Emerald ash borer: signs, spread and firewood rules

What the emerald ash borer is

The emerald ash borer (*Agrilus planipennis*) is an invasive beetle that attacks and kills all species of ash (*Fraxinus*). It has killed millions of ash trees in North America.¹ So far, ash is the only kind of tree found infested here.⁵

The adult has a metallic green back and an emerald green underside. It is 8.5 to 14 mm long (about 1/3 to 1/2 inch), so it is easy to miss.¹ The larvae do the damage: white, flat grubs that grow from 2 cm to 5 cm long (about 3/4 inch to 2 inches).¹ They feed under the bark on the trunk and on branches thicker than 2.5 cm (1 inch), and they attack healthy trees as well as weak ones.⁵ Infested ash trees generally die after 2 to 3 years, and heavily infested trees have died after only 1 year.¹

Where it came from and where it is now

The beetle is native to China and eastern Asia and is believed to have arrived by accident in imported wood packaging or crating.² It was first detected in North America in 2002 in southeast Michigan⁶, and in Canada in July 2002 in Essex County, Ontario.²

Canada and Quebec

As of the CFIA page dated July 27, 2026, the beetle is present and regulated in all southern and middle areas of Ontario, Quebec and New Brunswick, and in Thunder Bay, Winnipeg, Halifax and part of Hants County, and Burnaby, New Westminster, Surrey and Vancouver.¹

Quebec has the longest list. It covers Montréal, Longueuil, Laval, Québec City, Sherbrooke, Trois-Rivières, Lévis and many regional county municipalities (MRCs). The zone keeps growing: Saguenay and the Charlevoix MRC were added in March 2025, and La Tuque and the Bonaventure and Charlevoix-Est MRCs on April 30, 2026.⁷ Check the CFIA list and map of regulated areas for your town or MRC before you move wood.

United States

Life cycle

Penn State Extension describes a one-year cycle. Its dates are for Pennsylvania, so expect them to shift where you live.⁸

1. Adults emerge in late May and early June, chewing out through a D-shaped exit hole. Activity peaks from mid-June to early July.⁸
2. Adults feed and lay eggs. They chew notches in ash leaves.⁵ Females live 21 to 22 days and lay 60 to 90 eggs.⁸
3. Larvae feed. Eggs hatch in 7 to 10 days, and the larvae tunnel under the bark, carving S-shaped galleries.⁸
4. Winter and spring. Larvae spend the winter in shallow chambers in the bark, then pupate in late April or early May.⁸

So for most of the year the insect is hidden under the bark. That is exactly where a split of ash firewood carries it.

Signs of emerald ash borer damage

First make sure the tree is an ash. Exit holes are small and hard to find, so look closely.⁵

How it spreads

The emerald ash borer is most commonly spread through the movement of firewood and other infested ash wood products.¹ Adults can fly up to 10 km (about 6 miles), but they generally stay near where they emerge.² A load of firewood can beat that in one drive.

Pests and eggs are hard to see on wood, so a lack of visible signs does not mean the wood is pest-free.⁹ APHIS warns that moving firewood even a short distance can spread pests, and that they can end up hundreds of miles away.¹⁰

Rules on moving firewood

Canada

In a regulated area, the CFIA regulates ash trees, logs, wood and nursery stock, firewood of all tree species, and the vehicles that carry them. They may leave only if treated to kill every life stage of the beetle and with a CFIA inspector's written permission.² For firewood:

• Ash firewood may not leave a regulated area, for commercial or private use.⁷
• Non-ash firewood can leave only through facilities registered in the CFIA's Approved Facility Compliance Program.⁷
• Moving firewood within a regulated area is allowed, and within non-regulated areas if the route doesn't cross a regulated area.⁹
• Moving firewood out of a regulated area needs a CFIA certificate for heat-treated firewood, or a compliance agreement.⁹

Penalties can reach $15,000 as an administrative monetary penalty, and up to $250,000 and/or two years in prison on prosecution.

Buy local, burn local

The CFIA's advice is simple:⁹

• Buy and burn firewood close to home.
• Ask your supplier where the wood came from.
• Buy wood cut less than 80 km (about 50 miles) from where it is sold.

In the US, APHIS says to buy firewood near where you will burn it, or heat-treated firewood with a state or federal certification mark.¹⁰ A Purdue University entomologist also suggests not stockpiling beyond one season's needs.¹¹

If you sell firewood, expect buyers to ask where it was cut, and know the regulated-area status of where you cut and deliver. Selling by the cord? See how big a cord of wood is.

You can also browse the

Can you burn ash with emerald ash borer?

Yes, near where the tree grew. Iowa State University Extension says infested ash doesn't need to be treated or chipped when removed. If you keep it for firewood, use it on your property and don't take it anywhere new.⁴ The Don't Move Firewood campaign agrees, and says to check local rules before moving it past your property line.¹²

• Deal with it soon. Dispose of infested wood as soon as you can, to lower the chance that beetles come out this year.¹² Purdue advises burning firewood before spring.¹¹
• Season it outside. Firewood brought indoors, especially in the first year after cutting, can release beetles in the house. They won't infest anything and won't live long.⁴
• Don't spray it. Do not treat firewood with insecticides.⁴
• Or chip it. A chipper or a municipal compost site are alternatives.

What to do if you suspect it

1. Don't move the wood until you know the rules.
2. Take photos of the signs and note the exact location.
3. Report it. In Canada, outside a regulated area, contact the CFIA or use the form on its emerald ash borer page.¹² Inside one, if you cut or trimmed an ash, call your city, municipality or the CFIA to learn how to dispose of it.² In the US, use the APHIS report form or call 1-866-322-4512.⁶

In Canada, the CFIA does not remove infested trees or pay compensation; the owner is responsible.²

Treatment in brief

Treatment deserves its own article. In short, Penn State Extension says removal is the main option, but an insecticide (imidacloprid) can be effective when applied in May or early June, and large trees should be treated before they are infested.

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