Ash Borer: All You Need to Know for Protecting Your Trees

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The Emerald Ash Borer (EAB) is an invasive beetle known to infest and kill ash trees.

Originating from northeastern Asia, EAB was first detected in the United States in 2002 and has continued to spread across the country, devastating landscapes and urban tree populations.

EAB was recently found in Forest Grove, Oregon on June 30, 2022, marking the first confirmation on the West Coast.

This pest poses a significant threat to entire habitats and ecosystems, particularly those dominated by Oregon Ash.

 

Ash Borer
Source: U.S. Department of AgricultureCC BY 2.0, via Wikimedia Commons

 

The beetle’s presence could lead to severe damage to sensitive riparian zones and urban forest covers.

Identifying the signs and symptoms of an EAB infestation early is essential to manage and control the spread of this destructive pest.

Common indicators include D-shaped exit holes on the bark, thinning tree canopies, and woodpecker activity.

It is crucial for homeowners with ash trees to understand EAB treatment methods and regulations in their region to protect their landscapes and help mitigate the impact of this invasive species.

The Emerald Ash Borer: An Overview

Origin and Spread in North America

The Emerald Ash Borer (EAB) is a metallic green beetle scientifically known as Agrilus planipennis.

This destructive insect is native to Asia, including countries like China, Japan, Korea, and Russia.

Unfortunately, EAB made its way to the United States and was first discovered in Michigan in 2002.

Since then, it has spread throughout North America, causing significant damage to ash trees. Some factors contributing to EAB’s rapid spread:

  • Human transport of infested ash wood products
  • Natural dispersal of the EAB

 

Source: Flick, user: USDA APHIS

 

Identifying the Emerald Ash Borer

Here are some key features to help identify EAB:

  • Color: Metallic green
  • Size: About 0.5 inches long and 0.125 inches wide
  • Shape: Elongated, slightly flattened body

To spot EAB infestation, be on the lookout for the following signs:

  • D-shaped exit holes in the bark of ash trees
  • Thinning or dying branches in the upper canopy
  • New sprouts growing from the base of the tree

Pros and Cons of EAB:

  • Pros: None. EAB is a destructive pest with no known benefits
  • Cons: Causes widespread death of ash trees, affecting urban and rural landscapes alike

Impact of EAB Infestations

Effects on Ash Trees

Emerald ash borer (EAB) infestations have detrimental effects on ash trees.

The EAB kills ash trees within 2 to 4 years of infestation. Some common symptoms include:

  • Thinning canopy
  • Yellowing leaves
  • Bark splitting

For example, the black, green, white, and blue ash tree species are all susceptible to EAB infestations.

 

 

Consequences for Ecosystems and Biodiversity

EAB infestations can have significant impacts on ecosystems and biodiversity:

  • Loss of ash trees
  • Reduction in habitat for birds and other wildlife
  • Disruption in nutrient cycling

Ash trees provide essential ecosystem services such as:

  • Hosting birds and other animals
  • Filtering water
  • Moderating temperature
  • Reducing erosion

Comparison of Ash Trees Susceptible to EAB:

Species Susceptibility Importance in Ecosystem
Black Ash High Wetland habitat, wood
Green Ash High Riparian habitat, wood
White Ash High Upland habitat, wood
Blue Ash Low Rare, unique habitat

Some common effects of EAB infestations on ecosystems include:

  • Loss of specific habitats for birds and other organisms
  • Decreased availability of food sources for animals such as insects and birds
  • Decline in ash tree populations, negatively affecting genetic diversity

As EAB infestations continue, it’s essential to educate on prevention and management methods to protect ash trees and the ecosystems they support.

Detection and Prevention of EAB Infestations

Signs of Infestation

Emerald ash borer (EAB) is a destructive wood-boring pest affecting ash trees1. Here’s what to look for:

  • Woodpecker activity: Increased presence of woodpeckers feeding on ash trees may indicate EAB infestation2.
  • D-shaped exit holes: The beetles create distinct, small, D-shaped exit holes in the bark3.

