Barbecue-goers are being warned about the risks of swallowing wasps, as the pest enjoys one of its most active seasons in years.

Museum Victoria entomologist Patrick Honan said there had not been this much wasp activity in Victoria for 15-20 years.

"It's probably because we've had a mild summer and a mild winter before that," he told 774 ABC Melbourne's Jon Faine.

A normal wasp nest contained about 30,000 workers, Mr Honan said.

In Europe, wasp nests die over winter, with the queen emerging from hibernation to start a new nest in the spring.

In Australia, about 10 per cent of nests survive through winter and then continue to grow in the spring.

"You'll have 100,000 workers in a single nest," Mr Honan said.

European wasps were first recorded in Victoria in 1977 and were particularly active in the 1980s and 90s.

Both European wasps and the more aggressive English wasp can be found in Victoria, with the latter mainly found in and around the Dandenong Ranges.

Late summer and early autumn is the peak time for wasps because the wasps' nests are at their largest.

"There are more wasps per nest and more wasps in general than at any [other] time of year," he said.

Wasp dangers include swallowing, disturbing nests

Mr Honan said people should be especially careful when having a barbecue, as people have been hospitalised in Australia after taking in food or drink that a wasp was hiding in.

"There have been many occasions where people have been stung and the throat swells up and blocks off the air pipe," he said.

Bumping into or stepping on an English wasps' nest is also dangerous.

"There are thousands of workers that then go on the defensive," Mr Honan said.

Wasps prey on native insects that are part of local ecosystems.

They also are an issue for wine growers, as they attack grape crops.

Mr Honan said while wasps are at their annual peak now, their nests will start to decline as winter sets in.

"Over the next few weeks we'll start to see less and less wasps," he said.

'Pure evil' attacks pet dog

Talkback caller Dave from Mt Evelyn described European wasps as "pure evil".

"I'm a gardener and I've been doing it for 25 years and this is the worst year I can ever remember for European wasps," he said.

Dave said the wasps were attracted to the smell of two-stroke petrol, along with fruit and meat. He suggested people tie up their rubbish bags and avoid feeding their pets outside.

"Never leave a bone out, mate, forget it," he said.

"We've got a 10-year-old Labrador, I made that mistake, and I've come home from work and he's bounded up the driveway to greet me and his head looked like the Elephant Man because he'd been bitten by a few wasps."

He said he used a homemade insect repellent rather than an aerosol.

"Mix one cup of hand soap ... with 20 drops of peppermint oil and top it up with water, and that kills them and it acts also as a great deterrent," he said.

"I take a bottle to work with me every day because they are everywhere."