What is the status of purple loosestrife and zebra mussels? We don’t hear about them nearly as much anymore. Does that mean we “solved” them? Or that the environment has somehow just gotten used to them?—Lillian Valence, Huntsville, Ont.
Sadly, neither. Both invasives remain ongoing problems in the province, says Lauren Rogers of the Invasive Species Centre in Sault Ste. Marie, Ont. They’ve both been here for a long time. That means they’ve had a long time to get a firm foot in the door and invade further. “Invasive species rarely remain confined to a single area,” she says. They spread to new habitats as the conditions there become more favourable. Of course, the opposite is also true: an invasive could potentially decline, or disappear naturally in one area, if environmental conditions change beyond what the species can tolerate, she points out. Ha. See you in hell, invasive! Except, changes that would negatively impact an invasive species would likely also negatively impact the species we want to keep around.
It’s not impossible to “solve” (that is, eradicate) an invasive species; the Asian long-horned beetle, for example, was permanently kicked out of Mississauga and Toronto. But that was an unusual case. “Eradication is costly, and usually only works for early, limited infestations,” says Rogers.
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And the environment would never “get used” to an invasive species. Take zebra mussels: “Even if they become a ‘normal’ part of an ecosystem, they would likely still change how the ecosystem works,” says Sydney Currier, the aquatics invasive species coordinator at the Invasive Species Centre. Since zebra mussels are filter feeders, they make lake water clearer by removing algae and plankton; this means less food is available for native species. “Clearer waters also allow sunlight to penetrate deeper, which can fuel the growth of green algae growing on the bottom of rivers and lakes—the kind that’s associated with toxic algae blooms,” says Currier. (Disappointingly, zebra mussels don’t eat toxic algae. They only eat the helpful algae.)
So, why aren’t you hearing about purple loosestrife and zebra mussels anymore? We can tell you that Cottage Life isn’t writing about them as much. (The last time we did a story on purple loosestrife was 1993.)
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“This happens often,” says Currier. “Because funding is limited, agencies prioritize new or early-stage invasive species. They’re more likely to be stopped,” she says. “Long-established invasives shift into quieter, long-term management strategies rather than headline-worthy eradication efforts.” Want to do your part in the fight against zebra mussels and purple loosestrife? Learn how to help the experts monitor them and stop their spread: visit invasivespeciescentre.ca.
Got a question for Cottage Q&A? Send it to answers@cottagelife.com.
This article was originally published in the Spring 2026 issue of Cottage Life.
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