Michigan Is Banning Untreated Firewood Statewide Starting in 2027

A stack of firewood tossed in the back of a car for a camping trip doesn't look like a biosecurity risk. Michigan's Department of Agriculture and Rural Development (MDARD) disagrees strongly enough that, starting January 1, 2027, bringing untreated firewood into the state will be prohibited outright, under the state's long-standing Insect Pest and Plant Disease Act (Act 189 of 1931). The announcement, made September 17, 2026, lands alongside a more immediate piece of news: a spotted lanternfly population was just confirmed in Berrien County, pushing the number of Michigan counties with confirmed populations of the invasive insect to eight.

What the quarantine actually restricts

The rule is straightforward in scope: untreated firewood brought into Michigan from anywhere else will no longer be allowed. MDARD's announcement lists specific exemptions rather than banning wood movement entirely — firewood that has been heat-treated and certified by MDARD, another state's department of agriculture, or the USDA (carrying an authorization certificate or label) remains permitted, as does kiln-dried dimensional lumber, wood pellets, and wood chips no larger than one inch in two dimensions. Raw wood headed directly to a processing facility is also exempted. Michigan's Department of Natural Resources separately runs a voluntary "Certified Invasive-Free" seal under the Michigan Invasive Species Program, which in-state producers can apply for once their firewood is properly heat-treated. MDARD has said enforcement in the rule's first year will focus mainly on public education and awareness rather than penalties, working jointly with the DNR. The proposal went through a public comment period that closed in February 2026 before this fall's formal announcement.

Coverage of the new rule is explicit that it isn't aimed at a single pest. MDARD and state invasive-species communications name the Asian longhorned beetle, oak wilt (a fungal disease rather than an insect, but one that also spreads through infected wood), and spotted lanternfly as the specific targets of the firewood restriction — a broader net than any one quarantine zone could realistically cover, since all three can travel undetected in a stack of wood that looks completely ordinary.

The Berrien County detection that's driving the news cycle

MDARD confirmed a spotted lanternfly population in Berrien County on September 10, 2026, found through trapping and surveillance work carried out by the Southwest Corner Cooperative Invasive Species Management Area, a regional program MDARD helps fund, with the detection confirmed in cooperation with the USDA. Berrien County is a significant grape-growing region, and while MDARD's release notes the detection itself was not inside a vineyard, Michigan State University Extension has asked local grape growers to stay alert given spotted lanternfly's documented preference for grapevines among its host plants. A separate population was also confirmed around the same period in Washtenaw County, bringing the statewide county list to eight: Berrien, Jackson, Lenawee, Macomb, Monroe, Oakland, Washtenaw, and Wayne.

MDARD's guidance actually differs depending on which county a resident lives in, reflecting how long the insect has been established there. In Jackson, Lenawee, Macomb, Monroe, Oakland, and Wayne counties — where spotted lanternfly is already established — an earlier June 2026 MDARD release told residents simply to squish any they find, without needing to report each sighting. Berrien and Washtenaw, as newer detections, are being treated differently, with residents encouraged to report sightings through the Michigan DNR's "Eyes in the Field" reporting tool or a local MSU Extension office so the state can track how far the population has actually spread. MDARD's communications are also careful to note what spotted lanternfly does not do: it doesn't typically kill the plants it feeds on outright, though heavy, sustained infestations can cause localized plant stress and affect crop yields, and it poses no direct risk to human or animal health.

Why firewood specifically is the target

Firewood has been a recognized pathway for moving tree-killing and wood-boring pests for years, which is why Michigan's Department of Natural Resources has long advised campers not to move firewood more than 10 miles from where it was cut unless it's been heat-treated — guidance that predates this new statewide quarantine and will continue to apply alongside it. Michigan State University Extension's guidance on the subject is similarly direct: buy firewood near where you'll actually burn it, or buy certified heat-treated or kiln-dried firewood instead of transporting wood from home, since vendors selling local or certified wood are typically available near popular camping destinations. The practical challenge, as MSU Extension acknowledges, is that buying strictly local firewood is the ideal solution in theory but can be difficult to enforce and isn't always available in practice — part of why a hard statewide rule, rather than guidance alone, is the direction Michigan has now taken.

Heat treatment itself isn't a quick process. MSU Extension's materials on firewood sanitization describe commercial kiln treatment as typically running one to three days at temperatures between 120 and 220 degrees Fahrenheit, after which the wood is considered safe to transport without the risk of carrying live insects or disease spores. That length of treatment is also why certified heat-treated firewood tends to cost more than an untreated bundle picked up on the side of the road — the cost reflects a real sanitization process, not just a label.

• Starting January 1, 2027, Michigan prohibits bringing untreated firewood into the state, under Act 189 of 1931, with exemptions for certified heat-treated firewood, kiln-dried lumber, wood pellets, and small wood chips.
• The rule specifically targets the Asian longhorned beetle, oak wilt, and spotted lanternfly — pests capable of traveling undetected inside ordinary-looking firewood.
• A spotted lanternfly population confirmed in Berrien County in September 2026 brought the statewide county total to eight, with a separate Washtenaw County detection confirmed around the same time.
• MDARD's public guidance differs by county: squish-and-move-on in counties where the insect is already established, but report sightings through the DNR's "Eyes in the Field" tool in newer-detection counties like Berrien and Washtenaw.
• Commercial heat treatment typically takes one to three days at 120-220°F, according to MSU Extension — a real process that explains why certified treated firewood costs more than an untreated roadside bundle.

Invasive pests rarely need an obvious entry point to establish themselves — a stack of firewood or an unnoticed egg mass is often enough. A free Sevacorp inspection is a useful way to check a property for early signs of wood-boring or invasive pest activity before it becomes a larger problem.

• Sources:
• Michigan Department of Agriculture and Rural Development — "MDARD, MISP Take Next Step in Preventing Invasive Pests From Entering Michigan" (Sept. 17, 2026) — https://www.michigan.gov/mdard/about/media/pressreleases/2026/09/17/mdard-misp-take-next-step-in-preventing-invasive-pests-from-entering-michigan
• Michigan Department of Agriculture and Rural Development — "Spotted Lanternfly Confirmed in Berrien County" (Sept. 10, 2026) — https://www.michigan.gov/mdard/about/media/pressreleases/2026/09/10/spotted-lanternfly-confirmed-in-berrien-county
• Michigan Department of Agriculture and Rural Development — "MDARD Encourages Michiganders To Watch for Spotted Lanternfly This Summer" (June 22, 2026) — https://www.michigan.gov/mdard/about/media/pressreleases/2026/06/22/mdard-encourages-michiganders-to-watch-for-spotted-lanternfly-this-summer
• Michigan Dept. of Environment, Great Lakes, and Energy (EGLE) — "Spotted Lanternfly" newsroom repost (Sept. 28, 2026) — https://www.michigan.gov/egle/newsroom/mi-environment/2026/09/28/spotted-lanternfly
• Michigan Department of Natural Resources — "Firewood" (camping and lodging guidance) — https://www.michigan.gov/dnr/things-to-do/camping-and-lodging/firewood
• Michigan State University Extension — "Firewood Best Practices for Healthy Forests" — https://www.canr.msu.edu/news/firewood-best-practices-for-healthy-forests
• Michigan State University Extension — "Firewood Sanitization Technologies" — https://www.canr.msu.edu/news/firewood-sanitization-technologies