Emerald Ash Borer

PEST ALERT:  Ash Trees Dying from Emerald Ash Borer


Multiple Ash Trees in Campus West Infected with EAB

A Devastating Threat to Our Ash Trees

  • Ash trees are among the most common shade trees
  • Over 200 million ash trees have been lost nationwide
  • Experts predict 99% of untreated ash trees will die
  • Treatments are proven to be effective

Emerald Ash Borer: Colorado’s Growing Crisis

The Emerald Ash Borer (EAB), an invasive beetle from Asia, is one of the most destructive and costly pests in U.S. history. It is now infecting trees in Fort Collins, just as it has devastated ash trees across the country.

How EAB Infects Ash Trees

  1. Eggs Laid on Bark – Adults emerge and feed on Ash leaves.  They then mate and lay eggs on the bark of ash trees.
  2. Larvae Burrow Inside – When the eggs hatch, larvae tunnel into the tree, feeding on the inner layers (phloem and cambium), which disrupts the tree’s ability to transport water and nutrients.
  3. Galleries Form – The larvae create winding tunnels under the bark, cutting off the tree’s nutrient supply.  They then pupate into adults and emerge the following season.
  4. Tree Decline & Death – Tree becomes stressed, weakens, and dies within 2-4 years of infestation.

What You Can Do

  • Inspect Your Trees – Check for signs of infestation, including D-shaped exit holes, bark splitting, or thinning canopies.
  • Plan for Treatment – Preventative treatments have been proven effective in protecting ash trees.
  • Water Year-Round – Keeping your trees well-watered throughout the year helps maintain their health and resilience. Well-hydrated trees also respond better to treatment.
  • Avoid Moving Firewood – EAB spreads through infested firewood, so never transport logs or branches.
  • Start Planning – Remove unwanted ash trees to reduce the spread of EAB. Infected trees become much more hazardous to remove.

Take Action Today!

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