Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org
1. When and where was the emerald ash borer (EAB) first detected in Pennsylvania?
The emerald ash borer (EAB), Agrilus planipennis, is an invasive highly destructive wood-boring insect that attacks ash trees. It has killed more than 40 million ash trees in the states of Michigan, Ohio, Indiana, Maryland, and Illinois. It was detected for the first time in Pennsylvania in late June 2007. EAB adults were found on a green ash tree in Cranberry Township, Butler County through a joint effort by federal and state agriculture departments, the Pennsylvania Department of Conservation and Natural Resources (DCNR), and The Pennsylvania State University, Department of Entomology, Penn StateExtension. As a result of this first detection in Pennsylvania, an order of quarantine was issued for Allegheny, Beaver, Butler, and Lawrence Counties in Pennsylvania. Pennsylvania Department of Agriculture Secretary Dennis Wolff said, "Emerald Ash Borer poses a major threat to ash trees." Secretary Wolff also stated, "To best manage any effects of an infestation, we're working to determine whether this is an isolated incident or a more widespread problem."
Since this initial detection, EAB infestations have been discovered in Mercer (2008), Westmoreland (2009), Washington (2009), Armstrong (2009), and Indiana (2009) Counties in western Pennsylvania and in Mifflin (early in 2009) and Juniata (late in 2009) counties in central Pennsylvania. In mid-May 2010 Bedford County and in July 2010 Centre, Somerset, Fulton, Union, and Cumberland counties were added to the list of Pennsylvania counties were the EAB has been detected. Clarion County was added to this list in September 2010.
In May 2011 the EAB was detected in southern Lycoming County. This brings the total number of counties confirmed for the emerald ash borer in Pennsylvania to 19. Early in July 2011 the EAB was detected in southern Wyoming County. On July 5th Huntingdon County was confirmed positive for the EAB. Eight adult EAB specimens were recovered from a purple panel sticky trap baited with manuka oil in a small wooded lot in Mt. Union, PA adjacent to warehouse. The EAB was confirmed in Sullivan County on Thursday July 28. The location is along Rt. 87 east of Colley, PA in Colley Township in northeastern Sullivan County. One EAB adult was taken on a purple panel sticky trap.
In mid-March 2012 the EAB was confirmed on trees in a residential area in Warrington, Bucks County.
In early June 2012 the EAB was confirmed in two locations in Perry County. The first site was in a campground on the Susquehanna River in Liverpool, PA. The second location was at the first eastbound truck pull-off on Rt. 322 as you enter Perry County. Both of these sites are USDA-APHIS, Otis Lab's trap efficacy test sites.
The EAB was also found in Venango County. This site was turned in by the USDA and was found by visual / destructive survey in a campground in Emlenton, PA.
Additionally, the EAB was confirmed on a trap in an USDA-APHIS, Otis Lab's trap efficacy test site at the State Center in Selinsgrove, Snyder County.
In early July 2012 the EAB was confirmed in Franklin County. In late July 2012 the EAB was confirmed in Jefferson County.
In early August 2012 the EAB was confirmed in Clinton County on a purple panel prism trap.
In early December 2012 the EAB was detected by a PDA employee in a visual/destructive sample near Watsontown, PA in Northumberland County. Confirmation of another positive EAB population in a new Pennsylvania county occurred on December 17, 2012. The sample was collected from the Interstate 80 westbound Rest Area in Montour County near Mooresburg, PA.
On January 8, 2013 an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management collected a sample of the EAB near SGL 79 in Cambria County.
In April 2013 employees of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management collected a sample of the EAB in Fayette County.
Early in May 2013 the PA Department of Agriculture confirmed the EAB in Blair County.
In early June 2013 an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management collected a sample of the EAB in Forest County.
On June 21, 2013 an arborist work crew collected an adult EAB in the Allegheny National Forest in Elk County near the recent finds in Forest and Jefferson Counties.
In early July 2013 the EAB was collected by an USDA employee and confirmed in Bradford County near Troy, PA. Later in July 2013 an employee with the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management submitted a sample of the EAB from Warren County. This detection has been confirmed. Later in July the EAB was collected by a DCNR employee and has been confirmed in Clearfield County.
