In everyone's impression, mosquitoes, insects with only a few millimeters, do not fly high, do not fly far, and can only fly on the ground. After all, the figure was there, and there was only a pair of wings two or three millimeters long and a pair of degraded balance bars.
Mosquito wings Source: Sahibul-Saif Sheykh Abdul Kerim al-Kibrisi - WordPress.com
Now, scientists' research has upended the perception of mosquitoes' ability to fly.
In the semi-desert areas south of the Sahara Desert, malaria-carrying mosquitoes can use wind power to fly up to 290 meters above the ground in one night, hundreds of kilometers away.
In 2013, scientists at the National Institute of Allergy and Infectious Diseases (NIAID) traveled to the Sahara to catch and sample local mosquitoes for the next 617 days. The aim is to study the migratory capacity of mosquitoes in different regions.
They used helium balloons to drop the paint vertical sticky net at a distance of 40 meters to 290 meters above the ground.
Helium balloons and sticky nets Source: Literature 1
As a result, they captured 461,000 insects, including 2,748 mosquitoes, and 235 were just the genus Anopheles that could carry malaria. That is, mosquitoes can fly up to 290 meters high. It's hard to say if you've laid a sticky net higher up, and maybe you can catch mosquitoes that fly higher.
Species and numbers of mosquitoes caught at different flight altitudes Source: Literature 1
You might think that nets close to the ground will catch more mosquitoes. However, in practice, on the contrary, the number of mosquitoes caught by the sticky net increases with the increase in height. This suggests that mosquitoes can also migrate at high altitudes.
More than 80% of the mosquitoes caught are females, and it is known that female mosquitoes can bite people, and 90% of mosquitoes have sucked human blood before flying.
By capturing the data obtained by the mosquitoes alone, scientists are not sure where the mosquitoes came from or how far they flew. Because it is only a sampling of a certain location, it can only indicate that mosquitoes have appeared in a certain location.
But with the help of meteorological modeling tools, using existing data, taking into account both wind direction and wind speed, the scientists calculated the mosquito's likely flight trajectory. The scientists eventually concluded that a mosquito, relying on its own flight ability and wind power, flew up to 295 kilometers in a nine-hour night flight.
Combined with modeling tools, the scientists analyzed the migration distances of different species of mosquitoes Figure Source: Literature 1
If one were to imagine, it would be hard for anyone to believe that such an inconspicuous creature could fly that far. Not only ordinary people, scientists will be shocked when they first see this data. In 2019, scientists published their findings in the journal Nature.
Although the mosquitoes themselves have limited flight distances, with the wind, it is no problem to fly farther and higher to bite people and spread diseases.
That's why mosquitoes appear even if your family lives in a high-rise building on the 21st floor. After all, mosquitoes can fly up to a height of several hundred meters, do you care about the height of 21 floors and more than 60 meters?
You might think that mosquitoes are only found at low altitudes, but in high-altitude areas like the Himalayas, there are also mosquitoes.
In 2007, scientists sampled mosquitoes in The Gawar Special Area of India and captured mosquitoes at different altitudes of 300-1000m, 1000-2000m, and 2000-3000m. A total of 34 species of mosquitoes were found, including 5 genera: Aedes mosquitoes, Anopheles mosquitoes, Asedes mosquitoes, Culex mosquitoes and blue ribbon mosquitoes.
Mosquito species appear at different altitudes, and as the altitude increases, the number of mosquito species that appear decreases Figure: Literature 2
The temperature in the low altitude area is humid and hot, and there is no doubt that mosquitoes can be caught here, but at a high altitude of 3000m, although there are not many mosquito species found, only a few, but it also shows how strong the survival ability of some mosquitoes is.
Of course, mosquitoes can fly to dozens of stories high through elevators and some pipes, but these are not explained by scientific research, this is just everyone's speculation, from some possible ways to analyze. But now you should know that with just one pair of wings and the wind, mosquitoes can fly directly from the outer layer to the 21st floor.
<h1 class="pgc-h-arrow-right" how do mosquitoes fly >? </h1>
Mosquitoes and bees fly in a similar way, both by flapping their wings and fanning the air to obtain upward force. The difference is that mosquitoes flap their wings faster and vibrate at a small angle of only about 40 degrees, half as much as bees. That is to say, if according to the reasoning, mosquitoes cannot obtain enough lift like bees.
If the mosquito chooses the bee's large-angle flapping wings, then the buzz of the mosquito when flying is estimated to be twice as large, and the flight sound is louder, and it is easy to be found.
In 2017, scientists unlocked the secrets of mosquito flight through slow motion. Scientists from the University of Oxford used 8 ultra-high-speed cameras to photograph how a mosquito flew from 8 angles.
Experiment shooting mosquitoes in flight Source: https://newatlas.com/
The slow-motion mosquito flapping frequency is 700 times slower than it actually is, and then a 3D model is made through computer simulations that allow scientists to understand the changes in the airflow of mosquitoes in flight.
Flight view of mosquitoes in 8 perspectives Image source: nature video
According to the results of the study, mosquitoes in the process of flapping wings, like bees, in the leading edge of the wing will produce a small vortex, this air flow reduces the pressure above the wings, that is, in the process of flapping wings will obtain a certain amount of lift.
Leading edge vortex generated by mosquitoes Source: nature viedo
But in addition to the vortex of the leading edge of the wing, the mosquito also forms a vortex on the trailing edge of the wing, which is different from the honey bee. The reason why it can create a vortex behind the wings is because its wings are not vertically fanned down, but will be reversed during the fanning process.
Trailing edge airflow Source: nature video
When the hind edge of the wing is flipped, the trailing edge of the wing aligns with the fluid produced by the flapping of the leading edge of the wing, creating a vortex that regains some extra lift.
In addition, mosquitoes also create a rotational resistance during the fan wing process to support the weight of their bodies.
Rotation resistance Image source: nature video
This may explain why mosquitoes can still get enough lift by beating at small angles, because it compensates for the disadvantages of flapping wings at small angles by generating additional vortexes.
In the future, scientists may apply mosquito flying technology to smaller drones, and can only hope that such drones will not buzz...
bibliography:
1、Huestis D L, Dao A, Diallo M, et al. Windborne long-distance migration of malaria mosquitoes in the Sahel[J]. Nature, 2019, 574(7778): 404-408.
2、Pemola Devi N, Jauhari RK. Mosquito species associated within some Western Himalayas phytogeographic zones in the Garhwal region of India. J Insect Sci. 2007;7:1‐10. doi:10.1673/031.007.3201
3、http://www.ox.ac.uk/news/2017-03-30-new-study-sheds-light-how-mosquitoes-wing-it
Producer: Popular Science China
Producer: Su Chengyu
Producer: Computer Network Information Center, Chinese Academy of Sciences