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Lake County Forest Preserves | Preservation, Restoration, Education and Recreation


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Emerald Ash Borer

Emerald ash borer (EAB), Agrilus planipennis, is a non-native invasive beetle that was discovered in southeastern Michigan in the summer of 2002. Adult EAB consume ash leaves but cause little damage. It is their larvae that cause damage, feeding on the inner bark of ash trees and disrupting the flow of water and nutrients within the tree.

Since its discovery, EAB have killed tens of millions of ash trees throughout the northeastern United States and eastern Canada. Damage from EAB has cost property owners, municipalities, nurseries and the forest products industries tens of millions of dollars.

EAB facts

  • Native to Asia
  • Likely came to U.S. in wood packing material
  • Infests only true ash trees (Fraxinus spp.)
  • Adult beetles are metallic green, 1/2 inch long, 1/8 inch wide
  • Adults make D-shaped exit hole in bark upon emergence
  • Adults emerge May through July
  • Adult lifespan is two to three weeks
  • Eggs are laid in bark crevices of ash trees
  • Eggs hatch in seven to 10 days
  • Larvae tunnel under bark, creating S-shaped tunnels (galleries)
  • Larval galleries cut off flow of water and nutrients to the tree
  • Larvae overwinter in chambers within the sapwood of ash trees
  • Larval galleries are the eventual cause of ash tree death
  • Heavy woodpecker damage on ash trees can be a sign of infestation

What we are doing

Our forestry crews monitor sites for signs of infestation and make determinations on treatment options or tree removal. Learn more »

Damaged ash trees that pose a risk to public safety or property are removed. Avariety of native tree species are planted in place of ash trees that are removed in landscaped areas.

We are currently participating in a biological control study on the effects of parasitic wasps.

What you can do

Familiarize yourself with the proper identification of ash trees and EAB. Learn more »

Monitor the health of local ash trees for dying branches at the top of the tree, known as crown dieback. Removal should be considered where damaged ash trees pose a risk to human safety or property. It is possible to treat ash trees that have not yet been infested. Contact local arborists for assistance with these determinations.

Transport of firewood remains a problem. Purchase firewood locally from a known source. Do not move any ash firewood or logs outside of a quarantined area. Be sure to use your firewood in the cold months so no EAB survive until spring.

Impact from EAB is now visibly apparent throughout the Chicago area. Tree removal is widespread due to damage from this forest pest. We recommend planting a variety of native tree species in place of ash trees that are removed in landscaped areas. Biodiversity, short for biological diversity, keeps our air and water clean, regulates our climate, and protects against devastating losses when invasive species, such as EAB, arrive in our local ecosystems.

Identify EAB

  • eab-adult-macro
  • eab-adult
  • eab-crown-dieback
  • EAB


Research Assistance

Find further information about identifying species, living with wildlife and other natural resource topics.
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