Early in August 2013 a PA DCNR, Bureau of Forestry, Div. of Forest Pest Management sample was submitted and confirmed positive for the EAB in Cameron County on state forest land north of Emporium. Additionally, the EAB has been confirmed at two locations in western Erie County. An employee with the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management submitted two positive samples of the EAB from West Springfield on purple panel traps. One site is at the I-90 Rest Area, and the second site is at the Elk Creek access near Erie Bluffs.
Late in August the EAB was collected in Montgomery County near the border with Bucks County by an employee with the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management on a purple panel trap. A capture and confirmation of the EAB in Tioga County was made by an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management north of Leonard Harrison State Park also on a purple panel trap. The EAB was collected and confirmed in Potter County. These collections were made at two locations on purple panel traps near Sizerville State Park and on Rt 607 by an employee with the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management. The EAB was confirmed in Luzerne County in the lower portion of Ricketts Glenn State Park. This specimen was collected by an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management on a purple panel trap. The EAB was also confirmed in a roadside tree on Rt 11, just south of I-80 in Columbia County. This specimen was a destructive collection sample made by an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management.
On October 18, 2013 the EAB was confirmed at two sites in Dauphin County by the national program. One sample was collected by a PA Department of Agriculture employee at a Dalmatia, PA address. The second sample was from along Rt. 147 just north of the Clarks Ferry Bridge.
On March 27, 2014 the EAB was confirmed from Susquehanna County near Montrose, PA on State Route 29. A PA DCNR employee submitted the sample through the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management.
On April 10, 2014 a sample collected from Berks County on I-78 near Bernville, PA by an employee of the Pennsylvania Department of Agriculture was confirmed positive for the EAB.
On April 22, 2014 the EAB was collected by an employee of the PA Dept. of Agriculture and has been confirmed in Lebanon County at Bullfrog Road near Grantville, PA.
A sample from Greene County, PA that was collected by an employee of the PA DCNR, Bureau of Forestry, Div. of Forest Pest Management was confirmed positive on April 30, 2014 as the EAB. This sample was from Rt. 21 near Waynesburg, PA.
A panel trap sample from Gettysburg, PA on federal land in Adams County was submitted by an employee of the US Forest Service. It was confirmed positive for the EAB on July 30, 2014.
A sample of the EAB was collected on July 31, 2014 by a PA Dept. of Agriculture plant inspector from private property in Dillsburg in York County. It was confirmed positive on August 7, 2014.
An EAB sample collected on July 19, 2014 was submitted to the PDA by a citizen in Crawford County. It was confirmed as positive on August 12, 2014. The location of the specimen is at a private residence in Meadville, PA.
A sample of the EAB was collected in Ashland in Schuylkill County by a PDA employee on September 5, 2014. It was confirmed as positive by the USDA on September 10, 2014.
A sample turned in by employees with the USDA Forest Service from McKean County that was collected on February 17, 2015 has been confirmed as the EAB.
The EAB was confirmed from a roadside sample collected on May 8, 2015 in Lancaster County by an employee of the PA Department of Agriculture.
In early May 2016 a PA Department of Agriculture (PDA) employee collected and submitted a sample of the EAB from a roadside tree near the town of Hauto in Carbon County.
In mid-May 2016 an employee of the PA Department of Conservation and Natural Resources (PA DCNR) collected specimens of the EAB from Benton Township in Lackawanna County.
In late June 2016 official confirmation of the emerald ash borer (EAB) occurred in Philadelphia County. The EAB specimens were collected from two separate sites in Philadelphia County. These specimens were submitted to the PA Department of Agriculture by an employee of the Philadelphia Parks and Recreation.
In late July 2016 the PA Department of Agriculture (PDA) received final confirmation on a sample of the emerald ash borer (EAB) from Lehigh County Pennsylvania. The EAB sample was taken from trees at a corporate center in Allentown PA, by an employee of the PDA after a report from an employee of the PA Department of Conservation and Natural Resources (PA DCNR).
