The emerald ash borer (EAB) is a destructive wood-boring beetle that attacks and kills ash trees (Fraxinus spp.). The beetles' larvae burrow into and tunnel below the inner layer of bark, damaging the trees ability to transport water and nutrients. The cummulative damage typically kills the tree within two to four years. Native to Asia, EAB was first discovered in the U.S. near Detroit, Michigan in 2002 and has since spread to over 35 states. This tiny insect is responsible for widespread ash mortality in Iowa and many other states.

As of October 2024, EAB has been confirmed in all of Iowa's 99 counties. The Iowa Department of Agriculture and Land Stewardship (IDALS) has been recording the spread of EAB since it was first discovered in Iowa in 2010. See EAB county detection map.

IDALS has issued a news release for all first EAB detections in a county. The most recent include Emmet County (October 2024) and Palo Alto (April 2024).

October 17, 2024 - Emerald Ash Borer Confirmed in Emmet County - Now all 99 Counties

April 1, 2024 - Emerald Ash Borer Confirmed in Palo Alto County

The most common observed sign of infestation is canopy thinning and dieback. Branches in the upper one-third of the tree's canopy will die and more branches will progressively die downward over time. As the tree declines, leafy sprouts often shoot from the trunk and/or main branches. Other indicators include 1/8 inch "D"-shaped exit holes, vertical splits in the bark, "S"-shaped feeding galleries in the vascaular tissue beneath the bark, and woodpecker damage to the bark.

Signs and Symptoms of EAB (E-2938) - .pdf

Preventative treatment can be used to protect healthly and valuable ash trees. Treatment may also provide protection on lightly infested trees, provided the damage is minimal. Without ongoing treatment, any infested trees will die. For more on treatment options and other considerations, see the below Iowa State University Extension and Outreach four-page resource.

Emerald Ash Borer Management Options.

The USDA's Animal Plant Health Inspection Service (APHIS) EAB federal domestic quarantine was eliminated in 2021. However, some state-level exterior quarantines exist in place to restrict the movement of EAB regulated articles into certain states. Regulated articles may include firewood of any hardwood species, ash logs, ash chips/mulch, ash trees, green ash lumber and tree debris of ash. It is important for individuals and businesses to determine if regulations exist prior to the transportation of such articles outside of Iowa. Contact IDALS for assistance in determining regulation status in other states. Opportunities may exist for the movement of EAB regulated articles to a state with regulations through permits, certificates or a compliance agreement. This includes, but is not limited to firewood producers.

The transportation of firewood and ash articles are no longer regulated within Iowa. However, because EAB and other invasive pests can unknowingly hitchhike in firewood, people are reminded to use firewood locally sourced from the area where it will be burned to keep damaging tree pests from being transported to new areas.