Kent Priestley’s moving story [“Twilight of the Giants,” Jan. 9] about the fate of our Eastern hemlocks conflates two very different issues. While focusing on the admirable work of locating and documenting “specimen” hemlocks in the Southern Appalachians, the article also seems to endorse the position of large-scale use of chemical insecticides as a viable tool for saving woodland hemlocks from the scourge of the hemlock woolly adelgid (HWA).
Synthetic insecticides being utilized by chemical arborists are tree-specific, expensive and their effectiveness is of limited duration (two to three years). It would be both physically and fiscally impossible to utilize such chemical treatments to provide long-term protection to any significant portion of our Southern Appalachian hemlocks—never mind the (unknown) long-term ecological consequences [for] riparian forest soils. [Perhaps] the only the long-term benefit of the chemical strategy would be to those who are paid to apply or manufacture the chemicals.
Fortunately, there [appears to be] a long-term biological strategy for saving our hemlocks that [could] be cost-effective and ecologically viable: controlling adelgid numbers with HWA-predator beetles, such as Sasajiscymnus tsugae, aka Sassie, a tiny beetle from Japan that is the native predator of the HWA (that was accidentally imported from Japan). Sassie has been approved for release in the eastern United States after extensive USDA testing and quarantine in Connecticut … and is currently available for purchase by private citizens.
Sassie can [potentially] be effective in controlling HWA in wild areas as well as neighborhoods. A release of 50 to 100 beetles on a large hemlock would have about the same cost (and the same short-term refoliation effects on the target tree) as a systemic chemical-insecticide application. However, the beetles would begin reducing adelgid densities on other hemlocks within a one- to three-acre area during the first season [and] … would spread to adjacent hemlock areas.
This is based on careful observations of both private and public beetle releases in the Brevard/Cashiers area, where it is possible to walk through large areas of forest in the vicinity of USDA beetle releases (dating back to 2003) and see thousands of previously HWA-defoliated hemlocks across hundreds of acres that are returning to health with vigorous new growth and dramatic reductions in HWA densities. And in Brevard, a grass-roots effort involving private individuals, groups and city and county officials is seeing successes in its efforts to extend biological control of HWA throughout the city and surrounding areas.
The loss of large, specimen trees is a tragedy. The loss of all our native hemlocks would be an ecological disaster. This doesn’t have to happen! We should redirect both federal and private expenditures from short-term chemical applications to the production and release of HWA predator beetles for long-term protection of all our hemlocks.
How can you help? Start a grass-roots effort to release beetles in your community or adopt a wild area that needs help. You may contact me by e-mail (firstname.lastname@example.org) for information on beetle sources and release strategies. Talk to politicians at all levels about directing more resources to public beetle-production labs, or donate to one yourself. Spread the word to friends, neighbors and arborists that there is a natural alternative to short-term chemical treatments for HWA. Time is of the essence.
— Patrick Horan