In mid-September 2016 the PA Department of Agriculture (PDA) received confirmation on a sample of the emerald ash borer (EAB) from Northampton County Pennsylvania.
This brings the total number of counties confirmed for the emerald ash borer in Pennsylvania to 62.
State and federal regulatory officials continue to conduct surveys for the EAB.
The federal quarantine on the EAB and external quarantine on firewood from outside Pennsylvania are still in effect. This means it is legal to move firewood, ash, and the insect between counties inside the state, but it is not legal to move non-compliant items out of the state, nor is it legal to move non-compliant firewood into the state.
2. What is being done on a statewide basis about this new pest?
Federal, state, and local authorities are working together to educate the citizens of Pennsylvania about the accurate identification of ash trees and EAB, options for protecting valuable shade trees, and locations where dead or dying ash trees can be taken for proper disposal. Since 2002 federal agencies, and state educational institutions have been conducting research to learn more about the biology of EAB, its rate of spread, methods for detection of EAB, and natural enemies that may attack the EAB, and how insecticides may be applied to protect ash trees in infested areas.
3. Where did the EAB infestation in the United States come from?
The EAB is believed to have arrived in North America on solid wood packing material from China. The native range of EAB is eastern Russia, northeast China, Japan, Korea, Taiwan, and Mongolia. Before June of 2002, this species had never been found in North America, and very little was known about it.
4. How did the EAB get to the United States?
We don't know for sure, but it most likely came in association with ash wood used for stabilizing cargo in ships or for packing or crating heavy consumer products.
5. What types of trees does the EAB attack?
In North America, it has only been found in ash trees. All species of ash in the plant genus Fraxinus and their cultivars appear to be susceptible to the EAB in North America. It does not attack mountain ash in the plant genus Sorbus. Ash trees in the forest, woodlots, and landscapes are affected. Larval galleries (tunnels beneath the bark) have been found in trees or branches measuring as little as 1-inch in diameter.
6. Where was the EAB first found in the United States?
In 2002 the EAB was discovered in six counties in southeastern Michigan and in Ontario, Canada. Our ability to detect and find the EAB has substantially improved since then, however, and we now realize that a much greater area was infested than what was initially thought. Those areas include all but four counties in Michigan. It has also been found in Ohio (2003), Indiana (2004), Illinois (2006), Maryland (2003; 2006), Pennsylvania (2007), West Virginia (2007), Virginia (2003; 2008), Missouri (2008), Wisconsin (2008), Minnesota (2009), Kentucky (2009), New York (2009), Tennessee (2010), Iowa (2010), Connecticut (2012), Kansas (2012), Massachusetts (2012), and New Hampshire (2013), Colorado (2013), North Carolina (2013), Georgia (2013), New Jersey (2014), Arkansas (2014), Louisiana (2015), Texas (2016), Nebraska (2016), and Delaware (2016) making the EAB a national pest problem. Most of these infestations are not new, we are simply getting better at finding infestations as survey methods improve. However, it is important to watch for symptoms and signs of the EAB in non-quarantine areas where this metallic wood-boring beetle may have been accidentally transported. Much of the spread of the EAB to other states is believed to be through the movement of infested firewood, nursery stock, and other ash wood products.
7. What happens to infested ash trees?
The foliage in the crown of EAB-infested trees begins to thin above infested portions of the trunk and major branches because the larval stage of this wood-boring insect destroys the water and nutrient conducting cells and tissues beneath the bark. Heavily infested trees exhibit canopy dieback usually starting at the top of the tree. One-third to one-half of the branches may die in one year. Most of the canopy will be dead within 2 years of when symptoms are first observed. Sometimes ash trees push out sprouts from the trunk after the upper portions of the tree dies. Although difficult to see, EAB adults leave a capital "D"-shaped emergence hole in the bark. This exit hole is approximately 1/8 inch in diameter.
