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© Lora Denis
Hemlock Woolly Adelgid ovisacs © Stephanie Muckle
Harold Mitchell Nature Reserve, located in the Niagara Region, is a stunning mature forest containing red maple-hemlock swamp. Eastern hemlock on the property shades the forest floor and the nature reserve’s many vernal pools, providing temperature regulating services, shelter and habitat important to many plants and animals. The hemlock trees here are one of the last mature stands in southern Ontario, and their protection is vital to safeguard this important habitat.
This past spring, Ontario Nature staff spent a week at the nature reserve treating Hemlock trees against Hemlock Woolly Adelgid (HWA), which is a rapidly emerging threat to Ontario’s hemlock trees. This non-native invasive insect feeds on the nutrient and storage cells of hemlock needles, causing mortality of trees in as little as four years. Staff injected 31 mature hemlock trees with TreeAzin, an insecticide made from Neem tree seed extracts, the only botanical pesticide for rapid control of HWA. By treating the largest and most significant trees against HWA, we hope to preserve the forest structure that is so important to this habitat.
HWA is native to Asia and was first reported in Eastern North America in 1951, where it was likely brought in through infested nursery stock. HWA was first detected on Harold Mitchell Nature Reserve in 2019. Through a partnership with Niagara College’s Ecosystem Restoration Program and Niagara Falls Nature Club, surveys to track the spread of the species within the nature reserve have taken place annually. By 2023, 99% of trees surveyed showed evidence of HWA and varying levels of canopy decline. This is a sharp increase from 2021, when surveys detected HWA on only 43% of trees.
Ontario Nature – in consultation from the Natural Resources Canada, Canadian Food Inspection Agency and Lallemand Plant Care – has developed an integrated pest management strategy to tackle HWA on the nature reserve. These steps help further Ontario’s Biodiversity Strategy’s (2023-2030) target of reducing the harmful impacts of invasive species and contribute to preventing the spread of HWA in Ontario.
The Invasive Species Centre recommends the following actions to prevent the spread of Hemlock Woolly Adelgid:
To learn more about Hemlock Woolly Adelgid, visit the Invasive Species Centre website.
Ontario Nature gratefully acknowledges the financial support of the Invasive Species Centre and the Niagara Community Foundation (NCF), which is a public foundation serving the people of Niagara since 2000. NCF connects donors to causes, and communities to resources through permanent endowment funds, providing grants to eligible charitable organizations in culture, health, education, environment, recreation and social service sectors. NCF turns intention into impact.
Northern leopard frog © Jozsef Szasz-Fabian