 

 

Best Practices for Prevention

Preventive measures against EAB infestations include:

  1. Avoid firewood movement: Transporting firewood can spread EAB. Use firewood from local sources4.
  2. Monitor ash trees: Regularly inspect ash trees for signs of infestation and report to your local extension office5.
  3. Quarantine: Know the quarantines in your area; follow state and federal regulations to prevent EAB spread6.
  4. Insecticides: Professional treatments can help protect ash trees from EAB. For example, ArborMectin and ACECAP Systemic Insecticide Tree Implants7.
Method Pros Cons
Use local firewood Reduces the risk of EAB spread Limited firewood sources
Monitor ash trees Early detection of infestations Time-consuming; requires expertise
Quarantine Preventive control of EAB spread Restricts firewood and tree material movement
Insecticides Effective treatment; saves affected trees Requires professional application; cost

Consider hiring a professional arborist for the assessment and treatment of your ash trees.

Follow their advice to ensure the best possible control of EAB infestations.

Treatment Options for Infested Ash Trees

Insecticide Treatments

Homeowners can opt for insecticide treatments to protect their ash trees from emerald ash borers.

For smaller trees, DIY treatments may suffice. Refer to the Homeowner Guide to Emerald Ash Borer Insecticide Treatments for a list of products available for homeowner use.

When dealing with larger trees, it’s recommended to consult a certified arborist.

They can offer professional treatments and suggest the best insecticide products, such as:

  • Ace-Jet (acephate)
  • ACECAP Systemic Insecticide Tree Implants (acephate)
  • ArborMectin (emamectin benzoate)

Refer to the Professional Guide to Emerald Ash Borer Insecticide Treatments for more info on application methods and timings.

Non-Chemical Alternatives

Besides insecticides, non-chemical alternatives can also help manage emerald ash borers. Homeowners can:

  • Remove weak or stressed ash trees to reduce the chances of infestation
  • Use biological control agents such as parasitic wasps (seek advice from an arborist)

For more information on emerald ash borer management, you can visit emeraldashborer.info.

Remember, always follow the pesticide label instructions when applying insecticides.

 

 

Pros of Insecticide Treatments:

  • Can be highly effective in protecting ash trees
  • Options available for both homeowners and professionals

Cons of Insecticide Treatments:

  • Requires annual applications for continuous protection
  • Potentially harmful to the environment and other organisms

Comparing Insecticide Treatments and Non-Chemical Alternatives

Factors Insecticide Treatment Non-Chemical Alternative
Effectiveness High Varies
Cost Varies Lower
Environmental Impact Higher Lower
Ease of Application Moderate Moderate
Professional Help Required Recommended for larger trees Depends on method

Keep these facts in mind when deciding the best course of action for your ash trees. Consult with a certified arborist for tailored advice.

 

Bug Control Recommendation Tool

What type of pest are you dealing with?

How severe is the infestation?

Do you require child/pet/garden safe treatments (organic)?

Are you willing to monitor and maintain the treatment yourself?


Managing the Impact on Communities

Community Efforts and Programs

Communities across the United States and Canada have been greatly impacted by the invasive emerald ash borer (EAB) as it has caused the death of millions of ash trees.

To combat this issue, community members, scientists, and tree care professionals work together to create programs for managing and preventing EAB infestations.

Some efforts include canopy thinning, which helps reduce dieback and restore stormwater retention capacity in affected areas (source).

Email campaigns and public workshops are organized to educate people about identifying EAB and reporting sightings to local authorities.

Additionally, these campaigns encourage the conservation of ash wood products to prevent the further spread of EAB and create healthier habitats for animals in the affected regions.

Conserving Ash Wood Products and Trees

Ash wood products play a vital role in providing food, water, and nutrients for many animals.

Thus, conserving these resources is essential to counter the threat of complete extinction of ash trees due to EAB.

