Protecting Ontario’s Eastern Hemlock (Tsuga canadensis) from Hemlock Woolly Adelgid (HWA): A Practical Guide for Practitioners, Landowners and Land Managers, was developed by the Ontario Woodlot Association (OWA) and partners with funding from the Invasive Species Action Fund between 2024 and 2026 as part of the Hemlock Champion Project. 

The guide provides foundational guidance on approaches for HWA management to support hemlock conservation. Forestry practitioners, landowners and land managers will find this guide indispensable. Hemlock woolly adelgid (Adelges tsugae; HWA) is an invasive insect that poses a significant threat to Ontario’s native eastern hemlock (Tsuga canadensis) by disrupting the flow of nutrients throughout the tree and eventually causing death. 

Eastern hemlocks are a slow growing and long-lived species that play an important role in vast areas of Ontario’s forest ecosystems. As of this writing, HWA has already infested much of the eastern United States and southwestern Nova Scotia. It has also been found in Ontario along eastern Lake Erie, the Niagara Region, Toronto, Grafton, and neighboring municipalities. All eastern hemlocks will likely be at risk in Ontario to an HWA infestation within projected best case climate scenarios. 

Download the Guide

When should I take action? As soon as possible.

“With this guide, any landowner or land manager with eastern hemlock can begin preparing for or managing HWA and take action to protect hemlocks. Informed management and timely action offer the best means of reducing hemlock mortality across the landscape.”

— Sionaid Eggett, Program Manager, Ontario Woodlot Association

"I wish we had treated more trees sooner in stands near the Annapolis Valley and in Kejimkujik National Park. As these last great hemlock forests decline faster than we can get them treated, we realize what will soon be lost forever, and at that point it’s often too late to deploy pesticides."

— Donna Crossland summarizing the sentiment from what she’s witnessing on private woodlots and protected areas with HWA in Nova Scotia.