Sunday, November 26, 2017

Hemlock Woolly Adelgid Bio Control Lab Established

The New York State Department of Environmental Conservation (DEC) and Cornell University have announced the creation of a new biocontrol laboratory on the Cornell campus focused on protecting the state’s population of hemlock trees.

The $1.2 million lab, partially funded by DEC with monies from the State’s Environmental Protection Fund and headed by Cornell entomologist Mark Whitmore, is expected to be dedicated to researching and rearing biological controls to stop the spread of the invasive pest Hemlock Woolly Adelgid (HWA), which is threatening trees in about half of New York’s 62 counties and more than 15 other states.

HWA, a tiny insect from East Asia first discovered in New York in 1985, attacks forest and ornamental hemlock trees. It feeds on young twigs, causing buds to die and needles to dry out and drop prematurely.

Hemlock decline and mortality typically occur within four to ten years of HWA infestation in the insect’s northern range. Damage from the insect has led to widespread hemlock mortality throughout the Appalachian Mountains and the southern Catskill Mountains with considerable ecological damage, as well as economic and aesthetic losses. HWA infestations can be most noticeably detected by the small, white, woolly masses produced by the insects that are attached to the underside of the twig, near the base of the needles.

Biological control, or biocontrol for short, is the use of natural enemies to manage the population of a pest. In the case of HWA, this means using predatory insects found in areas where HWA is native. The focus of the HWA biocontrol lab is to research methods to grow healthy colonies of predatory insects and evaluate their effectiveness in managing HWA population growth. The goal is to establish multiple predator species throughout New York to reduce HWA populations below the level where they cause hemlock trees to die.

Eastern hemlock trees are among the oldest trees in New York with some reaching ages of more than 700 years. They typically occupy steep, shaded, north-facing slopes and stream banks where few other trees are successful. The trees help maintain erosion control and water quality, and the hemlock’s shade cool waters providing critical habitat for many of New York’s freshwater fish, including native brook trout.

Invasive species are detrimental because of their ability to reproduce quickly, outcompete native species, and adapt to new environments. Because invasive species did not evolve with the other species in their new location, they often do not have natural predators and diseases that would normally control their population within their native habitat. Some economists estimate that invasive species cost the United States more than $120 billion in damages every year.

More information on HWA, including identification, control techniques, and reporting possible infestations can be found at Cornell’s New York State Hemlock Initiative or on DEC’s website.

New Yorkers are encouraged to call DEC’s toll-free Forest Pest Information Line at 1-866-640-0652 to report possible infestations.

Photo: A hemlock woolly adelgid infestation, courtesy USDA.

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2 Responses

  1. Don Pachner says:

    I sincerely hope the new laboratory can come up with a solution. I moved to the Adirondacks from a home around the corner from The Nature Conservancy’s first nature sanctuary, Mianus River Gorge Preserve, where remnants of old growth hemlocks within 45 miles of NYC were at risk due to the wooley adelgid. They obtained an import license from USFWS for a beetle that was a known predator of the wooley adelgid; however, the beetles stayed in the treetops, not the lower branches that were being attacked by the aphids, and the approach was not successful. This will take much experimentation and patience.

  2. Mark Whitmore says:

    Thank you for the thoughtful comment. Biological control is a complex and time consuming process requiring tons of research to implement. Unfortunately the first beetle introduced for biocontrol of HWA, Sasajiscymnus tsugae, which was released at Mianus River Gorge, was unable to control the adelgids. After losing many large hemlocks to HWA they have begun treating the remaining trees with insecticide to keep them alive. It is to keep hemlocks alive in these priority areas until we have sufficient numbers of predators available to control HWA across the landscape. Our lab at Cornell is currently working on two predators, Laricobius nigrinus and Leucopis piniperda/argenticollis (Silverflies). It will take many years for the populations of these predators to become abundant enough to effect sufficient control so that HWA are not damaging to hemlocks. We are thinking that with early detection of spot infestations of HWA in the Adirondacks and a rapid response to control them with insecticides we can keep HWA out of the Adirondacks for long enough so we can get the biocontrol predator populations built up elsewhere, like in the Catskills. At some point in time when biocontrol becomes effective we will no longer need to treat trees and hopefully our hemlocks will have survived the incursion of this deadly invasive non-native pest.