Emerald Ash Borer

While ash trees are very hardy and particularly beautiful in the fall, a new wave of exotic insects have been introduced to North America and pose a threat to our beautiful ash trees. This insect is called the Emerald Ash Borer (EAB).

When are my trees at risk and what should I look for?

An adult emerald ash borer beetle has distinctive metallic green coloring and is typically between 1/3 to ½ inch long. Adult beetles feed on foliage, but do little damage to the tree. The grub-like larva is the stage that poses the greatest risk for damage. Sometimes you will be able to see the S-shaped larval galleries under the bark.

EAB will spend the winter as mature larva in a small chamber in the outer sapwood of the ash tree. In early spring, the larvae will transform into pupae within the chamber. As the spring turns into summer, the adult beetle will emerge from the chamber and chew its way to the surface. The beetle will typically leave behind a D-shaped hole in the bark. This is one of the ways to identify that your ash tree has been infested with EAB.

Once an ash tree has been infested, the canopy of the tree will begin to thin in the upper portions of the canopy. However, this is not a guaranteed indicator of EAB. Several other diseases of ash trees can be associated with this symptom. It is best to contact your local arborist to properly diagnose EAB.

Another indicator of EAB infestation is increased woodpecker activity. Woodpeckers, especially during the winter, like to feed on the EAB larvae.

There are many solutions for effectively preventing and treating Emerald Ash Borer if diagnosed early. Your local arborist will develop a treatment or prevention plan that will be the most effective for your unique property. Find your local arborist here or view the full PDF.

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