Get local news delivered to your inbox!

Mosquitoes need to feed on blood in order to reproduce. But how do they choose whom to feed on? boonchai wedmakawand/Moment via GettyImages

It’s rare to attend an outdoor party in warm weather without hearing people complain about mosquitoes. They swat away, sit in campfire smoke, cover up with blankets and eventually just give up and go indoors. On the other end of the spectrum, there are plenty of people who don’t seem bothered by mosquitoes in the slightest.

As a medical entomologist who’s worked with mosquitoes for more than 40 years, I’m often asked why some people seem to be mosquito magnets while others are oblivious to these blood-feeding pests buzzing all around them.

Most mosquito species, along with a host of other arthropods — including ticks, fleas, bedbugs, blackflies, horseflies and biting midges — require the protein in blood to develop a batch of eggs. Only the female mosquito feeds on blood. Males feed on plant nectar, which they convert to energy for flight.

Blood-feeding is an incredibly important part of the mosquito’s reproductive cycle. Because of this, a tremendous amount of evolutionary pressure has been placed on female mosquitoes to identify potential sources of blood, quickly and efficiently get a full blood meal, and then stealthily depart the unlucky victim. If you check some, or all, of the mosquito’s search boxes, then you may find that you are a mosquito magnet.

This video by Deep Look explains some of the ways mosquitoes feed on blood.

Depending on when during the day they are active, mosquitoes use sight, sound and olfactory cues to identify a potential source of blood. Most night-active species rely on olfactory or receptor cues. The most important chemical cue is the carbon dioxide that all vertebrates, including humans, release with each breath and through their skin.

Mosquitoes are very sensitive to CO2 and can sense a CO2 source that is many meters away. Receptor cells on the mosquito’s antennae and legs bind CO2 molecules and send an electrical signal to the brain. When more molecules hit their receptors, the higher the CO2 concentration and the closer they are to the host.

However, there are many nonliving carbon dioxide sources such as cars, boats, planes and trains. To separate living from nonliving sources of CO2, mosquitoes rely on the secondary olfactory cues that living animals produce. Metabolic processes like breathing and moving generate these scent cues, including lactic acid, ammonia and fatty acids that act as additional olfactory clues that help female mosquitoes zero in on their next blood meal.

So, carbon dioxide production is the first mark of a mosquito magnet. Because the production of CO2 and secondary attractants is linked to metabolic rate, the higher the metabolic rate, the more attractants are produced. Metabolic rate can be genetically determined, but it also increases as the result of physical activity.

The human mosquito magnets you can spot at summer parties may have a genetically high metabolic rate or may be more physically active than other attendees. They may also be undertaking other activities that increase their metabolic rate, such as the consumption of alcohol. Increased metabolic rate is why runners attract more mosquitoes during their cooldown stretching exercises. Pregnant women, perhaps due to their increased metabolic rate, attract a disproportionately large number of mosquitoes as well.

This video by Business Insider explains some of the factors that can make a mosquito magnet.

Natural body odors are also important cues used by mosquitoes to select a host. For example, some species of Anopheles mosquitoes are attracted to specific components of foot odor. These mosquitoes transmit human malaria and feed indoors in the middle of the night. By feeding on a sleeping person’s feet, the mosquitoes avoid the head, where most of the CO2 is produced, and reduce the chance of waking the victim.

Mosquitoes active during the day and at dawn and dusk also use visual signals to identify a host. Mosquitoes usually fly close to the ground. From this vantage point they view their potential hosts against the horizon. Dark colors stand out and light colors blend in, so the way a person is dressed will determine the number of mosquitoes they attract. Wearing lighter colors may not just help keep you cool, but will help you evade a mosquito’s notice.

Mosquitoes can visually detect motion, again by contrasting a silhouette against the horizon. This is why people who walk near a saltmarsh in the middle of the day after a large emergence of saltmarsh mosquitoes are inundated by mosquitoes that visually detect their presence.

There is also a psychological component to mosquito activity. Some people simply do not notice the mosquitoes around them. A single mosquito flying around some people will elicit a strong response — you’ve probably seen someone go nuts trying to track down the droning sound of one mosquito in order to finish off the tiny bloodsucker.

Other individuals are not bothered and do not notice the mosquitoes that are attracted to them, even when the insects are feasting on their blood. Some mosquitoes specialize on feeding on parts of the body that are difficult to see and difficult to swat. For example, Aedes aegypti is a mosquito species that prefers to feed on humans, mostly around the ankles.

Whether or not you’re a mosquito magnet, their bites feel just as itchy!

Jonathan Day does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

This article is republished from The Conversation under a Creative Commons license.

Once you’ve been bitten by a mosquito, wash the affected area to prevent infection and itchiness from occurring.

Apply a cold pack, a handful of ice cubes wrapped in a washcloth or a bag of crushed ice for no more than five minutes to provide temporary relief.

