The natural range of Agrilus planipennis, or the emerald ash borer, is eastern Russia, northern China, Japan, and Korea. Before June of 2002, it had never been found in North America.

We don't know for sure, but it most likely came in ash wood used for stabilizing cargo in ships or for packing or crating heavy consumer products.

In North America, ash trees are the only tree species to be attacked by EAB. Trees in woodlots, as well as landscaped areas, are affected. Larval galleries have been found in trees or branches measuring as little as 1-inch in diameter. All species of North American ash appear to be susceptible. EAB was also found in white fringetree (Chionanthus virginicus) in an area of Ohio in 2015, though widespread attack of white fringetree has not been reported.

In 2002, EAB was first found in six counties in southeastern Michigan, but as the ability to detect and find EAB improved, the number of EAB finds in different states and areas of Canada has risen. EAB infestations are now found in 35 states, as well as five Canadian provinces, making EAB an international pest problem. It is important to watch for signs and symptoms of EAB in areas where it hasn’t been seen before.

The leafy canopy of infested ash trees will begin to look thin. EAB chews through the tree’s water and nutrient-conducting tissues, strangling the tree. If there is a high population of EAB in the tree, the leafy canopy in ash trees will start to die. A third to a half of the branches may die in one year. Most of the canopy will be dead within 2 years of when symptoms are first seen. Sometimes ash trees push out sprouts from the trunk after the upper portions of the tree dies. The adult beetles will leave a “D”-shaped hole in the bark, roughly 1/8 inch in diameter, when they emerge in June.

The adult beetle is dark metallic green in color, 1/2 inch-long and 1/8 inch wide. This guide has photos and other good information on the beetle.

Recent research shows that the beetle can have a one- or two-year life cycle. Adults begin emerging in mid to late May with peak emergence in late June. Females usually begin laying eggs about 2 weeks after emergence. Eggs hatch in 1-2 weeks, and the tiny larvae bore through the bark and into the cambium - the area between the bark and wood where nutrient levels are high. The larvae feed under the bark for several weeks, usually from late July or early August through October. The larvae typically pass through four stages, eventually reaching a size of roughly 1 to 1.25 inches long. Most EAB larvae overwinter in a small chamber in the outer bark or in the outer inch of wood. Pupation occurs in spring and the new generation of adults will emerge in May or early June, to begin the cycle again. View the EAB life cycle

We know EAB adults can fly at least 1/2 mile from the ash tree where they emerge. Many infestations began when people moved infested ash trees from nurseries, logs, or firewood to other areas that did not have infestations. Shipments of ash nursery trees and ash logs with bark are now regulated, and transporting firewood outside of the quarantined areas is illegal, but transport of infested firewood remains a problem.
PLEASE - do not move any ash firewood or logs outside of the quarantined area.

Research has shown that EAB was infesting ash trees in Michigan 10 to 12 years before its initial discovery in 2002. The initial infestation probably started from a small number of beetles. Over the next few years, the population began to build and spread. By 2002, many trees in southeastern Michigan were dead or dying. In North America, native ash trees have little or no resistance to EAB, and natural enemies have so far had little effect when EAB populations are high.

Healthy ash trees are also susceptible, although beetles may prefer to lay eggs or feed on stressed trees. When EAB populations are high, small trees may die within 1-2 years of becoming infested and large trees can be killed in 3-4 years.

Many agencies and universities are working together to educate citizens about identification of ash trees and EAB. There are options for protecting valuable shade trees. Research has helped further the knowledge about the biology of EAB, its rate of spread, methods for EAB detection, other natural enemies that may attack EAB, biocontrol measures that may help lower and/or control EAB populations, and how insecticides can be used to protect trees in infested areas. Check out the website’s menu for more detailed information.

EAB is now considered the most destructive forest pest ever seen in North America. The scope of this problem will reach the billions of dollars nationwide if not dealt with. State and federal agencies have made this problem a priority. Homeowners can also help by carefully monitoring their ash trees for signs and symptoms of EAB throughout the year.

Contact your county Extension office or the nearest Department of Agriculture office. You may also contact the USDA Emerald Ash Borer Hotline toll-free at (866) 322-4512.

This Website provides reliable, objective and timely information from researchers, personnel affiliated with numerous universities, state and federal agencies, educators and outreach specialists in the USA and Canada. Information is reviewed and approved by the website content managers and researchers affiliated with the Michigan State University Dept. of Entomology, the Dept. of Forestry and MSU Extension. Our goal is to help you find answers to questions about EAB, either directly or through links we provide to many other EAB-related websites. Please check this site often because information changes frequently. Funding to support this website is provided by the USDA Forest Service.