The plague hasn't led to an increase in cases of the Ross River virus, but this was no reason to be complacent, mosquito researcher Cameron Webb warns.

It only takes one bite for a mosquito to pass on the virus. The more bites received, the greater the risk.

"At the moment, the good news is we're not seeing an increase in Ross River virus activity around the coast. Primarily the concern is nuisance biting," said Dr Webb, of NSW Health Pathology.

"It's important to remember that they don't hatch out of the wetlands already carrying the virus. They've got to bite an animal first before they can pass it on."

Nevertheless, Dr Webb said there were plenty of reasons to avoid mosquito bites, "even if we aren't in the middle of an outbreak of disease" [For example, bites can become infected].

A combination of rain and big tides following a hot and dry summer were key factors in the mosquito invasion, which has affected most of the east coast.

"About two weeks ago, we had huge amounts of rain up and down the coast. That fills up not only our wetlands, but all the bushland pools and paddocks and backyard areas," he said.

"A lot of those areas have mozzie eggs waiting to hatch."

It takes about a week to 10 days for the mosquitoes to "complete development and start buzzing about".

Some people are fearful of using mosquito repellents, but Dr Webb said they were "actually quite safe to use if you follow the instructions".

"More people probably have adverse reactions using a repellent that they've mixed up themselves with a recipe on the internet.

"I know it's the Australian way to do it ourselves, but a concoction of essential oils and other chemicals is probably far more likely to cause a skin reaction."

Dr Webb urged people to choose a repellent from "your local supermarket or pharmacy".

"Irrespective of what ingredients they have in them, they've been approved for use and sale in Australia. They've been through checks for safety and efficacy."

Repellent must be applied in a "nice even coat over all exposed areas of skin".

"I see people spraying a dab here or there. They spray it on the back of their shirt or on their hat. That's not going to provide protection.

"It has to disrupt the smell of skin that turns the mosquito on to come and bite. If you don't have the coverage, the mosquitoes will find that chink in your armour and come in and bite."

Some people can't stand the smell of repellent, but Dr Webb said the odourless varieties were "very effective" and worth trying for those who find "the other products a bit unpleasant or are problematic in some other way".

Heavier duty products were for those going on long bushwalks, fishing or spending time in areas where there are a lot of mosquitoes.