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P.E.I. Invasive Species Council begins preparing for arrival of invasive insect

December 5, 2023  By Caitlin Coombes, Local Journalism Initiative Reporter

Despite being nearly microscopic insects, hemlock woolly adelgid produces a white woolly coating as they grow on Hemlock trees such as those found at Kejimkujik National Park. Contributed by Parks Canada/Special to SaltWire.

The P.E.I. Invasive Species Council (PEIISC) has begun raising public awareness about an invasive species impacting hemlock trees in Nova Scotia.

The hemlock woolly adelgid (HWA) is an invasive species known to infect hemlock trees in North America and has been present in the Maritime provinces since arriving in Nova Scotia in 2017.

The microscopic insects suck fluid from the infected Hemlock trees and grow a distinctive white woolly protective coating and travel via migratory birds, firewood and human activity.

Concerned that the invasive insect could pose a threat to hemlocks on the Island, the PEIISC has begun working to raise public awareness of HWA in the province.


Clay Cutting, an invasive species technician with the PEIISC, told SaltWire on Nov. 20 that HWA poses long-term, irreversible damage to hemlock trees if not found and treated quickly.

“Once you see it, you kind of realize it’s a pretty big issue,” he said.

Clay Cutting, left, and Chase Guindon, members of the P.E.I. Invasive Species Council, conduct hands-on investigations across the province to manage invasive species. – Contributed/Special to SaltWire. Caitlin Coombes, Local Journalism Initiative Reporter.

Cutting is working to create a detailed list of as many hemlocks as possible across P.E.I., improving each tree’s chances of survival and recovery from an HWA infection.

The presence of HWA on the Island could cause considerable damage to the forest environment, especially if substantial portions of P.E.I.’s hemlock population are lost.

“Invasive species thrive on disturbance and the presence of invasive species causes disturbance.” Cutting said, describing the process of “invasive meltdown,” wherein the presence of one successful invasive species can lead to several additional invasive species.

Treatment and cure

Organizations across the country have been working together to combat HWA as it spreads across Nova Scotia, including Parks Canada, the Canada Forest Service, and the Canadian Food Inspection Agency to name only a few.

Due to the size of the HWA and the hemlocks they prefer, infected trees often require aggressive treatment and quarantine for several years.

Lucas Roscoe, an invasive species expert at the Atlantic Forestry Centre, told SaltWire there are several factors which make HWA both successful and difficult to control.

“One of the main reasons why they are so damaging is that they have nothing that’s actually predating them, and because of that their populations can just skyrocket,” he said.

Matthew Smith, project manager at Kejimkujik National Park in Nova Scotia, began working to control HWA when the species began infecting hemlock trees within the National Park.

“When it’s in an area, you can’t eradicate it. It spreads very quickly and the trees begin to decline,” Smith said.

Matthew Smith, project manager at Kejimkujik National Park in Nova Scotia, said HWA spreads quickly. – Contributed/Special to SaltWire.

Individual trees can be treated with insecticides injected into the tree and bark sprays, both time-consuming treatments.

In November 2023, the Canada Forest Service introduced an insect predator to HWA across Nova Scotia to control the population of the invasive species naturally.

“I don’t think you’re ever going to get away from injecting trees. The idea with this insect is it may be able to fill gaps that the insecticides can’t,” Roscoe said.

Laricobius Nigrinus beetles feed on HWA without upsetting the environment and food chains indigenous to the province and were released in the wild and in control pens within Kejimkujik National Park.

If the beetles are cold-hardy enough to withstand winter in Atlantic Canada, they could help provide a natural balance to HWA alongside chemical treatments.

Preparedness in P.E.I.

The P.E.I. Invasive Species Council is working to gather as much information about Island hemlock trees as possible, preparing for the arrival of HWA either in the next several years through natural means or within a year through human dispersion.

The Canadian Food Inspection Agency (CFIA) and the council have collaborated to install two firewood collection boxes, where travellers can dispose of their firewood before travelling through the province.

Clay is encouraging Islanders to connect with the council and share information about their hemlocks to help him build a plan for tree monitoring and to get people engaged with their trees.

“Engaging with the environment before it’s gone can really inspire action because these are gorgeous trees and the environments which they create are equally gorgeous,” Cutting said.

Caitlin Coombes is a Local Journalism Initiative reporter for The Guardian.

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