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Emerald Ash Borer Discovered in Kossuth County

Now confirmed in all but 7 of Iowa’s 99 counties

Emerald ash borer has been found in Kossuth County for the first time. The invasive, ash tree-killing insect from Asia has now been confirmed in all but seven of Iowa’s 99 counties since its original detection in 2010.

Adult beetles were collected from infested trees by the Iowa Department of Agriculture and Land Stewardship in rural Algona. Federal identification confirmed the samples positive for EAB.

EAB is a significant threat to native ash tree species, typically killing a tree within two to four years after becoming infested. It is the cumulative damage by the larvae (immature stage) feeding on the inner bark that eventually kills ash trees. The feeding cuts off the tree’s ability to transport water and nutrients.

Indicators of an infestation may include canopy thinning, leafy sprouts shooting from the trunk or main branches, serpentine (“S”-shaped) galleries under the bark, bark splitting, woodpecker damage and 1/8-inch D-shaped exit holes.

While adult beetles can disperse locally by flying, long distance spread of this insect is attributed to people moving infested material, including firewood. People are encouraged to use locally sourced firewood where it will be burned to help limit the spread of EAB.

Now is the time to decide a course of action for ash trees at risk of EAB attack (within 15 miles of a known infestation). Landowners and managers can choose to wait and see what happens, remove declining ash trees and replace them with other species, or use preventive insecticide treatments to preserve and protect valuable and healthy ash trees. Spring, from mid-April to mid-May, is the best time to treat for EAB. Insecticides are most effective when the ash tree is actively growing, and uptake is at its peak. Tree service companies can apply insecticide trunk injections through the summer if soil moisture is available.

See Iowa State University Extension and Outreach publication ENT57, Emerald Ash Borer Management Options, for more details about EAB treatment.

The State of Iowa continues to evaluate the potential spread of EAB on a county-by-county basis. Before a county can be declared positive, a life stage of the insect must be collected and confirmed. Anyone who suspects an infested ash tree in a county not currently known to be confirmed with EAB is encouraged to contact one of the following:

  • Iowa Department of Agriculture and Land Stewardship, State Entomologist Office, 515-725-1470.
  • Iowa State University Extension and Outreach, Entomology, 515-294-1101.
  • Iowa Department of Natural Resources, 515-725-8200.

Additional information on EAB, including a county detection map, can be found at


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