquitoes

We've all been there- you were outside on a nice summer night, and you wake up the next morning with a bunch of itchy, red bites.

How did you not notice the mosquito on you?

The answer lies within the mechanics of their takeoff from your skin!

In a study done at UC Berkley, the takeoff methods of mosquitoes were compared to those of fruit flies using three high speed cameras. Mosquitoes are just as fast as fruit flies, but only use about a quarter of the leg force that fruit flies do to push off. 

61% of the force used to accelerate the mosquito comes from its wings!

In addition to the greater wing use, mosquitoes legs are much longer, which extends the takeoff time for mosquitoes, dissipating the acceleration further.

Okay, so how does this relate to class?

Let's say we compared a fruit fly flight to a mosquito flight, and we assumed they were travelling the same distance. NOTE: we are only comparing the acceleration from caused by their legs pushing off- not wings.

deltaX = Vi(t) +1/2at^2

deltaX will be the same for both. Vi will be the same for both (0m/s). We know from the study that mosquitoes take longer to takeoff from their long legs. So, t will be larger for mosquitoes. If deltaX is to remain the same as the fruit fly's deltaX, then acceleration of the mosquitoes must decrease to equal the fruit fly! So the acceleration of a mosquito is smaller than that of a fruit fly.

Is there anything with forces here?

Yes! We know that F = ma. If the mass is negligible, as it would be for a mosquito/fly, then the only thing that determines the force on your skin is acceleration. So, the force for a mosquito pushing on us would be smaller than that of a fruit fly, because the acceleration is smaller. So we usually won't notice a mosquito leaving our skin!

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