The Emerald Ash Borer

The environmental, social, and economic impact this pest is having on Ohio’s rural and urban forests is staggering.

The Division of Forestry is taking proactive steps on state forests, as well as encouraging municipalities and woodland owners to do likewise. EAB larvae feed on the living portion of the tree, directly beneath the bark. This eating habit restricts the tree’s ability to move essential water and nutrients throughout the plant. In three to five years, even the healthiest tree is unable to survive an attack.

This pest can be difficult to identify because the symptoms that infested ash trees exhibit are much like the symptoms of our native ash borers. The main symptoms of an EAB infested tree are branch dieback, sprouting around the base of the tree, and unusual woodpecker activity.

Signs of an EAB infestation are very unique. These include 1/8-inch, D-shaped exit holes, and if the bark is peeled back, a serpentine pattern of tunnels packed with sawdust.

Emerald Ash Borer (Agrilus planipennis) is an ash tree-killing insect from Asia that was unintentionally introduced to southeastern Michigan several years ago. In February of 2003, it was first found feeding on ash trees in northwest Ohio.

This Asian pest is part of a group of insects known as metallic wood-boring beetles. EAB affects all species of native ash found in Ohio. Because North American ash trees did not coexist in association with this pest, they have little or no resistance to its attack.


Ohio’s Ash Population
When Emerald Ash Borer was first discovered in Ohio (2003), the only available hard data for the number of ash trees came from the USDA Forest Service’s Forest Inventory & Analysis (FIA) Program. This was data last released in 1991.

At that time, the Forest Service listed Ohio as having 3.8 billion white ash trees. When, adding the relative percentage of green, blue, and pumpkin ash in our state, that led to a number of just greater than 5 billion total ash trees in Ohio. These numbers represent all sizes of trees, including seedlings.

The Forest Service has released its latest FIA data for our state and they are now using a new data collection process that does not count all trees. The new system counts only trees that are at least one inch in diameter. This new data indicates a total of more than 254 million ash trees (all species) one inch in diameter and greater*.  The new Forest Service counting method accounts only for the economically significant number of trees.

What do I need to know about firewood?
Emerald Ash Borer can become established when infested firewood is transported to new areas. Help stop the movement of exotic pests. DO NOT MOVE FIREWOOD.