Emerald Ash Borer Found in Wayne County

This insect kills ash trees

Last Updated: August 18, 2008


The Emerald Ash Borer (EAB) is an exotic beetle from Asia that was accidentally introduced into North America prior to 2002. Its larvae feed on and kill ash trees. It is present in parts of Illinois, Indiana, Michigan, Ohio, Pennsylvania, West Virginia, Virginia, Maryland, Ontario, Canada and as of July 25, 2008, in Missouri.

MU Extension is part of an interagency task force that has been preparing for the arrival of EAB in Missouri. Now that EAB has been confirmed in the Show-Me State, response will be guided by the Missouri Emerald Ash Borer Action Plan which was recently completed by the task force. Taking a proactive approach through education and public awareness will greatly help reduce the impact of EAB in Missouri.


Frequently Asked Questions

Emerald Ash Borer
Photo Credit: David Cappaert, Michigan State University, Bugwood.org

Where and when was Emerald Ash Borer (EAB) found in Missouri?

On July 23, 2008, an employee with the U.S. Department of Agriculture APHIS' Plant Protection and Quarantine program collected 7 suspected EAB, Agrilus planipennis specimens from a purple prism trap placed in the U.S. Army Corps of Engineers' (USACE) Greenville Recreational Area on Lake Wappapello in Wayne County, Missouri.В  The trap was placed at this location as part of the EAB National Survey, which targets high risk sites for EAB trapping in 48 States.

Those seven beetles were confirmed to be EAB on July 25, 2008, by the U.S. Department of Agriculture.В 

Has EAB been found anywhere else in Missouri?

No. EAB has not been found anywhere else in Missouri.В  Trapping efforts continue, but to date, the insect has not been found at any other location.

What is being done about EAB at the Greenville site?

Efforts continue to determine the extent of the infestation at the ACOE Greenville Recreation Area through on-the-ground visual surveys. As of August 11, 2008, the total distance between infested trees is approximately 1.75 miles; 0.75 mile to the west and 1 mile to the east from the positive trap site. ALL infested trees are currently located on USACE land.

Is the area where EAB was found under quarantine?

Yes. As of August 8, 2008 the USDA Animal and Plant Health Inspection Service (APHIS) issued Federal Order DA#2008-44, 8/8/08 that placed Wayne County under a federal quarantine. This means that the interstate (between state) movement of EAB-host wood and wood products from Wayne County is regulated, including firewood of all hardwood species, nursery stock, green lumber, waste, compost, and chips of ash species.

This Federal Order allows Missouri 30 from August 8, 2008 to place an equivalent parallel quarantine in place for the intrastate (within state) movement of EAB-host wood and wood products from Wayne County or face an interstate quarantine for the entire state.

For information on regulatory requirements for movement of articles out of Missouri, contact APHIS State Plant Health Director, Mike Brown 573-893-6833.

What other actions have been undertaken to address this pest?

Several state and federal agencies (including MU Extension) had just completed the Missouri EAB Action Plan in the eventual arrival of the insect in the Show-Me State. That plan is now guiding all efforts. Click on the attached PDF file to view the complete plan.

What is being done about EAB in the rest of the state?

Annual surveys to detect the arrival of EAB are conducted by the Missouri Department of Conservation, the Missouri Department of Agriculture and the U.S. Forest Service at selected state parks, public and commercial campgrounds, and high-risk urban sites.В  These efforts include visual surveys as well as the use of purple prism-shaped traps and trap trees.В  All survey efforts will continue throughout the state.В  These trapping efforts are part of a national effort to monitor and limit the spread and impact of EAB.

The Missouri Department of Agriculture, Missouri Department of Conservation and the Missouri Department of Natural Resources have initiated an education and outreach program on the EAB and other pest species that are transported in firewood. A poster was produced in August 2006 and is being posted in campgrounds and recreational areas to alert the public to this threat.

A Missouri Conservationist article in March 2007 described the threat from EAB and other "hitchhiking bugs" that can be transported in firewood.В  Note that this publication was written before EAB was found in Missouri.


EAB Background

Where did the Emerald Ash Borer (EAB) come from?

The native range of EAB is eastern Russia, northern China, Japan and Korea.

When was EAB first discovered in North America?

EAB was first identified in southeast Michigan in 2002. It likely arrived several years earlier.

How did it get to North America?

Although no one knows exactly how the insect gained admittance to the U.S., it most likely arrived in solid wood packaging materials that originated from Asia. This could include ash wood used for crating, pallets or stabilizing cargo in ships.

Where is EAB now?

As of August 2008, EAB had been found in Illinois, Indiana, Michigan, Ohio, Pennsylvania, West Virginia, Maryland, Virginia, Missouri and now Wisconsin.

