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Mosquitoes after a wet Sydney week: clear the standing water before the warm-up
Sydney has had a cool, showery week - more rain today and tomorrow, then the weekend turns warmer. That warm-up is exactly when wet-week water starts producing mosquitoes. The useful move is to clear the standing water now, before the larvae that are sitting in it become adults.
Mosquitoes need two things: still water and warm weather. This week has delivered the water - four or five days of showers have filled pot saucers, buckets, gutters and wheelbarrows across Sydney - and the weekend forecast is delivering the warmth, with temperatures climbing from 20C today to 23-24C by Sunday and Monday. Most mosquitoes breed in water that has sat still for around a week, so the larvae sitting in your yard right now are on track to emerge just as the weather warms. Clearing the water is the single highest-value pest-control job of the weekend.
Why rain followed by warmth means mosquitoes
Mosquitoes lay eggs on or beside standing water, and the larvae develop in the water itself. The exact time depends on the species and the temperature, but a rough guide is that eggs laid at the start of a wet week can produce adults within about a week in mild spring weather - faster as it warms. That is why the pattern is so predictable: the rain fills the containers, the larvae develop while the week is still cool, and the warm-up is the finishing step. Sydney does not need a swamp to breed mosquitoes; a saucer under a pot plant or a pool of water in a wheelbarrow is enough.
You do not need to treat every puddle. The goal is to remove water that will sit still for days. Water that drains away or dries out within a day or two is rarely a mosquito source.
Where the water collects
After a wet week, walk the yard once and look for anything that holds water. The usual spots are:
Pot plant saucers and the bases of large pots - a classic breeding spot because they hold water all week.
Buckets, wheelbarrows, watering cans, bins and toys left out in the rain.
Gutters and downpipe outlets blocked with leaves - shallow, still water that stays warm in the sun.
Bird baths, pet water bowls and animal troughs.
Low spots in the garden, driveway or paving where water pools and does not drain.
The wet-week clearing checklist
The clearing is simple and does not need chemicals. A ten-minute sweep this weekend breaks the cycle before it starts:
Tip out pot saucers, buckets and any container holding water; tip onto soil or lawn rather than leaving a new pool.
Clear leaves from gutters, downpipe outlets and drain grates so water keeps moving.
Change bird bath and pet water at least weekly, and scrub the sides lightly to remove eggs.
Store buckets, toys and containers upside down or under cover when not in use.
Level low spots in paving or garden beds, or fill them with sand or gravel so water cannot pool.
Water tanks and larger sources
Rainwater tanks should be screened so mosquitoes cannot enter, and the overflow and inlet should be checked after heavy rain. Larger sources - ponding that does not drain, a green pool, a blocked drain holding water for days - are worth addressing at the source rather than treating the surface. If you choose to use a product in water that cannot be removed, use a label product for its intended use and follow the current label exactly. Do not tip oils, detergents or improvised mixtures into garden water; they are not a safe substitute for clearing the source.
The APVMA explains correct chemical use. For water sources, removal and screening come first; any product use should follow the label and be limited to what the label allows.
When to call for help
Most mosquito problems around a home are fixed with water removal. Call a licensed technician if you are being bitten regularly even after clearing obvious water, if mosquitoes are coming into the house at night and resting indoors, if you suspect a neighbour's yard, a green pool or a drainage issue you cannot fix yourself, or if you want outdoor entertaining areas treated before the warm months peak. A technician can locate the real breeding source, treat what cannot be removed and advise on screening and long-term prevention.
MOSQUITOES AROUND THIS WEEK?
Text your suburb and where you are being bitten.
Tell us whether it is around the house, in the garden or near a pool or water tank, so we can confirm what is needed.