Emerald ash borer in Minnesota: Over a billion ash trees at risk as spread moves north

(FOX 9) - The emerald ash borer, an invasive insect that tunnels into ash trees and kills them, was first detected in Minnesota in 2009, and the state has been working to slow its spread ever since.

Battling an invasive pest across Minnesota

What we know:

Minnesota has more ash trees than any other state, making the stakes especially high. The loss of those trees carries serious environmental and economic consequences, and the Minnesota Department of Agriculture (MDA) has been at the center of a coordinated, statewide response.

The MDA leads a multipronged effort that includes early detection surveys, biological control and public education. The goal is not to eliminate the emerald ash borer entirely, but to slow its spread — giving communities, landowners and forest managers more time to plan and respond before ash trees are suddenly lost.

Early detection surveys are conducted along the leading edge of infestations and on high-risk travel corridors.

With additional grant funding from the Minnesota Department of Natural Resources (DNR), the MDA has been able to conduct more than 200 extra early detection surveys in cities across the state, leading to numerous new community detections. MDA staff also hold community management workshops to get more people actively looking for signs of the pest.

What they're saying:

The Walz-Flanagan Administration has placed significant emphasis on minimizing the impact of the emerald ash borer, allocating essential funds to early detection efforts.

Biological control and public awareness

On the biological control front, three species of parasitoid wasps are being released in Minnesota to attack the emerald ash borer. These wasps do not sting people or damage trees — they simply target the pest. Since 2010, 700,000 wasps have been released at 56 infested sites across the state.

Research on their impact is ongoing, but early results show promise. The long-term goal is for the wasps to establish self-sustaining populations that help keep emerald ash borer numbers lower over time, particularly in forests where removing thousands of trees is not practical.

What you can do:

Humans are actually the number one way invasive species spread, often by accidentally transporting them on objects like firewood.

The MDA has made a significant effort to change public behavior to limit the spread of the emerald ash borer.

There are two main ways the public can help — by not moving firewood and by reporting suspicious insects or signs of infestation through the Report a Pest program.

The spread is picking up — and moving north

For many years, a combination of management efforts and environmental conditions kept the emerald ash borer spreading slower in Minnesota than expected. That is no longer the case., with 60 Minnesota counties now considered infested, mostly in the central and southern parts of the state.

In recent years, infestations have started moving north, a trend tied to rising winter low temperatures.

The Source: This story is based on information from the Minnesota Department of Agriculture.