The European wasp, considered one of the worst in the world, has so far been prevented from becoming established in Western Australia — but keeping it that way requires constant public vigilance.

"Western Australia is the only place in the world that's kept them from establishing for so long," Marc Widmer, a senior technical officer with the Department of Primary Industries and Regional Development said.

Sorry, this audio has expired The 40-year fight to keep the European wasp out of WA

"It's an environmental scourge. It's an agricultural pest and it is certainly a human amenity pest.

"They can build up very high populations and they love to live in built up areas with people.

"They can sting people, pets and livestock as well, and the cost to the community and control of the pest would be very high if they established here."

Fighting the wasps since 1977

The presence of European wasps in Western Australia was first reported 40 years ago, when a visiting entomologist saw one land on his scone in the Perth suburb of Nedlands and reported it to authorities.

Since then they have not been able to keep the state entirely wasp free, but have mounted an aggressive eradication program.

European wasps nest in holes in the ground. ( Supplied: Department of Agriculture )

"We are always going to get fertilised queens accidentally shipped over here in freight and cargo from the eastern states," Mr Widmer told ABC Radio Perth.

"There is nothing we can do about that and that is why the nests are mainly found in industrialised areas because they are the freight end points for all this cargo.

"The queens wake up in those places and start to seed new nests in nearby areas."

The department sets out surveillance traps every year and does its own monitoring, but also relies on the general public to report European wasp sightings.

To do that effectively people need to be able to discern a European wasp from the more common paper wasp.

How to identify a European wasp from a paper wasp. ( Supplied: Department of Agriculture )

"They look so similar to the paper wasp and that is a bit of problem, because we are getting calls all the time about the very common paper wasp," he said.

"If you look on our website and see the pictures we actually have a reckoner showing the differences and the similarities.

"European wasps are more bee shaped — they are more squat and not that long, elongated shape with the narrow waist.

"But the main thing is that they have black feelers — so the antennae are completely black."

Ground nesters

European wasps nest in the ground and are attracted to meat.

"If you see wasps flying into a hole in the ground, that is suspicious," Mr Widmer added.

About 95 per cent of the nests are subterranean and all you will see is that hole in the ground with hundreds of wasps coming and going.

"If you see wasps going for meat products, bugs on the grill of your car, your barbecue, pet food ... that is suspicious, give us a call.

"Last year we found and destroyed 52 nests, the year before that it was 83, so it does vary but it is quite high."

The pests and diseases information service can be contacted at 08 9368 3080.