UWA professor explains why flies are so annoying this time of year

Margaret River Discovery Co tour guide Sean Blocksidge can attest to the annoyance of flies this summer. Photo by Margaret River Discovery Co.
Margaret River Discovery Co tour guide Sean Blocksidge can attest to the annoyance of flies this summer. Photo by Margaret River Discovery Co.

Have you ever wondered why the flies are so annoying this time of year?

From the second week of December, until the third week of January is peak bushfly season for the South West, particularly Busselton.

University of Western Australia professor in biological science Theo Evans told the Mail that flies were not measured on numbers, but on their nuisance level.

"We can't measure how many flies there are in an area because they actually travel large distances," he said.

"They move with the wind and can go as far as 300 kilometres."

Professor Evans said flies were considered a nuisance because they treat humans as "walking drinking fountains".

"They are trying to find moisture, it is why they go straight for our eyes, nose and mouths," he said.

It is the strong easterly winds that bring the flies to coast, where in summer everyone wants to be.

"They are not smart creatures but they are smart enough to know that if you fly over the ocean they will probably die," Professor Evans said.

The unusually wet November also played its part in what feels like an increase in fly population.

"The wet weather in November kept the flies away and now that it is hot and dry it feels like there is more of them," he said.

So how do we stop them being a nuisance?

Professor Evans said the most effective way is through the increase of dungbeetles.

He said there are two types of dungbeetles around the South West, one that is active in the winter and the other is active over summer.

"The summer dungbeetles haven't quite got up and running yet and so there is a gap between the two," Professor Evans said.

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As a result, it allows the flies to "have a free for all" until the summer dungbeetles take an effect.

The dungbeetles reduce the amount the flies can breed by eating where they lay their eggs - cow dung.

If you are frustrated with the amount of flies around your home, Professor Evans recommended not using fly spray outside.

"It is fine to use inside the home, but outside if you have cobwebs and spiders, they kill more flies than we would," he said.

UWA are currently collaborating with other universities across Australia to bring in a spring active dungbeetle from Morocco.

However, Professor Evans said once this occurs we won't see its success for a couple of years but he is hopeful that it would breach the gap between winter and summer.

Professor Evans was driving back from his holiday in Margaret River while talking to the Mail, so we asked him "do you think there are more flies this year?"

He said yes, but not by much.

"I'm 53 years old and when I was kid, the family would come down this way for holidays," he said.

"We have this photo of us kids eating a sausage and we are covered in flies.

"Everyone would eat inside because it was impossible to eat outside."

This story Humans "walking drinking fountains" for flies first appeared on Busselton-Dunsborough Mail.