Insect that kills ash trees found in Moorhead for the first time

Emerald ash borers have killed hundreds of millions of ash trees throughout 36 states since it was first discovered in the U.S. in 2002

Ash trees
An ash tree.
Dave Samson / The Forum

MOORHEAD — The emerald ash borer has reached Moorhead.

This wood boring insect, native to Asia, has killed hundreds of millions of ash trees throughout 36 states since it was first discovered in the U.S. in 2002.

An insect larva found by a Moorhead city forester was submitted for testing, and the Minnesota Department of Agriculture confirmed that it was an ash borer. It's the first such confirmation in Moorhead or Clay County, state officials said Thursday, March 2.

There are now 39 Minnesota counties, including Clay, where emerald ash borers have been found. The emerald ash borer was first discovered in Minnesota in 2009.

The forester in Moorhead found evidence of the ash borer while pruning trees in early February in the Meadows neighborhood near Clearview Court and Eagle Drive.


"The tree had visible woodpecker damage and when the bark was peeled back galleries and insect larvae were present," state officials said in a statement.

The emerald ash borer is a small, metallic green beetle native to Asia that is about 1/2 inch long and 1/8 inch wide.
Photo by Marianne Prue, Ohio Department of Natural Resources Division of Forestry,

What will the City of Moorhead do?

Ash species in Moorhead that are susceptible to the emerald ash borer include green ash, black ash and white ash. Other tree species are not susceptible, including the many varieties of mountain ash, according to city officials.

With ash trees making up nearly 26% of the 26,500 trees in Moorhead’s urban forest, the city’s forestry department has had a long-term management plan to prepare for the insect's arrival, city officials said.

"The Forestry Division has been removing and replacing declining ash trees for several years at an average of 234 trees annually over the last three years," Moorhead officials said in a statement.

The City of Moorhead said Thursday that its foresters "will immediately implement a plan to remove small ash trees that provide fewer benefits, while simultaneously treating and preserving larger ash trees, retaining the many benefits they provide. Forestry plans to replace all removed ash trees as soon as possible with primary planting taking place in spring and fall. Any homeowner who is impacted by removal or treatment of an ash tree will be notified in advance."

As a result of the discovery in Moorhead, state officials established an emergency quarantine of western Clay County, from Minnesota Highway 9 west to the North Dakota border, to limit the movement of firewood and ash tree material out of the area.

Along with it being the first emerald ash borer confirmed in Clay County, it's also the first in northwestern Minnesota, state officials said.


"The detection is unfortunate but not unexpected, given the location is near a highly traveled corridor in the state. The public can help limit the spread of this harmful forest pest by not moving firewood and reporting any suspected infestations" to the Minnesota Department of Agriculture at 1-888-545-6684 or , state officials said.

mn map.PNG
The Minnesota counties in red are where the emerald ash borer has been detected.
Minnesota Department of Agriculture map

What about North Dakota?

As adults, emerald ash borers cannot fly more than a mile or two on their own, according to the North Dakota Department of Agriculture. However, ash borers may hitch a ride on firewood and ash nursery stock to cover long distances.

“This detection, just 2 miles from the North Dakota border, is now the nearest detection to our state,” North Dakota Agriculture Commissioner Doug Goehring said in a statement. “The North Dakota Department of Agriculture and our partners have been preparing for emerald ash borer’s eventual arrival for many years. (The department) maintains a quarantine that restricts movement of regulated commodities such as firewood from infested areas and will be expanded to include the newly infested area.”

North Dakota has more than 90 million ash trees in native and rural forests, according to state officials.

The City of Fargo has been diversifying its urban forests with other tree species to reduce boulevard ash populations, North Dakota said. Fargo's ash trees have been reduced to less than 24% of all the city's trees.

The North Dakota Department of Agriculture encourages travelers to leave firewood at home and only buy firewood locally. Other potentially contaminated materials include ash logs and branches, nursery stock and wood chips. Such materials are subject to regulations.

“Moving regulated materials from a quarantined to a non-quarantined area without a permit can result in civil penalties of up to $5,000,” North Dakota officials said in a statement.


What should homeowners do?

The City of Moorhead suggested homeowners with ash trees in their yards develop a plan to manage their trees.

Ash borers "can spread quickly, so determining options for private trees should be done soon, especially if homeowners wish to retain their trees," city officials said.

Ash borer larvae kill ash trees by tunneling under bark and feeding on the part of the tree that moves nutrients up and down the trunk. Ash borer tunneling can cause the bark to split open, revealing S-shaped galleries underneath.

Woodpeckers like to feed on ash borer larvae, and woodpecker holes may indicate the presence of ash borers.

Homeowners who need help identifying tree species or determining if trees are infested with ash borers can contact Moorhead Forestry at 218-299-5422 or, or the Clay County Extension educator at 218-299-7338 or .

A virtual informational meeting for residents and tree care professionals in Clay County will be held at 10 a.m. Thursday, March 16. Experts from the Minnesota Department of Agriculture will give a brief presentation on ash borers followed by a Q-and-A session.

For more information on the meeting, visit

At the meeting, the public will have a chance to give input on a proposal to add Clay County’s emergency ash borer quarantine to the state’s formal quarantine.


The Minnesota Department of Agriculture is taking comments now through April 14 and recommends adopting the quarantine on April 17. The proposed quarantine language can be found at .

Comments on the proposal can be sent to Kimberly Thielen Cremers at or the Minnesota Department of Agriculture, 625 Robert St. N., St. Paul, MN 55155.

North Dakota residents with questions or seeking more information on ash borers can visit . Suspected infestations can be reported at the same link or by leaving a voicemail at 701-328-5110 or emailing .

I cover the politics beat – come see me at a local government meeting sometime. I'm also the night reporter on weeknights. 👻
What To Read Next
Get Local