The Great Smoky Mountains National Park is planning to release two new predatory beetles to stop the spread of the hemlock woolly adelgid, an invasive insect that has devastated hemlock forests throughout the eastern United States.
The park began releasing predatory beetles, which feed exclusively on adelgids, in 2002. Park managers are hopeful that the addition of these two new beetle species will help even further.
Both beetle species are small black lady beetles and will be released at sites throughout the park. One of the beetles comes from Osaka, Japan, where the Smokies strain of invasive adelgid originated. The other comes from Washington, where a similar adelgid species occurs and has been kept in check by the predatory beetle.
Park managers currently utilize two other beetle species for controlling the adelgid, they also originate from Washington and northern Japan. In the long-term, park officials expect beetles to control the invasive beetle.
The park also employs injecting leaves with horticultural oil and stem and soil injections of systemic insecticides. About 600 acres are being sprayed annually. More than 250,000 hemlock trees across 11,000 acres have been hand-treated with systemic pesticides and more than 545,000 predatory beetles have been released. Each beetle species is first quarantined and researched in depth before given approval for release.