Terrestrial Invasive Species

More Information

Terrestrial invasive species enter and spread across Ontario in a variety of ways. They stow away in our luggage when we travel and in packaging material when we import products into Ontario. They spread when we transport raw wood and other forest products, and animal carcasses. Some escape from gardens.

Photo: Janice Gilbert/MNR

Terrestrial Invasive species harm biodiversity, agriculture, forestry, public health, tourism, outdoor recreation and our economy.


Pathogens like invasive fungi that kill trees are a big threat to Ontario’s forests. For example, three tree species – American chestnut, butternut and eastern flowering dogwood – could be lost from Ontario because of invasive fungi. The fungi that are killing them are: chestnut blight, butternut canker and dogwood anthracnose.


Invasive insects like the emerald ash borer, Asian long-horn beetle and sirex wood wasp are also a big threat to Ontario’s forests. The emerald ash borer is a beetle that’s native to Asia. It probably arrived in Ontario in packing material from Asia. It attacks and kills ash trees, and has killed millions of ash trees in southwestern Ontario since 2002.


Invasive terrestrial plants are threatening our farms, fields, forests, prairies and savannahs. Some, like garlic mustard, grow along forest edges, trails or roads, and quickly invade forests that are disturbed. They threaten native plants and the animals that depend on them. Others, like giant hogweed, can hurt humans.


Invasive terrestrial animals are also a concern. The mute swan, red-eared slider and European starling are examples of invasive terrestrial animals that are harming Ontario’s biodiversity.


Animal diseases caused by invasive micro-organisms like bacteria, viruses and parasites are a big threat to Ontario’s terrestrial wildlife. Chronic Wasting Disease and White Nose Syndrome are examples of diseases caused by invasive micro-organisms that are threatening Ontario’s biodiversity. Some invasive micro-organisms also cause illnesses, like Avian Influenza and West Nile Virus, in humans. The micro-organisms that cause these illnesses are carried by wildlife and spread to humans.


The Ontario Ministry of Natural Resources works with partners including the federal government to prevent the introduction and spread of terrestrial invasive species in Ontario.


The Canadian Food Inspection Agency is the regulatory agency that protects Canada's wild and cultivated plants from invasive plants and plant pests. The Canadian Food Inspection Agency has authority under the International Plant Protection Convention (IPPC) and the Plant Protection Act and regulations made under this Act. The Ontario Ministry of Natural Resources’ Forest Health and Silviculture Section works with the Canadian Food Inspection Agency to protect the health of Ontario's forests from invasive alien insects.


The Canadian Food Inspection Agency also has authority to deal with animal diseases under the Health of Animals Act and membership in the World Organization for Animal Health.


The following links provide information on a few of the many terrestrial invasive species and micro-organisms that are a concern in Ontario.


Forest Pathogens




Terrestrial Plants


Wildlife Diseases & Diseases Spread by Wildlife to Humans


For information on the health affects of invasive viruses, bacteria and parasites spread by wildlife, like, Lyme disease and West Nile virus, please visit the Ontario Ministry of Health and Long-term Care’s Publications page.


For information on plant species (including invasive species) that disrupt agricultural and horticultural systems, please visit the Ontario Ministry of Agriculture, Food and Rural Affairs’ Weeds in Ontario page or the Ontario Weeds website. To learn about plant species that are considered noxious weeds in Ontario (including invasive species like European buckthorn and spotted knapweed), please visit Noxious Weeds in Ontario.