Emerald Ash Borer

The emerald ash borer, Agrilus planipennis, is a destructive, invasive wood‐boring pest of ash trees, Fraxinus spp. Emerald ash borer (EAB) is native to eastern Asia. It was first detected in North America in 2002, when it was discovered in Detroit, Michigan.  

Now EAB has spread to 36 states including Texas. The first detected county in Texas was Harrison County in 2016. 
 
EAB has killed millions of ash trees across the country. Ash trees are widespread in the U.S. and all 16 native ash species are at risk of attack. Ash trees with low population densities of EAB often have few or no external signs of infestation. 

To report any symptomatic ash trees, please call the EAB hotline at 1-866-322-4512.  

Current situation 

We began our EAB detection program in 2009 by strategically deploying detection traps each spring. These traps are checked each spring and summer to capture EAB emergence and track movement.  

As of July 2024, there are 26 confirmed Texas counties with EAB: 

EAB will continue to spread in and around these areas, and it is possible that more detections will occur in other counties. We will continue to track the movement of EAB through our detection program and will remain vigilant in evaluating further EAB sightings across Texas.  

EAB Known Infested Counties Map (USDA-APHIS) 

Ash trees

Ash trees make up a large population of urban forests. In Dallas, for example, they account for over 5% of the city’s canopy cover.

Ash trees are important to our environment and our economy. They help fill the forest canopy and provide shade for the forest floor. They also keep our ecosystems diverse and stable. Nearly 100 species of insects rely on ash trees to survive.

They provide shade—cooling our streets and homes, keep the air clean and water pure, maintain soil quality, manage storm water runoff, and beautify the places we live, work, and play.

Ash trees also provide us with a variety of different products.  

White ash wood is pliable and strong but still lightweight. Because of these unique qualities it is used for products like baseball bats, hockey sticks, guitars, boat oars, flooring, and furniture.  

White ash also provides food for different wildlife species like cardinals, finches, and wood ducks.  

Black ash wood is not as strong as white ash, but it has a pleasing grainy look that makes it a unique choice for furniture. Young black ash wood is also flexible enough to bend and used for cabinet making.

Identifying ash

Knowing how to recognize an ash tree from other tree species is an important part of managing EAB. Most tree species in Texas have alternate branching. However, ash trees have opposite branching. Ash tree leaves also have opposite compound leaves. The bark on mature ash trees is in a fishnet or diamond pattern. 

Signs and symptoms

Ash trees within the first stages of attack often have few or no external symptoms of EAB infestation.  

Seeing EAB adults near an ash tree is a tell-tale sign it may be infected. EAB adults are dark green, one-half inch in length, and one-eighth inch wide. They fly between May and June, depending on environmental conditions.  

Symptoms of an infestation may include:

• Dead branches near the top of a tree

• Leafy shoots sprouting from the trunk.
• Bark splits exposing s-shaped larval galleries.
• Extensive woodpecker activity
• D‐shaped exit holes

Management

Plant diversity

The first step to stopping EAB starts when planting. When you replace those lost because of EAB or simply add new trees to the landscape, planting multiple species is one of the best ways to prevent significant losses in the future.  

A general guideline to follow is known as the 10-20-30 rule. This simple rule of thumb suggests that a tree population should include no more than 10% of any one species, 20% of any one genus, or 30% of any one family. For example, if you plant 10 trees, two of them can be diverse types of ash tree, one Red and one Berlandier, and then the rest need to be other types of trees, such as elm, oak, maple, or sycamore. Having a greater diversity of trees reduces the likelihood that they will be severely affected by an outbreak of any single pest or pathogen.
For information and guidance on tree planting visit the Texas Tree Planting Guide.

Saving trees

If you have ash trees on your property, then you have some decisions to make. The first choice is whether, or not, the tree is important enough to save. If it is a tree that provides shade to your sunporch or if planted in memory of a loved one, the answer may be ‘yes.’ If you decide this is the case, then you have options.

Several commercially available insecticides are registered for treatment of EAB. Trees can be treated with soil injections or drenches, trunk injections, or trunk sprays. Systemic insecticides that list emamectin benzoate as the active ingredient are recommended in areas where EAB is present. These insecticide injections can protect a tree for 2-3 years for either treating active infestation or to prevent attacks of EAB.

If you decide the tree is not important, the wood can be used for mulch or used for firewood. However, know that EAB can survive for up to two years after a tree is cut down. So, if you chop down an infested tree and move it to your woodpile, you may be moving EAB closer to other, still-healthy trees.

