Roberts at base of ash tree
David L. Roberts, Ph.D.
Senior Academic Specialist
Michigan State University
Discoverer of the Emerald Ash Borer

MSU logo


Emerald Ash Borer

First photo of emerged EAB found

 A new exotic beetle that has been killing ash trees in southeastern Michigan was identified last week as Agrilus planipennis.  The common name of the beetle as suggested by this discovery is the "Emerald Ash Borer (EAB)"
  (Fig. 1 Adult )  July, 2002

EAB adults on young leaf
Photo courtesy of Ken Chamberlain, OSU/OARDC
research button

dot  M.S.U.'s 2003 EAB Research Results: Some Interpretations & Recommendations
dot  M.S.U. Evaluation of Insecticides to Control EAB Adults & Larvae
dot  Ash Decline Research History and Management
dot  Survival of EAB in Wood Chips
dot  Ash Wood Chips In Depth Research


im  What's Killing the Ash Trees?  
  The Emerald Ash Borer: A Threat to Ash in North America
  Ash Decline: Is It the Emerald Ash Borer or What?
  EAB:  Early Detection is Important 
  New Exotic Pest: the Emerald Ash Borer
  The Survival of EAB in Ash Wood Chips Investigation

id button dot  Ash Tree Identification Guide 
dot  Stages of EAB Decline & Whether Treatment is Warranted
dot  Homeowners Winter Study, Examine Your Trees Now!
photo dot  Photo Gallery I of Emerald Ash Borer & Indicators
dot  Photo Gallery II more EAB &  Tree Symptoms
mgt button dot  EAB: Winter Management Through Sanitation
dot  M.S.U. Recommendations for Homeowners Who Want to Treat Their Trees Against EAB
dot  What are my choices Now & How well do Insecticides work for EAB?
dot  MI Dept of Ag. Expands Quarantine Order: Dec. 2004  link reference of 2014
button  MI Dept of Ag. Expands EAB Detections Outside of Quarantine: Jan, 2005  link reference of 2014
document btn


dot   The Emerald Ash Borer: A Threat to Ash in North America .pdf 
dot   EAB: Management Options .pdf 
dot   M.S.U.'s 2003 EAB Research Results: Some Interpretations & Recommendations .pdf
dot   M.S.U. Evaluation of Insecticides to Control EAB Adults & Larvae .pdf
dot   EAB: Winter Management Through Sanitation .pdf 
dot    Alternatives for ASH Species .pdf 
im   Extension Bulletin E-2925: Recommended Alternatives to Ash Trees for MI Lower Peninsula .pdf  
dot   New Exotic Pest, Emerald Ash Borer & Revised Control Techniques.pdf 
dot   Ash Decline in Michigan Fall 2001 Report. pdf
dot   M.S.U. CIPS Emerald Ash Borer Pest Alert
dot   USDA Emerald Ash Borer Pest Alert.pdf
news button
dot  Press Release & Media Files - A Historical Progression Leading to Discovery in Print
link button dot  Wood Disposal Sites, Industry Contacts, & Other Resources
dot  M.S.U. Horticulture Recommended Trees for Lower Michigan
dot  M.S.U. & Agencies Emerald Ash Borer Site
bullet  SEMIRC Ash Utilization Options Project  
im  Gun Lake Indians Harvest Black Ash for Basket Products
dot  Champion Ash Highlight: Ode to My Mother & the Ash Tree

dot  Homepage to Landscape Tree Diseases

EAB Larvae Stages
larval stages

Mixed larval stages collected from single location on tree. 
Maybury State Park, MI  August, 2002 

Larvae feeding in ash
single larvae
Photos courtesy of David Cappaert

four lavae in pupal chambers over winter
Over Winter Larvae

EAB: Winter Management Through Sanitation 


  An ash log kept over winter reveals four Larvae found when bark chipped away.  They become active under the bark with the onset of spring/summer warmth until emerging as an adult EAB insect. Photo D. Roberts - March, '03

M.S.U.'s 2003 EAB Research Results:
Some Interpretations and Recommendations
Article published in the Landsculptor Magazine, March, 2004
David L. Roberts, Ph.D.
Michigan State University Extension

