May 23, 2002
Clip 'N Keep:
Could this be an Asian Long-Horned Beetle

By Jennifer Hobson, OMAFRA Nursery Crops Specialist, Horticultural Science Division, University of Guelph

Since an Asian Long-Horned Beetle (Anoplophora glabripennis Motchulsky), (ALHB) adult was found in a Waterloo warehouse two years ago, there has been much concern over just where this pest might be lurking in the rest of Ontario. Many calls have come in from distraught nursery growers, landscapers and homeowners who have seen strange insects and damage in their plantscapes. I cannot over emphasize how much I WELCOME the calls regarding suspicious looking insects because early detection is our only chance at eradicating this aggressive pest. The Canadian Food Inspection Agency (1-888-682-2242) has investigated reported ALHB incidents and will continue to do so. ALHB-type damage is difficult to diagnose since the beetle will feed on a wide range of hardwood trees, both stressed and vigorously growing. I've put together the following problem-solving chart and photo collection to help assess whether you might have found an actual ALHB or its damage. Please do not hesitate to call CFIA, MNR or myself if you have any questions about this pest.

Foliar damage
  1. Skeletonized leaves may indicate feeding of other beetle larvae and adults (e.g. Japanese beetle, leaf beetles). Look for larvae on the upper or lower surfaces.
  2. Rolled or shredded leaves, chewed holes, and the presence of caterpillars may indicate feeding damage of leafrollers and other moth larvae.
  3. Bark-stripped stems may indicate ALHB adult feeding damage (Photo 1). Note: some adult wasps cause similar damage.

Bore holes in tree
  1. Numerous, pencil-sized holes in the heartwood (with no opening to the outside bark) may be caused by larvae of the pigeon tremex. Look for carcasses of female adults on tiny spear, stuck in bark (they often are unable to remove ovipositor after egg-laying).
  2. Other borers, including ash borer and poplar/willow borer cause similar damage and exit holes as ALHB. Adults (or larvae) must be obtained to confirm identification.
  3. Increment cores are sometimes used to assess growth of woodlot trees. Look for small (5-7 mm) clean holes in bark that lead to centre of the tree on a horizontal plain.
  4. ALHB makes i) adult exit holes in the bark and ii) egg niche scars in the bark. The exit holes (Photo 2) are slightly larger than the diameter of a wooden pencil (9-11 mm), they are cleanly-bored out and one can usually find sap streaks and sawdust along the bark and at the tree base. The egg niche scars (Photo 3) are shallow grooves chewed into the bark, a little larger in diameter than the exit holes.

Decline or dieback
  1. Many trees respond to drought stress through leaf scorch, dieback and sometimes mortality. Maple, ash and oak seem to be more susceptible to physiological drought.
  2. ALHB infested trees undergo rapid dieback and mortality due to destruction of heartwood by tunnelling larvae. Look for egg niche scars tunnels underneath loose bark.

Look-alike beetles
  1. Adult Whitespotted Sawyer look very similar. They are mottled to bronze-black with some white spots on the female. Their backs are rough whereas the ALHB are smooth. Antennae are longer than the body and segments are all greyish-black.
  2. Plant bugs are often mistaken for ALHB (e.g. Western conifer seed bug). Plant bug wings are thickened and leathery at the base, followed by membranous tips. ALHB wings are hard throughout.
  3. Adult ALHB (Photo #5) are glossy black with many irregularly shaped white spots. Antennae are longer than body and segĀ­ments alternate between white and black.