Natural enemies of an invasive tree-killing bug are being used to save Hemlock trees
Some 20 volunteers headed into the woods of High Tor last fall at the south end of Canandaigua Lake with a curious set of tools. Their mission, with “beat sheets” and ski poles: Scoping for evidence of a special beetle sent to combat the spread of an invasive insect killing hemlock trees.
Lindsay McMillan, associate director with the Canandaigua Lake Watershed Association, was in the group that day.
“We found one beetle,” she said, describing the field project on Nov. 12 using ski poles to shake hemlock branches infested by hemlock woolly adelgid in search of the Laricobius beetle — affectionately nicknamed “Little Lari.” The predatory beetles were released in High Tor in 2016 to stem the spread of hemlock woolly adelgid.
Finding just one Little Lari that day was evidence of progress. It may take several years for the beetles to become established, so annual surveys like this one help monitor the populations.
“We are certain they have become established,” said Charlotte Malmborg with the New York State Hemlock Initiative. Malmborg provided the latest on research and management of the hemlock wooly adelgid (HWA) during a workshop Tuesday at the Naples Library. Multiple generations of Little Lari are at work in New York state in this method being used to save as many hemlock trees as possible.
Since HWA was first discovered in New York state in the 1980s the pest has done massive damage to the Eastern hemlock — the state’s third most common tree species and a foundation of forests. Hemlocks are significant in maintaining healthy wildlife habitats as well as preserving the landscape and clean, fresh water.
While certain pesticides can be used to help control HWA, biocontrol methods using natural predators from the Pacific Northwest like the Laricobius beetles offer a chemical-free, longterm option.
Malmborg talked about a special lab at Cornell University’s main campus in Ithaca, the Hemlock Woolly Adelgid Biocontrol Research Lab. Headed by forest entomologist Mark Whitmore, the biocontrol lab officially opened in 2017, but the Hemlock Initiative has been releasing biocontrols in New York since 2009. The Whitmore Lab houses two colonies of Laricobius beetles. The lab also handles shipments of two silver fly species, another HWA predator from the Pacific Northwest, which is processed for release.
The Finger Lakes region is a good testing ground for the biocontrol program, with HWA attacking the forests of High Tor and areas around the lakes.
In addition to rearing biocontrol insects, the Whitmore Lab is using genetic techniques to understand more about the behavior of these insects and assess success of the program. So far, HWA predators are only being released on conserved public lands in partnership with the state and regional organizations, as the project is still in the research and development stage. But a long-term goal is for HWA management across public and private lands.
Malmborg said there is a lot of enthusiasm for managing HWA in New York state, with work by the Whitmore Lab and many supporters. The lab is part of the Cornell College of Agriculture and Life Sciences and is mainly funded by the state Department of Environmental Conservation. Other funders include the state Department of Environmental Protection, the U.S. Forest Service as part of the Great Lakes Restoration Initiative, USDA-APHIS, and the US Environmental Protection Agency.
The workshop was sponsored by Ontario County Soil & Water Conservation District, Canandaigua Lake Watershed Association, and Cornell Cooperative Extension of Yates County.