The box shown above is one of several such purple boxes hung from trees around Hacklebarney State Park, near Chester, New Jersey. The boxes are part of a USDA survey for Emerald Ash Borers. These beetles are not originally from North America; instead, they arrived from eastern Asia sometime prior to 2002, when the first specimens were discovered in the Detroit area. Since then it has spread to 10 states in the Midwest and Mid-Atlantic regions.
This species poses a serious threat to native ash trees, potentially rivaling the destruction caused by Chestnut blight and Dutch elm disease in the last century. The USDA website on the emerald ash borer describes their potential impact:
Emerald ash borer is a serious pest and quarantines are established around infestations. Larvae feed in the phloem and outer sapwood producing galleries that eventually girdle and kill the tree. This invasive pest has had a devastating impact on communities that now face significant tree removal costs associated with dead or dying ash trees that pose a threat to public safety.The USDA has posted images of the borers and some signs of infestation.
Ash trees are as important ecologically in the forests of the northeastern United States and eastern Canada, as they are economically. Ash trees fill gaps in the forest and provide shade for the forest floor. They are very desirable for urban tree planting because they grow well under difficult conditions. Ash wood is valued for flooring, furniture, sports equipment (e.g., baseball bats, hockey sticks, oars), tool handles, and supplies for dairies, poultry operations and beekeepers.
Other repercussions include decreased property values, losses in the long-term supply of ash wood, decreased air quality, increased electricity use during hot weather, and negative impacts on Native American cultures that use ash wood for traditional crafts and ceremonies. In addition, there are other detrimental impacts on wildlife and natural ecosystems. As a vital component of forest succession, ash colonizes and stabilizes disturbed areas. In addition, ash is one of the few native trees able to out-compete weeds that prevent most other species from becoming established.
The potential destructiveness of emerald ash borers is a reminder that we need to be careful about what sorts of plants, insects, and other creatures are introduced to the continent. Unfortunately this is difficult in an era of widespread globalized trade and international travel. It is all to easy for a species to be introduced, either accidentally or deliberately.