GRAND RAPIDS, Mich. (WOOD) — The Michigan Department of Natural Resources has added two new invasive species to the state’s watch list and removed another.
One of the new threats is the mountain pine beetle, described as an aggressive and destructive bark beetle commonly found across the western United States and Canada. Hot and dry summers, along with mild winters, have helped the insect expand its range, creeping closer to Michigan.
Susie Iott, an invasive species program specialist with the Michigan Department of Agriculture and Rural Development, says the beetle attacks several pine species, including one that serves as key habitat for a threatened bird.
The mountain pine beetle is one of two new invasive species added to Michigan’s watch list. (Courtesy Michigan DNR) 
Adult mountain pine beetles leave “galleries” inside the wood, which allows a separate fungus to take hold and stain the wood. (Courtesy Michigan DNR) 
Pine trees infested with mountain pine beetles typically turn yellow or red the following year. (Courtesy Michigan DNR/Bugwood.org)
“White and red pines are primary species in our forest ecosystems, and jack pine serves as critical habitat for the Kirtland’s warbler,” Iott said in a statement. “If the mountain pine beetle were to become widely established in Michigan, it would cause severe losses across multiple industries, including timber products, plant nurseries and tourism.”
Mountain pine beetles typically move by being transported on logs and firewood. MDARD issued a quarantine on any firewood or bark-lined pine products from the western U.S. and Canada in 2020.
The other threat is water-primrose. It’s an aquatic plant native to the southeastern United States and was first used in ornamental landscapes. Now, they have spread to wetlands, establishing dense mats along shorelines, stealing resources from native species.
There are established populations in four counties across Michigan, three in metro Detroit and Ottawa County.
“(Those populations) indicate the species can survive and thrive in Michigan’s climate,” the DNR said in a statement. “Once established, water-primrose can be very difficult to remove, making early detection critical.”
The DNR says herbicides can be effective against water-primrose, but only if detected in an early stage.
Another invasive plant has been removed from the state’s watch list — not because it has been eradicated but because it is now established widely across Michigan.
European frog-bit now has established populations across six states, plus Quebec and Ontario. It is now commonly found along the coasts of Lake Erie and Lake Huron and inland lakes and ponds across the state — including stretches of the Grand River in Ottawa County.
Like water-primrose, European frog-bit grows in dense mats along the surface. It can slow down boat traffic and cut down the amount of oxygen and light in the water column, which impacts the food chain for waterfowl and fish.
Despite being removed from the invasive species watch list, the European frog-bit remains a prohibited plant, making it illegal to possess, introduce, import, or sell in Michigan. State and local management groups will continue efforts to remove known populations of the plant.
