Itching for truth: why are some people mosquito magnets?
UQ Mythbusters
They buzz, they bite, they bother. Mosquitoes are just an itchy part of life. Especially in Australia, which is home to more than 300 kinds of mozzies, making it the third most mosquito-rich country in the world.
Following a warm and wet summer, parts of Australia have seen mosquito numbers spike. But have you ever wondered why some people are mosquito magnets, while others go unbitten? And is it true that certain food and drinks make you a more likely target for mozzie bites?
To help clear the air (heh), Contact sat down with mosquito expert Associate Professor Nigel Beebe from UQ’s School of the Environment to swat some common mosquito misconceptions.
Do mosquitoes prefer certain blood types over others?
No, there’s no evidence to say that certain blood types – that is, certain antigens that sit on the outside of the red blood cell – influence a mosquito’s attraction to you.
So, how does a mosquito choose who to bite? Do they tend to target certain people?
Different types of mosquitos find their hosts in similar but different ways. Due to evolution, most mosquitoes are attracted to carbon dioxide (CO2), which is in the air that we exhale. If a mosquito finds what we call a ‘CO2 plume’ and flies up the plume gradient, they’ll inevitably find a host.
Once they’ve found you, the mosquito will then detect how much heat you give off, otherwise called your heat signature, as they can prefer warmer hosts.
Then they will land on your skin and touch you a few times to determine your skin’s oil breakdown products created by your microbiome. From there, they will find the best place to bite in relation to your skin capillaries, before biting.
Image: Chris/Adobe Stock
Image: Chris/Adobe Stock
Is it true that consuming certain foods or drinks makes us more attractive to mozzies?
When it comes to what you eat or drink, there's very little evidence to show that it changes your attractivity to mosquitoes.
There have been some experiments in Africa with a particular type of mosquito, where some people had beer, and some people didn't have beer. The tests found that the people who’d had beer would be slightly more attractive to mosquitoes.
I think when you drink alcohol, you might generate a stronger heat signature (this is caused by the dilation of skin blood vessels), or a stronger olfactory (sense of smell) signature in your CO2 plume (not in the CO2 plume but from the skin), which makes you an easier target for mosquito bites.
You can’t get mosquitoes if you don’t have a pond or pool in your backyard – true or false?
That’s not true. When we do fieldwork and we knock on doors to do mosquito surveys, it's the people who are adamant about not having mosquitoes in their backyard who are often the ones that do. It’s very common. People have very ‘busy’ backyards, and mosquitoes can breed in even a small amount of standing water. For example, bird baths, old tyres, pet water bowls, and even water sitting in gutters.
Image: New Africa/Adobe Stock
Image: New Africa/Adobe Stock
How effective are natural mosquito repellent products, like citronella oil?
Natural oils don’t work very well as repellents because they’re just not formulated to have the right level of repellency. The repellent formulation is to make the repellent last longer on the host – natural oils have poor repellency and don’t last. This means they might only work for between 15 to 30 minutes.
But solutions like DEET and Picaridin have been around for a long time, and we know that mosquitoes dislike them.
Research studies have suggested that, rather than being repelled by solutions like DEET and Carradine, mosquitoes smell it, process it with their brains, and decide that they don’t like it. So, the mosquitoes make a conscious decision that they don’t like it.
But overall, the natural oils and mosquito repellent bracelets we see on the market tend not to work very well. I’d suggest you stick to a commercially available repellent, which through trials, we know does work.
Do mosquitoes prefer certain blood types over others?
No, there’s no evidence to say that certain blood types – that is, certain antigens that sit on the outside of the red blood cell – influence a mosquito’s attraction to you.
So, how does a mosquito choose who to bite? Do they tend to target certain people?
Different types of mosquitos find their hosts in similar but different ways. Due to evolution, most mosquitoes are attracted to carbon dioxide (CO2), which is in the air that we exhale. If a mosquito finds what we call a ‘CO2 plume’ and flies up the plume gradient, they’ll inevitably find a host.
Once they’ve found you, the mosquito will then detect how much heat you give off, otherwise called your heat signature, as they can prefer warmer hosts.
Then they will land on your skin and touch you a few times to determine your skin’s oil breakdown products created by your microbiome. From there, they will find the best place to bite in relation to your skin capillaries, before biting.
Image: Chris/Adobe Stock
Image: Chris/Adobe Stock
Is it true that consuming certain foods or drinks makes us more attractive to mozzies?
When it comes to what you eat or drink, there's very little evidence to show that it changes your attractivity to mosquitoes.
There have been some experiments in Africa with a particular type of mosquito, where some people had beer, and some people didn't have beer. The tests found that the people who’d had beer would be slightly more attractive to mosquitoes.
I think when you drink alcohol, you might generate a stronger heat signature (this is caused by the dilation of skin blood vessels), or a stronger olfactory (sense of smell) signature in your CO2 plume (not in the CO2 plume but from the skin), which makes you an easier target for mosquito bites.
You can’t get mosquitoes if you don’t have a pond or pool in your backyard – true or false?
That’s not true. When we do fieldwork and we knock on doors to do mosquito surveys, it's the people who are adamant about not having mosquitoes in their backyard who are often the ones that do. It’s very common. People have very ‘busy’ backyards, and mosquitoes can breed in even a small amount of standing water. For example, bird baths, old tyres, pet water bowls, and even water sitting in gutters.
Image: New Africa/Adobe Stock
Image: New Africa/Adobe Stock
How effective are natural mosquito repellent products, like citronella oil?
Natural oils don’t work very well as repellents because they’re just not formulated to have the right level of repellency. The repellent formulation is to make the repellent last longer on the host – natural oils have poor repellency and don’t last. This means they might only work for between 15 to 30 minutes.
But solutions like DEET and Picaridin have been around for a long time, and we know that mosquitoes dislike them.
Research studies have suggested that, rather than being repelled by solutions like DEET and Carradine, mosquitoes smell it, process it with their brains, and decide that they don’t like it. So, the mosquitoes make a conscious decision that they don’t like it.
But overall, the natural oils and mosquito repellent bracelets we see on the market tend not to work very well. I’d suggest you stick to a commercially available repellent, which through trials, we know does work.
What’s the best way to protect ourselves from mosquito bites this summer?
Because it’s been a protracted wet summer, there are a lot of ‘flood mosquitoes’ around, which develop in puddles. They’re an aggressive biting mosquito, and they are prolific at the moment because of the extended rainfall.
To avoid being bitten, wear loose-fitting clothing in lighter colours. Avoid fabrics like Lycra, as mosquitoes will still bite you through active wear. Mosquitoes tend to be most active at dawn and dusk, so you might like to wear a repellent at those times of day.
And if you do notice mosquitoes in your backyard, particularly at dusk, make sure to check your yard for any standing water sources, like birdbaths, buckets, and pet water bowls. If you do have a pond and you’re struggling with mosquitoes, consider adding a few fish into the pond – they'll eat mosquito eggs and larvae, which will keep your backyard mosquito numbers in-check.
Finally, if you have been bitten and are struggling with itching, try applying an anti-itch cream or ointment, or taking an antihistamine to help settle the welts.
School of the Environment
The School of the Environment brings together expertise in environmental science, ecology, conservation, marine biology, earth sciences, geography, zoology, wildlife, biodiversity, genetics, evolution and human society.
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