Efforts to knock down invasive Japanese beetle in Vancouver appear to be working

Eradication efforts to keep a voracious plant-eating invasive insect from establishing itself in British Columbia appear to be working.

Japanese beetles were discovered in downtown Vancouver in 2017 and immediately recognized as an invasive species that, if allowed to proliferate in the province, could devastate plants and commercial crops.

"It has not just implications for us," said Sophie Dessureault, who manages pests such as insects and invasive plants for the Vancouver Park Board. "This one has implications beyond our own borders."

The beetle, Popillia japonica, which is established in other provinces, is an invasive pest that feeds on the roots of grass and the foliage of more than 300 plant species.

Four years ago, a beetle was discovered in a trap in Vancouver's False Creek, marking the first sighting of the insect in B.C.

It's unclear where it came from, but multiple agencies began working together to put traps in place to capture more of the insects, while also spraying a larvicide in affected areas in Vancouver to kill the grubs of the beetle, which live in the soil.

In that first year, the Canadian Food Inspection Agency, which is responsible for trapping the beetles, placed 1,425 traps and caught 958 Japanese beetles in 42 of them.

That number skyrocketed to 8,276 trapped beetles in 2018, before the spraying program began knocking numbers down.

Traps around the province

The CFIA says the majority of traps are in Metro Vancouver and the Fraser Valley. There are also some traps on Vancouver Island and in B.C.'s Interior.

In 2020, one beetle was found in Port Coquitlam and in 2018, one was found in South Delta.

Last year, just 214 beetles were trapped in 39 out of 2,507 traps. All but three of the beetles were found in David Lam Park, where the first Japanese beetle was found in 2017.

"These results indicate that the beetle population is decreasing and there is continued progress toward the eradication of the beetle in Vancouver," the CFIA wrote in an email to CBC News.

Dessureault is also happy with the progress and the collaboration between the federal government, province, municipality and other partners, such as the Invasive Species Council of British Columbia and British Columbia Nursery and Landscape Association.

According to entomologists like Judith Myers, a professor emeritus with UBC's zoology department, numbers will have to get to zero for the threat from the beetle to disappear completely.

"Maybe it's possible that they will be able to contain it and get rid of it totally," she said. "Eradication means you have to get rid of every single individual and keep up the effort for years past when you think, 'Oh, maybe they're all gone.'"

'Where are the little guys hiding now?'

Dessureault says that is the plan among officials working on the problem.

"Where are the little guys hiding now? The last ones," she said. "Because as the numbers get smaller, it's going to be harder to detect where they are. And the fear of course is that we miss something."

Since 2017 there has been a regulated area around the downtown parts of Vancouver where the beetle has been found. There are rules about moving soil or plant waste out of the area by commercial landscapers, property maintenance contractors and companies.

From June 15 to Oct. 15, they must dispose of those materials at a temporary transfer station operated by the City of Vancouver at 301 W. 1st Ave. The rules are meant to prevent beetles from travelling out of the area.

"They are kind of notorious hitchhikers," said Dessureault.

Residents are asked to use city-provided green bins to dispose of plant waste such as grass clipping and pruned branches.

Officials also want people to shake off picnic blankets to prevent beetles from being inadvertently transported to other areas.

Anyone who sees a Japanese beetle can report it here.

Adult Japanese beetles are around 10 millimetres long, metallic green and have bronze-coloured wings. Their larvae are C-shaped, white and have a yellowish-brown head.