8. What does the adult stage of the EAB look like?
The adult is a flatheaded wood-boring beetle in the insect family Buprestidae that's slender, elongate, dark metallic green, 1/2 inch-long and 1/8 inch-wide (12 mm long and 3 mm wide) beetle. Females are larger than males.
9. What is the life cycle of the EAB?
Recent research shows that the EAB can have a one- or two-year life cycle. Adults begin coming out of ash trees in mid- to late May with peak emergence in late June and early July. After emerging, adults eat ash leaves around the leaf margins for about two weeks. Females usually begin laying eggs about 2 weeks after emergence. Eggs hatch in 1-2 weeks, and young larvae bore through the bark and into the cambium (the active growing area between the bark and wood where nutrient levels are high). Larvae feed beneath the bark for several weeks, usually from late July or early August through October. Cream-colored EAB larvae typically pass through four stages, eventually reaching a length of 1 to 1.25 inches (26-32 mm). Larvae have a 10-segmented abdomen with a pair of brown pincer-like appendages on the last segment. 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 begin to emerge in May or early June, to start the cycle again.
EAB adults may begin to emerge during mid-May described by a growing degree day (GDD) range of 450-500 GDD (using a threshold air temperature of 50°F). Adults may be active through August. Adult EAB emergence peaks from late June to mid-July that occurs around 1000 GDD based upon research conducted in Michigan.
10. How does the EAB move from one location to another?
We know EAB adults can fly at least 1/2 mile from the tree where they emerge. Many infestations, however, are started when people unintentionally move infested ash firewood, ash nursery trees, or logs into uninfested areas. 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 ash firewood remains a problem. Please - do not move any ash firewood or logs outside quarantined areas.
11. How long has the EAB been in Michigan?
No one really knows for sure. Experts feel that the EAB may have been in the Detroit area for at least 12 years. The initial infestation probably started from a small number of beetles. Over the next few years, the population of the EAB began to increase 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 the EAB, and natural enemies have so far had little effect when EAB populations are high.
12. Does the EAB only attack dying or stressed ash trees?
Healthy ash trees are also susceptible, although the EAB 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 may be killed in 3-4 years.
13. How big a problem is the EAB?
The EAB is becoming an international problem, with infestations in Canada as well as Michigan, Ohio, Indiana, Illinois, Maryland, Virginia, Pennsylvania, West Virginia, Missouri, Wisconsin, Minnesota, Kentucky, New York, Tennessee, and Iowa. The economic damage from the EAB problem could reach the billions of dollars nationwide if not dealt with effectively. State and federal regulatory agencies have made the EAB problem a priority. Homeowners can also help by carefully monitoring ash trees for symptoms and signs of EAB throughout the year.
14. Are there other insects that can cause similar damage to ash trees in Pennsylvania besides the EAB?
There are two species of wood-boring caterpillars and several species of wood-boring beetles that also develop in ash trees in Pennsylvania. None of these other species of wood-boring insects that attack ash create a capital "D"-shaped emergence hole the size of that created by an adult EAB when it comes out of an ash tree. Some of the other wood-boring species that attack ash include the ash/lilac borer, Podosesia syringae, the banded ash clearwing, Podosesia aureocincta, the redheaded ash borer, Neoclytus acuminatus, the banded ash borer, Neoclytus caprea, and the eastern ash bark beetle, Hylesinus aculeatus. When the five species listed above emerge from an ash tree, they create round emergence holes in varying sizes. These round holes range from approximately 1/16-inch to 1/4-inch (1.5 mm to 6 mm) in diameter.
15. Who do I contact to get more information, get a specimen identified, or to report a potentially infested ash tree?
Contact your local county Penn State Extension Office, the nearest Pennsylvania Department of Agriculture regional office, or the Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry's Division of Forest Pest Management office. You may also contact the Pennsylvania EAB hotline at 1-866-253-7189. Additional information on the emerald ash borer is available by visiting the following web sites:
The above list of frequently asked questions (FAQs) was provided by Gregory Hoover, Department of Entomology, The Pennsylvania State University, and Dr. Deborah McCullough and Robin Usborne, Michigan State University Extension in July 2013 (revised September 2016).