Emerald Ash Borer Confirmed in Grundy County

New infestation of invasive pest discovered in Dike

September 13, 2018, 10:26 am | Dustin Vande Hoef, Julie Tack, Laura Sternweis

DES MOINES, Iowa ā€“ The emerald ash borer, a destructive insect that attacks and kills ash trees, has been detected for the first time in Grundy County. There are now 65 counties in Iowa with confirmed infestations.

emerald ash borer.Insect samples were collected from a city-owned tree in Dike after an Iowa Department of Agriculture and Land Stewardship worker noticed ash trees showing the signs of a tree under attack. The collected samples were positively identified as EAB by a federal identifier.    

The adult emerald ash borer is a metallic green insect measuring about one-half inch long. The female beetles lay eggs on the bark of ash trees. Following egg hatch the larvae bore into the bark to the fluid-conducting vessels underneath. The larvae feed and develop, cutting the flow of nutrients, eventually killing the tree. EAB is native to Asia.

The beetle can fly only short distances. There is also the ever-present risk of spreading EAB and other tree-killing pests through human transport of firewood. Use locally-sourced firewood when burning it at home, and when traveling, burn firewood where you buy it.

EAB-infested ash trees can include sparse foliage or thinning of the canopy, excessive sprouting of epicormic shoots from the trunk or main branches, increased woodpecker activity, serpentine (ā€œSā€-shaped)  galleries under the bark, vertical bark splitting, and 1/8 inch D-shaped emergence holes.

At this calendar date, the window for all preventive treatments has closed. If a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, he or she should have landscape and tree service companies bid on work, review the bids this winter, and treat beginning spring 2019 (early April to mid-May). More details pertaining to treatment are available in Iowa State University Extension and Outreach publication PM2084. To find a certified applicator in your area, download PM3074 and follow the steps.

The State of Iowa continues to track the movement of EAB on a county-by-county basis. To report a suspected infestation in a new location, 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.

To learn more about EAB and to view known locations in Iowa, please visit http://www.iowatreepests.com.

For more information contact any of the following members of the Iowa EAB Team:


About the Authors: 

Julie Tack

Iowa Department of Natural Resources