• Question: What is emerald ash borer?
  Answer: Emerald ash borer, Agrilus planipennis, is an exotic, invasive beetle that belongs to the metallic wood-borer family (Buprestidae). It infests and destroys native North American ash trees.


• Question: Where did emerald ash borer come from?
  Answer: Emerald ash borer is an insect native of Asia (eastern Russia, northeastern China, Mongolia, Taiwan, Japan, and Korea), where it can be found on several species of ash and is not considered a pest. Apparently, it was introduced by accident into Michigan via infested ash crating or pallets.


• Question: How long has emerald ash borer been in the United States? In Ohio?
  Answer: Emerald ash borer was first discovered in the United States June 2002 in the Detroit, Mich. area. The beetle was first found in Ohio Feb. 28, 2003 in Whitehouse, near Toledo (Lucas County). Evidence suggests that emerald ash borer had been in the United States for at least 10 years before it was detected.


• Question: Where has emerald ash borer been found?
  Answer: Emerald ash borer infestations have been confirmed in Michigan, Ohio, Indiana, Illinois, Maryland and Ontario, Canada. In Ohio, the beetle has been found in Auglaize, Cuyahoga, Delaware, Defiance, Erie, Franklin, Fulton, Hancock, Hardin, Henry, Huron, Logan, Lorain, Lucas, Marion, Medina, Mercer, Miami, Sandusky, Seneca, Ottawa, Paulding, Warren, Williams, Wood and Wyandot counties.

Identification and Diagnosis

• Question: What does emerald ash borer look like?
  Answer: Adults are dark metallic green, a half-inch long and one-sixteenth of an inch wide. Larvae are flat, legless, heavily fragmented, creamy white, and reach one inch in length when fully mature. To see pictures of the beetle, go to Link.


• Question: How do I tell if my ash tree has been infested by emerald ash borer?
  Answer: Common signs of infestation include D-shaped exit holes through the bark about one-eighth of an inch wide, S-shaped larval galleries just beneath the bark, thinning canopy, vertical splits in the bark, and unusual shoots sprouting from the main trunk or base of the tree. To see pictures of these symptoms, go to Link.


• Question: I think my ash tree has emerald ash borer. What should I do?
  Answer: First, take a look at the diagnostic check-off list available on this Web site at Link. If you find enough evidence of infestation, call the Ohio Department of Agriculture’s emerald ash borer hotline, (888) OHIO-EAB.


• Question: Who do I contact for more information and assistance?
  Answer: Contact the Ohio Department of Agriculture or your local Extension educator. For a list of contacts, go to Link.

Biology and Behavior

• Question: What is the life cycle of emerald ash borer?
  Answer: Emerald ash borer produces only one generation per year. Adults emerge from late May through early August, with emergence peaking in early July. They feed on foliage for one to two weeks prior to mating. Females produce about 50 to 100 eggs, which are laid individually on the bark surface or within bark cracks and crevices. As larvae hatch, they tunnel into the tree, where they feed on the phloem and outer sapwood. Larvae continue to feed through summer and into the fall, with most completing their development prior to over-wintering in the outer bark or just under the inner bark within the outer inch of sapwood. Pupation occurs in mid- to late-spring. Adults emerge soon thereafter to complete the cycle.


• Question: How does emerald ash borer spread?
  Answer: After emergence from their host tree, emerald ash borer adults fly to nearby ashes to mate and lay eggs. In addition, humans can contribute to the rapid spread of this beetle. The Ohio and Maryland infestations have been traced to infested nursery stock imported from Michigan before the insect was discovered. Transport of firewood and other ash materials from infested areas is another way of artificial propagation.


• Question: How fast can emerald ash borer spread?
  Answer: Emerald ash borer is a strong flier. Scientists have found in laboratory studies that the beetle has the physiological potential to fly up to six miles in a 24-hour period. However, infestations are spreading at a much slower pace: less than half a mile each year, based on research and observations.

Tree Damage and Impact

• Question: What damage does emerald ash borer cause?
  Answer: Emerald ash borer larvae tunnel under the bark of the host tree, feeding on the phloem tissue. The damage caused by the larvae disrupts the flow of nutrients between the tree’s roots and canopy. This damage results in canopy thinning, branch dieback, and eventually tree death. Larvae can destroy ashes within two to four years, but a heavy infestation could kill a tree in as little as one year.


• Question: Does emerald ash borer attack other trees beside ashes?
  Answer: Emerald ash borer is only known to attack ash trees in North America.


• Question: Does emerald ash borer attack healthy ash trees?
  Answer: While most native borers only kill severely weakened trees, emerald ash borer also kills healthy trees. Some of the trees attacked by the insect appear to have been stressed or weakened by drought, disease, or poor soil; however, many healthy ashes have been infested and killed as well.


• Question: What size trees does emerald ash borer attack?
  Answer: Emerald ash borer infests ashes ranging from one-inch-caliper nursery stock to large, fully mature trees in forests.


• Question: How can this pest impact Ohio?
  Answer: If not contained, emerald ash borer has the potential to wipe out ash as a component of Ohio forests and landscapes. Ash is one of the most common Ohio trees. It is also one of the primary commercial hardwoods in the United States and a very popular landscape tree. The spread of this insect threatens Ohio’s natural resources, as well as the wood manufacturing, nursery, landscaping, and firewood industries that rely on ashes. For details, go to Link.

