Some people can sit outside all summer long and not suffer from mosquito bites. It’s mostly about the invisible chemical landscape of the air around us. Mosquitoes take advantage of this landscape by using specialized behaviors and sensory organs to find victims by following the subtle chemical traces their bodies leave behind. In particular, mosquitoes rely on carbon dioxide to find their hosts. When we exhale, the carbon dioxide from our lungs doesn’t immediately blend with the air. It temporarily stays in plumes that mosquitoes follow like breadcrumbs.
“Mosquitoes start orienting themselves to those pulses of carbon dioxide and keep flying upwind as they sense higher concentrations than the normal ambient air contains,” said Joop van Loon, an entomologist at Wageningen University in the Netherlands. Using carbon dioxide, mosquitoes can lock onto targets from up to 164 feet (50 meters) away.Things start getting personal when mosquitoes get about 3 feet (1 m) away from a group of potential targets. In close quarters, mosquitoes take into account a lot of factors that vary from person to person, including skin temperature, the presence of water vapor and color.
Scientists think the most important variable mosquitoes rely on when choosing one person over another are the chemical compounds produced by the colonies of microbes that live on our skin.”Bacteria convert the secretions of our sweat glands into volatile compounds that are taken through the air to the olfactory system on the head of the mosquitoes.”
As mentioned above, mosquitoes actually use their eyes to target victims. Jay explains that mosquitoes are highly visual, “especially later in the afternoon, and their first mode of search for humans is through vision.” Wearing dark colors (navy, black) and red make you easier to spot, says Jay. (Note to self: Check camouflage summer wear.)
2. Blood type
It’s all about the blood for mosquitoes; well that and nectar. Adult mosquitoes survive on nectar for nourishment, but females rely on the protein in our blood for the production of eggs. So it’s little surprise that some blood types may be more desirable than others. Research has found, in fact, that people with Type O blood are found to be twice as attractive to mosquitoes than those with Type A blood; Type B people were in the middle. In addition, 85 percent of people produce a secretion that signals what blood type they are; mosquitoes are drawn to those 85 percent more than the non-secretors, regardless of blood type.
Mosquitoes can sense carbon dioxide up to 160 feet away; so the more one exhales, the more attractive they become. Larger people exhale more. Also to note, since human beings exhale carbon dioxide through the nose and mouth, mosquitoes are attracted to our heads, which explains the whole “mosquitoes buzzing about the ears all night” misery.
4. Heat and sweat
Mosquitoes apparently have a nose for other scents besides carbon dioxide; they can sniff down victims through the lactic acid, uric acid, ammonia and other compounds emitted in sweat. They also like people who run warmer; a hot sweaty human must seem quite delicious to them – couch potatoes, rejoice. Strenuous exercise increases the buildup of lactic acid and heat in your body, while genetic factors “influence the amount of uric acid and other substances naturally emitted by each person, making some people more easily found by mosquitoes than others.”
5. Lively skin
Some research has shown that the types and amount of bacteria on one’s skin can play a role in brining on the mosquitoes as well. Our dermal casing is naturally teeming with microscopic life, and the whole shebang creates a distinct fragrance. In one study, a group of men were divided into those who were highly attractive to mosquitoes and those who were not. The delicious ones had more of certain microbes on their skin than the unattractive ones, but fewer types – a larger community but less diverse. The bacteria factor could also explain why some mosquitoes are drawn to ankles and feet, an especially ripe source of bacteria.
Women with a bun in the oven are probably those least wanting to attract mosquitoes, but alas, some species are evidently more attracted to pregnant women than women who are not. One study in Africa found that pregnant women are twice as attractive to malaria carrying mosquitoes as non-pregnant women; researchers believe it is due to an increase in carbon dioxide – they found that women in late pregnancy exhaled 21 percent greater volume of breath than non-pregnant women. They also discovered that the abdomens of pregnant women were 1.26°F hotter, adding to the mosquitoes-like-warm-bodies component.