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Predator Beetles Released In Jocassee To Battle Hemlock Woolly Adelgids

About 2,500 predator beetles were released May 7 in the Laurel Fork Creek drainage area of Jocassee Gorges near the Foothills Trail in Pickens County. These insects feed on hemlock woolly adelgids, which have been decimating Eastern hemlock populations along the East Coast.

The team that released the predator beetles was a cooperative partnership made up of representatives from the U.S. Forest Service, S.C. Forestry Commission and S.C. Department of Natural Resources (DNR).

The DNR manages the Jocassee Gorges property in Pickens and Oconee counties. The predator

Photo SCDNR Greg Lucas
beetles, which can cost up to $5 apiece, were reared in a private lab in Pennsylvania. The U.S. Forest Service furnished them to DNR at no charge. The predator beetles are native to Japan and feed on adelgids there. These beetles are not the common ladybug that sometimes mass around homes-the predator beetle released in Jocassee Gorges is about a tenth the size of the well-known ladybug and never leaves the forest.

"This is an important first step in helping to control hemlock woolly adelgids in Jocassee Gorges," said Rusty Rhea, an entomologist with the U.S. Forest Service based in Asheville, N.C. "It's not a silver bullet or a cure-all by any means. These predator beetles will never eliminate the adelgids, but rather they can slow the adelgids' spread and give the trees a fighting chance."

Hemlock woolly adelgids have been in the United States since 1924. A native of Asia, it recently moved rapidly into the Southern Appalachians and decimated the Eastern hemlock in areas like Shenandoah National Park in Virginia. The adelgids cannot fly and spread by the immature "crawler" life stage. These small immature adelgids crawl, are blown in winds or are possibly spread by songbirds. By feeding on the internal portions of young twigs, the hemlock woolly adelgid retards or prevents tree growth. This causes needles to discolor from deep green to grayish green, and to drop prematurely. The loss of new shoots and needles seriously impairs tree health. Defoliation and tree death can occur within five to seven years of initial infestation.

Foresters and scientists say that unless the hemlock woolly adelgid is controlled, it could prove as devastating to hemlocks in the forest as American chestnut blight. Chestnut blight was introduced into the United States in 1900 and virtually wiped out the dominant tree in the Southern Appalachians by 1950. Chemical control of the hemlock woolly adelgid is possible in urban settings, but biological control of the adelgid is the only real option in the forest.

The shade of Eastern hemlocks is vitally important in cooling Jocassee Gorges trout waters. Although systematic surveys are not yet complete, the hemlock woolly adelgid has been found in many areas of the 44,000-acre Jocassee Gorges lands.

Demand for the predator beetles far exceeds demand, and several new labs are gearing up for production this year. Clemson University has begun production of the predator beetles, and a few public and private labs will produce about a half-million or so this year, to be distributed among 13 Eastern states that have infestations. Clemson University has one of the best production units for the predatory beetles.

- Written by Greg Lucas -


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