Emerald Ash Borer: Invasive Species Threatens Winnipeg Elm and Ash Trees

As the urban canopy of Winnipeg faces a new chapter in its battle against invasive pests, the arrival of the Emerald Ash Borer (EAB) has shifted from a distant threat to a local reality. For decades, our city has been defined by its lush, green boulevards, but the recent discovery of EAB in the Glenwood area signals a significant challenge for our ash and elm populations.

At Green Drop, we’ve spent decades helping trees—and the people who love them—thrive. We aren’t just tree experts; we’re your neighbors, and we know exactly how much our urban forest means to the character of Winnipeg. However, a new invader is on the march, and it’s one every homeowner needs to have on their radar: the Emerald Ash Borer.

What is the Emerald Ash Borer?

The Emerald Ash Borer (EAB) is a metallic-green wood-boring beetle native to East Asia. While it might look small, its impact is devastating. Unlike native pests that often target weakened trees, the EAB is aggressive, attacking and killing even the healthiest ash trees.

The real damage happens beneath the surface. The larvae of the beetle feed on the inner bark (the cambium layer), effectively “girdling” the tree. This cuts off the vital flow of water and nutrients, leading to a rapid decline and, eventually, death.

The Current Situation in Winnipeg

While EAB was first detected in the Archwood area in 2017, its spread was surprisingly slow for several years—likely due to our harsh prairie winters. But as of April 2026, we’ve seen the “first significant detection” since that initial find.

This video provides a direct look at how the City of Winnipeg is currently managing the removal of infested trees to slow the spread of the Emerald Ash Borer.

The beetle has now jumped the Seine River into the Glenwood neighborhood. Dozens of infected trees have already been marked for removal. This is a critical moment for Winnipeg’s canopy; in other North American cities, EAB has been known to decimate urban ash populations within a single decade.

Why are our Elm Trees at Risk?

You might be wondering: “If it’s called the Ash Borer, why are we talking about Elm trees?”

As arborists, we look at the urban forest as a whole. Winnipeg is famous for having one of the largest remaining stands of American Elms in North America, largely because of our aggressive management of Dutch Elm Disease (DED).

When a major species like Ash—which makes up roughly 30% of Winnipeg’s public trees—is threatened, it puts an immense strain on the entire ecosystem. The loss of ash trees increases the “heat island” effect and shifts the pressure of urban stressors onto our remaining elms. Furthermore, the techniques used to manage EAB often mirror the vigilance required for DED. Protecting one often means being smarter about the other.

5 Signs Your Tree Might Have Emerald Ash Borer

As the City focuses on public land, the responsibility for trees on private property falls to homeowners. Here is what our ISA-certified arborists recommend looking for:

1. Crown Dieback: The leaves at the very top of the tree begin to thin and die off.
2. Woodpecker Damage: Known as “blonding,” this happens when woodpeckers strip away outer bark to get to the larvae beneath.
3. D-Shaped Exit Holes: When adult beetles emerge, they leave a very distinct “D” shape in the bark.
4. Epicormic Shoots: Small “sucker” branches growing from the base or trunk of the tree—a sign the tree is under extreme stress.
5. S-Shaped Galleries: If bark has fallen off, you may see serpentine, S-shaped tunnels etched into the wood.

How to Protect Your Yard

The best defense is a proactive offense. Here’s how you can help:

• Don’t Move Firewood: This is the #1 way EAB spreads. Always buy and burn your wood locally.
• Professional Injections: For high-value ash trees, we can apply specialized insecticide treatments (like TreeAzin) that protect the tree from the inside out.
• Strategic Pruning: Regular maintenance by a certified arborist ensures your trees are healthy enough to withstand environmental stressors.
• Diversify Your Planting: If you are looking to add to your yard, consider species other than ash to help build a more resilient urban forest.

Get a Free Assessment

At Green Drop, we believe in science-backed tree care. If you’re worried about your ash trees or want to ensure your elms are protected for the season ahead, our team is here to help. We offer professional assessments to catch infestations early, giving your trees the best chance at survival.

Don’t wait until the canopy starts to thin. Contact Green Drop Trees today for a free yard assessment and let’s keep Winnipeg green together.