If you come across a tree with dead branches, sawdust-like material on the ground around it, shallow scars in bark or small, dime-sized holes in it, take a closer look. Those things could be signs of Asian longhorned beetles.
The wood-boring beetles are an invasive species that kill the trees they feed on. Tens of thousands of trees in Ohio, New York, Massachusetts, New Jersey and Illinois have been lost since the beetle was found in the U.S. in 1996, according to a U.S. Department of Agriculture factsheet.
The USDA is asking Ohioans to keep an eye out for the beetles and the damage they cause, especially this month as they emerge from trees.
“[Infestation confirmations] pretty much all have been through public findings — people reaching out to extension agencies saying ‘hey, my tree is covered in holes … can you help me figure out why?’” said Kyle Costilow, acting director of the USDA’s Ohio ALB eradication program.
Asian longhorned beetles arrive in the United States primarily through international trade. There are currently quarantines in Ohio, New York, South Carolina and Massachusetts. The beetles were first confirmed in Ohio in 2011.
They spend the majority of their lifecycle as larvae within trees, Costilow said.
“The larva can stay in larval form for several years,” he said.
Then they come out to reproduce and lay eggs back in the trees. August is the time when people are most likely to see the beetles themselves, as the adult beetles emerge from the trees.
“This is when we have peak flight season,” Costilow said.
The beetles infest 12 different species of hardwood trees, including maple, birch, elm, ash, willow and more.
“With it doing damage in the heartwood of the tree, it removes timber value and a lot of the structural integrity of trees,” Costilow said. “That’s our concern.”
When the USDA confirms an infestation, the next step is to inspect trees in the area, and then remove any infested trees at no cost to the landowner, Costilow said.
The current quarantine zone in Ohio is in Clermont County. In Ohio, maples are the bugs’ favorite host tree. Clermont County has a lot of old farmland that has turned back into wooded areas, Costilow said.
“Maples are usually one of the first trees to move into those old farm fields that were left fallow,” he explained. More than 98% of infested trees in Ohio have been maple.
The USDA has been able to eradicate other infestations in Ohio in Monroe Township, Batavia and Stonelick townships and East Fork State Park through tree removal and chemical treatments.
Within the U.S., the beetles usually spread when people move wood from an infested area to another area.
“The biggest issue with this pest is going to be human movement, and that typically occurs in firewood,” Costilow said.
Quarantined areas have restrictions on moving potentially-infested wood. The USDA also encourages people to get firewood locally, or where they plan to burn it when traveling, or to buy wood that has been properly heat treated to kill pests if it is not local.
The USDA has also designated August “Tree Check Month” and is encouraging Ohioans to check their trees for Asian longhorned beetles or signs of them.
The adult beetles’ bodies are about an inch to an inch and a half long, and are black with white spots. They have black and white antennae that are longer than their bodies. They also have six legs and feet that can look bluish in color.
The damage to the trees, however, is often easier to spot. When the beetles emerge from trees, they make a perfect circle exit hole about three-eighths of an inch in diameter, Costilow said.
“You can take a No. 2 pencil and insert it an inch or two into the tree,” he said.
They also leave sawdust-like material, called frass, on the ground around the trees, and shallow, oval or round wounds in bark at their egg sites. Sap might weep from the wounds. Another common sign is branches or limbs falling from trees that look healthy otherwise.
If you see signs of Asian longhorned beetles, or the beetles themselves, call 1-866-702-9938 or visit asianlonghornedbeetle.com to report it.
The USDA encourages people to take pictures of the beetle or tree damage, and to catch the beetle in a durable container and freeze it so it can be identified. USDA staff can confirm sightings and respond to get rid of the bugs.
STAY INFORMED. SIGN UP!
Up-to-date agriculture news in your inbox!