Invasive species compete with native animals and plants for food and habitat, causing severe, costly and often permanent damage to important habitats and ecosystems. 

Invasive animals often lack natural predators or population controls, allowing them to reproduce and spread quickly. 

Invasive plants spread easily, grow quickly and tolerate many soil types and weather conditions, allowing them to crowd out slower-growing native plants.

Invasive species: 

• Affect Indigenous communities by reducing the availability of culturally-important native species. Some Indigenous communities use the bark and needles from Hemlock Trees to treat colds coughs and fevers, and many Oak Trees hold cultural significance as symbols of heritage or landmarks. In the Anishinaabe culture, Oak Trees represent teachings of humility
• Cause expensive damage to properties, reduce property values and make natural areas, like shorelines, less accessible for recreation and nature appreciation
• Cause significant damage to the York Regional Forest, street, park and backyard trees, wetlands, woodlands, grasslands and our numerous lakes, rivers and streams
  • These provide habitat for a wide range of native wildlife, clean the air and water, prevent flooding, capture and store carbon, and play other key roles in maintaining a healthy, sustainable environment
  • Invasive plants such as Dog-strangling Vine, European Buckthorn and Garlic Mustard are well-established in the York Regional Forest and have displaced the native food and habitat sources for native wildlife
• Pose a health and safety risk to residents:
  • Phragmites can cause flooding on roads by plugging drainage ditches or sight-line issues for motorists
  • Poisonous plants like Giant Hogweed and Wild Parsnip can cause severe burns when touched
  • Sharp shells from Quagga and Zebra Mussels can result in cuts or scrapes
  • Stings from swarming European Fire Ants can be painful

Early detection and preventing invasive species from spreading is the most successful way to minimize the damage and costs of invasive species and education campaigns are key to raising awareness.

The image below shows once an invasive pest is established, the cost to manage it becomes more expensive and is less effective. 

Invasion Curve adapted from the Generalised Invasive Curve (Victorian Government, 2010)

York Region uses integrated pest management approaches to actively manage established invasive species found on Regional roads, Regionally-owned properties and in the York Regional Forest. This includes monitoring, controlled burns, mowing, pruning, hand removal, removing and replacing hazardous trees and herbicide treatment. Priority is given to species that pose a health and safety risk like poisonous Giant Hogweed or Phragmites that can cause flooding on roads by plugging drainage ditches or sight-line issues for motorists.

All herbicides used by York Region to treat invasive species are approved for use in Canada and Ontario. The Region follows best practices and regulations identified under Ontario’s Pesticides Act, 1990. Herbicides are applied by licenced applicators who must follow all label directions and ideal weather and site conditions.  

Invasive species can spread naturally (by wind, water or animals) or through human activity (by attaching to bikes, clothing, footwear, pets, tire treads, firewood or boats). York Region residents and visitors play a vital role in preventing the introduction and spread of invasive species. Here’s how:

Spot it  
Learn how to identify different types of invasive species and their signs and symptoms.

Bag it
Place invasive plants in a securely-tied plastic bag in the garbage – not yard waste, compost or green bin.

• Never put invasive plants in your backyard compost. Even when uprooted, invasive plants can spread seeds or grow roots in your compost pile
• You might find Dog-strangling Vine and Garlic Mustard on your property or in your garden. These aggressive plants can take over your garden making it difficult for native flowers to grow and provide food for important pollinators like the Monarch butterfly

Keep it clean
Wash outdoor shoes, bikes, vehicles, boats and check your pets between trips.

• Cyclists: clean your bike with a gentle brush before and after rides
• Horse riders and dog walkers: brush off your animal’s feet and coat before entering and leaving the York Regional Forest or any natural area
• Walkers and runners: brush the bottom of shoes and clothes before entering and exiting the York Regional Forest

Don’t move it
Don’t move firewood, wood waste, plants, shrubs or trees between properties. This helps prevent the spread of invasive species to areas not yet infected.

Look before you leave
Before leaving the cottage, campsite or coming back into Canada be sure to check your car, recreational vehicle, camping gear or equipment so not to accidentally transport pests from one area to another.

Plant native 
When native plants thrive in your garden, bees, birds and butterflies can flourish too. Learn more at york.ca/BeesAndButterflies

Report it 
Report sightings of invasive species using EDDmapS, iNaturalist, the Canadian Food Inspection Agency's online tool or call the Invading Species Hotline at 1-800-563-7711. Depending on the pest, you may be asked to take a photo and put it in a sealable bag or container.

