Emerald Ash Borer Discovered in 4 More Iowa Counties

Invasive pest confirmed in Buchanan, Hamilton, Hardin and Pottawattamie counties

June 22, 2018, 9:25 am | Dustin Vande Hoef, Julie Tack, Laura Sternweis

DES MOINES, Iowa – A destructive pest of ash trees has now been confirmed in Buchanan, Hamilton, Hardin and Pottawattamie counties. The emerald ash borer, an exotic pest from Asia, was first found in Iowa in 2010 and has now been detected in 61 Iowa counties.

Insect samples were collected from ash trees in Winthrop (Buchanan County), a rural area east of Randall (Hamilton County), Eldora (Hardin County) and Council Bluffs (Pottawattamie County). The samples were submitted to the USDA’s Animal and Plant Health Inspection Service, which confirmed them positive for EAB. Buchanan and Hardin counties involved ash trees on private property, whereas Hamilton and Pottawattamie County findings occurred in the right-of-way along I-35 and I-80, respectively.     

“June is typically the time of year we receive a surge in phone calls about poorly looking ash trees. We urge people to continue to report suspicious symptoms in counties that are not yet known to be infested,” said Mike Kintner, Iowa Department of Agriculture and Land Stewardship EAB and gypsy moth coordinator. “People can really help minimize the spread of this pest by not giving it a ride in infested firewood between counties or from home to campsite.”

Since the dispersal of this beetle by natural flight is limited to only short distances, people serve as the mode of transportation involving longer distances. Beneath the bark in the larval stage, EAB can unknowingly be transported in firewood. Numerous other insects and diseases also can hitchhike in firewood. Iowans are encouraged to use locally sourced firewood, burning it in the same county where it was purchased.

Adult beetles begin to emerge from May to June and can be found throughout the summer months. The metallic-green beetle is slender and approximately 1/2 inch long. After emerging from a tree, the beetle leaves behind a telltale D-shaped exit hole approximately 1/8 inch in diameter.  

EAB-infested ash trees can include branch dieback in the upper crown, water sprouts along the trunk and main branches, vertical bark splits, D-shaped emergence holes, S-shaped tunneling under loose bark, as well as woodpecker damage. EAB larvae kill ash trees by tunneling under the bark and feeding on the part of the tree that moves nutrients up and down the trunk. Starved trees usually die within two to four years.

The State of Iowa continues to track the movement of EAB on a county-by-county basis. Citizens who suspect an EAB infestation in ash trees in their area are encouraged to contact one of the following:

  • Iowa Department of Agriculture and Land Stewardship, State Entomologist Office, 515-725-1470.
  • Iowa Department of Natural Resources, 515-725-8453.
  • Iowa State University Extension and Outreach, Entomology, 515-294-1101.

At this calendar date, the treatment window for soil-applied preventive treatment measures (soil injection, soil drench or granular application) and basal bark sprays has ended. Trunk injections can be done now through the end of August if a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation.

Good ground moisture is essential for systemic insecticide movement in a tree. Full details are available in Iowa State University Extension and Outreach publication PM2084, Emerald Ash Borer Management Options. To find a certified applicator in your area, download PM3074, Finding a Certified Pesticide Applicator for Emerald Ash Borer Treatment, and follow the steps.

To learn more about EAB and view maps of its distribution, please visit


About the Authors: 

Julie Tack

Iowa Department of Natural Resources