Invasive emerald ash borers are moving north and according to Thunder Bay's city forester, a quarter of the trees surrounding the city are at risk.
"I don't think it's if it gets here. I think it's when it gets here," said Shelley Vescio on Friday as she launched a campaign to cover urban ash trees with green ribbons.
"We have 64-hundred ash trees on our boulevards and in our parks so it has the potential to kill every one of them."
The emerald ash borer is one of the worst invasive species and is believed to be migrating from the Windsor area largely through moving firewood.
Vescio said through improving shade and stormwater management, local ash trees have a $400,000 ecological and socio-economic value.
Urban forest program specialist Lee Amelia said there's some urgency in treating ash trees with insecticide at a cost of a couple of hundred dollars per tree.
Effects don't surface for a couple of years and if left untreated and devoured by ash borers, a mature tree could cost as much as $1,500 to remove.
"If a tree isn't treated, there's no chance of it surviving," he said.
Volunteers will be wrapping the trees in green ribbons through July and August.