Wild Pigs 

Wild Pigs include species like Wild Boars, Feral Domestic Pigs (escaped Pot-bellied or Farmed Pigs) and hybrids of the two. These invasive animals can harm natural areas, pollute water and compete with native wildlife for resources like food, water and space. They can also destroy crops and transmit disease to livestock, wildlife and humans.

Wild Pigs have been reported in Ontario but have not yet been spotted in York Region. If you think you’ve seen one report it to the Ontario Government, using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

York Region is working with the Ministry of Natural Resources and Forestry to share the latest updates and raise awareness about Wild Pigs among local city and town bylaw and animal control teams.

Learn more about Wild Pigs at Invasive Species Centre.

Photo Credit: AGCanada.com

Nutria

The Nutria (Myocastor coypus) is an invasive, semi-aquatic rodent that looks like a beaver or muskrat. It has two bright orange front teeth and a long, rat-like tail. The Nutria is mostly found near water but can adapt to a variety of habitats. It eats large amounts of native aquatic plants and can also carry disease and parasites.

Nutria is in the United States of America, primarily in the Gulf Coast. There are currently no established populations within Canada. Nutria have been regulated as a prohibited species under the Invasive Species Act to prevent this invasive animal from entering Ontario.

The Region collaborates with the Invasive Species Centre and Ministry of Natural Resources to share communications and raise awareness about this invasive species of concern.

Learn more about Nutria at Invasive Species Centre 

Photo Credit: Observation © Joseph Aubert, 2023. iNaturalist.org

Beech Bark Disease (BBD)

Beech Bark Disease (Cryptococcus fagisuga/Neonectria spp. complex) is caused by an invasive insect-fungus combination. The invasive Beech Scale insect (Cryptococcus fagisuga) feeds on the bark of Beech Trees, creating cracks that allow a native fungus (Nectria) to enter. This disease causes cankering of the tree, deformation of stems and, in some cases, tree death.

Beech Bark Disease is currently in York Region. The Region is monitoring Beech Trees for both Beech Bark and Beech Leaf disease and will remove infected trees if necessary.

Be on the lookout and report suspected sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Beech Bark Disease at Invasive Species Centre
Not sure what type of trees you have? Check out Forests Canada to find out.  

Photo Credit: Matthew Borden, Bartlett Tree Experts, Bugwood.org

Oak Wilt

Oak Wilt (Bretziella fagacearum) is an invasive fungus that restricts water and nutrient flow through Oak Trees causing leaves to wilt and eventually die. It spreads above ground by sap beetles carrying fungal spores from infected to healthy trees and below ground through root systems that connect healthy trees to infected ones. 

Oak Wilt has been detected in Ontario but has not yet been found in York Region. If you spot it, help  stop it from becoming established by reporting suspected finds to the Canadian Food Inspection Agency

In 2024, York Region completed a threat assessment for trees on Regional roads and the York Regional Forest and identified priority areas to monitor. If Oak wilt is detected in the Region, we are prepared to respond and assist our partners.  

Learn more about Oak Wilt at Invasive Species Centre
Not sure what type of trees you have? Check out Forests Canada to find out.

Asian Longhorned Beetle (ALHB) 

The Asian Longhorned Beetle (Anoplophora glabripennis) is a shiny, black invasive insect with white spots that lays its eggs in the bark of hardwood trees like Maple, Birch, Poplar and Willow. When larvae hatch, they burrow into the tree, damaging its ability to transport water and nutrients and eventually killing it.

The Asian Longhorned Beetle has been eradicated from Ontario but it’s important to be on the lookout as individual detections can still occur. Report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more at about Asian Longhorned Beetle at Invasive Species Centre.
Not sure what type of trees you have? Check out Forests Canada to find out. 

Photo Credit: Taylor Scarr, OMNRF

Beech Leaf Disease

Beech Leaf Disease is caused by a tiny, worm-like organism that feeds on the leaves and buds of Beech Trees leading to branch dieback and eventually tree death.  

Beech Leaf Disease has been found in York Region. The Region is monitoring Beech Trees for both Beech Bark and Beech Leaf disease and will remove infected trees if necessary. Be on the lookout and report suspected sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Beech Leaf Disease at Invasive Species Centre.
Not sure what type of trees you have? Check out Forests Canada to find out.