Common strategies for conserving ash wood products include:

  • Inspecting ash trees: Regular checks for signs of EAB infestation, such as D-shaped exit holes and S-shaped larval galleries under the bark.
  • Establishing quarantine zones: These zones prevent the movement of EAB-infested ash wood materials outside of the infested areas.

To compare the different methods of conserving ash wood products and trees, a comparison table is provided:

Method Pros Cons
Chemical treatment Effective in prevention Not a long-term solution; costly
Canopy thinning Reduces dieback May not prevent EAB infestation
Quarantine zones Limits EAB spread Requires constant monitoring and enforcement

Using a combination of these methods, communities can minimize the impact of EAB infestations on ash trees, preserving the ecological balance and protecting the diverse habitats that depend on these important tree species.

 

 

Conclusion

In conclusion, the emerald ash borer (Agrilus planipennis) is highly dangerous due to its destructive impact on ash trees.

As an invasive beetle native to Asia, it lacks natural predators in North America, enabling it to spread rapidly and decimate ash populations.

The larvae tunnel beneath the bark, disrupting the tree’s ability to transport nutrients, ultimately leading to tree death.

This poses ecological and economic threats, affecting forests, urban greenery, and industries reliant on ash wood.

Protecting your trees from the emerald ash borer requires a multi-faceted approach.

Regular inspections are crucial for early detection of infestations, as signs like thinning canopies and D-shaped exit holes become apparent.

Prevent the spread by refraining from moving firewood and infested plant materials. If detected, promptly remove and destroy infested trees.

Footnotes

  1. USDA APHIS | Emerald Ash Borer 
  2. Emerald ash borer resources | OSU Extension Service 
  3. USDA APHIS | Emerald Ash Borer Beetle 
  4. Emerald ash borer resources | OSU Extension Service 
  5. USDA APHIS | Emerald Ash Borer Beetle 
  6. PDF What other activities have changed or will change? – USDA 
  7. Professional Guide to Emerald Ash Borer Insecticide Treatments 

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about EABs. Scroll down to have a look at some of them.

Letter 1 – Ash Borer

A Better Picture and A Potato Bug Question
Hi Bugman,
I sent you a picture of a bug that we have been trying to identify a few days ago. I got a better picture today and thought I would pass it along.

I have looked in grasshoppers, wasps, leaf hoppers, and a few other sections on your site to try to find it’s identity.

I have another question for you that I have been searching for the answer to for a long time. Why do potato bugs exist? Do they have a purpose?

They freak me out in a way that nothing else does. I am hoping if I can find their purpose, I can accept their existence.

Thanks for your great website! I have spent lots of time here since I discovered it last week.
Laura

Laura’s Original Email
(04/25/2008) Can you tell me about this insect?
Hello,
One of my hobbies is identifying bugs in my garden. This one has me stumped. I live in Sacramento, CA and I have only seen these guys cruising on our teepee made of crepe myrtle.

They are reddish with yellow stripes. I have seen them range from 1/2 to 1 inch long. They first popped up about 1 month ago. I have lived in this area for 10 years and never seen them before.

Can you give me any information about these guys? Thanks!
Laura Stillmunkes
p.s. The pictures are not great. I can try to get a better one if it would be helpful. They move fast!

Hi Laura,
This response has been on our back burner since your original email. Thanks for sending a more in focus photo. We believe this is a Red Headed Ash Borer, Neoclytus acuminatus, but the map of submissions on BugGuide doesn’t show any reports in California.

There are reports in Washington State and Texas. There are other closely related species found in California, but your photo does appear to be the Red Headed Ash Borer.

Our quick web research has been unable to determine if there are reports of the Red Headed Ash Borer in California. Perhaps one of our readers can be more definite. The Potato Bug is part of that mysterious web of connectivity known as the Balance of Nature.

