• A mosquito identifies her warm-blooded quarry by the carbon dioxide they exhale. (Getty Images)
With the warm and wet Australian summer comes a much darker menace: the mosquito, bane of barbecues and saboteur of backyard soirees. Find out how to avoid being bitten with expert advice from Sydney entomologist Dr Cameron Webb.
By
Nicola Heath

20 Jan 2016 - 11:02 AM  UPDATED 20 Jan 2016 - 11:02 AM

We’re in the midst of a mozzie invasion. A warm and wet start to 2016 has seen a spike in mosquito numbers in Sydney and the east coast.

“It doesn’t matter if mosquitoes are in our swamps or suburbs, as soon as we get water into these habitats mosquitoes can start to reproduce and emerge in bigger numbers.” says medical entomologist Dr Cameron Webb, who goes by the Twitter handle @mozziebites. “During summer it can take just a week for mosquitoes to hatch out from eggs and emerge as adults.”

It’s the female mozzie that is responsible for those irritating bites. “The male and female mosquitoes live quite happily on plant juices and sugars, but for the female mosquito to produce eggs, she has to have that additional protein hit from blood,” explains Dr Webb. “She’s only biting you to lay a couple of hundred eggs somewhere.”

If you feel unduly targeted by mosquitoes, it’s likely it’s due to the way you smell. 

If you feel unduly targeted by mosquitoes, it’s likely it’s due to the way you smell. A mosquito identifies her warm-blooded quarry by the carbon dioxide they exhale. It’s then the smell of the skin that determines whether she goes in for the bite. “It comes down to three or four hundred different chemical compounds - the stuff we sweat out or the bacteria that’s growing on our skin,” says Dr Webb. These compounds create an aromatic cocktail that either draws a mosquito in, or sends her on her way. 

Mosquito bites aren’t just uncomfortable, they pose a serious health risk through the transmission of diseases like dengue fever in Far North Queensland and Ross River virus, a non-fatal but often debilitating illness that rose in infections from 5000 to 9000 in 2015 thanks to a very mild winter followed by one of the warmest springs on record and heavy summer rainfall. They’re also responsible for the spread of Zika virus, which is found in parts of Africa, South-East Asia, Polynesia, Micronesia, Indonesia and South and Central America.

Here are Dr Webb’s tips to keep mozzies at bay this summer.

GET THE RIGHT REPELLENT

Topical repellents containing one of two chemical compounds provide the longest lasting protection against mosquito bites. Those two active ingredients are DEET (diethyltoluamide or N,N-diethyl-meta-toluamide) and picaridin. Developed by the US Army in 1944, DEET is “the gold standard mosquito repellent internationally”, while picaridin is a synthetic derivative of table pepper developed by Bayer in the 1980s. “Any of the repellents that contain those two formulations essentially switch off the appetite of the mosquitoes, so when she’s flying around she doesn’t want to come and bite,” says Dr Webb.

Products that contain plant-based extracts like tea tree oil and lavender are also effective up to a point.

Products that contain plant-based extracts like tea tree oil and lavender are also effective up to a point, says Dr Webb. “They do provide some protection against mosquitoes but you normally have to reapply them far more frequently than DEET or picaridin.”

ANKLE BITERS

While DEET is safe to use on babies three months and older, another option to keep kids and babies mozzie-free is to cover them up. “Put netting over the pram or play area to create a physical barrier between the babies and the mosquitoes,” suggests Dr Webb.

OUTDOORS

Avoid mosquito havens like wetlands at dawn and dusk when the insects are most active, and make sure you’re not creating a home for them in your backyard. “Mosquitoes will breed in pot plant saucers and birdbaths, drains and gutters,” says Dr Webb, “so making sure they’re cleaned out at least once a week will stop them producing mosquitoes.”

INDOORS

Well-maintained flyscreens will help keep your house bug-free, while plug-in units or a bedroom fan, which disrupts the flight of the mosquito, can help prevent that dreaded mozzie buzzing in your ear as you lie in bed. 

Love the story? Follow the author here on Twitter at @nicoheath. 

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