A destructive insect that has already killed thousands of ash trees, has now been confirmed in another Northeast Iowa county.

According to the Iowa Department of Agriculture and Land Stewardship, the emerald ash borer has been discovered in Winneshiek County.

An arborist had noticed evidence of EAB damage to an ash tree in Decorah recently. A specimen larva was sent to a lab, where it was positively confirmed as the emerald ash borer.

The metallic-green beetle deposits it's eggs in the bark of a tree, where they hatch; the larva then bores into the inner bark, disrupting the flow of water and nutrients to the tree, killing it.

There is currently a quarantine to restrict movement of firewood and nursery stock out of non-quarantined areas of other states, to try to keep the insect from spreading.

The pest was first found in Iowa in 2010, in Allamakee County. It has now been detected in about one-third of Iowa's counties.

In Northeast Iowa, that includes: Allamakee, Black Hawk, Bremer, Dubuque, Linn and Winneshiek Counties.