Ash Trees and Native Pests

• Question: How do I distinguish emerald ash borer from native borers?
  Answer: Emerald ash borer leaves a D-shaped exit hole that is very distinct. To learn how to distinguish between emerald ash borer and native borers, go to Link.


• Question: How do I know if I have an ash tree?
  Answer: Go to Link to access an Ohio State University Extension fact sheet that will help you identify ash trees.


• Question: How common are ash trees in Ohio?
  Answer: Ash is one of the most common trees in Ohio, present in every forest type of the state. According to the most recent forestry survey (1991), there are 3.8 billion white ash trees in Ohio. While ash trees are found in every Ohio county, most are present in the elm/ash/red maple forest that covers more than 850,000 acres in northern Ohio. Ashes are also common in landscapes all over the state.


• Question: What species of ash trees are there in Ohio?
  Answer: Green ash (also known as red ash), Fraxinus pennsylvanica, common along streams in all but extremely hilly Ohio; many cultivated varieties exist. White ash, Fraxinus americana, especially in northeast Ohio. Black ash, Fraxinus nigra, common in northern and southwestern Ohio. Blue ash, Fraxinus quadrangulata, on limestone soils in western Ohio. Biltmore ash, Fraxinus biltmoreana, especially in southwest Ohio, thought by some to be a variety of white ash. Manchurian ash, Fraxinus mandshurica, non-native and sometimes planted as a landscape tree and in windbreaks. And European ash, Fraxinus excelsior, non-native and rarely planted. American mountain-ash, Sorbus americana, and European mountain-ash (rowan tree), Sorbus aucuparia, aren’t true ashes. Emerald ash borer is not known to infest them.


• Question: What other insects and diseases attack ash trees?
  Answer: Natives borers — such as banded ash clearwing borer and redheaded ash borer — commonly infest ashes in Ohio and can cause similar symptoms to those of emerald ash borer. Diseases such as ash yellows, ash anthracnose and verticillium wilt can also attack ashes.

Treatment and Research

• Question: Should I treat my ash trees?
  Answer: Members of the OSU Extension Nursery, Landscape, and Turf Team have developed the following recommendation regarding the use of insecticides for controlling EAB in Ohio: "Ash trees within Ohio Department of Agriculture’s EAB quarantine, as well as those outside the quarantine but within the vicinity (i.e. 10-15 miles) of a known infestation, are considered to be at risk. Annual insecticide treatments should be considered by those in these areas who want to try to protect their ash trees."


• Question: Are there any insecticides that kill emerald ash borer?
  Answer: Research trials and experience have shown that different types of insecticides can protect trees from EAB. However, success is not assured. Research suggests that best control will be obtained when treatments are initiated in the earliest stages of infestation before visible symptoms are present, or perhaps even the year before trees are infested. It is also important to realize that treatments will have to be repeated each year. In some cases, it may be more cost-effective to remove and replace the tree. For details about insecticides and their effectiveness, go to Link


• Question: Are there any species of ash that are resistant to emerald ash borer?
  Answer: Ohio State University researchers are studying Asian trees — in particular Manchurian ash, Fraxinus mandshurica — as a possible source of resistance genes against emerald ash borer. For more information about this research, go to Link.


• Question: Are there any natural enemies or biological control agents available to fight emerald ash borer?
  Answer: Emerald ash borer has natural enemies: fungi, bacteria, parasitic wasps and woodpeckers, for example. But so far those enemies aren’t knocking them back. That being said, many studies are gearing up to look for emerald ash borer enemies — those in both North America and Asia — with the goal of finding one or more to use to control the pest naturally. If, indeed, a candidate is found, and it happens to come from Asia, then further research will be needed to see if it’s safe for non-target insects and native ecosystems overall. Only then could it be deployed.

Prevention and Eradication

• Question: Are there any quarantines in place in Ohio to prevent the spread of emerald ash borer?
  Answer: There are two EAB quarantines in Ohio: one established by the Ohio Department of Agriculture and another one established by the U.S. Department of Agriculture. The state quarantine makes it illegal to move all hardwood firewood, ash trees and parts of an ash tree out of 26 counties: Auglaize, Cuyahoga, Delaware, Defiance, Erie, Franklin, Fulton, Hancock, Hardin, Henry, Huron, Logan, Lorain, Lucas, Marion, Medina, Mercer, Miami, Sandusky, Seneca, Ottawa, Paulding, Warren, Williams, Wood, and Wyandot. Violators face state fines up to $4,000. In addition, on Dec. 1, 2006, USDA quarantined the entire states of Illinois, Indiana and Ohio — more than doubling the previously quarantined area, which included the lower peninsula of Michigan. The federal order prohibits the movement of quarantined materials out of the state of Ohio without federal certification. These materials include all hardwood firewood; ash nursery stock and green lumber; and any other ash material including logs, stumps, roots, branches, as well as composted and uncomposted wood chips. Federal fines are much steeper than state fines.


• Question: Is it safe to transport ash firewood?
  Answer: It’s unsafe and also illegal to take, haul or otherwise transport ash firewood out the quarantined zones. The Ohio Department of Agriculture is also asking Ohioans to not transport any firewood around the state. Unseen but harmful tree pests - emerald ash borer, gypsy moth, longhorn beetle, Dutch elm disease - may be in that wood. By hauling it you can unwittingly spread them. It’s best and safest to use only local firewood.