Tree removal

The cost of removing dead or dying trees can be straining on budgets. Local communities and homeowners may pay to try and prevent infestation or remove infested trees from their properties.  

The best way to do this is to hire a trained professional who has experience removing EAB infested trees. You should always be sure that whoever you contact is insured and bonded in case of an accident, which is information real professionals should be happy to share.  

It is also vital that you dispose of dead trees properly to slow the spread of EAB and ensure the dead tree does not damage or harm any person, pet, or property. Since EAB can survive in the wood of a dead tree for years, this is a vital step no matter how long the tree has been dead for. This is also why it is important you burn, bury, or chip the tree where it is, rather than transport it somewhere else. Transporting it may spread EAB to new counties that are currently EAB free.

Removing ash trees that are in poor condition or infested with EAB can help to slow the spread of the insect. Infested wood must be disposed of properly by chipping as insects can still emerge and travel to other trees, even after a tree has died and been cut down.

EAB lifestyle

Adult EAB lay eggs in the bark of ash trees in late summer. The larvae burrow into the bark which provides shelter during winter months. The larvae feed under the bark (in the phloem and cambium) disrupting the flow of nutrients within the tree, hindering the transport of nutrients and water within the tree. When the beetles emerge as adults, they leave D-shaped holes in the bark about one-eighth of an inch wide.

EAB weaken trees in the winter and kill them in the summer. Because they are invasive to the U.S., our ash trees don’t have any natural defenses against them. Once an ash tree is infested with EAB, it is likely it will die. In areas where EAB is well established, it can kill an ash tree within one year of the first infestation.

Community preparedness

We can help communities develop, communicate, and implement an EAB preparedness plan.

An EAB preparedness plan will not necessarily prevent EAB or the loss of community ash trees, but instead give communities information and decision-making tools, minimizing any suffering caused to the community by this invasive insect. 

Losing and removing all the community ash trees without a mitigation or replacement plan could cause a/an:

• Permanent loss from urban forest that will take years, or generations to replace.
• Increased storm water runoff and water consumption.
• Increase energy costs and higher temperatures, in urban and suburban areas.
• Decrease in property value and neighborhood character.
• Impact bird and arthropod communities that rely on this resource for food, shelter, and reproduction.

• Community guides

  • Community Forest Planning: Emerald Ash Borer
  • EAB State Summary of Potential EAB Impacts

Control

We investigate suspected EAB infestations with particular concern to detections occurring in previously un-infested counties.

Don’t move firewood

EAB can spread long distances in wood. Buying and using only local firewood can keep EAB from spreading to new locations. Movement of ash nursery trees and other wood products can also potentially allow EAB to reach new areas and create satellite populations.

The Texas Department of Agriculture (TDA) handles regulating the movement of potentially infested products from areas of known EAB outbreaks by implementing and enforcing EAB quarantines.

An EAB quarantine regulates the movement of firewood, ash nursery stock, ash timber and other material that can spread EAB. It is important to know where the emerald ash borer quarantines are if you are traveling between infested states or counties. 

• Leave firewood at home. Do not transport firewood, even within the state.
• Use firewood from local sources near where you are going to burn it, or purchase firewood that has been certified to be free of pests (it will say so on the label included with the packaging).
• If you have moved firewood, burn all of it before leaving your campsite.

Biological control

The Operation Biocontrol Program being conducted by USDA APHIS has successfully released parasites that specifically target EAB across the eastern U.S. In other regions, these parasites have been recovered and show promising results as they suppress EAB populations to low densities but, as of 2023, none of these tests have been successful in the Southern U.S.

Trapping efforts

We are responsible for Texas’ EAB detection program. Triangular purple box traps are placed in ash trees to learn if EAB is present in the area. The traps have an adhesive coating that captures insects when they land.  The color attracts EAB and is easy for people to spot among the foliage. If you see an EAB trap, stay clear of it. It is capturing vital data that could be compromised if you disturb it. 
In preparation for the arrival of EAB to the state, we helped develop a multi-partner, state EAB response plan. 
The EAB response plan includes establishing each involved agency’s responsibilities, removing ash trees as a preemptive measure, selecting ash tree treatments and planting tree species not susceptible to EAB. This assessment and implementation process typically takes 60-90 days and then is given to the public for comment before being implemented.