The Scientific Reasons Behind Why You Get So Many Mosquito Bites

I love the heat and consistent sunshine that characterize summers in North Carolina. This time of year, I can spend more time outside doing things I love: hiking, biking, walking my dog and spending time on the beach. But that time in nature is quickly spoiled when I find myself covered in red, itchy bumps after just a few minutes outdoors. Mosquito season starts in March and can last until as late as November in some states. That means it’s still peak mosquito season right now. 

If you’re like me, you get frustrated by the number of mosquito bites you acquire. It’s downright infuriating when I come inside sporting several new welts while my friends report that they don’t have a single one. 

Why is that? It’s not that I’m particularly unlucky. There are actually scientific reasons why mosquitoes single out certain people. Here’s why mosquitoes bite and how you can make yourself less of a target this summer. For more, learn about how to safely remove a tick and how you can alter the colors of your hydrangeas. 

Why do mosquitoes bite?

Contrary to what you might think, mosquitoes don’t bite people for food; they feed on plant nectar. Only female mosquitoes bite, and they do so to receive proteins from your blood needed to develop their eggs. 

Why are some people more prone to bites?

There are several factors that impact why some people are more prone to mosquito bites than others:

Blood type

A common belief is that mosquitoes are attracted to certain blood types, considering mosquitoes bite humans for their blood. Blood type is determined by genetics, and each blood type is created based on the different sets of specific proteins, called antigens, on the surface of red blood cells. There are four main blood types: A, B, AB and O. 

While there are no firm conclusions as to which blood type is more attractive to mosquitoes, several studies have suggested people with type O are most appetizing to mosquitoes. A 2019 study observed mosquito feeding behavior when presented with different blood type samples, and found mosquitoes fed from the type O feeder more than any other. A 2004 study also found that mosquitoes land on blood group O secretors (83.3%) significantly more than group A secretors (46.5%).

However, these studies are not definitive, and much is still up in the air about mosquito preferences when it comes to blood type.

Clothing color 

Mosquitoes are highly visual hunters when it comes to finding a human to bite. This means movement and dark clothing colors like black, navy and red can stand out to a mosquito. Research has shown that mosquitoes are more attracted to the color black, but there has been little additional research into why this is the case. 

Carbon dioxide

Mosquitoes use sight and smell to find hosts to bite. One of the quickest ways mosquitoes can sniff out a person is through the carbon dioxide emitted when we breathe. According to research published in the journal Chemical Senses, mosquitoes use an organ called a maxillary palp for carbon dioxide detection and can sense it from 164 feet away. 

Because carbon dioxide is a huge attractor, people who emit more of it — larger individuals and people who are breathing heavily when working out — are more attractive to a mosquito. 

Body odor and sweat

Mosquitoes are attracted to more substances and compounds than just carbon dioxide. Mosquitoes can find people to bite by smelling substances present on human skin and in sweat, including lactic acid, uric acid and ammonia. 

A new study found that mosquitoes are attracted to compounds called carboxylic acids that every human produces through sebum, a waxy coating, on their skin. The sebum is eaten by the millions of beneficial microorganisms found on human skin, which produces more carboxylic acid — and will, in turn, produce an odor similar to cheese or smelly feet that appears to attract mosquitoes. Lead researchers on this study said mosquitoes are sensitive to human odor and that even perfumes or colognes can’t mask it.  

Researchers are still learning why certain body odors are more attractive to mosquitoes, but they do know that genetics, bacteria on the skin and exercise all play a factor. Genetics impact the amount of uric acid emitted, while exercise increases lactic acid buildup. 

Beer

In a small study, mosquitoes were observed to land on participants more frequently after consuming a small amount of beer. But before you swear off outdoor brews, know that the study only had 14 participants, and it found that mosquitoes may only be marginally more attracted to people who have been drinking beer.

Why do some people swell from mosquito bites more than others?

Mosquito bites can range in size from small little spots to large welts. Why is this the case?

Bites affect people differently. The size and severity of a bite relate to how your immune system responds to the saliva introduced by the mosquito when it bites. When mosquitoes bite, they inject some saliva when drawing blood. This saliva contains certain anticoagulants and proteins, triggering the immune system to respond to these foreign substances. 

Our body responds by releasing histamine — a chemical released by white blood cells when your immune system is fighting allergens — which causes the itchiness and inflammation of the bite. 

How to prevent mosquito bites

The best way to handle a mosquito bite is to not get them in the first place — but oftentimes, that’s easier said than done. 

Some common ways to prevent mosquito bites include:

• Use repellents and bug sprays (Repel, Off Deep Woods and other brands that contain DEET)
• Use natural repellants (citronella essential oil, neem oil, thyme essential oil)
• Avoid going outside at dawn or dusk 
• Avoid dark-colored clothing, specifically black
• Avoid standing water and try to eliminate standing water near your home
• Use mosquito netting when camping or sleeping outdoors
• Wear long sleeves and pants
• Prevent mosquito bites when traveling internationally

If you’re using DEET insect repellent, make sure to follow the Centers for Disease Control and Prevention’s guidelines (PDF) about the strength and proper application.

How to treat mosquito bites

Mosquito bites, while annoying, are often not severe and will resolve in a few days. In the meantime, there are several treatments to alleviate the itchiness and inflammation:

• Clean with rubbing alcohol if a fresh bite
• Take an oatmeal bath 
• Use over-the-counter antihistamines such as Benadryl or Claritin
• Apply mild corticosteroid creams
• Use aloe vera to reduce inflammation
• Try a cold compress or ice pack for 10 minutes

Though difficult, try as best you can to not itch the bite too roughly to prevent any sort of skin reaction or infection. 

Mosquito-borne diseases and illnesses

While the majority of mosquito bites result in welts that heal in a few days, mosquitoes are known carriers of many deadly diseases and illnesses, including but not limited to:

Mosquitoes are often considered one of the deadliest animals on earth. Mosquito-borne diseases kill more than 725,000 people a year the World Health Organization estimates, with malaria accounting for the vast majority of deaths (600,000). 

While malaria and other mosquito-borne diseases hit Sub-Saharan Africa the hardest, mosquitoes pose a risk to every continent and nation. Most types of mosquitoes in the US are nuisance mosquitoes — mosquitoes that do not spread germs that make people sick — but there have been outbreaks of West Nile, dengue, chikungunya and Zika in a few states and territories. 

There are several steps you can take to control mosquito populations and minimize risk. Make sure to properly cover and store water containers around your home and drain any standing water to prevent mosquitoes from laying eggs. For treatments, you can use an outdoor adulticide to kill adult mosquitoes or larvicides to treat bodies of standing water that will not be used for drinking and cannot be drained. 

Infected bites will often look extremely red, swollen and warm or have a red streak that spreads outward from the bite. See a health care provider if you have signs of infection or if symptoms worsen. 

For more, read about the five smart ways to repel mosquitoes this summer, the mosquito forecast tool launched by Google and Off, and how you can make your own DIY traps for mosquitoes, hornets and other flying pests.

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