The Emerald Ash Borer: A Threat to Ash in North America
April 24, 2004 Revision
David L. Roberts, Ph.D.
Michigan State University Extension

   The Emerald Ash Borer (Agrilus planipennis), a lethal insect to ash (Fraxinus sp.), was discovered in Michigan in May, 2002, by Dr. Roberts, but was probably introduced into the state at least five years previously from Asia, its native origin. The insect kills ash trees by destroying the tree’s water and nutrient conducting vessels. The EAB is so aggressive that ash trees may die within two - three years after they become infested with the beetle. All species of ash seem to be susceptible, but certain varieties may decline more slowly. Mountainash, not a true ash, is not susceptible to the EAB. If not contained the potential epidemic resulting from the EAB could rival Dutch Elm Disease, as the insect advances across North America. States which become infested could lose billions of dollars in forest products, and quarantines imposed by state and federal agencies may have dire consequences for plant and wood products industries. Because of their tolerance of adverse sites, ash trees have been planted extensively in urban/suburban landscape areas; their removal and replanting costs can be staggering.

Diagnosis/Detection of the EAB:
    Initial symptoms of the EAB on ash trees begin with a general yellowing and thinning of the foliage. Then, branches begin to die from the top of the tree downward. Dieback of the branches continues until the tree dies. On some trees with moderate EAB infestations, epicormic shoots (sprouts, suckers) may emerge from the trunk or larger branches. Absolute confirmation of the EAB depends on at least one of the following: D-shaped emergence holes about 1/8 inch diameter, serpentine tunneling, or the presence of the adult or larvae in infested trees.

    Another unique characteristic is the presence of woodpecker activity on many EAB-infested trees. In fact, woodpecker activity may be the first signs of EAB and should be heeded, particularly if you want to save ash trees from death by the EAB. Early detection is crucial if trees are to be saved! Woodpeckers make about 1/4-1/2 inch jagged round holes in the bark as they extract EAB larvae for food.

Life Cycle of the EAB:
    In Michigan, the adult EAB begins to emerge from ash trees in late May and feed on ash foliage (leaves) for sustenance. Adults are slender, elongate, green metallic beetles measuring 3/8 to ½ inches (7.5- 13.5mm) long. After mating, the adult female may lay as many as 60-90 eggs over her 2-3 week life. Larvae hatch in 7-10 days, burrow through the bark and begin the back and forth (serpentine) tunneling, which is distinctive for this insect. The tunneling directly beneath the bark in the water and nutrient conducting vessels by the larvae is the destructive portion of the insect’s life cycle. Larvae continue to feed through the summer and into the fall. Larvae are distinctly segmented and by late summer and early fall may measure 1-1/4 inches (26-32mm).  EAB overwinters as larvae and undergo metamorphoses and change into an adult in late April through May, thus repeating the cycle.

EAB Management:
    One of the first decisions that a tree owner must make is whether to save ash trees from the EAB or allow the EAB to kill their tree(s). Saving an ash tree from EAB destruction may be a long-term and expensive investment for which there is no guarantee of success. The decision to save an ash must be made promptly when the EAB is detected in a locality, because ash may decline from healthy to beyond salvage in just a few months.

Cultural Management: If trees are to be saved, maintain trees in good vigor with sufficient water and fertilizer. Trees in good health will be better able to fight off the insect as well as more efficiently take up the insecticides which are necessary to save trees from destruction by the EAB.

Sanitation/Wood Management: The overall goal is to reduce the build-up of populations of the EAB, which can continue to attack healthy trees or spread to new geographical locations. Infested trees not treated with insecticides, should be removed and destroyed so they do not serve as breeding reservoirs for the insect. Infested ash wood should be buried, burned or chipped, preferably before May every year- adults will still emerge in the spring and summer from ash wood which was cut the previous winter. Ash wood can be used for firewood, but, if saved, it should be covered and sealed with a tarp from May through August to prevent escape of emerging adults. Ash firewood, ash nursery trees and any kind of ash wood CANNOT be transported out of the quarantine area-visit for updated quarantine information.

firewd btn The Mich. Department of Agriculture, USDA and DNR are gearing up for another "firewood blitz" on Labor Day weekend (the Thursday and Friday before Labor Day) at four public rest stops in Michigan in an effort to stop the spread of emerald ash borer in firewood. Besides checking travellers' firewood for ash, there will be an educational component on EAB as well as a survey of travellers. For firewood regulations check MDA site.


