Why one area of Sydney has been swarming with mosquitoes

For weeks, residents in south-west Sydney have complained about a plague of mosquitoes. Relief could be at hand within the next fortnight, as authorities deal with the main infestation in a wastewater facility in Liverpool. Mosquito expert Dr Cameron Webb said the mosquito numbers in south-west Sydney were two to three times higher than usual for the time of year, and the culprit species was the “brown house mosquito”.

Residents in Chipping Norton and nearby areas have borne the brunt of the nuisance, but the mosquitoes have also been spotted swarming inside train carriages travelling from south-western Sydney to the city. Sydney Water has been working to kill larvae and remove frogbit weed from the oxidation pools at the Liverpool Water Resource Recovery Facility, which provided a perfect breeding ground for the pest. “Operational staff and licensed contractors have deployed boats, helicopters, excavators, sucker trucks and other specialised machinery to clear the aquatic material contributing to mosquito breeding,” a Sydney Water spokesperson said.



“To date about half the vegetation has been removed. Field assessments show a 98 per cent reduction in larvae across 10 of 12 sites since Friday.” Before-and-after photos of the weed being removed from Liverpool Water Resource Recovery Facility.

Credit: Dr Cameron Webb The spokesperson said the impact of mosquitoes should be reduced by 90 per cent within a two-kilometre radius over the next two weeks. Webb, who works with NSW Health Pathology and the University of Sydney and has been involved in the response to the outbreak, said he was pleased with how Sydney Water had responded. He expected the control measures to work, but would monitor the situation to make sure there was not a resurgence over summer.

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