The emerald ash borer.

The invasive insect that kills ash trees has been detached in 91 of Iowa’s 99 counties.

State officials have confirmed the emerald ash borer has been found in Dickinson and Humboldt Counties for the first time. Mike Kintner is the emerald ash borer coordinator for the Iowa Department of Agriculture. Kintner says emerald ash borer larvae was found just outside of Arnolds Park after getting a tip from a professional who works in the landscaping industry.

“Basically what he saw and a lot people see this time of year is the woodpecker activity on the tree,” Kintner says. “…There was some woodpecker flocking and mobbing where the woodpeckers will come and feed on the emerald ash borer that’s underneath the bark.”

The destructive beetles were also found outside of Dakota City. In addition to woodpecker activity, Kintner says a thinning leaf canopy at the top of an ash tree is a clue because the insects attack the top third of the tree first and then progress downward.

“Bark splitting is one thing, too,” Kintner says. “There’s vertical splits on some of the larger branches and even smaller branches if you look up into the tree. That’s caused by the larvae feeding on the bark and sometimes the bark will split.”

Kintner says if you have an ash tree on your property and you live within 15 miles of a confirmed emerald ash borer infestation, now is the time to consider whether you’ll start treating the tree.

“Preventative insecticides do work and those can either applied as a homeowner if the tree is under a certain amount of size,” he says, “…or basically you can go with a certified applicator, a professional method, too.”

Here’s the state’s list of confirmed emerald ash borer infestations. The eight Iowa counties where infestations have not yet been identified are Emmt, Kossuth, Mitchell, Monona, Osceola, Palo Alto, Plymouth and Woodbury.

The pest was first discovered in the United States in 2002, in southeast Michigan. It was confirmed in Iowa eight years later.


(Reporting by Ed Funston, KILR, Estherville)