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Winter Wanderings: Invasive species to watch out for in the winter

By: Michael Hindy, Three Shores CISMA Coordinator


As the last of the trees have lost their leaves, we all know that snow is just around the corner. Whether it’s snowshoeing, skiing, snowmobiling, or spending hours on the lake ice fishing, winter in the Upper Peninsula has something for everyone to enjoy outdoors. Did you know that while you’re enjoying all the beauty an Upper Peninsula winter has to offer, you can help protect our peninsula from invasive species? That’s right, invasive species are still fighting to take over our natural habitats even in the wintertime.

In the past when I used to hear the term “invasive species” I used to think “that’s a summertime problem to fix.” And while it’s true that several invasive species are hiding under the snow waiting until spring, some invasive species are actually easier to identify in the winter, including invasive phragmites and hemlock woolly adelgid.


During the summer, invasive phragmites grow a strong, thick tan stem with deep ridges up to 20’ in height and produce bluish-green leaves with thick, fluffy seed heads. In comparison, native non-invasive phragmites grow much smaller, reaching a maximum height of 6.5’ and producing yellow-green leaves with smaller seed heads. Most often the invasive phragmites species can be found on shorelines, wetlands, and roadside ditches. In the winter, both native and invasive phragmites will senesce and turn brown. During this time, the invasive phragmites grass will have intact fluffy seed heads and hold onto its leaves while the native phragmites grass will have leaves that easily separate from the plant. The invasive phragmites plant also tends to grow in very dense patches that eliminate natural refuges for fish and wildlife, and the dense growth of this species allows it to maintain a mostly upright position amongst the weight of the snow, making it easy to spot above the snow line. If you are enjoying winter recreational activities and spot an invasive phragmites plant, reporting the sighting and location to the Three Shores CISMA can go a long way in preventing the spread of the species.


If you’re out enjoying one of the many trails amidst our forests, another invasive species to watch out for is the hemlock woolly adelgid. Native to Asia, hemlock woolly adelgid (HWA) is a small invasive insect that attacks eastern hemlock trees in Michigan. This insect inserts its long mouthparts near the base of the needle on a hemlock tree and begins to feed on the tree’s stored starches, disrupting the flow of nutrients within the tree. As a result, trees infected with HWA often die within 4-10 years. These afflicted eastern hemlock trees are a significant component of Upper Peninsula forests, as they provide key thermal cover for deer in winter and provide shade to keep trout rivers and streams cold.


Luckily, at this time HWA has never been found in the Upper Peninsula, however, it’s always important to provide early detection to prevent it from becoming widespread in our peninsula. While detecting the small HWA insect may seem impossible in summer, in wintertime the HWA produces white woolly masses in winter. To detect HWA, first aim to identify if the tree is an Eastern hemlock. Eastern hemlocks are conifers that grow small cones and keep their needles year-round. The needles are flat and attach individually to the tree (not in bunches like pine trees), with two white stripes on the underside of the needle. Needles are usually short (<0.5”), and often get confused with the longer needles of the balsam fir. Once you’ve confirmed you have an eastern hemlock tree, look for a white, woolly mass on the underside of the branch near where the needle attaches to the tree. Often these masses will resemble the end of a Q-tip. If you’re not sure if you have HWA, please still report the infestation to the Three Shores CISMA and we will be able to help confirm your sighting.


Here at the Three Shores CISMA, we are dedicated to stopping the spread of invasive species throughout Chippewa, Luce, and Mackinac counties. If you spot any invasive species while enjoying the wonders of our Upper Peninsula winters, please contact your Three Shores CISMA at threeshorescisma@gmail.com or by calling 906-630-7139. If you would like any more information on the identification or management of invasive species, the Three Shores CISMA has free resources we will happily distribute to you. Thank you for continuing to fight against the threat of invasive species.

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