Emerald Ash Borer

an emerald ash borer adult on a tree trunk

Emerald Ash Borer

Emerald Ash Borer (EAB) is a pest that attacks Ash Trees. EAB larvae feed on the inner bark of Ash trees which prevents the tree from transporting water and nutrients. In Wisconsin, the majority of the Ash trees are already dead due to Emerald Ash borer as the pest spreads from tree to tree rather quickly. Some Ash trees, however, are thriving because of continued emerald ash borer treatment.

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How To Identify Emerald Ash Borer

Early Signs

  • D-shaped exit holes in bark (about ⅛ inch in diameter)
  • Notches on the side of leaves
  • Metallic-green colored beetles

Late Signs 

  • Yellow leaves
  • S-shaped “tunnels” underneath the bark
  • Thinning crown

For Homeowners 

  • Proper tree health – stressed trees will be more prone to infection
  • Proper mulching, watering, and pruning
  • Avoid too much fertilizer
  • Prune infected branches

For Professionals

  • Professional Tree health care services
  • Pruning
  • Insecticide application to kill crawlers (adults will die naturally)

Emerald Ash Borer Treatment

Step 1

Receive proper diagnosis from a Certified Arborist

Step 2

Professional pesticide injection

Step 3

Continue treatment every-other year

Emerald Ash Borer FAQs

What should I replace my Ash tree with?

If your ash tree was removed due to EAB, there are a number of trees we recommend planting in its place. Our professional arborists will recommend different options based on your desires for your property.

Do I need to continue EAB treatments for my ash tree?

Yes! To keep your ash tree from being re-infected from EAB, you must continue your treatments annually.

What damage does Emerald Ash Borer cause?

In the short-term, they cause damage to tree bark and leaves of the tree. If gone untreated, the tree will die and need to be professionally removed to prevent the spread of EAB in neighboring ash trees.

When should I be on the lookout for EAB?

Late June to Mid-August is when adults lay eggs in the ash bark, where the eggs then hatch. They will then make their way through the tree between August and October, live in the tree over the winter, and exit the tree as adults leave the D-Shaped exit holes.

Why is the Emerald Ash Borer a problem?

Ash trees make up roughly 15% of our tree population and are the 2nd most common tree in urban areas. Ash trees provide beauty and shade across the state. Wisconsin would seem empty without them. EAB is costing billions of dollars nationwide for trees that have gone untreated.

What is the best treatment for Emerald Ash Borer?

Ash trees need to be professionally treated every other year using science-based methods. Although there are DIY solutions available on the market, only the injection of a restricted pesticide by a licensed Arborist will prevent EAB from killing an Ash tree.

What trees are affected by Emerald Ash Borer?

In North America, ash trees are the only trees that are attacked by Emerald Ash Borer.

Should I be concerned if I have a healthy tree next to a tree with EAB?

Yes! EAB adults can fly up to ½ mile from where they emerge from the tree. Is important to keep a close eye on all ash trees in your area. NOTE: Moving ash tree firewood is an easy way to spread EAB and should be avoided to prevent the spread of EAB.

How do I prevent EAB?

The best way to keep your ash trees safe from EAB is to have an arborist come and inspect your trees annually. This way the EAB infestation can be caught early and prevent your tree from serious damage.