Save our trees. Be on the lookout for the Asian longhorned beetle!

by | May 19, 2021

Guest authors: Courtney Smith and Kelly Oten, NCSU Extension

The Asian longhorned adult is distinctive with long antennae and a spotted pattern. Image: Donald Duerr, USDA Forest Service,
The Asian longhorned adult is distinctive with long antennae and a spotted pattern.
Image: Donald Duerr, USDA Forest Service,

Gorgeous, vibrant maple trees are a common sight in North Carolina. These trees are some of the first to show fall color, painting our landscape. They are the second most common tree in our forests, and maples are also a favorite street or landscape tree. If you love the oranges and reds maple trees flash each fall, you may be dismayed to learn that the Asian longhorned beetle, an invasive pest of maples and other hardwoods, is getting uncomfortably close to North Carolina.

The Asian longhorned beetle is native to Asia. It feeds on about 29 species of hardwood trees, but maple is its favorite. It tunnels deeply into trees, feeding on tissues and eventually killing the trees by cutting off nutrient and water flow and reducing structural integrity.

In the U.S., the beetle was first detected in New York in 1996. Infestations have popped up sporadically in the Northeast and Midwest, but its recent discovery in South Carolina puts it closer to North Carolina than ever before. To protect the trees and forest ecosystems that we love, it is critical that infestations be reported and treated quickly. To accomplish this, we need all North Carolinians to be on the lookout—able to recognize and quickly report this beetle if you see it.

Asian longhorned beetle adults are quite eye-catching. Their shimmery black bodies are covered with white spots, and they have long antennae with white stripes. When these adults reach a suitable host tree, they gnaw pits into the bark to lay eggs. Once these eggs hatch, the immatures, called larvae, bore into the tree. The hungry larvae can bore deep within trees, reaching the xylem and heartwood to feed. Their unwelcome feasting disrupts nutrient flow, which weakens the tree and eventually causes death. The extensive tunneling leads to branches and trees that become prone to breaking, which is especially concerning in the Southeast where hurricanes are more prevalent. Clearly, we want to keep this pest from reaching our forests!

To stop the Asian longhorned beetle, early detection is critical. You can help stop this beetle by being on the lookout for signs and symptoms. Signs and symptoms include:

  • Perfectly round exit holes (about the width of a pencil eraser);
  • Branch breakage;
  • Gnawed egg-laying pits;
  • Bark cracking;
  • Frass, excrement that looks like stringy sawdust, near the base of the tree; and,
  • Early fall coloration

If you think you have spotted the beetle, it is important to report it so that it can be quickly eradicated. Unfortunately, management of the beetle is not a pretty sight. All infested host trees must be removed to stop the spread of this tree-killer. While it isn’t pleasant, this method has worked in several areas, like Illinois and New Jersey.

The Asian longhorned beetle was detected in South Carolina in 2020. Previously, the closest infestation to North Carolina was in Ohio. Since the pest is new to the Southeast, we don’t know much about its life cycle in a warmer climate. The landscape near the infestation in South Carolina provides unique challenges for professionals attempting to remove the beetle. However, research is ongoing to learn more about the pest’s lifecycle along with potential management methods.

While the Asian longhorned beetle is scary, there is hope! You can spread the word about the Asian longhorned beetle and be on the lookout for its signs and symptoms. Since the pest can move through wood materials, it is also important to buy and burn local firewood. Hopefully, if it is in our state, we can catch this pest early, saving those beautiful maple trees.