Probably the best-known invasive plant in Canada, purple loosestrife is found in every province. While the invasion likely originated when the plant’s seeds were carried over from Europe in ballast water, its attractive purple flowers mean that it continues to be sold at garden centres. If you do have it in your garden or spot some at the cottage, remove it in June or July while they’re flowering and before they go to seed. Pull individual plants or small clusters at the root. For larger patches, cut off at the stalk. Dispose of in plastic bags in the trash. Do not compost.
The emerald ash borer is an insect native to east Asia. It likely made its way to North America in wooden shipping packaging in the 1990s. It’s found in Canada from Manitoba to Nova Scotia and its larvae have killed thousands of ash trees by “girdling” under the bark, disrupting a tree’s ability to transport water and nutrients up the trunk. While there are government eradication programs, the best thing cottagers can do to avoid the spread is to not transport firewood from home to the cottage or vice versa.
Wild boars have been in Canada for about 20 years. Their feeding is very destructive to the habitats they forage in, they are known carriers of diseases like rabies and anthrax, and they have killed pets, livestock, and even humans. Officials are still trying to determine how far they’re spreading to implement control measures. If you spot one, report the sighting to your local ministry of natural resources office.
One invasive you definitely want to be cautious around is giant hogweed. The sap makes your skin extremely sensitive to sunlight and can cause painful blistering and second-degree burns. It can grow up to 14’ high and 3’ across. If you do come into contact with the plant, wash with soap and water and keep any skin that was exposed out of direct sunlight.
Zebra mussels are probably the first invasive species to land on most cottagers’ radar, clogging waterline intakes and coating boat hulls. Their impacts on habitats they invade can be even worse, out competing local species for food and altering the water quality (by making the water clearer which can increase aquatic vegetation and lead to algae blooms). If you’re trailing your boat from one waterbody to another, remove any weeds on the hull or prop, drain the bilge, and allow the boat to completely dry before putting it in another lake.
The round goby is one of many invasive fish species that threaten our waterways. They out compete native species for food, eat the eggs of popular sportfish, and are linked to botulism outbreaks in native birds and fish. Unfortunately, round goby is sometimes sold as bait fish. Know what it looks like and don’t use live specimens as bait. Never transport any live fish from one body of water to another. If you do catch a suspected invasive fish, don’t throw it back in the water. Keep it and contact the local MNR office.
To learn more about invasive species in your area, contact the national Invasive Species Centre. Online, you’ll find downloadable “Best Management Practices” developed by the Ontario Invasive Plant Council on how to safely and properly remove 25 of the most common invasive plants found in that province. Many of the species listed are found elsewhere in Canada.