Hemlock Woolly Adelgid (HWA) is a non-native, aphid-like insect. It is less than 1.5 millimetre in size and feeds on nutrient and water storage cells found in Hemlock tree needles. This can cause the tree stress and eventually, death.
While it hasn’t been found in Mississauga yet, it has been found in the following locations in Ontario:
Fort Erie
Grafton
Hamilton
Pelham
The Niagara Gorge
Wainfleet
What it looks like
Why Hemlock Woolly Adelgid is a threat
The loss of Hemlock trees caused by HWA can impact our ecosystem in the following ways:
Accelerated erosion and sedimentation
Reduced habitat and food sources for wildlife
Reduced shade for streams, which can impact fish and other aquatic organisms
Higher heating and cooling costs in residential areas
How it spreads
HWA can spread through the wind, animals or people moving around wood.
How to spot an infection
Hemlock trees infested with the HWA can be identified by:
White sacs (looks like small wool) at the base of the tree’s needles on younger twigs
Thinning and change of colour (greyish-green) at the crown of the tree
Early bud and shoot dieback (the gradual death trees or shrubs starting at the tips)
Loss of needles
Increased dropping of twigs and branches
Unhealthy looking branches
Yellowing and discoloured foliage
What we are doing
The City is actively monitoring for HWA in Mississauga woodlands that contain Hemlock trees.
In addition, the City is providing educational resources and awareness training to Mississauga residents and staff to increase chances of early detection of HWA.
What you can do
You can help protect Hemlock trees on your private property and the City by:
Learning how to identify Hemlock trees and HWA
Becoming aware of the signs of infestation on your trees
Contacting a tree care company to have your trees inspected if you suspect an infestation
Avoiding putting bird feeders in or near your trees, as birds can transport HWA
Not moving firewood, nursery stock or logs around
Sourcing your firewood from local forests
Buying Hemlock trees from local sellers and ask them where the tree is from
Inspecting the tree before you buy it
Increasing your tree’s resilience to HWA and other pests and diseases by keeping it healthy