Why do mosquitoes always find you, no matter where you hide?

No matter where you hide, mosquitoes will find you. American scientists have revealed the chilling secret of this tiny insect's ability to track its prey.

According to a research team from the California Institute of Technology, mosquitoes use a three-pronged approach that combines olfactory, visual and thermal cues to locate any nearby hosts. It is this combination of three different types of sensory information that makes it so difficult to avoid them, and they can even detect our presence from up to 50 meters away. Photo: ABC News - The Walt Disney Company

To test their hypothesis, the team conducted a number of experiments with female mosquitoes in a wind tunnel, manipulating different types of sensory signals to see which conditions they responded best to. Injecting a high concentration of carbon dioxide gas into the wind tunnel – to simulate human breathing – caused the mosquitoes to follow the airflow.Photo:BBC

In a second experiment, the team placed a dark object on the floor of the wind tunnel to serve as a visual cue for the mosquitoes. They found that when CO2 was injected into the tunnel, the mosquitoes focused on the object, but when there was no CO2, they ignored it at all. This suggests that mosquitoes only pay attention to visual cues if they have been told by their sense of smell. Photo: Microbe Investigations

“Our experiments show that female mosquitoes do this in a rather elegant way when foraging,” said Michael Dickinson, lead author of the study. “They only pay attention to visual cues after they detect an odor that indicates a host is nearby. This helps ensure that they don’t waste time investigating false targets like rocks and vegetation.” Photo:EcoGuard Pest Management

Finally, to measure what kind of temperature mosquitoes were attracted to, the researchers heated an object to 37 degrees Celsius (about human body temperature) and left an object at room temperature. Mosquitoes were attracted to the warm object, regardless of whether CO2 was present. Photo: Citizen-Times

“These experiments show that attraction to visual features and attraction to warm objects are separate,” said Floris van Breugel, author of the study. Photo: Stanford Report - Stanford University

Analysis of how mosquitoes responded in three experiments led the researchers to create a “triple threat” model of how mosquitoes find their hosts. From 10 to 50 meters away, mosquitoes use their sense of smell to detect CO2 plumes. This is what initially draws them to humans and other animals. From 5 to 15 meters away, mosquitoes use their eyes, moving closer to us through visual cues. Finally, when they are within 1 meter of a host, they detect heat cues to get closer to their target. Photo: Lab Manager

It's this approach that makes avoiding mosquito bites so difficult, with researchers admitting that there's not much humans can do to repel mosquitoes.Photo:GeekWire

“Even if you could hold your breath indefinitely, another person breathing nearby or a few meters downwind would create a CO2 plume that could draw a mosquito close enough to you,” the authors write in their paper, published in Current Biology. “Therefore, the strongest defense is to become invisible, or at least visually camouflaged. However, even in this case, mosquitoes can still locate you by tracking your body heat signature.”Photo:www.self.com

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