Is Emerald Ash Borer Killing Your Trees? - U of I Extension

News Release

Is Emerald Ash Borer Killing Your Trees?

This article was originally published on July 1, 2009 and expired on August 1, 2009. It is provided here for archival purposes and may contain dated information.

The unwanted invasion of the Emerald Ash Borer (EAB) insect into Illinois is a story that continues to develop. New site confirmations document its presence away from the Chicago area, as far south as Bloomington, expanding the state quarantine lines. Infestations are now documented in southeast Missouri, southern Indiana and Kentucky.

As an exotic invasive insect, EAB has no natural predators or control in our country. It threatens all ash (Fraxinus spp) species in this country, particularly the large native green and white ash stands in the eastern U.S. In Illinois there are an estimated 130 million native and landscape ash trees that could be lost.

Illinois Department of Agriculture personnel have placed monitoring traps throughout the state to detect spread of this insect.

"These large, purple, kite-like traps, hung high in ash trees, contain a scent lure to draw the EAB beetles," explains Tony Bratsch, University of Illinois Extension horticulture educator. "The beetles then become stuck to the trap's sticky surface. Traps will remain through the early summer and then removed for evaluation."

So how do you know if EAB has come to your neighborhood or is killing your trees? Look for these symptoms on ash trees:

  • Presence and attack on either a healthy or weak ash tree. This is in comparison to native ash/lilac and redheaded ash borers that attack only weakened or stressed trees.
  • For older trees, a gradual decline and dieback occurs in the crown or top of the tree
  • Young ash trees will yellow and drop leaves prematurely
  • Significant lower trunk sucker growth occurs as the tops die
  • Bark will spilt or have fissures.
  • The boring larvae leave distinct "S-shaped" feeding tracks under the bark
  • Adult emergence holes are the size of a BB, an eighth-inch diameter which are distinctly "D-shaped" --- circular, but with one side of the circle straight.
  • Presence of adults on leaves and twigs. The EAB beetle is the length of a penny, bright green and narrow in body. It is elusive, often high in the tree and difficult to spot. It lightly feeds on ash leaves in the summer.
  • Woodpecker damage with random, large, feeding holes. This is compared to sap suckers, which makes feeding holes in straight, horizontal lines.

While it is possible that EAB may have gained a foothold in your community or county, it is a slow-moving insect that, to date, has been confirmed only as far south as the Bloomington area. This status could change when the traps are retrieved and evaluated later this summer.

Because of drought stress in 2006 and 2007 Bratsch says many ash trees became infested with native ash borers and are in decline. Do not confuse this condition with EAB infestation, even though similar crown decline and tree death occurs. Native ash/lilac and redheaded ash borer, false powder-post beetle and eastern ash bark beetle larvae also feed under the bark of ash, but they leave random feeding tracks and exit with larger, round, circular holes.

Though many chemical and biological control methods are being researched for EAB management, Bratsch says that control is variable for infested trees. However, tree life can be extended several years or more with proper treatment. Dead trees and those in late stages of decline should be removed. Preventative chemical control measures for non-infested trees are effective, but costly. Only when EAB is confirmed in a neighboring area are preventative measures recommended for non-infested trees.

Suspected EAB infestations can be reported through your local U of I Extension office. The Illinois Department of Agriculture also maintains a toll-free hotline for reporting: 1-800- 641-3934. For more information about EAB and the status of the current quarantine log on to

Source: Anthony Bratsch, Extension Educator, Horticulture (Serving East-Central and Southeastern Illinois),

Pull date: August 1, 2009