Hemlock Woolly Adelgid

Eastern hemlock, one of the most common trees in the Great Smoky Mountains, is under attack from the Asian hemlock woolly adelgid (HWA). This tiny, non-native aphid-like insect has been seen in most parts of the park, including on some of the massive old-growth hemlocks that may be 500 years old. No hemlock deaths have been recorded yet, but many trees show crown damage already.

HWA is the second adelgid to sweep through the park; in the 1960s the balsam wooly adelgid infested higher elevations, killing most of the mature Fraser firs. On Clingmans Dome, visitors gasp at the sight of fir skeletons dominating the views. It is hard to imagine what the park would look like without the hemlocks lining the creeks and climbing the hillsides. Ecologists cannot predict which species could replace hemlocks, which dominate many habitats in the park. Many birds, insects, and other animals depend of hemlocks for food and shelter.

The possible effects of destruction of hemlocks has been compared to the death of American chestnuts. But there’s one big difference: Park scientists and staff are prepared this time. They first saw HWA in the park last year, and they have already started aggressive management procedures. One of the most interesting is the introduction of tiny beetles that make a living eating HWA. Preliminary results show that beetles released in a few areas reduce the severity of the adelgid infestations. However, it is time consuming and expensive to raise the beetles, and vast areas need to be treated.

Federal funding may be available soon to set up a beetle rearing facility, but in the meantime, Friends of the Smokies and Great Smoky Mountains Association are bridging the time gap by providing money to set up a lab at UT to release beetles over a year earlier. The beetle rearing facility in the new biotech building on UT's Agriculture Campus will have walk-in incubating rooms with large growth chambers. Technicians will collect infested hemlock branches to feed the hungry HWA larvae.

Research is currently underway to evaluate the biology of the beetle and what effect a widespread release will have. The beetles apparently eat only HWA; it is hoped that their populations will fluctuate with the adelgid so that the hemlocks can withstand the infestations over time. Beetles may be released as eggs, larvae, or adults; research will help determine the best life stage.

Other control strategies include spraying trees with insecticidal soap, which is only feasible near roads, and injecting an insecticide into tree roots. The beetle release, if successful, has the great advantage of distributing these tiny predators throughout the park and continuing to work as adelgids reinfest the park from surrounding areas.

A special Save the Hemlocks T-shirt has recently been developed with all proceeds going to the effort. To help save the hemlocks, go to www.friendsofthesmokies.org or call 1-888-898-9102 to order your Save the Hemlocks T-shirt.


									Hemlock Woolly Adelgid Eastern hemlock, one of the most common trees in the Great Smoky Mountains, is under attack from the Asian hemlock woolly adelgid (HWA). This tiny, non-native aphid-like insect has been seen in most parts of the park, including on some of the massive old-growth hemlocks that may be 500 years old. No hemlock deaths have been recorded yet, but many trees show crown damage already. HWA is the second adelgid to sweep through the park; in the 1960s the balsam wooly adelgid infested higher elevations, killing most of the mature Fraser firs. On Clingmans Dome, visitors gasp at the sight of fir skeletons dominating the views. It is hard to imagine what the park would look like without the hemlocks lining the creeks and climbing the hillsides. Ecologists cannot predict which species could replace hemlocks, which dominate many habitats in the park. Many birds, insects, and other animals depend of hemlocks for food and shelter. The possible effects of destruction of hemlocks has been compared to the death of American chestnuts. But there’s one big difference: Park scientists and staff are prepared this time. They first saw HWA in the park last year, and they have already started aggressive management procedures. One of the most interesting is the introduction of tiny beetles that make a living eating HWA. Preliminary results show that beetles released in a few areas reduce the severity of the adelgid infestations. However, it is time consuming and expensive to raise the beetles, and vast areas need to be treated. Federal funding may be available soon to set up a beetle rearing facility, but in the meantime, Friends of the Smokies and Great Smoky Mountains Association are bridging the time gap by providing money to set up a lab at UT to release beetles over a year earlier. The beetle rearing facility in the new biotech building on UT's Agriculture Campus will have walk-in incubating rooms with large growth chambers. Technicians will collect infested hemlock branches to feed the hungry HWA larvae. Research is currently underway to evaluate the biology of the beetle and what effect a widespread release will have. The beetles apparently eat only HWA; it is hoped that their populations will fluctuate with the adelgid so that the hemlocks can withstand the infestations over time. Beetles may be released as eggs, larvae, or adults; research will help determine the best life stage. Other control strategies include spraying trees with insecticidal soap, which is only feasible near roads, and injecting an insecticide into tree roots. The beetle release, if successful, has the great advantage of distributing these tiny predators throughout the park and continuing to work as adelgids reinfest the park from surrounding areas. A special Save the Hemlocks T-shirt has recently been developed with all proceeds going to the effort. To help save the hemlocks, go to www.friendsofthesmokies.org or call 1-888-898-9102 to order your Save the Hemlocks T-shirt.