A tree-killing invasive species that already is threatening hemlocks in Hocking Hills has spread to three more Ohio counties.
The hemlock woolly adelgid has been discovered in Lawrence, Monroe and Vinton counties in southeastern Ohio. The species had been found in Meigs and Washington counties in 2012 and in Hocking County in 2013.
Known for the cottony sac shelters they weave on branches, the aphid-size adelgids feed on the nutrients that hemlocks store at the base of their needles. Adelgids can kill an adult tree in a few years.
Officials say the insects likely came into the United States on hemlocks imported from Japan. They were first found near Richmond, Va., in 1951. They since have spread to 18 eastern states, from Maine to Georgia.
The adelgid is primarily transmitted by wind and birds.
The most recent infestations were detected by Ohio Department of Agriculture and Department of Natural Resources officials in Dean State Forest in Lawrence County, Zaleski State Forest in Vinton County and in a landscape setting in Monroe, according to the state.
Officials say they have expanded the state’s hemlock quarantine to include the three newest counties. It restricts the movement of hemlock trees and materials out of infested counties and requires growers in non-infested counties to have materials inspected before they can be shipped.
By Mark Somerson - The Columbus Dispatch, Ohio (MCT)
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