Quarantine Expanded by MDA Officials: November 2, 2005 include 21 counties in Southeast Michigan and 31 outlying infestations:

  • Alcona County – Greenbush Township Barry County – Carlton, Woodland, and Irving Townships Benzie County – Almira, Homestead, Inland, and Platte Townships Berrien County – parts of the cities of Benton Harbor, Bridgman and St. Joseph, Chickaming, Lincoln, Royalton, St. Joseph, Benton and Weesaw Townships Cheboygan County - City of Cheboygan, Benton and Inverness Townships Chippewa County – Bay Mills and Superior Townships Huron County – Caseville and Lake Townships Ionia County - Campbell and Odessa Townships Iosco County – City of East Tawas and Baldwin and Plainfield Tonships Kalamazoo County - Wakeshma Township Kent County - Bowne Township Mason County – Hamlin Township Montcalm County - Richland and Home Townships Montmorency County – Montmorency and Hillman Townships Oceana County - Golden and Benona Townships Ogemaw County - Hill Township Presque Isle - Krakow and Posen Townships Roscommon County - Backus, Higgins, and Richfield Townships Sanilac – the entire county St. Joseph County - Leonidas Township Van Buren County - all of the City of Hartford and City of Watervliet and Bangor, Covert, and Hartford and Watervliet Townships. View EAB MDA Jan. 6, 2006 to Feb. 22, 2007 update site or interactive map site.

    Quarantine Expanded by MDA Officials December 27, 2004 Order:
    Amendment adds 7 counties to the EAB quarantine, now at 20 counties statewide:
    - - Branch, Calhoun, Clinton, Eaton, Genesee, Gratiot, Hillsdale, Ingham, Jackson, Lapeer, Lenawee, Livingston, Macomb, Monroe, Oakland, Saginaw, Sanilac, Shiawassee, St. Clair, Washtenaw and Wayne.
Dec 27, 04 quarantine map

Quarantine Expanded by MDA Officials July 15, 2004:
Included now are portions of: (dots on map) 

Plus Thirteen Counties
Genesee, Ingham, Jackson, Lapeer, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Shiawassee, Washtenaw and Wayne.
July 15, 2004  Expanded Quarantine Order
for complete regulations and details.

quarantine july04

Chemical Management: Because the EAB is so aggressive on ash trees, chemical treatments will be needed to save specific trees. Because little is known about the efficacy of specific chemicals and their delivery methods, individuals may want to try one or more of the treatments options, reviewed on the web site below. It is presumed that preventative (before infestation) treatments will be more effective than curative (after infestation) treatments. This web site will be updated as new information is gathered.
dot   EAB: Management Options .pdf
    The Emerald Ash Borer: A Threat to Ash in North America .pdf  

Ash Decline: Is It the Emerald Ash Borer
or Something Else?
February 26, 2003
David L. Roberts, Ph.D.
Michigan State University Extension

   Since the Emerald Ash Borer, (EAB) (Agrilus planipennis) was discovered June, 2002 and presumed to be the major factor contributing to ash decline in Southeast Michigan, there have been many false alarms of EAB findings in many other locations around Michigan. In fact, I spent a great deal of time during the summer and fall of 2002 chasing reports of the EAB in many regions throughout Michigan. Some of the false reported sitings came from other midwestern states adjacent to Michigan.

   There are many problems that can affect ash (Fraxinus sp.) and cause a general decline that can be mistaken for the EAB, so I’ll provide a brief discussion of the diagnostic clues for distinguishing the EAB and several other of the more common problems affecting ash.

