Gardeners are first line of defense against invasive wood-boring insects

Friday, October 8, 2010; 9:15 PM

Two invasive, nonnative boring insects stowing away aboard shipping vessels from Asia have not yet appeared in the District, Maryland and Virginia. But they have been spotted as close as North Carolina, New Jersey and Pennsylvania, and environmental advocates are asking gardeners, hikers and anyone else who enjoys the outdoors to report any sightings, which could increase the chances of limiting their damage.

The Nature Conservancy is requesting help from the public to watch closely for the insects - the Asian longhorned beetle and the emerald ash borer - which could be as devastating to hardwood forests as Dutch elm disease was when it began in the United States in the 1930s.

The Asian longhorned beetle was first found in the United States in 1996 in Brooklyn, N.Y. It arrived in wooden crates that carried plumbing supplies from China. The beetle has now been seen and identified in 15 states, Canada and Europe.

The largest infestation was discovered in Worcester, Mass., in 2008. It was because of thorough and prudent monitoring and the city's removal and replacement of infested trees that Worcester has a tree canopy today.

"Lurking in the Trees," a documentary available on DVD, covers the discovery and subsequent cleanup of a problem that was capable of decimating much of our native woodlands. The movie is excellent, and it's free from to those who have a use for the information.

These Asian insects traveled more than 7,000 miles and have become a severe threat to our urban, suburban and rural tree canopies. In the case of the Asian longhorned beetle, there can be a severe financial impact on the timber industry and on tourism if an infestation reduces fall leaf color changes in the north-central states and New England. The maple syrup industry could go into further decline as well.

Plants grown in Asia are similar to those found in this country, so the Asian longhorned beetle is well adapted to feeding on our diverse groups of trees. They especially like maples.

Emerald ash borers were discovered in the United States in 2002 near Detroit, and they have made tremendous headway eastward toward Washington metropolitan area. Since their discovery eight years ago, infestations have been confirmed in Maryland, Ohio, Indiana, Illinois, and Ontario, Canada.

These insects are not the only nonnative pests we are facing. Among dozens of nonnative invasive insects and diseases imperiling Eastern forests is the hemlock woolly adelgid. In the Appalachian mountains, it is killing hemlocks, which are important shade-tolerant conifers that create valuable wildlife habitats. The Web site has more information on the problem and ways to treat against it. The hemlock woolly adelgid is the only one of the four major pests and pathogens discussed in this article that can be treated.

All lovers of the outdoors can keep their eyes on the trees and learn how to identify insects they have never seen before. "Vigilant homeowners and gardeners have been the ones to detect the presence of foreign pests that had previously gone undetected in many areas," says Faith Campbell, senior policy representative with the Nature Conservancy's Forest Health Program. "A Massachusetts homeowner, who found a strange-looking bug in her back yard and reported it to the appropriate government agency, helped prevent the Asian longhorned beetle from spreading through the United States," she said.

Such vigilance is like the Aircraft Warning Service of the 1940s, when civilians aimed their eyes and ears to the sky, looking for enemy aircraft. Now we are being asked to use our binoculars to search the trees for tapered ovipositor craters and emergence holes for invasive insects.

This is an important partnership between foresters, arborists, entomologists and amateur gardeners to save our trees from devastation. At 1 1/2 to two inches in length, the Asian longhorned beetle is not a small insect. The adult is easy to spot, with its black body and white spots that look like stars on its back. It also has antennae the length of its body.

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