Frequently Asked Questions on the Emerald Ash Borer (1)

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 an estimated 25 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, Cooperative Extension.  As a result of this detection, a quarantine was imposed for Butler, Lawrence, Allegheny, and Beaver 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.” 

State and federal regulatory officials are conducting intensive surveys for the EAB near the detection site.  The quarantine is designed to help slow the spread of the beetle.  The EAB has forced similar quarantines in the other states where it has been found and in the Canadian province of Ontario. 

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 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 EAB detection, and natural enemies that may attack 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 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 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 (in 2003), Indiana (in 2004), Illinois, and Maryland, 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 beetle can have a one-, two-, or even three-year life cycle.  Adults begin coming out of ash trees in mid- to late May with peak emergence in late June.  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 the 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, and Pennsylvania and eradicated infestations in Virginia.  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, as does 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 a round emergence hole 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 on the EAB in Pennsylvania, get an EAB suspect specimen accurately identified, or to report a potentially EAB-infested ash tree?
Contact your local county Pennsylvania State University Cooperative 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:

*Pennsylvania Emerald Ash Borer Web Site - http://www.paemeraldashborer.psu.edu/

*National Emerald Ash Borer Web Site - http://www.emeraldashborer.info/

*Pennsylvania Department of Agriculture, Bureau of Plant Industry - http://www.agriculture.state.pa.us/agriculture/cwp/view.asp?a=3&Q=144707

* Pennsylvania DCNR, Bureau of Forestry, Div. of Forest Pest Management -
www.dcnr.state.pa.us/forestry/fpm_invasives_EAB.aspx

*Michigan Emerald Ash Borer Web Site - http://www.michigan.gov/eab/

*USDA, Forest Service, Northeastern Area Web Site - http://na.fs.fed.us/fhp/eab/

*USDA, Forest Service, North Central Research Station Area Web Site - http://www.ncrs.fs.fed.us/4501/eab

*USDA Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine (PPQ)
http://www.aphis.usda.gov/plant_health/index.shtml

*USDA Forest Service - http://www.fs.fed.us/

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(1) The above list of frequently asked questions was provided by Gregory Hoover, Department of Entomology, Pennsylvania State University, and Dr. Deborah McCullough and Robin Usborne, Michigan State University Cooperative Extension in July 2007.