Vinegar Fly. Supplied by Ary HoffmannFederation Fellow/ Research DirectorCentre of Environmental Stress and Adaptation ResearchDepartments of Genetics and ZoologyThe University of MelbourneParkvilleVic 3010AustraliaPh mobile 0408342834landline (03) 83444621FAX (03) 83447089email [email protected] Vinegar Flies. Photo: University of Melbourne

Rain and rotting fruit have contributed to Brisbane’s plague of what appear to be tiny black fruit flies.

The city has soaked up more than 600 millilitres of rain since January 1, prompting what scientists have called an “extraordinary event” of what are in fact “vinegar flies” across south-eastern Queensland.

Mike Muller, Brisbane City Council’s senior entomologist, has explained the invasion to reporters: “Vinegar flies are drawn to rotting fruit, effectively drawn to the complex sugars and the yeast.

“Those little ‘fruit flies’ as you call them, should effectively be called ‘vinegar flies’. They are attracted to the yeast and to the odours that come from fermentation,” he said.

The flies are different to the traditional Queensland fruit fly, which infects or “blows” the fruit.

“They don’t actually ‘blow’ the fruit, like a true Queensland fruit fly,” Mr Muller said.

“That is the reason why you often find them in your glass of wine, because they are homing in on the alcohol. They are homing in on the fermentation products.”

Mike Muller said he has never seen a period when the vinegar flies were so common. He said the numbers had just started to decline.

“I have never seen anything like that before, but it is probably associated with the wet weather conditions that we have had,” he said.

“All the leaf-litter in the gardens that is constantly wet; there is yeast growing there and that yeast is perfect breeding conditions for them in the gardens and forests in Brisbane,” he said.

“And then they will home in on the smells that are coming from over-ripe fruit and from alcohol.”Tips for getting rid of fruit flies or vinegar flies.

Meanwhile, Brisbane City Council recently began its intensive mosquito treatment program, targeting 3000 mosquito breeding sites around south-eastern Queensland.

Hot spots for the larvae of the hardy “saltwater” mosquito are the suburbs of Virginia, Boondall, Hemmant and Wynnum, within two to three kilometres of the tidal saltmarshes.

Dengue fever is found mainly in northern Queensland, and is not found around Brisbane because of the absence of the sole species of mosquito that transmits it, Mr Muller said.

“It used to be here in Brisbane until the 1950s, [and is] probably associated with the disappearance of rainwater tanks back then.

“And yes, we are very aware that a lot people have now got rainwater tanks back in their yards,” he said.

Queensland Health, the Queensland Institute of Medical Research and Brisbane City Council are continually monitoring this situation, Mr Muller said.

The original release of this article first appeared on the website of Hangzhou Night Net.