Webb said most of Sydney was experiencing a normal number of mosquitoes. However, the insects were more noticeable in October and November because people spent more time outdoors, there was generally water in the environment for the larvae, and warmer weather increased mosquito activity.

September and October had typical temperatures and rainfall across Greater Sydney, weather bureau data suggests, though it is tipped to be a warm, wet summer. Humidity increases with global warming, and international data suggests 2024 is shaping up to be the hottest year on record.

Brown house mosquitoes were only considered a minor threat to public health in Australia, Webb said, and typically bred in stormwater and wastewater. Other species bred in saltwater or stagnant water in bushland.

The main mosquito-borne disease that affects Sydney, mostly at the fringes, is Ross River virus. Webb said there were about 5000 cases across Australia.

Liverpool Council has been spraying public facilities such as toilet blocks and septic tanks. Backyards including swimming pools and pots can be secondary sources of mosquitoes.

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