What Is the Emerald Ash Borer?
The Emerald Ash Borer (EAB) is a metallic green beetle native to Asia that arrived in the United States in the early 2000s and has since killed hundreds of millions of ash trees across North America. It is now present across Iowa and is the most significant threat to ash trees in Central Iowa.
EAB attacks all species of North American ash trees (Fraxinus spp.). The larvae feed beneath the bark, cutting off the tree's ability to transport water and nutrients. An untreated ash tree typically dies within 2–4 years of infestation, often faster in weakened trees.
Iowa status: EAB is confirmed throughout Iowa, including Story, Boone, Hamilton, and Polk counties. If you have ash trees and haven't treated them, there's a very good chance they're already infested, or will be soon.
How EAB Kills Ash Trees
Adult beetles emerge in late spring to early summer and feed on ash leaves, but this feeding rarely causes significant damage on its own. The real threat is the larvae. After mating, female beetles lay eggs on the bark. When the eggs hatch, larvae bore beneath the bark and create winding, S-shaped galleries in the cambium, the living tissue just beneath the bark that moves water and nutrients throughout the tree.
After years of larval feeding, the tree's ability to transport water is completely disrupted. The result is:
- Crown thinning and dieback starting at the top of the tree
- "Blonding" - woodpeckers stripping bark to feed on larvae, leaving light-colored patches
- D-shaped exit holes (about 1/8 inch) in the bark where adults emerge
- Epicormic sprouting - water sprouts growing from the trunk as the tree tries to survive
- Death of the entire tree within a few years
Our EAB Treatment: Trunk Injection
Emma Joe's Tree Service uses direct trunk injection of EAB insecticide, the most effective and environmentally responsible treatment method available. We are Arborjet certified applicators, trained and equipped to apply these treatments correctly.
The insecticide is injected directly into the tree's vascular system, where it moves throughout the tree and kills larvae feeding beneath the bark. When applied correctly by a licensed professional, this treatment is 90% effective at preventing EAB-related decline.
Treatment Schedule
- Injections should be applied every two years to maintain protection
- Best results when treatment begins before the tree shows significant EAB damage - trees that have lost more than 50% of their canopy have a poor prognosis even with treatment
- Timing is ideally spring through early summer when the tree is actively moving water
Is it worth treating? Yes, if your ash tree is healthy or only lightly affected. Ash trees are often large, valuable landscape trees that are expensive to remove and replace. A biennial injection is far more cost-effective than removal and replanting. If the tree is already heavily in decline, we'll be honest with you about whether treatment makes sense.
Signs Your Ash Tree Has EAB
- Crown dieback starting at the top and outer edges
- D-shaped exit holes (about 1/8") in the bark
- Bark blonding from woodpecker activity
- S-shaped larval galleries visible under peeled bark
- Water sprouts (suckers) growing from the lower trunk
- Increased leaf drop or thinning canopy
What Happens If You Don't Treat
Untreated ash trees die. Once a large ash dies, removal becomes expensive and dangerous, dead ash wood becomes extremely brittle quickly, making removal much more costly and risky than removal of a live tree. Treating now is almost always the more economical choice when the tree has value to the property.
Service Area
We treat EAB throughout Central Iowa including Roland, Story City, Ames, Boone, Nevada, Huxley, Ankeny, Gilbert, and surrounding communities in Story, Boone, Hamilton, and Polk counties.