It’s no secret we love flies. We think they’re marvellous. There are more than 25,000 native species of flies in Australia and they’re all part of our biodiversity. Among other things, they are important pollinators, nutrient recyclers, insect predators and the food for many birds, lizards and mammals. Some species might seem hard to love, but are they really out to get us?
Dr David Yeates, Director of our Australian National Insect Collection, said they’re just being good parents.
“Female bush flies feed on sweat and female mosquitoes, midges and horse flies feed on blood to get the nutrients they need for their eggs,” David said.
So, what can you do to keep flies away from your sweat and blood?
There’s no such thing as a spray that only kills flies and mosquitoes. These chemicals also kill bees and butterflies and friendly garden spiders that prey on flies and mozzies. If you’re worried about insect declines and keen to support biodiversity in your backyard, sprays are not your best option.
The alternative is to spray yourself (or use a lotion or roll-on).
In the 1940s, CSIRO scientist Doug Waterhouse tested many different chemicals on his own skin, sitting in a cage surrounded by a thousand mosquitoes, watching to see which chemicals repelled them. The result was Aerogard.
“A spray such as Aerogard is still your best bet when you’re out among flies or mosquitoes,” David said.
Smoke them out
If you’re sitting outside enjoying a barbecue, you could try burning a mosquito coil. They contain insect repelling chemicals such as citronella, pyrethroid insecticides or pyrethrum, made from chrysanthemum flower heads (plants like to keep insects at bay too). They either kill (insecticides) or deter (plant chemicals) mosquitoes.
“This is fine, if you don’t mind breathing in the smoke, but if there are lots of mosquitoes around, some may get past the coil smoke and still bite. When outside, I always use both repellent and coils to avoid mosquitoes,” David said.
“Understanding flies’ behaviour can help too. Mosquitoes are more active at dawn and dusk. House flies enjoy shade and are attracted to food.”
Screen them out
A simple solution for keeping flies and mosquitoes at bay is to put some mesh between you and them. Think fly screens on your windows and doors, a mosquito net hanging over your bed or a piece of net fabric in front of your face.
Long sleeves, pants and socks will keep them off your skin, too.
Watch out for water
Mosquito life cycles are as short as nine days. They can breed in tiny pools of fresh water in pet water bowls, wheelbarrows, plant pot bases, ponds, old tins and more. They are the little wrigglers you see hanging just below the surface of the water.
“It’s best to empty water from containers in your backyard at least once per week and install sieves on water tanks,” David said.
“If you have a garden pond, think about encouraging mosquito predators, like fish, frogs and bats.
“Tell your neighbours too, because mosquitoes will fly quite a long way to find you, homing in on the carbon dioxide you exhale.”
Scoop the poop
Dog poo is another thing to remove from your back yard. It’s a favourite food of many flies, and females may lay their eggs in it if it’s big enough and wet enough.
Bush flies like to breed in the poo of farm animals. Dung beetles can do the work of cleaning up this poo, but not our native dung beetle species.
“Native dung beetles evolved to eat the dry, hard poo of native marsupials, not cow pats. In the late 1960s, we began introducing dung beetle species from Europe and Africa to clean up after animals like cows and sheep,” David said.
“If you’re a landholder and have a poo problem, consider purchasing dung beetles from a commercial supplier.”