Emerald Ash Borer Confirmed in Denver – What It Means for Your Ash Trees
Who would think a bug smaller than a penny could threaten whole neighborhoods of trees?
That’s exactly what’s happening in Denver.
Entomologists have now confirmed that emerald ash borer (EAB) – an invasive beetle responsible for killing tens of millions of ash trees across North America – is officially in the City and County of Denver. It was recently detected in traps and confirmed by lab testing, and city officials expect it to spread quickly across the metro area.
For homeowners and property managers with ash trees, this is the moment to pay attention and take action.
What Is Emerald Ash Borer – and Why Is It Such a Big Deal?
Emerald ash borer is a small, metallic-green beetle whose larvae tunnel under the bark of ash trees, cutting off the flow of water and nutrients. Over time, this starves the tree and leads to canopy dieback and, ultimately, tree death.
Across the United States and Canada, EAB has wiped out millions of ash trees. In Colorado, ash makes up roughly 15% of the urban forest, which means this one insect threatens a huge portion of Denver’s tree canopy.
Once EAB gets established in an area, untreated ash trees typically die within a few years.
What EAB’s Arrival in Denver Means for Your Property
Now that EAB has been confirmed in Denver, every untreated ash tree is at risk.
Here’s what that means for homeowners, HOAs, and commercial properties:
High removal costs later: Dead or severely infested ash trees become brittle and dangerous. Removing them – especially large ones near homes, cars, or power lines – can be significantly more expensive than proactive treatment.
Safety concerns: Dead limbs and failing trunks are a liability. Falling branches can damage property or injure people on sidewalks, in yards, or in parking lots.
Loss of shade and curb appeal: Mature ash trees provide shade, cooling, privacy, and character to your landscape. Losing them impacts both comfort and property value.
The key point: once EAB damage is advanced, treatment is rarely successful. Waiting until you “see a problem” is usually waiting too long.
Step One: Find Out if You Have Ash Trees
If you’re not sure whether your trees are ash, you’re not alone. Many property owners don’t know what species they have.
Ash trees typically have:
Compound leaves with 5–9 individual leaflets
Leaflets arranged in pairs directly across from each other on the stem
Opposite branching (twigs and branches grow in pairs on the stem)
Bark that can develop a diamond-shaped pattern as the tree matures
If you’re unsure, a professional arborist can identify ash trees for you during a site visit.
Step Two: Choose a Protection Plan (Before It’s Too Late)
For ash trees you want to keep, preventive treatment is the only reliable way to protect them from EAB.
At DLC Arbor, we use trunk-injected insecticides specifically designed to protect against emerald ash borer. When applied correctly by a licensed professional:
The treatment moves through the tree’s vascular system, where EAB larvae feed
It provides multi-season protection when timed properly
It avoids the drift and exposure risks associated with sprays
Preventive trunk injections are especially important for:
Large, mature ash that provide significant shade
Trees near homes, driveways, or high-traffic areas
Trees that are still healthy or only showing very early signs of stress
Once a tree is heavily infested or has lost a significant portion of its canopy, removal may be the only safe option – and that’s almost always more costly than years of preventive care.
What to Expect During a Site Review
If you suspect you have ash trees – or you already know you do – it’s a good idea to schedule a professional review.
During a visit, our team can:
Walk your property and identify all ash trees
Assess each tree’s health, size, and location
Look for early signs of EAB activity (thinning canopy, bark splits, woodpecker activity, etc.)
Recommend a treatment or removal plan based on your goals and budget
From there, we’ll design a tailored treatment schedule so you know exactly what to expect over the next several years.
Don’t Wait for Visible Damage
By the time emerald ash borer damage is obvious from the street, it’s often too late to save the tree.
Acting now – while your ash trees are still healthy – gives you:
The best chance of long-term survival
Lower overall costs compared to emergency removals
Peace of mind knowing you have a plan in place
Ready to Protect Your Ash Trees?
EAB’s arrival in Denver is a turning point, but it doesn’t have to mean losing every ash tree on your property.
DLC Arbor can help you:
Identify ash trees at risk
Prioritize which trees to protect
Implement a proven trunk-injection treatment plan
Let’s get ahead of this together.
📞 Call us at 303.378.8000
📅 Or request a free estimate to schedule a site review and EAB protection plan for your property.
