The emerald ash borer (EAB), a metallic green beetle native to East Asia, was first detected in North America in 2002 in southeastern Michigan and Windsor, Ontario. It has killed tens of millions of ash trees, impacting urban forests, ecosystems, and industries reliant on ash wood.
Background and Science
Likely introduced in the 1990s via infested wood packaging, EAB has since spread across the United States, Canada, and parts of Europe, devastating ash tree (Fraxinus spp.) populations. The EAB (Agrilus planipennis) is a wood-boring beetle in the Buprestidae family. Its larvae tunnel beneath the bark of ash trees, disrupting the tree’s ability to transport water and nutrients through the phloem and xylem. This girdling causes tree death within 2–5 years of infestation. EAB targets all ash species, with no natural resistance in North American ash trees. The beetle’s lifecycle includes egg, larva, pupa, and adult stages, completing one or two generations annually depending on climate. Adults emerge in spring, leaving D-shaped exit holes, and lay eggs in bark crevices.
Identifying Characteristics
Insect
- Adults: 7.5–15 mm long, metallic emerald green, with a slender, bullet-shaped body.
- Larvae: Creamy white, flat, segmented, up to 30 mm long, found under bark in serpentine (S-shaped) galleries.
Signs on Trees
- D-shaped exit holes (3–4 mm wide) on bark.
- S-shaped larval galleries under bark.
- Canopy thinning, dieback, and epicormic sprouting (shoots at the base or trunk).
- Increased woodpecker activity, as they feed on larvae.
- Bark splitting or blonding (from woodpecker damage).
EAB's Effect on Eagan's Urban Forest
More than a decade after emerald ash borer (EAB) arrived in Eagan, most untreated ash trees have died or are in irreversible decline.
With the initial infestation behind us, the City has shifted its focus from slowing the spread of EAB to managing its long-term impacts. Eagan Forestry now focuses on identifying hazardous trees, educating property owners, encouraging the replacement of ash trees with a diverse mix of species, and restoring parks and natural areas through strategic tree planting.
Dead Ash Trees Will Not Recover
Untreated ash trees with severe canopy loss will not recover. Although some trees may produce sprouts, these shoots do not indicate the tree is recovering. As dead ash trees deteriorate, they become increasingly brittle, hazardous, and more costly to remove. Prompt removal is strongly encouraged to help prevent injury or property damage.
Property Owner Responsibility
Responsibility for a tree is generally determined by the location of its trunk. The owner of the property on which the trunk is located is responsible for the care and management of the tree. If you have a dead or declining ash tree on your property, we encourage you to:
- Act promptly to remove dead or hazardous ash trees. Dead ash trees become increasingly brittle over time, making them more likely to become a safety hazard or cause property damage.
- Consider planting a replacement tree. Choose a species that adds diversity and is well suited to the planting site to help restore Eagan's community forest. Visit our Tree Planting Resources for recommended tree species and planting guidance.
Eagan Emerald Ash Borer Cost-Share Program
To assist Eagan residents with managing private ash trees, the City of Eagan offers an Emerald Ash Borer Cost-Share Program. The program helps offset the cost of removing dead or hazardous ash trees while also recognizing property owners who have invested in preserving healthy ash trees through preventative treatment.
Reimbursement Amounts
Eligible property owners may receive reimbursement for one or both of the following:
- Ash Tree Removal: 25% of the eligible cost, up to $200
- Preventative Ash Tree Treatment: 25% of the eligible cost, up to $100
Reimbursements are limited to the amounts above on a per-property, per-calendar-year basis, regardless of the number of trees treated or removed.
Eligibility Requirement
To qualify for reimbursement:
- Eligible ash trees must be located on private property within the City of Eagan and be verified by Forestry staff before removal or treatment.
- All work must be performed by a City of Eagan licensed tree contractor.
- The program is not retroactive. Reimbursement applications must be submitted to Eagan Forestry during the same calendar year the work is completed.
- Funding is limited, and reimbursements are awarded on a first-come, first-served basis.
- Approval is subject to available funding and verification that all program eligibility requirements have been met.
How to Participate
- Contact Eagan Forestry to schedule a site visit. Eligible ash trees must be located on private property within the City of Eagan and be verified by Forestry staff before removal or treatment.
- Contact a City of Eagan-licensed tree contractor to evaluate your ash tree(s) and recommend treatment or removal. View our current list of licensed contractors.
- Hire a licensed contractor to complete the work.
- Submit your paid, itemized invoice to Eagan Forestry to request reimbursement.
What the City is Doing
The City has completed the primary phase of its boulevard ash tree removal program and continues to manage the long-term impacts of emerald ash borer throughout Eagan's parks and public lands.
Current efforts include:
- Inspecting and removing hazardous ash trees on public property.
- Monitoring the health of previously treated public ash trees.
- Responding to storm-damaged and hazardous trees.
- Restoring parks and natural areas following tree removal.
- Planting a diverse and resilient mix of tree species.
- Providing education, technical guidance, and cost-share assistance to residents.
Disposal of Ash and Transportation of Firewood
Tree pests can be spread by transporting infested ash logs, tree debris, and firewood. Invasive insects such as Emerald Ash Borer, Spongy Moth, and Asian Longhorned Beetle—and even some native wood-boring insects—can be carried to new locations in untreated wood. To help protect Minnesota's forests and communities, the Minnesota Department of Agriculture regulates the movement of ash wood and firewood.
If you have ash wood to dispose of:
- Work with a local licensed tree care contractor to properly dispose of ash wood and other regulated materials.
- Keep ash wood local and do not transport it outside of regulated areas.
If you are transporting firewood:
- Buy it where you burn it. Purchase firewood near your destination and use it locally.
- Never transport untreated firewood long distances, as it can spread invasive insects and tree diseases.
For the latest information, visit the Minnesota Department of Agriculture's Emerald Ash Borer Quarantine page.
Questions
Learn More
If you'd like to learn more about emerald ash borer and ash tree management, the following resources provide additional information and guidance:
- Minnesota Department of Agriculture – Emerald Ash Borer: Minnesota's primary source for EAB information, homeowner resources, and current infestations.
- Minnesota Department of Agriculture – EAB Quarantine & Movement Restrictions: Current quarantine boundaries, firewood regulations, and ash wood transportation requirements.
- University of Minnesota Extension – Emerald Ash Borer: Identification, treatment options, and recommendations for managing ash trees.
- Minnesota Department of Agriculture – Emerald Ash Borer Information for Homeowners: Practical guidance for homeowners, including disposal, treatment, and hiring a tree care professional.
- Emerald Ash Borer Information Network: National information on emerald ash borer biology, spread, management, and research.