Unseasonably warm weather, rain, and high tides have created the perfect storm for dormant mosquito eggs to hatch all at once and swarm.
University of Sydney mosquito expert Cameron Webb said the problem was affecting Northern Rivers and south-east Queensland.
“It brings water into all of those coastal wetlands that have been dry for most of the summer,” Dr Webb said.
“Mosquito eggs have been waiting to hatch all summer and are very quick to take advantage of those favourable conditions.”
There are around 300 species of mosquitoes in Australia, with half a dozen types on the east coast that cause most problems for humans.
Dr Webb said he had no doubt it was Aedes vigilax, the salt marsh mosquito, causing the issues at the moment.
“They’re aggressive biters and they’re also found in really big numbers, unfortunately,” he said.
“It’s really those coastal mosquitoes that are causing such a problem.”
Millions of mozzies
The unseasonal spread of mosquitoes is happening up and down the east coast.
QIMR Berghofer Mosquito Control Lab Associate Professor Greg Devine said it happened wherever the environment was conducive to mosquitoes.
He said when blooms of mosquitoes start to attack people in their homes they take notice.
“The same problems will be common up and down the coast in both populated and unpopulated areas.”
Associate Professor Devine said tens of millions of mosquitoes hatched when conditions were right.
“They make their way up and down the coast and considerable distances inland,” he said.
He said council control measures, such as sprays, could wash away before the end of the extended season, causing the spike.
While mosquito numbers were up, that did not necessarily mean the risk of mosquito-borne diseases, such as Ross River virus, were up as well.
Dr Webb said that depended on whether the mosquitoes had bitten native wildlife that already carried the virus.
“Mosquitoes don’t hatch out of the wetlands already infected with the virus,” he said.
“They have to bite wildlife first, typically kangaroos and wallabies.”
The mosquito menace may continue for weeks.
“It’s really dependent on those fluctuations in temperature but also how much rain is about,” Dr Webb said.
“As long as the warm weather persists it wouldn’t be unusual to see mosquitoes persist.”
Dr Webb said mosquito numbers may continue to be high until the beginning of May.
Source ABC News