Australia is in for a long, hot summer. The recent bushfires have been devastating for communities and wildlife. Drought is also impacting many regions.
Understandably, people want to leave water out for thirsty birds and animals.
Health authorities generally warn against collecting and storing water in backyards as one measure to protect against mosquito bites and mosquito-borne diseases caused by, for example, dengue and Ross River viruses.
But it’s possible to leave water out for wildlife – and save water for your garden – without supplying a breeding ground for mosquitoes, if you take a few precautions.
For some mozzies, any water will do
Mosquitoes often look for wetlands and ponds to lay their eggs. But sometimes, anything that holds water – a bucket, bird bath, drain or rainwater tank – will do.
When the immature stages of mosquitoes hatch out of those eggs, they wriggle about in the water for a week or so before emerging to fly off in search of blood.
While there are many mosquitoes found in wetlands and bushland areas, Aedes notoscriptus and Culex quinquefasciatus are the mosquitoes most commonly found in our backyards and have been shown to transmit pathogens that cause mosquito-borne disease.Cameron Webb (NSW Health Pathology)
In central and north Queensland, mosquitoes such as Aedes aegypti can bring more serious health threats, such as dengue, to some towns.
Mosquitoes can also impact our quality of life through bites as well as the nuisance of simply buzzing about our bedrooms and backyards.
So how can you stop mozzies making a home in your backyard?
Empty water containers once a week
Mosquitoes need access to standing water for about a week or so. Reduce the number of water-filled containers available or how long that water is available to mosquitoes.
Emptying a water-filled container once a week will stop the immature mosquitoes from completing their development and emerging as adults.
If you’re leaving water out for pets or wildlife, use smaller volume containers that will allow for easy emptying once a week. You can tip any remaining water into the garden, as mosquito larvae won’t survive if they’re “stranded” on soil.
For larger or heavier items, such as bird baths, flushing them out once a week with the hose will knock out most of the wrigglers and stop the mosquitoes completing their life cycle.
Make sure garden water doesn’t slosh about
Be careful with self-watering planter boxes. These often have a reservoir of water in their base and, while it may seem like a water-wise idea, these can turn into tiny mozzie hotels!
A simple trick to keep water available to plants, but not mosquitoes, is to fill your potted plant saucers with sand. The sand traps and stores some moisture but there is no water sloshing about for mosquitoes.
If you’re collecting water from showers, baths, or washing machines (commonly known as grey water), use it immediately on the garden, don’t store it outside in buckets or other containers.
Gutters, ponds, tanks and pools
Make sure your roof gutters and drains are free of leaves and other debris that will trap water and provide opportunities for mosquitoes.
Ensure rainwater tanks (and other large water-storage containers) are appropriately screened to prevent access by mosquitoes.Cameron Webb (NSW Health Pathology)
A well maintained swimming pool won’t be a source of mosquitoes. But if it’s turning “green”, through neglect and not intent, it may become a problem. Mosquitoes don’t like the chlorine or salt treatments typically used for swimming pools but when there is a build up of leaves and other detritus, as well as algae, the mosquitoes will move in.
For backyard ponds, introducing native fish can help keep mosquito numbers down.
But if you want your pond to be a home for frogs, avoid fish as they may eat the tadpoles. Instead, try to encourage other wildlife that may help keep mosquito numbers down by creating habitats for spiders and other predatory insects, reptiles, frogs, birds, and bats.
Avoiding excessive use of insecticides around the backyard will help encourage and protect that wildlife too.
Mozzies can still come
There isn’t much that can be done about those mosquitoes flying in from over the back fences from local bushland or wetland areas.
Mosquitoes are generally most active at dusk and dawn so keep that in mind when planning time outdoors. But when mosquito populations are peaking, they’ll be active almost all day long.
Applying an insect repellent can be a safe and effective way to stop those bites.
Covering up with long pants, long-sleeved shirt and shoes will provide a physical barrier to mosquitoes. If you’re spending a lot of time outdoors, perhaps even consider treating your clothing with insecticide to add that extra little bit of protection.
Make sure insect screens are installed, and in good condition, on windows and doors. Mosquitoes outdoors can be bad; you don’t want them inside as well.
Authors: Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney