European wasps - they'll be back, and possibly more of them than before

30/10/2015

European wasp numbers reached plague proportions across Victoria last summer – but some are predicting that this season could be worse.

A King Valley winemaker said he was already planning for the aggressive pest, dashing hopes of would-be outdoor diners throughout the region.

"Last year was horrendous," said Fred Pizzini, owner of Pizzini Wines. "We eradicated about 40 nests within 600 or 700 metres of our cellar door."

Mr Pizzini said he would try to cull this year's crop of wasps with homemade traps using fermented honey water. "When we had functions, people were blaming us," he said. "It's not the fault of the venues. It is just a consequence of the conditions."

Museum Victoria entomologist Patrick Honan said last summer's wasp population hit a 20-year high, reaching plague numbers throughout the state. "Enough to get people's attention." 

He said it was still too early to tell whether the trend will continue. "At the moment, the wasp queens are currently waking up from hibernation and they will start looking for sites to found new nests." 

In Europe, where the wasps originated, winters are cold enough to kill most of the nests. But in Australia, where winters are warmer, 10 per cent of the nests usually survive.

Melbourne just had its coldest winter in 26 years, though it may not have been wet enough to drown the nests, which can hold up to 100,000 wasps.

"If we get a lot of spring rains those new nests will be drowned," Mr Honan said. "We're not going to know until mid-to-late summer, because that's when the nests get big enough to make an impact on people."

Tim Avenell, who works at a call centre for pest control company Rentokill, said that last summer was an "unusually freakish season" for wasps. "Every call was about wasps. You'd finish one call, there'd be another call. It was all over metro Melbourne."

European wasps love fruit and meat, which means they are particularly prone to spoiling barbecues and picnics.

Bees sting only once, but European wasps can sting repeatedly. Last March, a Wangaratta woman was stung 30 times when she knocked on someone's front door, disturbing a neighbouring nest.

David Gay, of the Australian Environmental Pest Managers Association, said he had a "gut feeling" the wasps will be back. There were just too many last summer.

"You'd never get them all," he said. "Given the larger base number, we'd expect that there would be a bigger starting number."

Mr Gay also has a theory that the popularity of urban beekeeping has made people hesitant to disturb nests. "Bees are sexy at the moment," he said. "Some people have got wasps but think they're bees and let them go."

Paul Van Der Sluys, who runs the Fairfield Boathouse and Tea Gardens, said lingering wasps can have a huge financial effect on his business.

"It was pretty disastrous," he said of last summer's plague, which lingered and actually hit hardest in March and April. "I think a lot of people probably didn't come back while [the wasps] were here."

Mr Van Der Sluys said the insects were particularly attracted to his food. "They were eating the chicken. They love sugar as well, so they were eating all the jam on the scones."

He said he usually tried to find and destroy wasp nests himself. But he thinks councils should be more proactive about helping businesses during wasp season.
"You ring the council and they say ring a pest exterminator," he said. "There should be someone walking around looking for these nests."

Mr Van Der Sluys leases his business from Yarra Council and the surrounding area is on council land. Councils around the city tell people who find wasp nests on private property to call an exterminator.

But it's hard to determine who is responsible when wasps fly everywhere. At what point do they become too big a problem?

"It's the same question with every pest," Mr Honan said. "Should the government be controlling rats and mice in your home? Should the government be working on some sort of pest control for your plants?"

Last March, Latrobe MP Jason Wood called for the government to spend $1.5 million to find a biological way to kill European wasps.

But Mr Honan said that he and other scientists tried and failed 20 years ago to come up with a successful wasp-killer.

The best way to get rid of wasps is to track down the nests one by one, he said.

"They'll always be here. And their population will always vary from year to year. And we'll always need to manage them in some way."

Most councils say people who find wasp nests on their property should call an experienced pest control professional. 

(Edited article and image from The Age, 27 September 2015)

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