Honey is more than just a delicious sweetener for tea — its microbial, anti-inflammatory and antibacterial properties make it an effective home remedy for treating mosquito bites.

Like honey, oatmeal has anti-inflammatory properties as well as saponins, which have cleansing properties. These features make oatmeal another effective option for treating mosquito bites. Grind up a cup or two of rolled oats in a blender until they’re powdery, and add them into a bath filled with warm water, rubbing any clumps of oatmeal onto the affected area.

When all else fails, you may experience relief from calamine lotion or a hydrocortisone cream. These lotions and creams are formulated specifically with the intention to relieve itching and irritation.

Because your body releases histamines when you’re bitten, an antihistamine, which lowers the histamine count in your system, provides relief from mosquito bites. Common over-the-counter brands include Claritin, Zyrtec and Benadryl. Calamine lotion also contains antihistamines that are applied topically.

An efficient way to relieve itchiness from a mosquito bite is to use your fingernail to press across the bite for about 10 seconds, then repeat the process at a perpendicular angle across the bump. This will leave an X-shaped mark on top of the bite. This should only be used as a method for temporary relief from itchiness, as the itchiness will most likely return once the X fades.

Scratching a bite can open up the wound and allow bacteria to enter, which may cause the wound to become more irritated or infected.

Get local news delivered to your inbox!

An apex predator, the mountain lion, has been quietly hunting interloping donkeys in Death Valley. For the first time, it has been caught on camera.

Three scientists have jointly won this year’s Nobel Prize in physics for their work on quantum information science that has significant applications, including the secure encryption of information. Frenchman Alain Aspect, American John F. Clauser and Austrian Anton Zeilinger were cited by the Royal Swedish Academy of Sciences for discovering the way that unseen particles, known as photons, can be linked, or “entangled,” with each other even when they are separated by large distances. The prizes carry a cash award of 10 million Swedish kronor (nearly $900,000) and will be handed out on Dec. 10. The money comes from a bequest left by the prize’s creator, Swedish dynamite inventor Alfred Nobel, who died in 1895.

This year’s Nobel Prize in economic sciences has been awarded to former U.S. Federal Reserve Chair Ben Bernanke and two other U.S.-based economists. Bernanke, Douglas W. Diamond and Philip H. Dybvig were recognized Monday for their research into the fallout from bank failures. The Nobel panel at the Royal Swedish Academy of Sciences in Stockholm said the trio's research had shown “why avoiding bank collapses is vital.” The panel says that the findings of the three in the early 1980s laid the foundations for regulating financial markets and dealing with financial crises.

What traits make raccoons more highly skilled bandits in urban areas? Here's what a study of the mischievous critters found out.

Artificial intelligence can spot differences in images from before and after a storm over wide areas in almost real time. It showed Hurricane Ian’s vast damage in Florida.

A University of Arizona professor who authorities say was fatally shot on campus by a former graduate student was an expert on desert water issues who faculty and former students described as a kind and brilliant colleague. School officials identified Thomas Meixner, who had headed the school’s Department of Hydrology and Atmospheric Sciences, as the victim in Wednesday afternoon’s shooting. According to campus police, someone called 911 asking for police to escort a former student, 46-year-old Murad Dervish, out of the building after recognizing him as someone who wasn't allowed to be there. State troopers arrested Dervish a few hours later. He's jailed and awaiting a court appearance. It wasn't clear whether he had a lawyer who could speak for him.

When an asteroid slammed into Earth 66 million years ago, it wiped out the dinosaurs — and triggered a global tsunami, research shows.

A new image showcasing a galactic pair, shared by NASA on Wednesday, is the striking result of using data from both space observatories.

Eleven people working for a leading turkey producer have been charged with animal cruelty in Pennsylvania after state police said they were caught on video kicking, stomping and beating turkeys at several farms. Pennsylvania State Police said Thursday that the Plainville Farms workers were responsible for capturing and crating turkeys destined for slaughter. An undercover investigator for People for the Ethical Treatment of Animals worked on a crew and captured graphic video showing workers appearing to mistreat the birds. Pennsylvania-based Plainville Farms says it has “zero tolerance” for such acts and has fired the implicated employees.

Wildlife agencies in the U.S. are finding elevated levels of a class of toxic chemicals in game animals such as deer. The discovery is prompting health advisories in parts of the country where hunting and fishing are ways of life and key pieces of the economy. Authorities have detected the high levels of PFAS, or per- and polyfluoroalkyl substances, in deer in several states, including Michigan and Maine. PFAS chemicals are industrial compounds used in numerous products, such as cookware and clothing. They are sometimes called “forever chemicals” for their persistence in the environment. The discovery of PFAS in animals hunted for sport and food represents a new challenge.

Get up-to-the-minute news sent straight to your device.