|Of a Different Nature: Emerald Ash Borers
by Michele L. Tremblay
What has three sides, no top or bottom, and is purple all over?
It’s an Emerald Ash Borer trap and you may have seen them hanging from trees along the sides or roads over the past two years—but what is an Emerald Ash Borer?
The Emerald Ash Borer is a beetle native to Asia. These beetles are efficient tree killers. The larva live under the bark of ash trees and feed on the vital parts of the tree that allow it to absorb water and nutrients; killing the tree within just a couple of years. The beetle spends its time in the upper crown of trees so it is unlikely to see the bright green adults that are a half-inch long and an eighth of an inch wide. Some may mistake the Six-spotted Tiger Beetle (also about a half-inch long), which is often seen on the ground. This bright green insect is a New Hampshire native and a voracious predator of ants, spiders, and other small prey. It is considered a beneficial insect so it should not be killed. With few exceptions, Emerald Ash Borers are only seen on the ground if they are dead.
The Emerald Ash Borer was first detected in the Midwestern United States in 2002. It likely entered North American through the Saint Lawrence Seaway several years before that time and since then, it has spread to at least thirty states from as far west as Kansas and east to New Hampshire and Québec.
“The Emerald Ash Borer is a good ‘flyer’ so there is a natural spread of this pest and then there is the artificial spread of the pest,” said Sharon Lucik, US Department of Agriculture Animal and Plant Health Inspection Service. The rapid expansion of this invading beetle’s territory is caused by people moving wood. Approximately 75% of all known outbreaks occurred around campgrounds.
Over 100 million trees have succumbed to the insects’ ravages of our ash trees. That’s bad news for our state. New Hampshire is the second most forested state in the union. Approximately 84% (4.8 million acres) of the Granite State is “the woods.” The annual contribution of forest-based manufacturing in Hampshire is nearly $1.15 billion and 8,160 jobs with a payroll of $384,000,000 according the 2011 report, The Economic Importance of New Hampshire’s Forest-Based Economy.
While not all of New Hampshire’s forests are composed of ash trees, all American species are susceptible to destruction by Emerald Ash Borers. “White ash is part of the northern hardwood forest,” said Kyle Lombard, Forest Entomologist, Bureau of Forest Protection, New Hampshire Department of Resources and Economic Development. This encompasses the non-pine forests north of Concord and up to the boreal forest, including most of the White Mountain National Forest and Sullivan, Cheshire, and Grafton counties. That’s about 7% of that area’s trees and 2.5% of the total forest area in the state. Urban area coverage is even higher. “Green ash were planted when elms died out from Dutch Elm Disease so the percentage of ash trees in cities will be higher”, said Lombard.
Beyond caring about New Hampshire’s forests for their natural and economic value, there are other implications of this infestation. A 2012 National Institutes of Health study with data collected from 1990 to 2007 reports that “There was an increase in mortality related to cardiovascular and lower-respiratory-tract illness in counties infested with the emerald ash borer.” The report cites that, in the fifteen states in the study area, the Emerald Ash Borer was associated with an additional 6,113 deaths related to illness of the lower respiratory system, and 15,080 cardiovascular-related deaths. The study conclusion suggests, “Loss of trees to the [Emerald Ash Borer] increased mortality related to cardiovascular and lower-respiratory-tract illness. This finding adds to the growing evidence that the natural environment provides major public health benefits.”
With all of the reports about invasive plants, animals, and insects, the situation for our natural world may seem hopeless but there are things that we can do.
Buy and burn only New Hampshire firewood in our state. When camping outside of New Hampshire, leave leftover camp wood at the campsite. The insects can be transported from states or provinces with infested trees.
Citizens can be scientists: be on the lookout for this deadly jewel-colored invader. Visit www.NHBugs.org to learn how to identify the insect, recognize the damage that it inflicts on ash trees, and document and report your own sightings to help track and contain this invasion. “On the northern edge of the outbreak. Look for unusual woodpecker activity, called ‘blonding’ because this is where the birds take off outer bark and leave the light colored inner bark, when looking for the Emerald Ash Borer,” said Lombard, “Woodpecker activity will appear shallow and flaky vs. the usual deep bore holes.”
Diversity is important. “Everyone is going to need to plant a variety of species,” said Lombard. The diversity of species mix will help protect against invaders and diseases and help assure that there are healthy forests and urban stands of trees.
Invasions are best identified and eliminated by early detection and then rapid response. With a curious mind, a sharp eye, and a strong networks of friends and neighbors, citizen scientists are one of best defenses against destructive invasive species.
You can learn more (and have fun) with these selected resources
New Hampshire Bugs Emerald Ash Borer webpage
New Hampshire Division of Forests and Lands
Wisconsin Department of Natural Resources kids' page on Emerald Ash Borer
National Institutes of Health Study on Emerald Ash Borer Study Abstract
Economic Importance of New Hampshire's Forest-Based Economy 2011