How does EAB harm ash trees?

The larval stage of EAB feeds under the bark of trees, cutting off the flow of water and nutrients. Branches of heavily infested trees will begin to die, usually near the top of the crown and progressing downward. The bark may crack directly over larval galleries. Adult beetles chew characteristic "D"-shaped exit holes as they leave former feeding sites below the bark. Infested trees gradually die over a two- to four-year period.

Which trees are susceptible?

All sizes and even very healthy ash trees can be killed. All of Missouri's native ash trees (green, white, blue and pumpkin ash), as well as many horticultural cultivars (cultivated varieties of ash or hybrids between species of ash), are susceptible to EAB infestation. Research studies are ongoing to test for resistance in various cultivars with the hope that some may survive an infestation.

How important are ash trees to Missouri?

Information from community tree inventories indicates that overall, ash trees comprise about 14 percent of street trees in Missouri communities and over 21 percent of trees in urban parks (data compiled by the Missouri Department of Conservation, 2005). The percentages rise to well over 30 percent in some parks and residential subdivisions. In natural forest stands, ash trees comprise about 3 percent of total trees (USDA Forest Service, Forest Inventory and Analysis data).

What does EAB look like?

The adult beetle is dark metallic green, bullet-shaped and about one-half inch long (7 to 13 mm) and 1/8 inch (3 mm) wide. While the back of the insect is an iridescent, metallic green, the underside is a bright, emerald green. The body is narrow and elongated, and the head is flat. The eyes are kidney-shaped and usually black. The EAB larva is white and flat, has distinctive bell-shaped segments and can grow up to 1.2 inches (30 mm) long.

How does EAB spread?

EAB moves short distances by flying and longer distances through movement of infested ash. Adults typically do not fly far from where they emerge, but this depends on the availability of food (ash trees). In Michigan, studies have shown that the vast majority of insects fly only several hundred yards from where they emerge. EAB is most commonly spread long distances through the movement of infested firewood, nursery stock or ash logs. Transport of infested firewood remains an ongoing concern for movement of EAB and other forest pests.

What is being done about EAB?

There is a national effort to limit the spread and impact of EAB. A national plan, coordinated by the U.S. Department of Agriculture, Animal Plant Health Inspection Service (APHIS), guides what federal, state and local officials must do to manage this insect.

Infested areas are quarantined, which means that selected materials such as firewood from deciduous trees, ash nursery stock, and ash logs may not be moved out of infested areas. Where outlying infestations are detected, large numbers of infested ash trees are sometimes cut and destroyed to reduce EAB populations. Research is underway in many universities and government agencies to find better ways to detect and manage this pest.

Are there any natural enemies of EAB?

Yes, scientists have observed parasitic wasps attacking egg or larval stages of the emerald ash borer in its native land. Efforts are underway to determine if these wasps could be safe and effective controls of EAB in America. Unfortunately, this process is time-consuming and these wasps may not be available for effective use in current EAB containment efforts. Other studies are testing various fungi and bacteria that infect beetles for possible use as "natural insecticides."


Risk Assessment

What is the possibility of EAB reaching Missouri?

High. EAB has already been found at the Lake Wappapello Army Corps of Engineers Greenville Recreational Area in Wayne County, Missouri.В 

What is the possibility of the insect surviving transit to Missouri?

High. EAB can survive under the bark of ash trees.В  In fact, the primary way this insect is moved is in firewood.В  We strongly encourage campers to leave the hardwood firewood at home and to use only local sources of firewood.В  If you must bring firewood, it is strongly suggested that you burn all of it. No hardwood firewood can be moved out of an area that has been quarantined (i.e., Illinois, Michigan, Indiana, Ohio, etc.).В 

What is the probability that it will spread to new areas in Missouri?

Moderate. The insect travels to new locations primarily on firewood.В  That is why it is so critical that Missourians leave their firewood at home and use wood only from local sources.

Is it likely to establish and maintain viable populations where introduced?

High. Here are three ways of looking at the relative probability that viable populations of EAB can be established if the insect is introduced in an area. Figure 1 shows the estimated total number of ash trees by county. If we look at the proportion of ash species from a timber volume point of view (for commercial purposes) as in Figure 2, or from a total number of trees (for aesthetic purposes) as in Figure 3, the relative risk increases outside of the oak-hickory dominated Ozarks. And, for any given county, the risk increases if there is a high concentration of ash trees in a localized area, such as a city or town.

Figure 1 Number of ash trees per county
Figure 2 Percent ash tree volume
Figure 3 Percent ash number of trees

What is the likely economic impact of EAB?