Emerald Ash Borer (EAB)

The Emerald Ash Borer (Agrilus planipennis) is a small, shiny green invasive insect that kills Ash Trees in as little as two years. The insect’s larvae burrow under the bark, cutting off the tree's ability to move water and nutrients, eventually killing it.

EAB is in York Region. York Region treats mature Ash Trees with TreeAzin™ to protect them from this pest. When used as directed TreeAzin™ poses minimal, if any, risk to people, pets, wildlife, soil and water. Be on the lookout for EAB and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Emerald Ash Borer at Invasive Species Centre.
Not sure what type of trees you have? Check out Forests Canada to find out.

Photo Credit: Debbie Miller, USDA Forest Service, Bugwood.org

Hemlock Woolly Adelgid (HWA)

Hemlock Woolly Adelgid (Adelges Tsugae) is an aphid-like invasive insect that attacks and kills Hemlock Trees. It attaches to branches and feeds at the base of needles taking nutrients and sap. HWA egg sacs look like tiny cotton balls found at the base of needles. 

HWA is established in Ontario but has not yet been found in York Region. If you spot it, help stop it from becoming established by reporting suspected finds to the Canadian Food Inspection Agency 

York Region monitors Hemlock Trees in the York Regional Forest; local cities and towns and conservation authorities monitor Hemlock Trees for HWA on their respective properties.

Learn more about this invasive insect at Invasive Species Centre 
Not sure what type of trees you have? Check out Forests Canada to find out.

Spongy Moth

Spongy Moth (Lymantria dispar dispar) is a defoliating insect that prefers to feed on Oak Tree leaves but will feed on the leaves of other hardwoods including Maple, Elm, Birch, Poplar and Willow.

In 2021, York Region experienced a significant Spongy Moth outbreak. Outbreaks generally follow a 7 to 10-year cycle with peak infestations lasting 1 to 3 years. York Region continues to monitor the York Regional Forest and street trees on Regional roads annually for signs of this pest.

Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more at york.ca/SpongyMoth

Spotted Lanternfly 

Spotted Lanternfly (Lycorma delicatula) is an invasive insect that sucks sap from the leaves and stems of a wide range of plants, shrubs and trees. After feeding it excretes a sugary, sticky substance called honeydew that promotes the growth of grimy, black sooty mould. This can weaken the plant or tree making it more susceptible to pests and disease.

The Canadian Food Inspection Agency (CFIA) has not confirmed any established populations of Spotted Lanternfly in Canada, but there have been sightings in Ontario and Quebec. If you spot it, help stop it from becoming established by reporting suspected finds to the Canadian Food Inspection Agency

York Region staff is working closely with partners including the Canadian Federal Inspection Agency, local cities, towns and conservation authorities to help raise awareness about pest.

Learn more about Spotted Lanternfly at Invasive Species Centre
Not sure what type of trees you have? Check out Forests Canada to find out.

Dog-strangling Vine (DSV)

Dog-strangling Vine (Cynanchum rossicum) is an invasive plant that spreads easily, crowding out native plants in the York Regional Forest, local parks and backyards. It is not a threat to dogs.

The Region controls Dog-strangling Vine in priority locations in the York Regional Forest and along Regional roads. Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Dog-strangling Vine at Invasive Species Centre 

Garlic Mustard

Garlic Mustard (Alliaria petiolata) is one of Ontario’s most aggressive forest invaders. It grows in a wide range of habitats and spreads quickly along roadsides, trails and fence lines. Once established it can takeover native plants like Trilliums and endangered American Ginseng and threaten biodiversity.

The Region controls Garlic Mustard in priority areas in the York Regional Forest. Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Garlic Mustard at Invasive Species Centre

Giant Hogweed 

Giant Hogweed (Heracleum mantegazzianum) is a poisonous, invasive plant that spreads easily along ditches and streams. 

It produces sap containing chemicals that can irritate the skin, causing severe burns, rashes or blisters, when exposed to sunlight. Depending on sensitivity, effects can last for months, and skin can remain sensitive to UV light for years. 

If you come across Giant Hogweed DO NOT touch any part of the plant without wearing protective clothing like long-sleeved shirts and pants, waterproof gloves and eye protection. 

If you think you’ve come in contact with Giant Hogweed:

• Wash affected areas immediately
• Keep the affected areas out of the sun
• Seek medical attention

Pets can also be affected by these plants and carry sap on their fur so it’s important to keep them away from areas where these plants have been spotted.

