Emerald Ash Borer Info

What is EAB?

The Emerald Ash Borer (Agrilus planipennis) is an invasive wood boring beetle, native to parts of Asia.  It was first discovered in Michigan in 2002, and has since killed tens of millions of Ash trees (Fraxinus spp.) across 21 states and Canadian provinces.  EAB was first confirmed in WI in 2008, then in Madison in 2013.  A current Wisconsin county EAB quarantine map can be found here: https://datcpservices.wisconsin.gov/eab/article.jsp?topicid=20.

EAB Identification.

EAB is a member of the metallic woodborer beetle group.  An adult beetle is approximately ½” long with a metallic, iridescent body that is emerald green in color.  The body is widest just below the head, and tapers down the length of the body.  It is highly unlikely to see an adult EAB; but they are most commonly viewed during mating periods extending mid-June to mid-July, in the later afternoon to early evening.  The EAB larva is a slender, cream-colored grub approximately 1.5” – 2” in length.  It has a bell-shaped body with brown protrusions located on the last segment.  It is the larval stage of EAB’s development that causes the damage and eventual death to our native Ash trees.

EAB Signs and Symptoms: 
  • Woodpecker damage or activity
  • Early fall color, canopy thinning, and branch dieback
  • Epicormic sprouting from base of tree or roots (“suckers”)
  • “D-shaped” exit holes
  • “S-shaped” feeding galleries under bark
  • Vertical bark splitting

Many of these signs and symptoms are difficult for the average homeowner to observe and take a trained eye for accurate identification.  Infested trees may not even show any signs or symptoms for the first 2-4 years of infestation.  Contact ITCS’s Certified Arborist to help make an accurate diagnosis and formulate a management plan.

Woodpecker damage
Woodpecker damage

Early fall color, canopy thinning, and branch dieback

Epicormic sprouting from base of tree or roots (“suckers”). Photo Courtesy of: Pennsylvania Department of Conservation and Natural Resources – Forestry , Bugwood.org

D-shaped exit hole
D-shaped exit hole

“S-shaped” feeding galleries under bark

Vertical bark splitting. Photo Courtesy of: Michigan Department of Agriculture, Bugwood.org


EAB Life Cycle:

The adult EAB beetle emerges in late May – June and lays its eggs on the bark of a typically stressed or declining Ash tree (though EAB is capable of attacking healthy trees as well).  After 2-3 weeks, the eggs hatch and the larva burrow beneath the bark and into the nutrient-rich cambium layer of the tree.  This is the layer responsible for the transport of nutrients and water within the tree.  The larva then feed on the cambial tissue, creating “S-shaped” galleries, and overwinter as pre-pupae in their gallery. In spring, the pre-pupae mature, and in 2-3 weeks emerge as adult beetles (late May – June).  As they emerge, each beetle leaves behind a “D-shaped” exit hole.  Some immature larva may take 2 seasons to emerge as adults, and will continue feeding until they are ready for emergence.  The adults feed on Ash leaves (little damage caused by this stage) for approx. 3-6 weeks, mate, and then repeat their life cycle.

Photos Courtesy of: Brian Sullivan, USDA APHIS PPQ, Bugwood.org

Photos Courtesy of: Brian Sullivan, USDA APHIS PPQ, Bugwood.org

I think I have EAB, what can I do?

The short answer is:  Don’t panic! EAB wil kill your tree if left untreated, but the good news is, there are treatments available today that are over 99.9% effective if administered in a timely manner.  The treatments work both as a preventative (preferable) and as a curative solution to EAB infestation and will protect your tree for up to 2 years!  Call ITCS today for a FREE estimate and consultation.  We are here to help you through this stressful ordeal and will help you decide if your tree is a good candidate for treatment.  Ask about our OMRI certified organic options that will fight EAB with less impact to the environment.


Other helpful Emerald Ash Borer links: