The Emerald Ash Borer in Denver: What Every Homeowner Needs to Know

Since first being discovered in the United States in 2002, the Emerald Ash Borer (EAB) has become one of the most destructive tree pests in North America. Now that it’s confirmed in the Denver Metro Area, it’s critical for property owners to understand the insect’s life cycle, how it affects ash trees, and what treatment options are available — including EAB injections — to protect the urban canopy.

At Colorado Premier Tree Care, we specialize in diagnosing and treating ash trees infested with Emerald Ash Borer. As ISA-certified arborists, we are committed to preserving the health and longevity of trees in the Denver region.

What Is the Emerald Ash Borer?

The Emerald Ash Borer (Agrilus planipennis) is an invasive beetle native to northeastern Asia. It was first detected in the U.S. near Detroit, Michigan, in 2002, likely introduced through wood packing materials. Since then, it has spread to over 30 states, killing hundreds of millions of ash trees across the country.

EAB targets all native ash species, including green ash and white ash, both of which are common throughout the Denver area.

Life Cycle and Entomology of the Emerald Ash Borer

Understanding EAB’s life cycle is key to effective treatment:

Adult Beetles emerge from trees in late May through early July.

After mating, females lay eggs in bark crevices.

The eggs hatch within two weeks, and larvae burrow into the tree to feed on the inner bark (phloem), disrupting the tree’s ability to transport nutrients.

This larval stage is the most destructive, lasting from summer into fall.

The larvae overwinter under the bark and pupate in spring, emerging again as adults.

Over time, this cycle results in the decline and eventual death of ash trees—typically within 2–4 years if untreated.

How Emerald Ash Borer Is Impacting Denver

The arrival of EAB in Denver and the Front Range is a serious threat to the urban forest. Ash trees make up roughly one in six of all trees in the Denver metro area, and many were planted as shade and street trees decades ago. Cities like Boulder and Longmont have already removed thousands of infested trees.

If you're a Denver homeowner or business with an ash tree, now is the time to act. Early detection and proactive treatment are the best ways to save your tree.

Emerald Ash Borer Identification Tips

Denver property owners should watch for:

Thinning leaves or canopy dieback

D-shaped exit holes in the bark

S-shaped larval galleries beneath the bark

Bark splitting or increased woodpecker activity

If you notice any of these signs, contact a certified arborist immediately.

EAB Treatment in Denver: What You Can Do

The most effective defense against Emerald Ash Borer is professional insecticide injection, specifically trunk injections using products like Mectinite from Rainbow Treecare Scientific Advancements.

At Colorado Premier Tree Care, our ISA-certified arborists offer:

✅ In-tree trunk injections that provide 2 years of protection

✅ Precise dosage based on tree size and health

✅ Application by trained professionals using EPA-registered products

✅ Preventative and curative options for Denver ash trees

Trunk injections are safe, efficient, and environmentally responsible. If your tree is still healthy or only showing minor symptoms, it may be a strong candidate for preservation through treatment.

Trust Colorado Premier Tree Care for Emerald Ash Borer Control in Denver

If you live in Denver, Lakewood, Arvada, Littleton, Centennial, or anywhere in the Denver Metro Area, don’t wait until it’s too late. Our team at Colorado Premier Tree Care has been proudly serving the Front Range since 2017, offering expert diagnosis, pruning, removal, fertilization, and EAB injections.

🌳 Protect your ash tree investment.

📞 Call Colorado Premier Tree Care today for a consultation on Emerald Ash Borer treatments in Denver.

📍 Serving residential and commercial properties across the Denver Metro Area.