Letter 2 – Ash Borers

insect id
Hello.
I have a pic of a bug that has been getting a home, is found by the fireplace in 3-4 at a time. I live in rural area. This is the first year I have had these type of pests. I have attached a pic of the pest. thank you for your help
Randy

Hi Randy,
This is some species of Ash Borer in the genus Neoclytus, most probably the Red Headed Ash Borer, Neoclytus acuminatus. Being more specific about your location, other than “rural area” would be helpful.

Letter 3 – Banded Ash Borer

Subject: what is this?
Location: Northern Kentucky
January 29, 2013 7:42 pm
Hi! It is January and these things are all over inside my house! It looks like a striped lightning bug?
Signature: Jessica

Banded Ash Borer

Hi Jessica,
We believe this is a Banded Ash Borer,
Neoclytus caprea, one of the wood boring beetles in the family Cerambycidae.  That is the closest match we could find on BugGuide

According to BugGuide:  “It often emerges indoors from firewood.  Sawlogs may become infested within 20 days of felling during the summery.”  T

hat supports our initial response to you that we suspected they emerged from firewood.  You do not have to worry about them laying eggs in your furniture or structural wood.  The warmth indoors caused them to emerge early.

Letter 4 – Banded Ash Borer probably

What is this beetle?
Cut and stacked some Ash logs. On Thursday the 17th of April it was warm and the sun was shining on the pile.

These beetles were chasing and mating all over the logs. I thought it was the long horn beetle. The pattern on the body is different. Can you help me figure out what it is? Thank You,
Shirley Larson

Hi Shirley,
We believe this is a Banded Ash Borer, Neoclytus caprea, as evidenced by images posted to BugGuide.

There are species with similar markings, so we will contact Eric Eaton to see if he can corroborate. We did find a link to a pdf that indicates hickory is a host tree.

Letter 5 – Banded Ash Borers emerge from wood pile

Subject:  Wasp, hornet, or bee?
Geographic location of the bug:  Blue Ridge Mountains, Clarke County, VA
Date: 03/30/2020
Time: 03:24 PM EDT
Your letter to the bugman:  I noticed 2 or more dozen of these in a firewood pile I have on the side of my yard. I need to stack it to season for next winter.

I don’t necessarily want to disturb bees if that’s what they are but I also don’t want to get stung by a swarm and find out if I’m allergic if they are Hornets or wasps.
How you want your letter signed:  Ross

Banded Ash Borer

Dear Ross,
This isn’t a “wasp, hornet, or bee” but rather a Longhorned Borer Beetle in the genus
Neoclytus, probably the Banded Ash Borer, a native species that we identified on BugGuide

According to BugGuide:  “Adults emerge May-Aug in the North, Feb-Nov in the South” and “often emerges indoors from firewood; sawlogs may become infested within 20 days of felling during summer.”  You will not be stung if you stack the wood.

Letter 6 – Probably Banded Ash Borer

New bug that we keep finding…what is it?
Location: Central Texas
February 12, 2012 6:00 pm
I live in Central Texas. In the last two weeks, I’ve been finding this bug in various places around the house (1-bathtub, 1-on some firewood we keep by the fireplace, 1-by front door, 1-crawling across living room floor).

They are obviously not nocturnal. I’ve tried searching similarities on the web, but am not finding anything that resembles it closely. It must not be too common, so what is it?
Signature: All Bugged Out

Banded Ash Borer

Dear All Bugged Out,
The mention of the firewood is significant as this is a Longhorned Borer Beetle, possibly a Banded Ash Borer,
Neoclytus caprea, or another member of the genus.  According to BugGuide, the larva feeds on the wood of oak and ash and they “Usually feeds on sick, dying or recently dead trees.” 

Authors

  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts
Tags: Emerald Ash Borer

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3 Comments. Leave new

  • This is an old post, but I’ve been trying to figure these guys out for a while and stumbled across this, so thought I’d chime in. I’m also in Sacramento, and — though I have no good photo at the moment (I’ll try, but my cheap camera is terrible for anything small) — I’m pretty sure these match what I’m seeing better than anything else I’ve looked at. When I try to find a range, though, I can still only find a few anecdotal accounts in CA, nothing with much authority, and not even enough anecdote to feel comfortable calling it not-quite-data-but-good-enough-for-now.

