Emerald Ash Borer – A First Hand Look

Ash-treeHealthy Ash

Do you have Ash trees in your landscape? If you live in many areas of the East you might have heard of this pest. Cornell calls Emerald Ash Borer (EAB) the “tiny green killer.” It was found in Detroit in 2002, and now has spread to 15 states and two Canadian provinces.

Thinning-Ash-canopyThinning ash canopy.

Before I get into this long post and bore your socks off, especially if you are not a gardener with ash trees on your property, I have a great, short post on Nature and Wildlife Pics, my new blog. It is a story, one almost so unbelievable to have happened, on dragonflies. You will find it entertaining – Story of the Web Stuck Dragonfly.

This post on the Emerald Ash Borer will prove very enlightening to those interested. Rather than regurgitate information from government websites like many might, I am giving you first hand site documentation as we learned it from the DEC.

I was on a trip Saturday hosted at the Reinstein Woods Environmental Education Center. It was a workshop offered by Cornell Cooperative Extension and the New York State Department of Environmental Conservation.

Our-groupThe participants and the DEC group leader in the orange vest.

Participants, of which I was one, learned about the issues surrounding EAB and the economics of addressing an infestation.

Dead-AshDead Ash

Do you know how to look for signs and symptoms of an EAB infestation in ash trees on your property or in your community?

Ash-alertMarked tree.

Probably not since it usually requires special knowledge and equipment by those validating infestations in an area. We were taken around the park by our knowledgeable DEC representative being shown trees affected. We saw the damage and located borer larvae.

Bark-of-EAB-infected-AshYoung ash tree with suspected damage.

Below is the EAB larvae gallery. May through July is the time to see the adults emerge.

EAB-Gallery-Larvae-holeShaved to see the gallery.


A tree being inspected and tagged.

Woodpecker holes, about 1/2″ OD, in the tree indicate they may have been feeding on the EAB. Woodpecker holes are larger than EAB holes, and not made in a D shape. Both type of holes are shown above and below.  The EAB hole is 1/18 inch OD. Woodpeckers are identified as a natural predator of the EAB, but unfortunately, they do not consume enough of them. Cornell has a field guide that also has the information I have posted only it is more inclusive and detailed. Here is a link to the Cornell downloadable pdf, eabfg.

EAB-Exit-HoleAdult Borer exit holes in a “D” shape.

Woodpecker-holeWoodpecker hole likely made to eat an EAB larvae.

In NY, the ash borer has infected many ash and it is looking rather grim for ash trees at this point. Many are being felled to try to mitigate the spread, but that is also a way in which the borer is being spread too. People are using and selling infected wood for firewood, and by the time the wood is dried, the borers are hatched and off in a new locale to infect more trees. This beetle has the potential to forever change the face of our NY forests and woodlots. These trees comprise 10 percent of NYS forests.

This workshop was geared to train Master Gardeners and Master Forest Owners to engage local forestry, landscape/nursery businesses, and communities to increase the awareness of the EAB. I was given a number of educational handouts to distribute for help with ID and who to contact, so I thought to spread the word by doing this post. This one has the NYS DEC contact information, but I imagine your state has a number as well.

EAB-Contact-InfoThe bookmark handout to help identify the EAB. and On the flip side…

EAB-ID-tagInsects that look like the EAB.

If you want one and I have enough left over, email me and I will send you one. It really is handy.

Adult-EABVial full of EAB.

You can see their size and metallic green color. Our instructor did not locate a live adult for us, even though he had the net at the ready.

EAB-Leaf-DamageAsh leaves showing adult EAB damage.

So how do you help?

Cerceris-Wasp-IDThis is from one of the handouts. Want this one as well? I will include it with the bookmark EAB identifier if you email me with your name and address. My email is on my About GWGT page.

One reliable way to find out if your area has an infestation is to watch a wasp. The female Cerceris fumipennis is a ground nesting parasitic wasp and collects buprestid beetles to line her nest. Locating the wasp is a way in which to monitor for the EAB. But there are other ways which we learned and I will share.

Late-EAB-infestation-in-AshLate infestation

EAB-CrackEAB crack at infested region.

Other ways to look for an infestation is to look for the telltale markers, like the crack above or the canker below.

EAB-CankerCanker likely formed from an EAB infestation with typical vertical crack below the canker.

EAB-Larvae-holeThis is how the experts check trees for EAB.

They strip or shave the bark off with a special knife at a trunk suggesting a gallery. Under the bark you see the gallery where the larvae tunneled.

EAB-Damage-under-BarkThe gallery forms in a zig-zag, s-like shape.

I did ask about the harm done to the trees from his bark removal. The instructor said that the trees are already doomed and this would not matter. He also mentioned they intentionally create these wounds or even completely girdle a tree to encourage borers for study. Since it is an attractant, that also brings borers into an area to trees yet infected, so it is something being weighed for continuing the practice.

Another question I asked, does it affect all ash and he said it does, even Asian ash species. Some Asian trees do have natural resistance though.

EAB-Second-InstarIn the hole above, the instructor pulled out a second instar. It is shown in his hand.

A tree that is compromised is very likely to get EAB if it is in the area. Two other issues affecting the Ash are Anthacnose in shade trees and Ash Yellows. Here are two examples of each.


Ash-YellowsAsh Yellows. The leaves are yellowed but this protrusion also is an indicator of the disease.

A big problem with the ash dying is ash grows rather densely in the forest. This leaves large areas open which changes the ecology of the forest. Different species of plant fill in the open areas and habitats change.

I then asked about what happens to the dead trees? He explained they are removed and destroyed. Since those still standing had woodpecker, owl and flicker holes I asked about their removal and is not leaving the trees better for the wildlife that build homes? He told me something very good to know.

Only four dead trees per acre is recommended to provide for wildlife. More would be no better because of competition between inhabitants. So this means that other tree species fill in for that purpose, plus ash is too hard a species for many of the animals that would make tree hole homes. Very good stuff to know.

Ash-tree-declineAsh tree showing tip decline and thinning canopy.

I wish I had good news to report, but the only way to save a tree is to get it injected. The cost is around $100 per application depending on where you get the quote and the size of the tree. It is not cost-effective to try to save a wood lot, only a specimen tree. I hope passing on what I learned first hand will help you ask the right questions and understand the severity of this problem. If only caring about whether baseball continues using ash for bats, or if you are concerned from an environmental point of view, science and the USDA are working hard to combat this pest with no natural enemies to fight it here in the States.  Here is an article on the biological control of Emerald Ash Borer. We were introduced to this by the instructor, but it is far too complicated to get into here. If you are curious, see the work being done to date.

About Garden Walk Garden Talk

I love to photograph, paint, draw, design, garden, travel the world, and pass on a few tips and ideas that I learned through experience as a Master Gardener and architect. I am highly trained in my field and enjoy my work each and every day. I garden in Niagara Falls, NY in zone 6-B. Find me at: http://gardenwalkgardentalk.com
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31 Responses to Emerald Ash Borer – A First Hand Look

  1. Nick Hunter says:

    Very informative and well illustrated post. Enjoyed it. I’ve been losing ash to ash yellows for about 20 years. I leave scattered trees for the cavity nesters creatures, but most eventually end up in the wood stove. Have not seen the borer here — yet.

    • Nick, our guide said in normal circumstance, the spread of this borer was at 5 miles per year, which was rather slow. But how it got spread so far and so fast was because of the transport of firewood across state lines. Many were taking the wood to summer cottages and hunting cabins, and it just spread from there. You would not likely see a borer but would see the chewed leaves. It takes years for trees to get as bad as the ones I showed. I thought the state was culling ash, but they had no program for it because ash is too common in the state. They recommended people take them down is what I was told.

  2. We have a giant ash tree right in the middle of the gardens plus four or five even bigger trees in the uncultivated areas down below. I am thinking of having the tree above treated. How effective are the injections?

    • It is recommended to treat a specimen tree like your large ash. Treatments often have to be repeated, but I asked on the success and he said it depends on the age of the tree, the stress from other disease, and how soon it is caught. He did say he saw many trees returned to health. One at this park was treated and looked great. The only problem with treating, is if other ash in the area get infected, it becomes something that will reoccur in time. It is why wood lots were not suggested for treatment. Too costly and too many ash would be missed for treatment.

  3. Donna, this is a great piece of work and instruction on the ash borer. Great job and help for those in the infected areas. Are you a Master Gardener in NY?

    • Yes. I have been one for a really long time. I was one of the people answering calls and greeting people with questions – two mornings a week. Many gardeners do not think very highly of MG’s, but these training sessions bring out the best ones – those always wanting to learn more and more.

      • That’s neat. I answer the phones and greet people at least one day a week as well as speak to various groups on the subject they choose. This Fall I will be teaching the new class of MG once a week. I love it. It’s good to know you.

        • I was asked to teach design to the MGs, but my job keeps me too busy. I use my free time now for my photos. Our Niagara Falls office was re-purposed due to state funding cuts, so myself and another MG friend of mine got told we had to go to the main office. It was too far to drive for either of us, so we both just gave up our two day a week public service.

  4. bittster says:

    It’s so sad to see yet another great North American tree lost to a carelessly introduced pest. I was just looking at old photos of chestnut trees with trunks so wide it probably took four men to reach around…. elm lined streets….. all gone. Some people say the only reasonable solution will be to let the borers eliminate ash from the forest and then after the borers die out, reintroduce. All that genetic diversity gone.
    I’m not thrilled about protecting individual trees. I understand the desire, but to pump a tree full of pesticides makes it a death trap to any insect that stops to take a bite. It’s a high price to pay I think.

    • The reason the injections is because some of the specimen trees are focal components of landscape design. The trees are necessary to the design in aesthetics and what shade it provides. Some are very old and it would be a tragic loss, like one at this park. That is likely true on the pesticide use, but being systemic, I am not sure if it effects the adults feeding on leaves or only the borers inside. I forgot to ask that question.

  5. Great information! The Emerald Ash borer finally made it to Wisconsin during the past year. We don’t have Ash trees here on our main property, but there are a few small ones up at our cottage, which we’ll probably have to remove. As a master naturalist volunteer, I’m interested in the pest, the damage, and the effects on the local ecosystems. It’s sad to see so many trees marked around here, and it’s going to change the Madison-area landscape dramatically. Thanks for the information and the illustrations.

    • There is a huge effect on the economy too. That is why, not the environment and habitats, there is such a push to get this contained or eradicated. Ash being a hard wood is used in many products.

  6. milliontrees says:

    Very interesting. One problem we are spared in California.

    NY Times had a big article today about the EAB: http://milliontrees.me/2011/09/30/environmental-impact-report-for-the-natural-areas-program-is-based-on-a-huge-mistake/. Didn’t add much info to your excellent report except the disappointing news that the exceptionally hard winter did not reduce EAB populations as had been hoped.

    • Thanks for adding. I mentioned it in my comment to Charlie. No such luck because we were having warmer winters which helped the beetle out quite a bit in the last few years. Last year was heavy snow cover, so even being cold, it may have saved many insects.

  7. It is so tragic; as the climate changes here on the west coast we are seeing whole ranges of forest devastated by insects that in the past would have been killed by harsher winters or the change in the amount of available water that stresses the trees and makes them vulnerable, a variety of new factors.

    • I fear there is much more to come. EAB was not a result of climate change though, but it could have some effect because Cornell originally thought our cold winters would kill them in our area and originally in Detroit. But we were having warmer winters except for last year. So next year will be telling and insects in our area.

  8. I saw some dead ash trees in Lockport. She didn’t know if it was simply age or if it was EAB.

    • It was important to know. She should have reported it to Cornell – at least to find out if it was EAB. Likely it was. That is how the insect spreads when homeowners ignore what is happening to trees. The tree lives for years infected, so imagine how many EAB got reproduced.

  9. carole says:

    My address for the Emerald Ash informatory is: I deleted your address after copying to send you the pamphlet.>
    This is the best information I have seen.Thank you Take Joy Carole

    • I had to delete your address but I will send you the pamphlet. Check out the links for Cornell. They have more info and more pictures. You could have emailed me the address then it would not be printed here on the post. Thank you Carole. I am glad you found the post interesting.

  10. My Heartsong says:

    I don’t even know much about ash trees but I know a bunch in the river valley did not survive the drought one year,and the beech trees were hit across the country so it hits home how precious trees are, and how vulnerable. The pine beetle is wreaking havoc out west. I will look into this.

  11. Last year I did a walk around at the Chicago Botanic Garden where we looked at ash trees. The garden is in the process of removing all their ash trees, they feel the injections are too expensive. Good to know about the four dead trees per acre rule.

    • The injections do get very expense if treating numerous trees. The state only recommended treating specimen trees, which I imagine those are at the Botanic Garden. I have seen far more than four dead trees occupied per acre, so I was surprised at the low number to keep. They took a dead ash down at a local park that still had a Flicker family in it. I was shocked to go back to see the chicks and the tree was gone.

  12. Oh wow, thank you for this really important information. I hadn’t heard of the ash borer before, but I have noticed many oaks in the woods behind where I live are thin and suspect looking. Now this makes me wonder if something is going on with a borer. Great pictures + tips, thank you!

  13. Rose says:

    Very informative post, Donna, and a valuable public service. The EAB is in our area, too, and I’ve been worried about our two ash trees. One is dying and needs to be cut down, but I’ve seen no tell-tale signs of the ash borer, so I’m hoping it’s just a disease that has affected it. The other one is healthy and beautiful, so I certainly hope the EAB hasn’t found its way here. In some areas around here, ash trees have all been cut down as a preventative measure.

    • May be Ash Yellows got the first tree, but chances are it could have been EAB that finished it off. You local cooperative extension should know if it is in your immediate area. Neighboring counties here have not had them yet. Erie had it first then Niagara.

  14. Great info here Donna. I have been following it here with local agencies and Cornell. We were just informed that it has moved into the South end of our county. Soon we will be surrounded and our woods laid bare. They took hundreds of trees down now in many parks and are treating hundreds more. I fear we will be taking down the four ash trees we have left soon before they become infected. There goes my canopy. It is such a shame all the way around.

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