University of Maryland Extension

Emerald Ash Borer (EAB)

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adult eab

Emerald Ash Borer (EAB) is a serious threat to Maryland ash trees. It has killed many millions of ash trees across the Mid-West and Eastern U.S. This invasive pest is well-established in Maryland and in the summer of 2015 it was also found on the eastern shore. Adult beetles begin flying about the time that black locust is in bloom.

The EAB is an invasive pest from Asia that feeds on and kills ash trees.  EAB will kill even large ash trees within three years after infestation.  Ash trees are one of the most common and important landscaping trees used in Maryland and are common in western Maryland forests. Ash wood is used for all traditional applications of hardwood from flooring and cabinets to baseball bats. 

EAB infested young ash trees
Young ash trees infested with EAB
Joseph O'Brien, USDA Forest Service,

Presence of the emerald ash borer typically goes undetected until trees show symptoms of being infested, usually the upper third of a tree will thin and then die back. This is usually followed by a large number of shoots or branches arising below the dead portions of the trunk. Other symptoms of infestation include small D-shaped exit holes in the bark where adults have emerged, vertical splits in the bark, and distinct serpentine-shaped tunnels beneath the bark in the cambium, where larvae effectively stop food and water movement in the tree, starving it to death.

exit holes
D-shaped exit hole
Photo: David R. McKay, USDA APHIS PPQ,

If you have ash trees that you want to protect from EAB, treatments will need to be made in March.  Large specimen trees will need to be treated by a certified arborist. Consult the North Central IPM Center's fact sheet for options, (PDF) "Insecticide Options for Protecting Ash Trees from Emerald Ash Borer". Be sure to check labels and instructions to make sure that Emerald Ash Borer is on the label.  To help you make a decision on treatment, Purdue University published an excellent (PDF) decision guide.

emerald ash borer on top of a penney
EAB beetle size
Photo: Lexa Panessidi, State of Michigan,
EAB  larvae
Various stages of larvae
Photo: David Cappaert,

larval galleries
Galleries made by larvae underneath the bark
Photo: James W. Smith, USDA APHIS PPQ,

To help stop this damaging beetle, homeowners and citizens who live in and travel through known infested areas can help.

    • Don’t move firewood – buy it where you burn it.  Hauling firewood is the most common way for damaging plant pests to be moved from one area to another.
    • Don’t plant ash trees.  As EAB is expanding its range in Maryland, diversified plantings of alternative tree species are recommended for residential landscaping.
    • The USDA expanded the federal quarantine to include all areas where EAB is under state quarantine under a federal quarantine area. Current quarantine information for other states can be found here at where is EAB.
    • The Maryland Department of Agriculture (MDA) confirmed the presence of the invasive, highly destructive emerald ash borer (EAB) beetle on the Eastern Shore in June 2015.
    • As of July 31, 2015, the Maryland Department of Agriculture rescinded the statewide quarantine prohibiting the movement of hardwood from the western to the eastern shore.
    • Reports of emerald ash borer from the Eastern Shore of Maryland should still be reported to HGIC by clicking on 'Ask Maryland's Garden Experts'.
    • Dead trees located in yards, near buildings or are street trees, will likely become hazardous trees and should be removed immediately by a reputable tree company. Ash trees become very brittle when they die and tree companies will not climb them for removal if they have been dead for more than 6 months.  Depending on the situation a crane may be needed thus increasing the cost.
    • Hire a reputable, insured, licensed arborist or tree company to remove any ash trees you plan to remove. Obtain estimates from multiple companies; ask for proof of insurance and a written estimate. The estimate should include wood disposal information (a reputable company will have this information) and site cleanup. Ask for references. The following websites can assist you in finding a licensed company: and
    •  An EAB infested tree with no more than 30% canopy dieback should be treated if you want to save the tree. Otherwise, the tree should be removed to help prevent the spread of EAB. Dead/dying trees act as a reservoir for the beetle. Trees should be removed in late winter or early spring before the adult beetles begin to fly.

Maryland Resources:

National Resources:

General Information:

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