Kitchener is home to some invasive species that affect our natural ecosystems. Learn about some of our invasive species and our response below.

On this page:

  1. Invasive species strategy
  2. Notable invasive species
  3. Other invasive species
  4. Resources and prevention

Invasive species strategy

We are currently developing an invasive species strategy that will help document and track invasive species populations. The strategy will also help us prioritize species and areas for management.

Subscribe to this page for updates on our invasive species strategy.   

Notable invasive species

Invasive species populations fluctuate over their life cycle, which makes some species a greater concern in some years than in others. We continuously monitor the health of our ecosystem to identify invasive species, the overall health of our urban forest and natural areas, and any threats to their health. When we determine that our ecosystem won’t be able to recover from the impacts of some invasive species on its own, we develop a management plan to address the impact of those species. Below are the notable species for which we currently have management plans in place.

Giant hogweed

Giant hogweed is an invasive plant species that was brought to North America about a century ago and is now spreading throughout southern Ontario. The tall, white-flowered plant impacts our ecosystem by shading out native species and can also be hazardous to human health. Giant hogweed sap can make skin extremely sensitive to sunlight and can cause severe burning and blistering. If it comes in contact with your eyes, it can also cause blindness.

Because of the potential health hazards, if any sap comes in contact with your skin, wash the affected area immediately with soap and water and keep it out of the sun. If you have a reaction to the sap, please see your doctor.

Our response

We respond to and manage giant hogweed populations as they are reported by City staff or residents. When a plant is reported, we will investigate it to determine whether it is giant hogweed or another species. For plants identified as giant hogweed, we will either spray with herbicide or dig the plant out completely. We maintain a record of reported sites for continuous monitoring to make sure the giant hogweed remains managed in those areas.

How to identify and report

Giant hogweed has thick hollow stems covered with reddish-purple flecks and stiff hairs filed with sap. It has large lobed leaves and, once mature, produces white flower clusters. It can resemble Queen Anne’s lace but the flowers on giant hogweed tend to be more widely spaced and can form a flower-head almost one metre wide. A number of plants look very similar to giant hogweed, like cow parsnip, purplestem angelica, woodland angelica, valerian, lovage and Queen Anne’s lace; however, these plants are not as large as mature giant hogweed.

If you think there is giant hogweed growing in a public space in your neighbourhood, report it by calling 519-741-2345. If you think you have Giant hogweed growing on your property, visit the Ontario’s Invading Species Program website for more information on how to manage and remove it.

 

Emerald ash borer

The emerald ash borer (EAB) is a destructive tree pest that kills more than 99% of ash trees it is present in. The winged adult lays eggs on ash trees, beneath the bark. Larvae hatch and feed beneath the bark, disrupting the tree's circulation of water and nutrients, causing the tree to die.

The presence of EAB is fatal to ash trees. Once infested, trees typically succumb to emerald ash borers within two to three years but can die within months of EAB first being detected. For more information, please visit Natural Resources Canada.

Our response

Our active management program is complete and we are now in the monitoring phase. We responded in two ways:

  1. To extend the life of some ash trees, TreeAzin chemical treatments were injected and regularly reapplied to approximately 1,400 trees. This delays the impacts of EAB on ash trees, keeping these trees for as long as possible to contribute to our urban forest canopy. This treatment is not a permanent solution, so once trees fail to EAB, they are removed.
  2. We removed ash trees affected by EAB to reduce the risk posed by dead trees near property. To date, approximately 5,000 trees have been removed. The remaining ash trees on City property will be reassessed in 2025 and further action taken as needed.

How the program affects your neighbourhood

If we mark an ash tree for removal, it is because it has declined beyond the point of return and can pose safety risks. We are no longer injecting any of our ash trees. Please do not inject trees at your own cost. We will continue to monitor any remaining ash trees on City property and remove them when needed.

If you have an ash tree on your property, we recommend consulting with tree care companies about its care. Before starting work, we suggest getting at least three estimates.

 

Other invasive species

While we have management programs in place for some notable invasive species, there are other invasive species in our city that we monitor. While some of these species may impact our ecosystem, they are currently not of concern as the ecosystem will recover naturally from any impacts. As invasive species populations fluctuate over their lifecycle, we monitor them to determine whether we need to develop management programs for any of these species.

Click the links below to learn more about some of the other invasive species you may see in Kitchener. The Ontario Invading Species Program also has more information on other invasive species found across the province.

 

Resources and prevention

Help prevent invasive species

The best way to manage invasive species in our community is to prevent them from being introduced altogether. Some quick and easy tips for how we can all help prevent the spread of invasive species are:

  • Clean your shoes, pets and gear before arriving at and before leaving a natural space to help prevent invasive plant seeds from spreading.
  • Clean, drain and dry your boat and fishing gear to help prevent aquatic invasive species from spreading.
  • Don't release pets if you can no longer care for them – especially fish. They can negatively impact the ecosystem and quickly become invasive. Visit the Kitchener-Waterloo Humane Society for more information on surrendering animals.
  • Don’t move firewood between regions. If you have to purchase firewood to burn in a different region, buy heat-treated (kiln-dried) firewood, which has been treated to avoid the risk of spreading invasive species.
  • Plant native species in your gardens, ponds and aquariums. Educate yourself on which species are invasive, because some plants can spread outside your garden and outcompete native species for resources. Buying plants from a reputable nursery can help you select the right species!

 

Additional resources

Visit these websites for more information on invasive species and how they’re managed in our region, in Ontario and across Canada: