Cornell and DEC Now Breeding Predators for Hemlock Pest

MOUNT MORRIS — Cornell University and the New York State Department of Environmental Conservation (DEC) announced the creation of a new ‘biological control lab’ on campus to protect the state’s ecologically important hemlock trees.

The lab, headed by Cornell Forest Entomologist Mark Whitmore, will research and rear ‘biological controls,’ specifically predatory Laricobius nigrinus beetles and silver flies, to slow the spread of hemlock woolly adelgids, invasive pests that threaten trees in roughly half of New York’s 62 counties and in more than 15 other states.

“Our team has been monitoring the spread of the hemlock woolly adelgid from our more southern states,” said Kathryn J. Boor, the Ronald P. Lynch Dean of the College of Agriculture and Life Sciences. “We’ve been preparing to meet the challenge of an invasive threat that, if left unchecked, will significantly impair water quality in our watersheds, particularly in the Catskills.”

The announcement of the $1.2 million lab, partly funded by the DEC with support from the state’s Environmental Protection Fund, was made at a ribbon-cutting ceremony Nov. 17.

Eastern hemlock trees are among the oldest individual plants in New York. Some are more than 700 years old. They often occupy shady, north-facing slopes and stream banks and help control erosion and water quality.

Shade from the trees cools streams that are home to many of New York’s freshwater fish, including brook trout.

The hemlock woolly adelgid is a tiny insect that attacks forest and ornamental hemlock trees, feeding on young twigs.

Hemlocks typically die within four to 10 years of adelgid infestation in the insect’s northern range. Damage from the insect has led to widespread hemlock deaths throughout the Appalachian Mountains and the southern Catskills.

The Cornell lab has been researching how effective L. nigrinus beetles and silver flies will be on the east coast at depleting their only food source, the adelgids.

“We’ve gone through a lot of trial and error, but I think we have a productive solution now,” said DEC Executive Deputy Director Kenneth Lynch. “And thanks to the investment in this lab by both Cornell and the state of New York, we’re moving the ball forward.”

Though colder temperatures generally slow the adelgid’s spread, offspring that survive cold winters build a more cold-tolerant population, which in turn puts colder regions such as the Adirondacks at greater risk.

Recent mild winters have favored the spread of the pest in New York.

“Implementing biological control is basically a numbers game,” said Whitmore, who is an Extension Associate in the Department of Natural Resources. “The possibility of releasing large numbers of biocontrol predators greatly enhances the chances of successful establishment and it also enhances the possibility of the predator populations to grow more rapidly.”

Cornell and government partners first released L. nigrinus in New York state in 2009, and silver flies in 2015.