Emerald Ash Borer:
   Because ashes may decline very rapidly from the EAB, often in 2-3 years from first infestations to death, several characteristics are often associated with the EAB.  Branch dieback, epicormic shoot (suckers) emergence from the trunk, tree death and wood pecker activity are commonly observed symptoms of the EAB; these same symptoms have been observed throughout Michigan on trees not affected by the EAB.  Hence, absolute and definitive proof of the EAB resides with observing at least one or more of the following traits:
LOOK  for One or More of These Indicators:
1)  “D-shaped” emergence holes: These insect exit holes are clearly D-shaped and typically measure about one-eight inch (4-5mm) across. These exit holes are very similar to those created by the two-lined chestnut borer on OAK and the bronze birch borer on BIRCH.
2) Serpentine tunneling: The EAB produces distinctive tunneling in declining ash trees, which is serpentine or zigzag in appearance.  The tunneling reaches about one-quarter inch in width for mature larvae in the late summer and fall. There are no other insects that create this distinct tunneling pattern on ash.
3) Adult EAB: Adult EAB insects are elongated, slim, metallic green and measure about three-eights to one-half inches (about 12-13 mm) long (size shown here is actually larger than life-size adult).  The adults would typically be observed in the vicinity of ash trees from May through August.
4) EAB Larvae: The EAB larvae can be found beneath the bark of ash trees, in tunnels from June though the fall. These larvae also over-winter in chambers a couple of ring layers deep in thin barked trees or in the inner bark of thick barked trees. Larvae are distinctly segmented with triangular segments and when mature measure one to one and a quarter inches (26-32 mm) in length. (D.Cappaert, MSU photo)

Ash Decline:
   Ash Decline is a catchall term used to describe the decline and death of an ash tree from nebulous or undefined incitants. Some of these incitants include borers, diseases, poor soil/sites, adverse planting techniques (ex. too deep), winter injury, drought, etc.
Ash Yellows:
   Ash Yellows is a disease caused by a Phytoplasma, a microorganism similar to a bacterium. Ash yellows disease often exhibits decline with witches-brooms of branches emerging from the trunk or branches of ash trees. These brooms are usually somewhat short, highly branched and exhibit yellowish, sickly foliage.

Various Borers:
   There are many other borers that attack ash trees. Some of the more common ones include the redheaded ash borer, some clearwing borers (ex., Lilac borer, Banded Ash borer), Carpenter Worm, etc. Most of these borers produce rounded exit holes of various sizes, depending on the insect. There are many other insects that are associated with ash including bark beetles and cambium miners.

Verticillium Wilt:
   Verticillium causes wilt on ash just as it does on many other deciduous plants such as maple (Acer), smoke tree (Cotinus) and redbud (Cercis). With certain species of ash however, the vascular staining so diagnostic on many woody plants is not conspicuous. Laboratory cultures are often required to confirm Verticillium.
   Anthracnose is a foliar disease caused by a fungus. The fungus typically attacks the leaves of ash trees during cool rainy periods in the early spring. Infected leaves often drop from trees and many people believe the tree is dying. Branches devoid of leaves may be mistaken for decline or EAB attacks but branches affected with anthracnose will re-foliate later in the spring and summer.
Canker Diseases:
   There are many fungi that cause cankers on the branches and trunks of ash trees. Two of the more prominent cankers found in Michigan are caused by Fusicoccum and Nectria fungi. Cankers on branches often appear as dead sunken areas with pustules or bumps containing fruiting bodies of the fungus. With Nectria, a target pattern often develops over several years. Please note that infestations of the EAB may lead to attack by fungal cankers; hence, both may be present in the same tree.

Butt Rots and Stem Decays:
   There are many disease organisms (primarily fungi) that attack the lower trunk, stems or the heartwood of ash trees. These may lead to a gradual decline in the health of the tree. Branch dieback death and loss of structural integrity may accompany these diseases. Specific symptoms include hollowed trunks, large cankers on one side of the trunk, dry rotted or wet rotted areas, and large callus tissues as the trees try to recover from the decay. Reproductive structure of the fungal incitant may be present. A shelf fungus is an example of a reproductive structure that often indicates an attack by a fungus.
Root Rots:
   Ash is susceptible to a variety of root rots. Armillaria is one of the more common and easily diagnosed root rots. Armillaria produces a white film beneath the bark of infected trees; this film resembles white paint. Any of these root-rotting diseases can lead to tree decline and death. Common practices such as wounding tree trunks with weed trimmers or lawn mowers, excessive mulch and too much water may lead to root rots.    If anyone observes signs of the EAB outside of the current six county-quarantined area delimited by Macomb, Oakland, Livingston, Wayne, Washtenaw and Monroe, please contact representative from Michigan Department of Agriculture, Michigan State University, Michigan DNR or the US Forest Service. Or, please feel free to contact me at my email address, make sure your return email address is included in your message in case I need to ask any further questions.

