Minnesota's Innovative Strategy Against The Emerald Ash Borer

Sometimes the smallest allies can have the biggest impact. That’s the hope behind Minnesota’s newest effort to protect its ash trees from the emerald ash borer, an invasive pest that's been devouring trees across the state.

We might be known for our 10,000 Lakes here in Minnesota, but did you know we also have *way* more ash trees? Way more than people, in fact. The Minnesota Department of Natural Resources (DNR) notes that our fair state has the highest volume of ash trees of any state in the U.S., with a combined total population of nearly a billion forestland and urban ash trees. That's billion, with a b, which is way more than Minnesota's human population of around 5.6 million!

Billion-Dollar Problem: An Invasive Beetle Threatens Minnesota's Forests

Minnesota’s ash trees are facing one of their toughest battles yet. The notorious emerald ash borer (EAB) has been killing ash trees across the Land of Lakes for nearly 15 years now. It was first spotted in Minnesota back in 2009, and according to the Minnesota Department of Agriculture (MDA), it has put ALL ash trees in the state in its crosshairs.

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Minnesota is Fighting the Emerald Ash Borer with a Tiny, Surprising Ally

The DNR says EAB kills ash trees by 'tunneling under the bark and feeding on the part of the tree that moves nutrients up and down the trunk.' But a quiet new strategy could help tip the balance against this notorious invasive species. And it's something we might consider a pest.

The DNR said earlier this week that, along with the U.S. Department of Agriculture's Forest Service, it released three species of non-stinging wasps (those would be the obiu agriliis, tetrastichus planipennisi, and spathius galinae if you're curious) to target EAB at different life stages, all designed to help slow its development-- all without harming other species.

The "Good" Wasps Are Here: How Tiny Predators Are Saving Ash Trees

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The DNR says the wasps are 'a targeted biological control strategy that reduces EAB populations and slows their expansion into uninfested forest areas,' it said in a release. And it appears to be working:

In 2025, 5,424 wasps were released in 200 acres of the infested area of the Chippewa National Forest. A total of 8,480 wasps have been released over the last two summers. Currently no new infestation areas are within the forest according to MDA’s EAB status map.

The DNR states that this program has been in existence since 2010 and, with the latest venture, has expanded to 55 different areas across the state.

I think it's fantastic that we can use a good 'ol-fashioned cure from Mother Nature as the solution to a problem that could be devastating for Minnesota's forest ecosystem. Here's hoping the wasps keep doing their thing!