Terrebonne citizens want return of anti-mosquito pesticides

Terrebonne citizens want return of anti-mosquito pesticides

Citizens of Terrebonne want their city to go back to using a biological pesticide against mosquitoes, even as experts increasingly lament the impact on the ecosystem.

“We can’t even go out for ten minutes and we’re automatically bitten,” launches François Cagney.

The resident of Terrebonne on Montreal’s North Shore noticed a greater than usual presence of mosquitoes in his garden this spring.

After checking with the city, Mr. Cagney learned that they would not be using Bacillus thuringiensis israelensis (Bti) this season to kill mosquito and blackfly larvae.

Upon hearing this news, he started an online petition demanding the return of Bti to his community, which has so far collected more than 500 signatures.

“I have a garden shed, but I don’t spend my whole life in it. […] I won’t put mosquito repellent on every night because I want to talk to my neighbors,” he says.

Terrebonne insists and signs

Despite allegations from some citizens, Terrebonne does not intend to reconsider its decision.

“To protect the biodiversity of its wetlands, which are home to vulnerable and endangered species, the city has halted the spread of Bti,” said its spokeswoman, Véronik Gravel.

The mosquito treatment and monitoring contract cost the community between $600,000 and $1 million and has had mixed results depending on weather conditions.

In 2017, Terrebonne even stopped using Bti, although the number of complaints received was not much higher than in previous years, Ms Gravel specifies.


“You have to live with these insects as much as possible. It’s not always easy, I get stung myself when I go into the woods! says Jean-Pierre Bourassa, Professor Emeritus in the Department of Environmental Sciences at UQTR.

Like many other experts, the entomologist has reservations about using Bti.

“By killing these insects, we remove food resources from the ecosystems where they would naturally be found,” continues André-Philippe Drapeau Picard, entomological information officer at the Montreal Insectarium.

An INRS team showed that Bti would markedly alter the metamorphosis time of wood frogs and American toads.

While more studies need to be conducted to understand the longer-term effects, “it is important to intervene as soon as possible. If we wait until we have all the data, it could impact the frog population in Quebec,” says Juan Manuel Gutierrez-Villagomez, a postdoctoral researcher at INRS.

How to repel mosquitoes easily

  • Wear long, light-colored clothing
  • Use insect repellents that have been proven effective, such as DEET or permethrin
  • Install a fan to imitate enough wind to keep mosquitoes from approaching
  • Do not allow standing water in your garden, such as B. in a boiler or an old tire to prevent mosquitoes from breeding there

Sources: Montreal Insectarium and Jean-Pierre Bourassa