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Hemlock Woolly Adelgid Initiative  

Do you have Eastern Hemlocks? CAKE CISMA is offering free surveys of hemlock trees for the invasive forest pest - hemlock woolly adelgid (HWA). Property owners within 5 miles of Lake Michigan can fill out the survey request form linked below. Surveys will be conducted this upcoming winter and property owners will be notified prior to the survey. 

A Tree Worth Saving 

One of our most beloved evergreens, the eastern hemlock (Tsuga canadensis) is also a critical part of our local ecosystems. Often found along ravines, hillsides, and stream banks, eastern hemlock offer habitat for wildlife and provide shade for streams, effectively lowering stream temperatures and increasing oxygen for fish and other aquatic species. Hemlocks provide aesthetic value and are loved by homeowners. It is estimated that Michigan is home to 170 million eastern hemlock trees. Unfortunately, this beautiful tree is now threatened by an invasive species: hemlock woolly adelgid (Adelges tsugae). 


Hemlock Woolly Adelgid

Hemlock woolly adelgid (Adelges tsugae) is a potential major pest of eastern hemlock (Tsuja canadensis). It decimated stands of native hemlock in the eastern United States, particularly in the Smokey Mountains National Park. While HWA has been detected in Michigan, its distribution is believed to still be limited to only a few counties. At this time we are doing everything we can to prevent the further spread. 

Hemlock woolly adelgids have specialized mouthparts that enable the adeglid to pierce the base of a needle, then suck out nutrients from cells in the shoots of their host tree. A host tree can die in as little as four years. 

What is being done? 

CAKE CISMA is conducting grant-funded surveys of hemlock trees within 5 miles of the lakeshore for HWA this winter. If we catch infestations soon enough there's still a chance to treat the affected trees before an infestation becomes widespread. 

Distribution of HWA in 2021

Click image to enlarge 

Frequently Asked Questions

Why do we survey in the winter? 

Cooler temperatures trigger HWA feeding activity, as hemlock woolly adelgids feed, they secrete a white, waxy material that creates ovisacs. The presence of these small, round, white masses makes it possible to identify infested trees - They're easier to see and we're less likely to spread them in the winter. 

Why do we survey properties within 5 miles of the Lake Michigan shoreline? 

The area within 5 miles of the Lake Michigan shoreline is the most probable area for new infestations. The adelgids tend to favor the temperatures and conditions found near the lake more than those inland. 

I don't live close enough for a survey, what can I do? 

It's never a bad idea to check up on the health of the trees on your property anyway. If we can't survey for you we highly recommend taking the time to survey yourself (if possible). Check out the website Eyes on the Forest (linked here) to learn how you can monitor trees in your own community.

What should I do if I think I've found HWA? 

To prevent the spread, please DO NOT move or cut the branch off! Take photos, mark the location, and report the possible infestation to us. We will follow up and will ensure the correct agencies are notified. 

Have we ever found HWA in Northern Michigan/the CAKE region? 

Yes, BUT we want to stress that the affected sites in the CAKE region are no longer active and haven't been for some time. You can view the infestation history map here. Long story short, infested nursery stock was brought to Emmet county and planted. Luckily, the infestation was caught early and it was limited - there haven't been any subsequent reports in our region since 2010. This example illustrates the importance of monitoring landscaping/nursery plants. 

What should I look for if I'm looking for HWA? 

  • Small, round, white, cottony masses, 1/16" to 1/4". 

  • Found on the twig at the base of the needles on the underside of hemlock tree branches.

  • Present year-round but most visible November through July.

  • Note that hemlock woolly adelgid infests eastern hemlock trees, not pines or spruces.

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