303.623.8733

A Silent Threat: Protecting Denver’s Ash Trees from the Emerald Ash Borer

Published: July 31, 2025

Tree Care Services

Our ISA Certified Arborists ensure that you get the highest quality tree care.

Free Estimates

We offer free estimates for tree planting, trimming, removal, cabling and bracing.

Plant Health Care Services

We believe in being proactive in preventing insect infestations and disease outbreaks.

Insect and Disease Control – A Silent Threat: Protecting Denver’s Ash Trees from the Emerald Ash Borer

Denver’s urban forest is one of its greatest assets, and ash trees make up a significant portion of our city’s beautiful canopy. However, a silent and destructive threat is looming over these trees: the Emerald Ash Borer (EAB). This invasive beetle has been spreading throughout the Front Range, and it poses a serious risk to every ash tree in the Denver community.

Understanding the threat and taking proactive steps with professional insect and disease control is the best way to protect your property and our urban forest.

What is the Emerald Ash Borer (EAB)?
The Emerald Ash Borer, or EAB, is a small, metallic-green beetle native to Asia. Its larvae are the true culprits, as they tunnel just beneath the bark of ash trees, feeding on the living tissue that transports water and nutrients. This feeding effectively “belts” the tree from the inside out, slowly cutting off its lifelines. Once an ash tree is infested, it will almost certainly die within 2-4 years if left untreated.
emerald ash borer
What are the Signs of an EAB Infestation?

Early detection is key to saving an infested tree. Since the damage happens beneath the bark, it can be difficult to spot until the infestation is advanced. Keep an eye out for these tell-tale signs:

  • Thinning Canopy: One of the first signs is a sparse or dying canopy, often starting at the top of the tree.
  • D-Shaped Exit Holes: As adult beetles emerge from the tree, they leave behind tiny, D-shaped holes about 1/8 inch wide in the bark.
  • S-Shaped Galleries: If the bark peels away, you may see distinct, winding S-shaped tunnels left by the larvae.
  • Increased Woodpecker Activity: Woodpeckers are a natural predator of EAB larvae. An increase in woodpecker damage on the trunk or limbs of your ash tree can be a strong indicator of an infestation.
  • Vertical Bark Splitting: As the tree attempts to heal, vertical cracks or splits may appear in the bark.

If you notice any of these signs, it’s crucial to contact a certified arborist immediately for an inspection.

emerald ash borer
Proactive Insect and Disease Control is Your Best Defense

Once EAB is in a community, it is a permanent threat. The most effective strategy is a proactive one. For healthy ash trees, our certified arborists can provide preventive treatments to protect them from infestation. These treatments are often administered as a trunk injection, which is highly effective and safe for the environment.

However, EAB isn’t the only threat to Denver’s trees. Our comprehensive insect and disease control services are designed to protect all your trees from a wide range of pests and pathogens, including:

  • Aphids and Mites: Common pests that can damage leaves and reduce a tree’s vigor.
  • Pine Beetles: A major threat to our coniferous trees like pines and spruces.
  • Fungal Diseases: Issues like Anthracnose or Cytospora canker can damage leaves, branches, and trunks.
  • Dutch Elm Disease: A devastating fungus that can quickly kill elm trees.
Our Approach to Tree Health in Denver

We believe in a science-based approach to tree care. Our certified arborists begin with a thorough inspection of your trees to accurately diagnose any issues. We then recommend a targeted treatment plan that is specific to your tree’s needs. We use only the safest and most effective methods.

Protecting your ash trees from EAB and maintaining the health of your entire landscape is an investment in your property and our community. Don’t wait until it’s too late!

If you have ash trees on your property or are concerned about any signs of insect and disease control problems, contact us today at (303) 623-8733 (TREE) or use our Free Estimate Form for a professional assessment.

Related Posts