Asian longhorn beetle
Native to China and Korea, Asian longhorn beetle (Anoplophora glabripennis), or ALHB, is a very serious pest of hardwood trees. In 2003, ALHB was first discovered in Canada - on the boundary between Toronto and Vaughan Ontario. This posed a serious threat to urban and natural forests in the region, both of which have a large component of maple and other vulnerable trees. Because the loss of these trees would have considerable impact on urban and natural landscapes and ecosystems, and cause billions of dollars of lost revenues in the forest, maple syrup and tourism industries, the Canadian Food Inspection Agency (CFIA) led an eradication program aimed at eliminating the beetle from the two cities. In order to eradicate the insect, infested trees were felled, as were any nearby trees that could be susceptible to the beetle. After removal of many host trees in the area of the ALHB discovery, the beetle was declared eradicated from Ontario in 2013. However, later that same year, ALHB was found again, this time in an industrial area near Pearson Airport, Mississauga Ontario. Similar eradication activities occurred and in 2020 ALHB was once again declared eradicated in Canada.
The first ALHB population detected in the United States was in 1996 in New York state. Since that time there have been several ALHB introductions and eradications in the U.S. Eradication programs are ongoing for ALHB populations in New York, Massachusetts, Ohio and South Carolina.
A mated adult female beetle chews a pit in the outer bark of the tree - on the trunk or branch junctions - and lays an egg in the hole. The egg hatches in 1-2 weeks, and the newly hatched larva feeds just under the tree bark in the phloem (inner bark) and on the surface of the sapwood. This feeding eventually kills the tree by destroying its vascular tissue. As the larva gets older, it begins to tunnel through the sapwood and heartwood of the tree to feed, causing structure weakness in the tree. The beetle stays in its larval form over the winter, then pupates in the spring. The adult beetle bores its way out of the tree, leaving a circular exit hole. In the Toronto area, most adult beetles emerge between late June and late August but continue to emerge into the fall. It takes the beetle one to two years to develop from the egg to the adult stage, depending on weather and climate.
Read more detailed information about ALHB biology and ecology in Ecology and management of exotic and endemic Asian longhorned beetle Anoplophora glabripennis.
Trees at risk
Though ALHB prefers maple (Acer) species, it also infests, and successfully develops in, birch (Betula), poplar (Populus), and willow (Salix) in Ontario. The beetle kills both healthy and stressed trees.
Read more about other host-trees of ALHB in the US
ALHB is not currently known to be in Canada. It is still found in New York, Massachusetts, Ohio and South Carolina.
Be on the lookout for signs of ALHB. You may see oviposition pits - crevices excavated by the female insect to lay her eggs in - on the trunk or at the base of the branches of live trees (see photo in sidebar). More conspicuous are the large exit holes made by the adult insect tunnelling its way out of the tree. They are circular, 6-18 mm across, and very deep. Try the pencil test - if you can place a regular pencil inside the hole to a depth of at least 2.5 cm it could be an ALHB exit hole. Adult beetles themselves are quite large and conspicuous having a shiny black body, 2-3.5 cm in length, with several white splotches, and long segmented antennae with bands of black and pale blue or white (see sidebar). In the Toronto area, they are typically seen from late June through to the fall. Have a look at branches that have fallen, or been pruned, from potential host trees for signs of ALHB larvae tunnelling through the wood of the branch.
Read more about how to detect ALHB
What you can do
If you think you have found Asian longhorn beetle in Canada, contact the CFIA Plant Health Surveillance Unit or call 1-800-442-2342 or 647-790-1012.