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Emerald Ash Borer (EAB)

EABEmerald Ash Borer (Agrilus planipennis) is an invasive, wood boring beetle. It kills ash trees by eating the tissues under the bark. This metallic green beetle is native to East Asia and was brought to the United States accidentally, in the wood of shipping crates from China.

EAB moves far by hitching rides.

On its own, the beetle will only fly a few miles. However, it is easily and quickly moved to new areas when people accidentally move emerald ash borer larvae inside of infested firewood, ash nursery stock, and other ash items.

EAB has been detected in Wisconsin. In 2008, EAB was detected in Ozaukee and Washington Counties. Since then, EAB has been found in many areas, and numerous counties are quarantined,including Waukesha County. EAB has also been found in numerous states and Canadian provinces.

When an area is quarantined, it means that the following items cannot be transported out of the quarantined area:

  1. The emerald ash borer, Agrilus planipennis Fairmaire, in any living stage.
  2. Ash trees.
  3. Ash limbs, branches and roots.
  4. Ash logs, slabs or untreated lumber with bark attached.
  5. Cut firewood of all hardwood (non-coniferous) species.
  6. Ash chips and ash bark fragments (both composted and uncomposted) larger than one inch in diameter (in two dimensions).
  7. Any other item or substance that may be designated as a regulated item if a DATCP pest control official determines that it presents a risk of spreading emerald ash borer and notifies  the person in possession of the item or substance that it is subject to the restrictions of the regulations.

AshTreeEABEAB kills ash trees and Wisconsin has a lot of ash trees. EAB is not a threat to human health but it kills our native ash trees of any size, any age, healthy or unhealthy. The larva (the immature stage of EAB) spends its life inside ash trees, feeding on the inner bark where we cannot see it. This feeding disrupts the trees' ability to move water and nutrients back and forth from the roots to the rest of the tree. The tree starves and eventually dies.

A tree that has been attacked by EAB can die within 2-4 years. It is estimated that more than 50 million ash trees are dead or dying in the Midwest because of this insect.

Wisconsin forests contain more than 770 million ash trees, nearly 7 percent of the tree population. In urban areas, we estimate that, on average, 20 percent of trees are ash.


Symptoms and Signs

EAB-infested trees usually have multiple symptoms and signs of infestation if they have been infested for several years. Be aware that similar signs and symptoms can be due to other causes. The symptoms an ash tree shows when it is infested with emerald ash borer are similar to symptoms caused by other ash pests or diseases in Wisconsin. For example, crown dieback can occur due to EAB damage, but can also be the result of drought stress, soil compaction or verticillium wilt, just to name a few.

Therefore, it is important to look for a combination of at least two symptoms or signs when trying to figure out if emerald ash borer is in your ash tree. If you see two or more from the list below report your findings.

Symptoms and signs of EAB infestation include thin foliage and/or dieback in the upper crown, epicormic sprouts on the stem or at the base, 1/8” D-shaped exit holes, S-shaped larval galleries under the bark, and heavy woodpecker activity.


EAB larvae are up to 1.5” long and have distinctive bell-shaped segments. Collecting a suspected EAB specimen (larvae or adult) is very important for proper identification. Freezing the insect or preserving it in rubbing alcohol will maintain the specimen until an expert can examine it. 


Reporting Suspects

Monitor for symptoms of EAB infestation and report suspect trees and insects to the Wisconsin EAB hotline (1-800-462-2803), or email reports to:

For Additional Information

Visit Wisconsin’s Emerald Ash Borer Information Source This website has information about emerald ash borer identification, locations, management, laws and much more. The information is for homeowners, community leaders, green industry professionals, scientists, and anyone who enjoys the outdoors. Please visit this site often to stay informed about this invasive pest.

(Photos and information courtesy of Wisconsin Emerald Ash Borer Information Source and Wisconsin Department of Natural Resources)