    So was wondering whether there’s anything more solid about these in CA since the time of this post.

    We certainly have a terrific yard for borers, really — lots of aging trees. We lost two elderly, sick plum trees and a middle-aged, also sickly apple to borer damage after we moved here — those were basically opportunistic attacks, though, they were planted poorly years ago and were probably weak before the borers. We’ve also thinned a lot of privet over the last year. I clean up lots of fallen wood, but I do tend to leave some larger bits around, too, as long as they’re away from the house — I’m trying to let our mini-woods draw more diverse species over time and so we tend to let some detritus stay to rot out, draw various fungi and insects and their predators, or develop into duff. I only meddle much if something is a safety issue for us or our pets, involves invasives with no good predators here, or is really likely to cause major damage to the house. That means there are any number of places borers could have popped from.

    But I’d love to get an ID on these guys and figure out how seriously to take them, since I’m pretty sure their search for food in the thinned yard has them aiming for our huge, ~100-year old pecan, which is almost certainly stressed from the drought here (not a tree I would plant in CA these days, but it’s a bit of a heritage tree from a different era.) We’ve drawn some Nuttall’s Woodpeckers, a mating pair, and that likely helps, but the tree is very large and would be a serious hazard if it got too weakened, so I’m watching carefully — would prefer to consider it all with a positive ID.

    Thanks for all that you do with this site. I can wander it pretty endlessly, just looking at all the neat critters.

    -Cricket

    Reply
    • Dear Cricket,
      Thanks so much for your extensive comment. According to BugGuide, the Red Headed Ash Borer has been reported from California. The habitat you have provided sounds wonderful and the woodpeckers should help to control the Red Headed Ash Borer population in your existing trees.

      Reply
  • This is an old post, but I’ve been trying to figure these guys out for a while and stumbled across this, so thought I’d chime in. I’m also in Sacramento, and — though I have no good photo at the moment (I’ll try, but my cheap camera is terrible for anything small) — I’m pretty sure these match what I’m seeing better than anything else I’ve looked at. When I try to find a range, though, I can still only find a few anecdotal accounts in CA, nothing with much authority, and not even enough anecdote to feel comfortable calling it not-quite-data-but-good-enough-for-now.

    So was wondering whether there’s anything more solid about these in CA since the time of this post.

    We certainly have a terrific yard for borers, really — lots of aging trees. We lost two elderly, sick plum trees and a middle-aged, also sickly apple to borer damage after we moved here — those were basically opportunistic attacks, though, they were planted poorly years ago and were probably weak before the borers. We’ve also thinned a lot of privet over the last year. I clean up lots of fallen wood, but I do tend to leave some larger bits around, too, as long as they’re away from the house — I’m trying to let our mini-woods draw more diverse species over time and so we tend to let some detritus stay to rot out, draw various fungi and insects and their predators, or develop into duff. I only meddle much if something is a safety issue for us or our pets, involves invasives with no good predators here, or is really likely to cause major damage to the house. That means there are any number of places borers could have popped from.

    But I’d love to get an ID on these guys and figure out how seriously to take them, since I’m pretty sure their search for food in the thinned yard has them aiming for our huge, ~100-year old pecan, which is almost certainly stressed from the drought here (not a tree I would plant in CA these days, but it’s a bit of a heritage tree from a different era.) We’ve drawn some Nuttall’s Woodpeckers, a mating pair, and that likely helps, but the tree is very large and would be a serious hazard if it got too weakened, so I’m watching carefully — would prefer to consider it all with a positive ID.

    Thanks for all that you do with this site. I can wander it pretty endlessly, just looking at all the neat critters.

    -Cricket

    Reply

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