August 8, 2007 | By: Carol Lea Spence
LEXINGTON, KY.

The hemlock wooly adelgid has been found in the forests of four southeastern Kentucky counties, but this year there has also been a sighting in Oldham County in the north central region and a possible sighting in Grayson County in the west.

An Oldham County homeowner found signs of the insect on two landscape trees and took samples to the University of Kentucky Cooperative Extension office to investigate further. 

“It was an accidental discovery,” said Lee Townsend, UK extension entomologist. “It’s important because it is far out of the known range of the insect in Kentucky.”

The Grayson County find is highly likely, but cannot be confirmed, because the specimen was in poor condition when presented to the Kentucky Division of Forestry.

Hemlock woolly adelgid is an aphid-like insect that is found in eastern hemlock forests. It first appeared in the eastern United States in Virginia in the 1950s. Since then it has spread to approximately half of the hemlock range from Connecticut to North Carolina. It was discovered in southeastern Kentucky in spring 2006. The infested area generally expands at a rate of 15 miles per year. This year’s sightings in Bell, Harlan, Leslie and Letcher counties are consistent with that pattern. Because the Oldham County find is nearly 200 miles outside the expected range, the find causes concern.

Townsend said that four years ago, when the Oldham County trees were introduced into the landscape, the insect had yet to be discovered in the area and consequently would not have been on anyone’s minds.

“Now I think the nursery industry is aware of this insect and of other invasive species that are around,” he said. “One of the main things you can do (as a homeowner) is get your landscape plants through a licensed nurseryman and landscaper rather than buying from someone who’s not licensed or who you don’t know.”

Homeowners should look for telltale white, wooly masses at the bases of eastern and Carolina hemlock needles. These cotton ball-like sacs offer a protective coating for the adelgid that lives within. The insects’ feeding will result in grayish-green foliage, premature needle drop, thinned crowns, branch tip dieback and eventual tree death.

The hemlock woolly adelgid can be spread by birds or carried on the wind. If left unchecked in the home landscape, the result could be the loss of valuable trees throughout the neighborhood. Townsend said that in the wild, as in the forests of southeastern Kentucky, the loss of the trees has a serious impact on the environment, with a detrimental effect on water quality in particular. Hemlocks commonly grow along streams and rivers, providing shade and cooler stream temperatures.

In an ongoing survey program covering the forests of eastern Kentucky, UK watches for diseases and invasive species of insects and plants, including the hemlock woolly adelgid, gypsy moth and the emerald ash borer. The Kentucky Division of Forestry, many of the state parks and nature preserves are on the lookout as well.

Townsend recommends that homeowners examine their landscape hemlock trees for the fuzzy white material the insect produces. 

“If you see that on hemlocks, you can get a sample of it and take it to the extension office in your county,” he said. “In some cases, it is spider egg cases, but what we’d really be concerned about is if it was the adelgid. We don’t know how much landscaping this particular landscaper did, so we don’t know how many infected trees might have been brought into the area and planted. That’s something we want to follow up on, as well.”

For more information about controlling the hemlock woolly adelgid in the landscape, contact the local extension office.

Contact: 

Lee Townsend, 859-257-7455