Asian Long-Horned Beetle (ALB), an invasive wood-boring beetle that attacks 12 types of hardwood trees in North America, was found for the first time in Charleston County in South Carolina this summer, with infestations discovered in 1,950 trees. “Just this past June, we confirmed a new infestation in South Carolina after a homeowner reported that they found a dead Asian longhorned beetle on their property,” said Josie Ryan, Animal and Plant Health Inspection Service’s (APHIS) National Operations Manager for the ALB Eradication Program. “We need the public’s help to find new areas where the beetle has spread, because finding it sooner means less trees will become infested.”
ALB attacks trees including: ash, birch, elm, golden raintree, London planetree/sycamore, maple, horsechestnut, katsura, mimosa, mountain ash, poplar, and willow. In its larval stage, the insect feeds inside tree trunks and branches during the colder months. The beetle creates tunnels as it feeds, then it chews its way out as an adult in the warmer months. Infested trees do not recover and eventually die. Infested trees can also become safety hazards since branches can drop and trees can fall over, especially during storms.
Fortunately, it’s possible to eradicate the pest with proper measures. Presently, there are active eradication programs operating in three states: New York, Massachusetts, and Ohio, as well as a response to the new infestation found in South Carolina. Thus far, the USDA and its partners have declared Brooklyn and Queens in New York free of ALB. The insect has also been eradicated from areas in Illinois, New Jersey, Boston, Massachusetts, other portions of New York, and portions of Ohio.
Unfortunately, the insecticide Imidacloprid is not effective against the larval stages of ALB that spend most of their time inside the heartwood of the tree. As a result, all infested trees must be completely removed. Even treated trees are removed and destroyed if they are later found to be infested.
Instead, insecticide treatments are used only on trees NOT known to be infested as a preventative. The insecticide is applied through either tree trunk or soil injections. According to APHIS, Imidacloprid can be effective when applied in the spring, early summer, or fall—prior adult emergence or when adults are feeding and laying eggs. It takes one to three weeks by trunk injection and up to three months by soil injection for Imidacloprid to distribute throughout the tree, depending on the tree’s size and health, and weather conditions. Once an area is identified for treatments, it is ideal to treat all host trees within that area to optimize effectiveness.
What To Look For
The beetle has distinctive markings that are easy to recognize:
- Black and white antennae that are longer than the insect’s body.
- A shiny black body with white spots that is about 1” to 1 ½” long.
- Six legs and feet that can appear bluish-colored.
Signs that a tree might be infested include:
- Round exit holes in tree trunks and branches about the size of a dime or smaller.
- Shallow oval or round scars in the bark where the adult beetle chewed an egg site.
- Sawdust-like material called frass, laying on the ground around the tree or in the branches.
- Dead branches or limbs falling from an otherwise healthy-looking tree.
It’s important landscapers follow state and federal laws, which restrict the movement of woody material, to keep the tree-killing pest from spreading outside of known infested areas. This includes firewood, which cannot move out of areas that are quarantined for ALB without a permit. “As people use firewood… we are also asking them to buy heat-treated and certified wood rather than move untreated firewood long distances, which can potentially spread ALB,” warned Ryan. “You can also responsibly gather firewood where you will burn it or buy it in the area where you will use it.”
ALB is not harmful to people or pets. If possible, landscapers should take pictures and capture suspicious insects in a durable container and freeze them, which helps preserve the insect for identification. Insect or tree damage can be reported by calling the ALB hotline at 1-866-702-9938 or reporting here. In South Carolina, you can report the beetle or tree damage by calling Clemson’s Department of Plant Industry at 864-646-2140 or by emailing firstname.lastname@example.org.
Keep an eye out for a special section on Trees in the Fall edition of Turf magazine. You’ll find tips from Husqvarna on felling a tree; grower J. Frank Schmidt & Son Co.’s take on trees to withstand changing climate conditions; and fall fertilization advice from the experts at Bartlett. In the meantime, visit Turf’s Tree Services® page for more articles.