A hotly-debated class of pesticides, which are toxic to bees, will no longer be allowed to be used in the City of Vancouver to improve the look of lawns ravaged by chafer beetles.

City council voted unanimously early Tuesday to ban neonicotinoids, which includes imidacloprid, an insecticide marketed and sold to kill the grubs.

"What we're saying is within the City of Vancouver, you cannot use this, regardless of what Health Canada says or the province has said," said Counc. Andrea Reimer.

The chemicals are legal in Canada, though Health Canada is currently reviewing the use of imidacloprid because of emerging evidence it hurts pollinators.

In Vancouver, their use has "dramatically increased to combat chafer beetle infestations," according to a city report that recommended the ban.

An insecticide marketed as Merit, with the active ingredient Imidacloprid, has been marketed and sold to kill chafer beetles. (CBC)

Outcry over use for chafer beetles

Under the city's health bylaw, the chemicals had been allowed in Vancouver for use "to control or destroy pests which have caused infestation to property," and landscapers were marketing imidacloprid under the brand-name Merit as an effective treatment for chafer beetles.

The practice drew criticism from scientists and environmentalists that a pretty lawn didn't justify the risk of introducing chemical pollutants, especially when an organic alternative — nematode worms — is also available. (The chemicals are also used in agriculture, but staff noted within city limits their primary use is on turf grass.)

The change, which comes into effect later this month, means neonicotinoids will no longer be allowed in the city, even in cases of an infestation. The change comes in the middle of the season when the chemical is generally used.

Reimer said there had been "intense media interest in adding this to our health bylaw," including growing public awareness on the importance of pollinators and a CBC News story on the chafer beetle concerns.

"That really spurred us," she said. "[Staff] were quite excited to ... work with the industry and with individuals to make sure that we're not having an undue, or any impact on bees if we can avoid it."

A portion of the flyer distributed by landscaping company Cutting Edge Vancouver to homes on the city's West Side, comparing Merit insecticide to the nematode treatment of chafer beetles. (CBC)

600 landscapers notified

City staff have been discussing the change with the B.C. Landscape and Nursery Association and others, according to a staff report.

"We think this ban has a significant benefit by taking one of the toxins out of our system," said Doug Smith, acting director of sustainability for the City of Vancouver, at council on Tuesday.

The city plans to send information about the change to the approximately 600 landscapers and retail businesses registered in the city.

It has also extended the exemption to watering restrictions available for homeowners who use nematodes to control chafer beetles — so they can use extra water for three weeks, rather than just two.

NPA Counc. Elizabeth Ball said that was key, since nematodes require a moist lawn.

"I think it's really important that we don't have poison but do have an alternative that is allowed to work."