The Asian longhorned beetle (ALB; Anoplophora glabripennis; Figure 1) is an invasive insect pest native to China and North and South Korea that threatens many hardwood trees in forests and landscapes in the United States. The pest is also referred to as the roundheaded borer because the segment below the head is round in shape.
Figure 1. Asian Longhorn Beetle Adults. Photos: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org.
The larval stages of the Asian longhorned beetle feed on the vascular bundles of plants, and affected trees succumb to death with years of repeated infestations. In addition, larval feeding compromises the structure of tree trunks. With extensive boring activity, those infested trees are vulnerable to falling during storms, endangering lives and property, and saddling homeowners and local governments with expenses.
ALB was accidentally introduced to the United States via global trade, possibly in packing materials such as pallets and crates. It was first positively identified in 1996 in New York. This pest is now reported in Massachusetts, New York, Ohio, Illinois, and South Carolina. Although ALB has not been reported in Georgia, it could pose a serious threat to hardwood trees in the state. Because ALB is challenging to manage, it is important to identify, report, and develop plans to eradicate it upon detection.
Asian Longhorned Beetle Description
Asian longhorned (or long-horned) beetle adults are about 1 to 1.5 in. long and black with small white spots on their bodies (Figure 1). The antennae are distinctly long with black and white bands. ALB females chew on the bark of young branches, creating depressions (also referred to as oviposition pits, where her eggs are laid) in the bark (Figure 2).
Figure 2. Depression (Oviposition Pit) in Tree Bark. Photo: Dennis Haugen, USDA Forest Service, Bugwood.org.
This feeding, especially by newly emerged adults, is referred to as maturation feeding—during which these adults obtain the much-needed nutrition from the tree’s sugar-rich tissues to mature their eggs.
ALB females lay white, rice-grain-sized eggs singly in the depressions they create (Figure 3).
Figure 3. Asian Longhorned Beetle Egg (the Size of a Grain of Rice) Laid on the Bark. Photo: Larry R. Barber, USDA Forest Service, Bugwood.org.
A female can lay up to 90 eggs in her lifetime. In about 14 days, the eggs hatch, and the emerging larvae bore into the bark. They feed on the tree's cambium layer under the bark, which transports water. Once the larvae increase in size, they move to the heartwood. All the larval stages of the Asian longhorned beetle feed on wood tissue and slowly develop inside the tree trunk (Figure 4).
Figure 4. Larvae of the Asian Longhorn Beetle. Photo: Thomas B. Denholm, New Jersey Department of Agriculture, Bugwood.org.
They undergo 13 growth stages, and their feeding creates tunnels and galleries within the tree trunk (Figure 5).
Figure 5. Extensive Tunneling Caused by Asian Longhorn Beetle Larval Feeding. Photo: Dennis Haugen, USDA Forest Service, Bugwood.org.
Along with feeding, they excrete the waste (frass), filling the infested galleries (Figure 6).
Figure 6. Frass Accumulated from Asian Longhorn Beetle Larval Feeding. Photo: Pennsylvania Department of Conservation and Natural Resources – Forestry.
They pupate inside the tree for 13 to 24 days (Figure 7). The eggs, larval stages, or pupae can overwinter inside the tree, but ALB adults do not survive freezing temperatures in the winter. Newly emerged adults inside the tree trunk chew on the wood to create a tunnel to exit the tree (Figure 8). The exit holes on the bark are round and 3/8 in. in diameter (Figure 9).
Figure 7. Pupa of Asian Longhorn Beetle Inside the Gallery. Photo: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org.
Figure 8. Newly Emerged Adult Asian Longhorn Beetle Creating an Exit Hole. Photo: Michael Bohne, USDA Forest Service.
Figure 9. Exit Holes Caused by Newly Emerged Adult ALB. Photos: (left) Dennis Haugen, USDA Forest Service, Bugwood.org, and (right) Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.
It is common to find various stages of ALB larvae overwintering inside a tree trunk. These larvae pupate, and adults emerge throughout the year, from April to December. The peak emergence of adults is noticeable in both the summer and fall. Adults typically fly a short distance from their emergence site and then begin feeding on leaves and bark for 2 weeks before mating and laying eggs.
Host Range
Commonly reported hosts for Asian longhorned beetles are ash (Fraxinus), birch (Betula), elm (Ulmus), golden raintree (Koelreuteria), London planetree/sycamore (Platanus), maple (Acer), horse chestnut/buckeye (Aesculus), katsura (Cercidiphyllum), mimosa (Albizia), mountain ash (Sorbus), poplar (Populus), and willow (Salix).
Damage and Symptoms
ALB larvae feed on the vascular bundles, especially the xylem tissue, which affects water transportation from the roots to the tree crown. Persistent feeding from larvae blocks the xylem vessels. The tree branches weaken and begin to show dieback symptoms (Figure 10).
Figure 10. Dieback Symptoms After Asian Longhorn Beetle Infestation. Photos: Dennis Haugen, USDA Forest Service.
Season-long feeding affects the entire tree, leading to death. The xylem-feeding habit of roundheaded borers reduces the tree’s structural stability, making them more likely to break during storms (Figure 11). The exit holes are deep because the larvae feed on the xylem tissue. The presence of depressions or oviposition pits on the bark and sawdust from the galleries at the base of the tree indicates roundheaded borer activity. Because ALB adults tend to fly only short distances after emerging, reinfestation of the tree is common. Branch damage and crown thinning appear within 3–4 years of initial infestation, and the trees die within 10–15 years.
Figure 11. Asian Longhorn Beetle Infestation Reduces the Structural Stability of Trees. Photos: (left) Michael T. Smith, Bugwood.org, and (right) USDA ARS, Agricultural Research Service, Bugwood.org.
Stop the Spread of Asian Longhorned Beetle
Quarantine areas have been established to restrict the movement of ALB. If a tree has been identified as positive for Asian longhorned beetle infestation, it should be removed. Live or dead wood, such as firewood or branches, should not be moved out of the quarantine areas.
Because this pest threatens hardwood trees and disrupts diversity in forest, residential, and recreational ecosystems, it is critical to report any new detections to stop the spread and save many trees in any region. Please report sightings to your county Extension office or the Georgia Department of Agriculture.
Status and Revision History
In Review on Jun 10, 2025
Published on Jun 16, 2025