(Back to top)

Emerald Ash Borer: Early Detection Is Important
March 21, 2003
David L. Roberts, Ph.D.
Michigan State University Extension

    Last summer and fall, we received numerous inquiries regarding treatments of trees, specifically which trees might be saved. Because it was difficult to keep up with these numerous inquiries, I developed a “Stages of Decline” for guiding the public on my web site; these stages ranged from Stage 1, virtually healthy to Stage 5, virtually dead. At that  time, many of us believed that trees exhibiting decline up to Stage 3, representing 40-50% decline or canopy loss, could be saved by insecticide treatments. Because of results from last summer/fall treatments, we now believe that trees beyond 10-20% decline (probably) cannot be saved. This is due to rapid tree decline and the fact that there is generally far more tunneling beneath the bark by EAB larvae than is visible in crown dieback. This extensive tunneling and disruption to the cambial tissues (those that transport water and nutrient) undoubtedly impedes the translocation of chemical treatments. Preventative Treatments & Early Detection:
    Two questions that Ash owners need to ask themselves if they would like to save their ashes are 1) can my tree(s) be saved? (Is it sufficiently healthy to be saved?), and 2) if my tree can be saved/ salvaged, am I willing to invest in treatments year after to year for many years to ensure survival of my ash(es). Remember, we are not certain at this time that treatments will be sufficiently efficacious to save ash trees from the EAB. Many studies are planned for the coming season and we will keep you apprised of the results. Recommendations for treatments that might be effective are summarized on my web site.    Of utmost importance, if trees are to be saved, treatments need to be applied  as preventative applications (before infestation) to healthy trees or as “curative” applications (after infestation) to trees exhibiting no more than 10-20% canopy loss. We suspect that the less the infestation, the greater the chances of saving particular trees. He/she who hesitates may lose his/her ash:
   Another important factor in these determinations is to realize that trees advance from healthy to beyond salvage very quickly. In some cases during 2002, trees were rated and advanced in decline by as much as 30-40% in just a couple months. Hence, many trees would have passed from salvageable to beyond salvage very quickly. The most rapid decline, whether noticeable or not, would occur during the larval feeding period from July through the fall. Still, trees that may have appeared OK last fall may be beyond salvage this spring. Woodpeckers as Early Detectors:
    One of my observations during the winter of 2001/2002, even before the insect was identified as the Emerald Ash Borer and as the culprit of the Ash Decline in SE Michigan, was that many affected trees were being visited regularly by wood peckers, primarily the downy and hairy wood peckers. I could simply drive down streets and determine which trees were infested and which trees were in an advanced state of decline. This woodpecker activity is summarized with photographs on my web site. Please consider that these birds will not necessarily visit all EAB-infested ashes.     During this past winter, I again correlated intense woodpecker activity with declining trees. In a number of instances, the EAB had moved into new neighborhoods last summer and the first sign of their presence was woodpecker activity this winter. Remember, EAB adults deposit eggs and larvae develop and cause severe damage during one season-the adults do not emerge and create the telltale D-shaped exit hole until the following year. Hence, external symptoms in trees often lag behind extensive, internal damage performed by “invisible” larvae (no exit holes). The woodpeckers’ activity may actually be the first sign of EAB infestations, telling us that those particular trees or neighborhoods are in trouble long before severe dieback and decline symptoms in the ash trees. Coupled with the fact that decline may advance very quickly, woodpeckers alert us to strongly consider NOW what we should be doing this coming spring. Like PANIC!!!!     Professional arborists and landscapers, as well as homeowners, need to heed these early signs, remember the rapid decline of EAB-infested ash and plan for early spring treatments if the saving/salvage of valuable ashes is a desired outcome. My web site has been recently updated with current recommendations, new information and photographs.  (Back to top)

