Mosquitoes have a view at night

Bloodsuckers: How mosquitoes actually find us

When mosquitoes are hungry - or need protein for their eggs - they usually find their way to a warm-blooded victim. Research has long been concerned with what exactly leads insects to involuntary donors: Is it the light under which the food source is located? Or their smell? In fact, the animals rely on three different signals to take their route to bloodletting, write Floris van Breugel from the California Institute of Technology in Pasadena and Co in "Current Biology" - and the carbon dioxide that we exhale plays a major role in this: Even at a distance of 50 meters from the exhale, the mosquitoes can perceive carbon dioxide molecules and follow this trail, as the group has observed experimentally.

Once they have reached a radius of 5 to 15 meters around their prey, they rely on visual impressions such as movements or outlines. Sighting is made easier for them by light, but the lighting is ultimately irrelevant to whether they really stab. Because on the last meter they use heat sensors with which the insects perceive the radiation from the body and steer precisely towards areas of the skin that are particularly well-perfused with blood. The researchers cannot therefore recommend avoiding these three signals because we naturally emit carbon dioxide when we breathe. If we are in a group of people, then we might be lucky. Because mosquitoes prefer people who have a rather monotonous bacterial colonization on the skin. Especially when Staphylococcus- Species dominate, men and women become more attractive to the animals - a species-rich skin flora, on the other hand, tends to deter them.

This article is included in Spectrum - The Week, 29/2015

Nevertheless, according to van Breugel, one is not completely defenseless, even if one does not want to use mosquito repellants. Because the best tactic is to confuse the animals - you just have to ask your loved ones to wear a contrasting shirt. This diverts the mosquito's visual attention.