High in urban areas and moderate in the forest industry. A quarantine could be implemented prohibiting the movement of all firewood, ash logs and ash nursery stock out of Wayne County. The economic impact in Wayne County will be moderate and primarily felt by firewood producers and the 12 sawmills located in the county. The impact will be even higher should surrounding counties be added to the quarantine. It is estimated that 3 percent of Missouri's forest is ash. The decision on a quarantine will be made after the infestation have been delimited.

The economic impact to Missouri towns is expected be high as towns struggle to remove dead ash trees. Standing dead trees will be serious threat to public safety. Removal of dead trees from cities, towns, parks, campgrounds will require millions of dollars. It is estimated that 14 percent of the trees in our towns is ash. There are very few ways to control EAB and no control measure has proven effective on a large scale. The infestation in Wayne County is fortunately located a distance from any town of significant size minimizing the initial economic impact to Missouri towns.

The state of Ohio estimates that the impact to their economy and to homeowners from EAB could reach $3 billion.

What are the likely environmental impacts?

High. It is expected that EAB will diminish ash in Missouri's forests to a very low level. This impact will be most felt in the urban areas.В 

What are the likely social and political impacts?

Medium. Everywhere EAB has been discovered, it has impacted communities and industries (i.e., forest products, arborists and nurseries).В Federal quarantines constrain industry and municipalities struggle to keep parks and streets safe.В As more and more states have confirmed the presence of this pest, federal funding for eradication and/or mitigation of this insect have dwindled to almost nothing. This leaves states and municipalities to find financial assistance from other sources.В 


How to Identify Ash Trees

Michigan State Extension has an excellent bulletin to assist you in distinguishing among some common deciduous landscape trees frequently confused with ash, including: elm, boxelder, mountainash, walnut and hickory.


Symptomatic Trees

Common symptoms expressed by ash trees under attack by EAB include a thinning tree canopy, excessive woodpecker activity (as they attempt to get to the larvae under the bark), and epicormic branching both on the tree stem and also at the tree's base.

Thinning Canopy

Thinning canopy
Woodpecker Damage

Woodpecker Damage
Epicormic Branching

Epicormic Branching


How to Identify EAB

The adult emerald ash borer is a bright green metallic beetle with a slender body (approximately 1/2 inch long and 1/8 inch wide). The adult beetle emerges from the tree leaving a D-shaped exit hole that is 1/8 inch in diameter.

An excellent Michigan State Extension Bulletin showing EAB signs and symptoms can be obtained.

Emerald Ash Borer damage
Damage from emerald ash borer
Photo Credit: James W. Smith, USDA APHIS PPQ, Bugwood.org

Emerald Ash Borer emergence hole
D-shaped emergence hole of adult EAB
Photo Credit: David Cappaert, Michigan State University, Bugwood.org
Emerald Ash Borer adult
Adult, emerald ash borer
Photo Credit: David Cappaert, Michigan State University, Bugwood.org

Emerald Ash Borer larvae
Larvae, emerald ash borer
Photo Credit: David Cappaert, Michigan State University, Bugwood.org

The larvae (immature stage) is flattened, cream-colored, approximately one-inch long when fully developed and feeds underneath the bark of ash trees, leaving S-shaped galleries packed with fine frass.

The beetles are most likely to be found on or around ash trees. Infested trees may show symptoms such as canopy dieback, vertical bark splits, sprouts from the base or on the trunk, D-shaped holes and woodpecker feeding.


Look-alike Insects

There are other insects and borers that are native to Missouri which also attack ash. So, you might check out the attached link before reporting a suspected find.

Look-alike insects

Top Row (From left to right): EAB, bark-gnawing beetle, Buprestis rufipes, green June beetle, caterpillar hunter.
Bottom Row (L-R): Japanese beetle, tiger beetle, green stinkbug, dogbane beetle, metallic wasp.


What You Can Do

Is there anything I can do now to protect the ash trees in my yard from EAB?

Keeping trees vigorous and healthy by proper pruning, mulching, watering and avoiding wounding helps them resist insect attacks. No insecticides are 100 percent effective against emerald ash borer attacks. Not bringing firewood from other states is one of the best ways to avoid bringing home unwanted tree pests.

If I have ash in my woods, should I be doing anything?

At this time, you need not change your scheduled timber management activities.

Is ash still a viable choice when considering what to plant in my yard?

In general, having a diversity of tree species in your yard, on your street or in your community is your best defense against all tree health problems. Plant no more than 10 percent of any one tree species in your yard. Because of the severe nature of the EAB threat, the wisest choice at this time is not to plant any ash trees.


To Report Possible EAB Sightings

You can report possible sightings of EAB by


Additional Information

More information is available at the following Web sites.

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