Asian Long-Horned Beetle
According to the U.S. Department of Agriculture, this black and white beetle "has the potential to cause more damage than Dutch elm disease, chestnut blight, and gypsy moths combined, destroying millions of acres of America's treasured hardwoods, including national forests and backyard trees." Native to China and the Korea peninsula, the bug was first discovered in the U.S. in New York in 1996. It has since been detected in New Jersey, Massachusetts, Illinois, and Ohio, where it has cultivated a taste for maple trees and other hardwoods such as elm, birch, and willow. Transportation of untreated wood is the main way this beetle spreads, and no effective control measures exist.
Thousand Cankers Disease
When the walnut twig beetle expanded out of its native range in the Southwest and into Utah and Colorado, it brought along a deadly fungus. In black walnut trees, Geosmithia morbida causes an ugly infection characterized by dozens of small lesions that cluster together into larger cankers, killing the tree's vital cambium tissue, a layers of cells under the bark that helps the tree grow fatter, and eventually the tree itself. Since the 1990s, the fungus has become widespread throughout the American West and is now making its way toward the East Coast's extensive native walnut populations. Thousand Cankers Disease was detected in Tennessee in 2010 then in Virginia and Pennsylvania in 2011. The transportation of firewood that harbors the walnut twig beetle is at least partially to blame for the fungus' rapid spread.
Sudden Oak Death
Cankers caused by Sudden Oak Death bleed a horrifying black or dark reddish ooze. A water mold pathogen causes the disease, which has killed tens of thousands of trees since it was discovered in California in 1995. At least 75 plant species are susceptible to SOD, including a variety of oak trees, common shrubs such as lilac and rhododendron, as well as the giant redwood forests on the West Coast. The disease has yet to spread beyond California and Oregon. But experiments have shown that species on the East Coast would be susceptible as well, and there's no known cure.
Emerald Ash Borer
The emerald ash borer has destroyed more than 50 million ash trees in the U.S. in just the past decade. The beetle, native to Asia, probably arrived in North America in wood packing material. Since its discovery in Michigan in 2002, infestations have been found from Minnesota, Iowa, and Kansas in the heartland to Virginia and all the way up to New York. The broad distribution is largely due to the beetle's accidental transportation in logs and firewood.
Goldspotted Oak Borer
A native of southeastern Arizona, this insect was first spotted in California in 2004. Since then, the goldspotted oak borer has killed approximately 80,000 oak trees in San Diego County. The bug's larvae bore their way inside the bark where they munch on the cambium tissue, resulting in red staining, oozing cankers, and leaf loss. The tree dies within a few years of infection. Environmental scientists in California think GSOB came to the state within firewood from Arizona. "The key management strategy for preventing GSOB spread," they say, "is to stop the movement of infested oak firewood to non-infested areas."