New Exotic Pest, The Emerald Ash Borer
'Agrilus planipennis'
July, 2002
David L. Roberts, Ph.D.
Discoverer of the Emerald Ash Borer
Michigan State University Extension

   We have recently made a significant breakthrough in the Ash Decline problem affecting 100,000's of ash trees in Southeast Michigan.  I was able to rear out the adult stage of an insect, formerly thought to be the two-line chestnut borer, from ash trees in late May and early June.  The insect could not be identified in the U.S. and after much difficulty, it was finally identified as Agrilus planipennis by experts in Eastern Europe.  Dr. Deb McCullough, MSU Entomologist and I proposed the name "emerald ash borer" as the new common name of the beetle, and this has been accepted by the national authorities. This species is native to China, Korea, Japan and other Asian countries and had not previously been found in North America.  The emerald ash borer insect appears to be very aggressive on ash trees of all ages and situations and we believe it is the major contributor to ash decline and death in the southeast region of Michigan.  The insect will have a significant economic impact on Michigan.
   This insect represents a new exotic pest for the U.S.(Native range of U.S. ash trees) and is currently believed to be limited to six counties in southeast region: Wayne, Washtenaw, Macomb, Monroe, Livingston and Oakland.  Nurseries in these six counties are quarantined from shipping ash trees out of this six county area.  I also found the insect damage in Windsor, Ontario.  Canadian officials have confirmed this and are now conducting their own survey to delineate the insect range there. (Update, Canadian quarantine is now in effect for the Windsor area.  The Canadian government recently prohibited ash trees and wood from leaving the infested area. The quarantine covers Windsor, Amherstburg, Essex, LaSalle and Tecumseh.)

   Dr. McCullough, Entomology MSU and I provided an educational update to industry association leaders in July, 2002 in downtown Lansing.  A press release, sponsored by MSU, MDA and the USDA took place on  Wednesday, July 17th.  Please feel free to refer inquiries to this website or print it for distribution to the public.  I'll keep this website current with new research information disclosed in cooperative efforts with Dr. McCullough.  Kristine Hahn, Horticulture Agent MSUE Wayne County and Master Gardener volunteers in Wayne, Oakland, and Washtenaw counties are conducting surveys for incidences and distribution of the borer.

   All nurseries in the affected regional areas have been notified by MDA and quarantines have been imposed on some nurseries with infested ash trees.  These quarantines are designed to prevent infested ash trees, logs, firewood and nursery stock from leaving the infested areas.  This will hopefully minimize the chances of spread to new areas. (See Management & Possible Control Techniques Listed .pdf)
    New Exotic Pest, Emerald Ash Borer & Revised Control Techniques.pdf 
 (Back to top)


Henry & June
actual size on
ash leaves
    More images   Next

2001 larvae from ash tree    David L. Roberts, Ph.D., Senior Academic Specialist
   Michigan State University
   College of Agriculture and Natural Resources

   173 Giltner Hall, East Lansing, MI  48824-1101
  Cell Ph: (248) 320-7124 preferred
  Lab Ph: (517) 355-4518

  Email:  with any comments or questions.

(Photo of lens cap:) 
Several insect borer larvae, believed to be the two-lined chestnut borer, taken from a declining ash in the fall 2001. Larvae 26-32 mm in length, are cream colored, dorso-ventrally flattened, and have a pair of brown pincer like appendages on the last segment.  (Fig. 2a)
MSU logo

 | Photo Gallery I-EABPhoto Gallery II-EAB | Ash Decline Research  |
| Stages of Decline | Link - Resources | EAB Home page |
| Site Directory  |  MSU Home Page | MSU Extension

Copyright © 2001- 2006-2014 Michigan State University
Disclaimer, Indicia, and Linking information
MSU is an affirmative-action, equal opportunity employer.

Modified:  2014, June   Email Web Administrator with any site inquiries.