The Region controls Giant Hogweed in priority locations in the York Regional Forest and along Regional roads. Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Giant Hogweed at Invasive Species Centre

Wild Parsnip

Wild Parsnip (Pastinaca sativa) is a poisonous, invasive plant that forms dense stands and spreads quickly in disturbed areas like abandoned yards, agriculture areas, open fields and roadsides.

The sap from Wild Parsnip can cause severe skin reactions when exposed to sunlight.  Contact with the sap can lead to painful rashes, blistering, and discoloration of the skin. Depending on sensitivity, effects can last for months, and skin can remain sensitive to UV light for years.  

If you come across Wild Parsnip DO NOT touch any part of the plant without wearing protective clothing like long-sleeved shirts and pants, waterproof gloves and eye protection. 

If you think you’ve come in contact with Wild Parsnip:

• Wash affected areas immediately
• Keep the affected areas out of the sun
• Seek medical attention 

Pets can also be affected by these plants and carry sap on their fur so it’s important to keep them away from areas where these plants have been spotted.

The Region controls Wild Parsnip in priority locations in the York Regional Forest and along Regional roads. Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Wild Parsnip at Invasive Species Centre.

Phragmites 

Phragmites is an aggressive invasive plant that spreads rapidly in wetlands and takes over native plants. It destroys shelter and food supplies for wildlife, can cause sight-line issues for motorists and flooding by filling roadside ditches.  

The Region is controlling Phragmites in priority locations in the York Regional Forest and along Regional roads. Be on the lookout and report sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Phragmites at Invasive Species Centre.

Purple Loosestrife

Purple Loosestrife (Lythrum salicaria) is an invasive plant that grows in wetlands. It spreads quickly and takes over native plants affecting nesting sites, shelter and food for birds.  

The Region doesn’t actively manage Purple Loosestrife because beetles are able to keep it under control. The plant might spread more during warm, wet summers but the beetles will manage it effectively.

Be on the lookout and report suspected sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Purple Loosestrife at Invasive Species Centre.

Water Soldier

Water Soldier (Stratiotes aloides) is an invasive aquatic plant present in Ontario and recently found in the southern part of Lake Simcoe in Cook's Bay. Water Soldier can crowd out native aquatic species and interfere with fishing, boating and swimming. Boat motors can break up the plant spreading it to new areas.

There is currently no risk to York Region’s water infrastructure that requires action. The Region collaborates with the Invasive Species Centre and Ministry of Natural Resources to share communications and provide staff support to assist with surveying/monitoring as required.

Be on the lookout and report suspected sightings using EDDmapS, iNaturalist or call the Invading Species Hotline at 1-800-563-7711.

Learn more about Water Soldier at Invasive Species Centre

If you or a group you’re involved with has an idea on how to tackle an invasive species, funding may be available through these organizations:

• Toronto Dominion Friends of the Environment Foundation Grant
• Ministry of Environment, Conservation and Parks Species at Risk Stewardship Program
• Invasive Species Centre Grant Opportunities

The Invasive Species Act, 2015, the Pesticides Act, 1990 and the Weed Control Act, 1990 can be used by provincial, regional and municipal governments and conservation authorities to manage invasive species in Ontario.

Learn more about invasive species regulation at Invasive Species Centre

The Invasive Species Act

The Invasive Species Act was established to prevent and control the spread of invasive species that pose a risk to Ontario’s natural environment. The Ministry of Natural Resources oversees the Act and is responsible for enforcing the regulations, managing invasive species and implementing control measures.

Learn more about the Invasive Species Act, 2015

The Pesticides Act

The Pesticides Act regulates pesticide use to protect the environment, human health and animal life and aims to minimize risks and ensure safe practices. The Ministry of the Environment, Conservation and Parks oversees the act and is responsible for conducting inspections, issuing licenses and permits and enforcing regulations related to pesticide use.

Learn more about the Pesticides Act, 1990  

The Weed Control Act

The Weed Control Act was established to protect farmland and the natural environment from noxious weeds. Most of the noxious weeds maintained under the Act are considered invasive. Cities and towns appoint Weed Inspectors to enforce the Act and landowners are required to control noxious weeds on their property. Any costs associated with removing noxious weeds on private property must be paid for by the landowner. In York Region this is typically enforced by city and town Bylaw Enforcement Officers.

Learn more about the Weed Control Act, 1990