Why mozzies bite (and what you can do about it)

Summer should be fun, not an itch fest. Here’s how to stop mosquito bites so you can savour the outdoors without fear of those little bloodsuckers.

Ah, summer – the season of sun-kissed afternoons, beach escapades and balmy evening barbecues.

But there’s one tiny menace that threatens to ruin all the fun: mosquitoes. 

Here is how to stop those pesky party crashers from turning you into their personal buffet.

Why do mosquitoes bite?

Dr Prasad Paradkar, a principal research scientist with the CSIRO, Australia’s national science agency, says there are around 3000 species of mosquitoes globally, and they all target different prey.

“Only around five to 10 species specialise in feeding on humans, and only the females bite because they need the protein in our blood to produce their eggs,” Dr Paradkar says.

Mosquito expert Associate Professor Cameron Webb, of the University of Sydney and NSW Health Pathology, says mosquitoes are attracted to us by the carbon dioxide we exhale, the warmth of our bodies, and the smell of our skin. 

Are some people mozzie magnets?

If you think mosquitoes have a particular penchant for your blood, you could be right.

Dr Paradkar says some studies have shown mosquitoes are attracted to people with type O blood.

What you wear can also be a factor because mozzies love the colour black.

Another study found these insects are also drawn to pregnant women, probably due to their higher body temperature and higher carbon dioxide levels.

“What we do know is that the way we smell attracts mosquitoes,” Dr Paradkar says.

“A compound called lactic acid that humans release in their sweat is an attractant – some people produce more of it, and it could be diet-related.”

Can you stop mosquitoes from biting?

Avoiding a mozzie massacre is all about prevention.

Assoc Prof Webb says a physical barrier is your best personal protection.

“Long-sleeved shirts, long pants, and covered shoes are recommended if outdoors, especially during periods when mosquitoes are most active such as late afternoon, dusk and dawn,” he says.

When it comes to insect repellent, he recommends formulations that contain DEET, picaridin and oil of lemon eucalyptus.

“These provide the safest and longest-lasting protection,” Assoc Prof Webb says.

Simple measures around the home, such as ensuring flyscreens are secure and eliminating stagnant water to reduce breeding sites, can also lower your chances of becoming their next meal.

“Mosquito eggs can lay dormant for a year waiting for rain, then hatch when exposed to water,” Dr Paradkar says.

Why do mozzie bites itch so much?

When a mosquito bites, it injects saliva that contains proteins to prevent blood clotting, Assoc Prof Webb says.

This triggers an immune response, releasing histamines that cause the characteristic red bump and intense itchiness.

The intensity and duration of the bite can vary from person to person.

“Our bodies react to the saliva and some of us are much more sensitive to mozzie spit than others,” Assoc Prof Webb says.

“Importantly, it is in the mozzie spit that viruses can be spread by mosquitoes too, so it’s best to stop the mosquito bites in the first place.”

If you do get bitten, keep the bite clean and dry, and use an antiseptic cream to avoid a secondary bacterial infection.

How to ditch the itch

It may feel good, but scratching will only provide temporary relief, and it may break the skin and lead to infection.

“Itching is an allergic reaction so in some cases, topical, over-the-counter creams containing anti-allergy ingredients can help,” Dr Paradkar says.

Other ways to ease the itch include:

• Cooling it down: Apply a cold, wet cloth or ice pack to the affected area to reduce inflammation. 
• Antihistamines: Oral antihistamines can help alleviate early symptoms and itching.
• Natural remedies: Honey, aloe vera and apple cider vinegar have anti-inflammatory and antibacterial properties that may help reduce swelling and infection.

More on mosquitoes, bites, stings and itchy rashes:

• Is Buruli ulcer the reason your skin won’t heal?
• Summer stings: How to treat insect bites
• Itchy skin driving you nuts? Here are a few causes
• Buzz off: What to do if you get stung by a bee

Written by Dimity Barber.