Common Insects and Mites: Exotic longhorned beetles

Biology

Native longhorned beetles (Cerambycids) feed in weakened, dying, or recently dead or downed timber, not healthy living trees; however, non-native species such as the Asian longhorned borer or ALB (Anoplophora glabripennis) will attack healthy trees, including maple, elm, willow, birch, and other hardwoods. This beetle has been found in Washington. A second potentially invasive species, the citrus longhorned beetle or CLB (Anoplophora chinensis), has been found in Washington once. These beetles pose a significant threat to landscape, agricultural (including fruit) and lumber trees if they become established. The two species are similar in appearance. The body is shiny black with irregular spots of white on the elytra (hardened wing covers or forewings). Adults are 1 to 1 1⁄2 inches long. The curved antennae are longer than the body and marked with bands of black and gray or black and white. Adult beetles feed on the bark of small twigs of host trees. The female ALB lays eggs in small oval depressions chewed in the bark of the trunk, while CLB makes a slit near the base of the trunk. The white to yellowish larvae are cylindrical with a rounded head region. They initially feed on green tissues beneath the bark, then tunnel deeper into the wood, causing extensive damage. Damaged trees usually die back first along the main trunk (the center and top branches). As the infestations move into the lateral branches the rest of the canopy begins to die as well. The adults chew their way out of the tree, leaving a 3⁄8 to 1⁄2 inch circular “bullet-hole” in the branch or trunk. Sap may flow from these holes and large amounts of sawdust may also accumulate at the base of the tree or in the branch crotches. Both of these exotic species may be confused with native beetles including the banded alder borer. It is also a large beetle (1 to 1 1⁄2 inches long), but has distinct dull (not shiny) black and white bands (not spots) across the body and antennae.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Although costly and undesirable, the only certain long-term control measure for invasive longhorned beetles is removal and destruction of infested trees.
• If you suspect you have found one of the exotic longhorned borers, try to capture it and seek professional help for positive identification.
  • Residents of OREGON: For help with identification, call the Oregon Department of Agriculture at (503) 986-4636 or 1-800-525-0137 or contact your local Extension office.
  • Residents of WASHINGTON: For help with identification, call the Washington State Department of Agriculture at (360) 902-2070 or 1-800-443-6684 or contact your local Extension office.
• To preserve an insect for identification, collect it in film canister or small jar (not a plastic bag, as they can easily chew out of them). The beetle may be killed and preserved in the freezer. Be sure to record the location and date you collect the specimen.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

For further information, including pictures of exotic and native longhorned beetles and how to report a possible sighting, refer to the Invasive Longhorned Beetles Fact Sheet (pdf) from the Washington Invasive Species Council.