Emerald Ash Borer

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Emerald Ash Borer 
Insects, Spiders, & More 

About the Resource:

The Emerald Ash Borer (EAB) is a highly destructive invasive pest that targets ash trees. Native to Asia, it was first discovered in North America in 2002 and has since caused significant damage to ash trees across the continent.

EAB Resource Center

Identification

  1. The Pest
    • Adult Beetle: The adult Emerald Ash Borer is a small, metallic green beetle measuring about 1/2 inch (12-15 mm) long and 1/8 inch (3 mm) wide. Its distinctive emerald-green color and coppery red underside make it recognizable.
    • Larvae: The larvae are white to cream-colored, legless, and have a segmented body. They are typically found under the bark of infested trees.
    • Pupal Stage: The pupae are cream-colored and found in the larval galleries just beneath the bark.
  2. Signs of Infestation
    • D-shaped Exit Holes: Adult beetles emerge from the tree through small, D-shaped holes about 1/8 inch (3 mm) in diameter.
    • S-shaped Galleries: The larvae create serpentine galleries under the bark, which disrupt nutrient and water transport, leading to tree decline.
    • Dieback: The canopy of infested ash trees may show thinning, yellowing, and dieback, starting from the top of the tree and progressing downward.
    • Bark Cracks: The bark may start to split or exhibit cracks as the tree reacts to the damage.
  3. Tree Decline Symptoms
    • Excessive Sprouting: Ash trees may develop many small shoots or sprouts on the trunk and lower branches as a response to stress.
    • Woodpecker Activity: Increased woodpecker activity is often a sign, as they feed on the larvae under the bark.

Management and Control

  1. Prevention
    • Avoid Moving Firewood: Do not transport firewood from infested areas to reduce the spread of EAB. Firewood can harbor larvae and facilitate the spread of the pest.
    • Use of EAB-Resistant Trees: Consider planting tree species that are not susceptible to EAB as replacements for ash trees in your landscape.
  2. Detection and Monitoring
    • Trap Trees: Set up trap trees by coating ash trees with an attractant to lure and capture adult beetles. This helps monitor and assess EAB populations.
    • Pheromone Traps: Use pheromone traps to attract and capture adult beetles, helping to monitor their presence and population levels.
  3. Chemical Control
    • Insecticides: Systemic insecticides can be applied to the soil or tree trunk to protect ash trees. These chemicals are taken up by the tree and kill the larvae feeding beneath the bark. Common products include imidacloprid and dinotefuran.
    • Timing: Insecticide treatments are most effective when applied in early spring or late summer when beetles are actively feeding or before larvae enter the tree.
  4. Cultural Control
    • Tree Care: Maintain the overall health of ash trees with proper watering, fertilization, and pruning to help them withstand the stress caused by EAB.
    • Remove Infested Trees: In severe cases, remove and properly dispose of heavily infested ash trees to prevent further spread of EAB. Ensure that the wood is chipped or burned to kill any remaining larvae.
  5. Biological Control:
    • Natural Enemies: Introduce or encourage natural enemies of EAB, such as parasitoid wasps, which can help control EAB populations. Several species of parasitoid wasps that target EAB larvae have been released in some areas.
  6. Regulatory Measures:
    • Local Regulations: Follow local and state regulations regarding the movement and disposal of ash trees and firewood. These regulations are often put in place to prevent the spread of EAB.

Challenges and Considerations

  • Wide Spread: EAB has spread rapidly across many regions, making it difficult to control once established. Early detection and management are crucial to prevent extensive damage.
  • Cost: Implementing control measures, particularly chemical treatments, can be expensive, especially for large trees or widespread infestations.
  • Tree Replacement: Ash trees may need to be replaced with non-ash species, which requires planning and investment in new plantings.

When to Seek Professional Help

  • Severe Infestation: If you suspect a severe infestation or if the tree is large and difficult to manage, consult with an arborist or pest management professional for advice on the best course of action.
  • Tree Health: For detailed assessment of tree health and appropriate treatment options, professional evaluation can help ensure that the correct measures are taken.

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