Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
June, 2011
Regional Report

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This purple box coated with sticky stuff is designed to alert state and federal agencies to the arrival of the dreaded emerald ash borer.

What's That Purple Thing in the Tree?

Last summer, while driving along the New York State Thruway in central New York, I stopped at a rest area to stretch my legs. As I walked about, I noticed an ash tree on the edge of the grassy clearing with a strange-looking , triangular purple box hanging in it. Closer investigation revealed a sign posted on the tree trunk below indicating that this was a sticky trap designed monitor for the presence of emerald ash borer (EAB) beetles. Driving to work a couple of weeks ago, I noticed one of these purple traps here in Vermont. Has the borer arrived in my neighborhood, I wondered?

Not yet. But it has gotten close, and this has a lot of people in New England worried. In July of 2010, it was found in a small area in New York State just 25 miles from the western borders of Massachusetts and Connecticut. In 2008 it was found only 30 miles from the Vermont-Quebec border.

Those odd-looking boxes hanging in the trees are being set out by state agencies in partnership with the USDA in many parts of our region to give an early warning of any incipient infestations. Early detection allows the best chance for stopping the EAB's spread, and these agencies are trying hard to make sure this devastating invader never makes it into New England.

The purple color of the two foot tall traps is thought to be attractive to the EAB. To further lure beetles, the traps are baited with an oil that contains compounds emitted by stressed ash trees, along with a very sticky coating to capture the insects when they land. The materials in the traps are non-toxic and pose no threat to people, pets, or wildlife. They will not lure beetles into uninfested areas, only give investigators a means to detect beetles if they arrive.

An Asian native that was accidentally introduced into the U.S. less than a decade ago, the emerald ash borer is thought to have arrived in wooden packing materials brought in by ship or air. Since its discovery in this country in southern Michigan in 2002, it has cut a swath of destruction as it has steadily expanded its range. So far this damaging pest has killed tens of millions of ash trees in at least fifteen states in the Northeast, Mid-Atlantic and Upper Midwest, as well as the provinces of Ontario and Quebec in Canada.

The emerald ash borer only attacks ash trees (those in the genus Fraxinus). While ash trees are valued ornamental plants, more importantly, native species such as white ash form a significant part of the forested landscape in our region and other parts of the country. Millions of trees on our hillsides and valleys are at risk if this invader is not contained.

The adult beetle is bright metallic green, about one-half inch long, and lays its eggs on the trees' bark. It's the larvae that hatch from these eggs that do the damage as they tunnel into the tree to feed under the bark, eventually emerging as adult beetles. Look for their D-shaped exit holes in the bark of infested ash trees. Dieback in the tree's canopy occurs when the borer's feeding destroys the water and nutrient-conducting tissues in the tree. Trees usually die within two or three years of infestation. Another clue that a tree may harbor borers is heavy woodpecker damage as the birds feed on the larvae inside the tree.

What can you do to help keep the emerald ash borer out of our region? First of all, don't disturb the purple traps. They need to be kept in place throughout the summer during the adult beetles' flight season. Traps are being monitored and will be removed in the fall and the results assessed. If you find a trap that has fallen out of tree, call the number listed on the sign posted with the trap or the USDA's toll-free EAB hotline at 866-322-4512 to report it, so it can be put back in place.

But the most important piece of information for the general public is the caution not to move firewood, as this is one way in which the borer can be introduced to uninfested areas. While the adult beetle can fly up to a half-mile from an infested tree, the primary way the borer is introduced to new areas is when people unwittingly move infested firewood to their property or to campgrounds, fishing spots, and parks as they enjoy these natural areas. If you are purchasing firewood, ask where it comes from. Many of the states that are currently fighting the borer enforce quarantines and fines to prevent potentially infested ash trees, logs, or hardwood firewood from moving out of areas where the borer is found.

You can also learn to identify the adult beetle and the tell-tale signs of borer damage, and report any sightings to state or federal agencies. For more information on the EAB and how to identify it, visit:

To report a possible infestation, visit these sites for specific state information:
New Hampshire:
New York:
Rhode Island:

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