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Hope for Hemlocks

“Besides climate change, I consider the Hemlock Woolly Adelgid to be one of the most important ecological problems facing New York forests,” says forest etymologist, Mark Whitmore of Cornell University. The Hemlock Woolly Adelgid is an invasive pest easily recognized by the white, “woolly” wax produced by females. Over time, feeding insects will rob a hemlock of its nutrients, thus killing the tree. Here in New York, losing our hemlocks would have devastating consequences on the environment.

“Hemlock is one of the most important forest trees that we have in New York State. It’s the third most common stem of all the trees in the state behind sugar maple and red maple,” Whitmore explains. The branches and needles of hemlocks act like feathery parasols which shade the forest’s lower levels from the sun’s rays. If these trees were to disappear, the vital protection they provide would vanish with them. “Ecologically, it’s what we call a ‘foundation species.’ It forms the habitat or the basis upon which many other species depend for survival. Hemlocks provide a habitat that keeps the ground water and the stream water at a cooler temperature. This allows the native brook trout to survive, to name one species of the many.”

According to Whitmore, the woolly adelgid was likely introduced into the Richmond Virginia area around the turn of the last century. “Since then it has spread the length of the Appellation Mountains from northern Georgia all the way up into southern Maine, New Hampshire, southern Vermont, and through New York. It got into New York and the Hudson Valley in the mid-1980s, and it’s been slowly moving north,” he says. Although our colder northern climate has slowed the advancement of the woolly adelgid, it is not enough to halt its spread. “Every indication is that this insect will gradually encompass the range of hemlock in New York, so it’s really important to use the little bit of time that we have. If you go to Minnewaska State Park, there are a lot of trees that are heavily impacted.”

While the threat to our state’s hemlocks is grave, work captained by Whitmore through the New York State Hemlock Initiative is offering hope. “The silver fly is native to the Pacific Northwest, and in the Pacific Northwest, the hemlock woolly adelgid is a native insect. It doesn’t kill the trees. Indeed, where we find it, we feel it’s been kept in control by the predators. It’s our intention to bring those predators out here and establish them,” Whitmore says.

The organization is also working with another predator known as the Laricobius beetle. “We call it ‘Little Lari.’ We’ve been working with Laricobius for a number of years, and we’ve released it in 19 different locations throughout the state.” While the silver fly and Little Larry are important predators in the fight against the hemlock woolly adelgid, Whitmore believes that more variety is needed. “I think what we need is a suite of predators, not just one or two,” he says.

Developing biocontrols such as silver flies and the Laricobius beetle takes time and care. “We go through very careful review of any control agents to be certain that it only eats the intended pray. This is a highly regulated process. We are strictly regulated by the USDA and by ourselves. There have been a lot of mistakes with biocontrols in the past. We don’t want to be the next one,” Whitmore says.

While Whitmore and his team continue their work in the lab at Cornell, the public has been stepping in to assist in mapping the presence of the woolly adelgid in our forests. “What we need are eyeballs in the Catskills,” says Whitmore. As it turns out, anyone with a love of the outdoors and a smartphone can provide those eyeballs.

Citizen scientists can report the presence or absence of the Hemlock Woolly Adelgid using an app called iMapInvasives. “iMapInvasives is a New York State product. You can use it for any invasive species, be it plant or animal. The hemlock woolly adelgid is listed specifically and includes ‘presence’ and ‘absence’ buttons. If you don’t find it, great. If you do find it, great. You can report either. As soon as anything gets on that app, I get informed of its presence. It’s really helpful for me to get all those reports, and we use them all in our work. It’s an amazing tool. A lot of people are working with it now, and the information is invaluable,” Whitmore says. “Given time, I do think populations of biocontrol insects will gradually establish and gradually increase. Our job is to find out what conditions are needed to get them established and how to get maximal population growth. That’s where things take time. We’re starting at ground zero, so that’s why it’s good to have support of individuals around the state to let us know where the adelgid is and what it’s doing. That will give us an idea of where we need to work.”

To use iMapInvasives, go to www.nyimapinvasives.org and request an account. After a little on-line or in-person training (your choice), you’ll be ready to report your findings.

For additional information, check out the newly-launched video about the hemlock woolly adelgid and iMapInvasives produced by Catskill Mountainkeepers at www.catskillmountainkeeper.org. You can also visit the New York State Hemlock Initiative’s website at blogs.cornell.edu/nyshemlockinitiative .