SeasonalModerate risk
Why Do Mosquitoes Increase After Rain?
Quick answer
Rain creates pools of still water where mosquitoes lay eggs, and some species’ eggs, laid on dry ground or container walls, hatch once flooded. In warm weather the larvae can develop into biting adults in about a week, so mosquito numbers often surge one to two weeks after heavy rain. High tides can have the same effect in coastal saltmarsh areas.
Why this happens
Container-breeding mosquitoes lay eggs just above the waterline in pots, tyres and gutters. When rain raises the water level, those eggs hatch.
Floodwater and saltmarsh mosquitoes lay eggs on ground that floods periodically. Large rain events or king tides can trigger mass hatching and large numbers of mosquitoes over wide areas.
Warm temperatures speed up development, so summer rain produces faster mosquito increases than winter rain.
What you can do
- After rain, walk around your property and tip out any container holding water.
- Check gutters, pot-plant saucers, tarps, toys and tyres.
- Screen rainwater tanks and maintain screens.
- Use repellent, long sleeves and screens during peak times.
When professional help may be needed
Mosquitoes can fly in from breeding areas beyond your property, which councils often manage. Residential barrier treatments can reduce resting mosquitoes for a period but will not stop new arrivals.
Related pest
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Understanding Pest Activity After Rain
Why storms and wet weather bring cockroaches, ants, mosquitoes and spiders into homes, what to expect in the days and weeks afterwards, and what to do before and after rain and floods.
GuideHow to Pest-Proof Your Home
A practical, room-by-room approach to reducing pests without relying on chemicals: remove what attracts them, close the ways in, and make your property less comfortable for them.
GuideCommon Brisbane Household Pests
A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.
Local information
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Sources & further reading
- Queensland Health — mosquito-borne disease and environmental health — Queensland Health
- NSW Health — environmental health and pest-borne disease — NSW Health
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