Asian longhorned beetle

Written by V.G. Nealis Revision 2024

• French common name: Longicorne asiatique
• Other common names: Starry sky beetle
• Scientific name: Anoplophora glabripennis (Motschulsky)
• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta
• Order: Coleoptera
• Family: Cerambycidae

General information and importance

Asian longhorned beetle is a large, wood-eating (xylophagous) beetle native to eastern Asia. It became a significant pest in China in the 1980s following major reforestation efforts with susceptible hardwoods. The insect was first intercepted in wood-packing materials in Canada and the United States in 1992. Breeding populations were discovered in New York, United States (1996), Toronto, Canada (2003 and 2013), and in North Carolina, United States (2020). Introductions have occurred in Europe since 2001. The European introductions were also associated with wood packing materials. Most of the introductions have occurred in urban environments. In June 2020, the insect was declared eradicated in Canada (Toronto and Mississauga) after 5 years of surveys failed to detect any new occurrences.

Asian longhorned beetle attacks a broad range of healthy deciduous, hardwood tree species. These species include some of the most common forest and urban trees in north temperate climates. The commercial and amenity values of these tree species underscore the potential risk posed by the establishment of Asian longhorned beetle in North America or Europe. Bio-economic models estimate the cost of removal and replacement of infested trees could be more than $10 billion CND and loss of merchantable maple for timber and syrup products as much as $800 million CND annually. Intensive surveys, removal and chipping of infected trees, and sustained, strict quarantines have eradicated Asian longhorned beetle from the original introduction sites in Canada.

Distribution and hosts

Asian longhorned beetle, native to China, North Korea, South Korea, and the Russian far east, can feed on a broad range of deciduous, hardwood species. In Canada, complete development of the insect has been verified on poplar (Populus), willow (Salix), maple (Acer), birch (Betula), elm (Ulmus), and ash (Fraxinus). Linden/basswood (Tilia) species have also been injured. Maples are the most attacked species; however, this may represent the group of trees that was prevalent in the original areas of infestation.

Host parts affected

Adult beetles feed on leaves and twigs of host trees. Larvae bore beneath bark, creating feeding tunnels in the sapwood and heartwood, interrupting translocation of resources and water.

Symptoms and signs

Adult beetles are large (20 to 35 millimetres long), distinctive insects with antennae longer than their body. They may be confused with other common, native wood-boring beetles in the same family, called “sawyer beetles” (Monochamus spp.). They are distinguished by their glossy black colour with scattered, white dots, hence the Chinese common name “starry sky beetle”. The 11 antennae segments alternate between blue/black and blue/white in colour.

Female adults chew pits (about 10 millimetres wide) in the bark, causing characteristic sap stains. Most of these pits have been noted within 3 metres of the ground. Females lay a single, large (5 to 7 millimetres), oblong egg in this pit. Round exit holes (6 to 14 millimetres in diameter) indicate where adults have emerged from feeding tunnels. These external signs are difficult to recognize without training. Feeding tunnels of small larvae are lateral under the bark. The tunnels turn upward in the sapwood and heartwood as they enlarge. Coarse sawdust may be seen around the base of trees and on larger branches where adults have exited through circular exit holes. Trees that have been infested for several years have dead branches and extensive decay.

Life cycle

In its native range, Asian longhorned beetle requires 1 year to complete a generation. This process can take multiple years in cooler northern locations. Adult beetles are most active from May to July. Adults are long-lived, however, and may be found on warm days throughout the growing season. Adults mate soon after emergence but feed for a 2-week period on twigs, leaf petioles, and leaf veins to complete reproductive maturation. Adult beetles often remain to lay eggs on the tree from which they emerged, potentially causing the same tree to be attacked repeatedly. Alternatively, adults may seek other suitable trees, which they locate through detection of chemicals (volatile organic compounds) released by the trees. There is evidence that drought-stressed trees produce more volatile compounds that attract the beetles. 

Female beetles chew pits in the bark of the host tree to lay a single egg per pit. Newly hatched larvae first feed on the degraded tissue around the pit. They then move through the cambium layer and tunnel laterally beneath the bark. As larvae grow, they excavate the sapwood and heartwood. Asian longhorned beetle usually overwinters inside the feeding tunnel as larvae. Larvae create a chamber near the outer bark where they pupate. Adults chew a circular hole in the bark to exit.

Damage

Trees of all size classes are susceptible. Damage to twigs and leaves caused by maturing adult beetles is considered inconsequential. Larval tunnelling causes significant damage to the cambium, sapwood, and heartwood layers where their feeding disrupts vital translocation functions. This feeding also compromises the structural properties of the tree. Individual trees may be repeatedly attacked during several years, successively killing branches and then the entire tree.

Prevention and management

The threat posed by Asian longhorned beetle as an invasive pest species has prompted active international quarantines and intense surveys. Canada has been active in developing international agreements to reduce the risk of inadvertent movement of xylophagous insects, such as Asian longhorned beetle, by ensuring wood-packing materials comply with international standards, including removal of all bark and treatment prior to use as packing material for shipping.

In Canada and the United States, detection of Asian longhorned beetle resulted in the felling and chipping of thousands of infested and susceptible trees. These successful eradication programs required several years of dedicated effort at significant cost. The benefits were avoiding additional costs of regulation and the loss of millions of trees.

The potential threat posed by Asian longhorned beetle resulted in several research initiatives on chemical, microbial, and biological controls. Public engagement was crucial to obtain consent for removal of trees and to create awareness about the movement of firewood (as this could facilitate spread). The successful extirpation of Asian longhorned beetle in Canda, however, has shifted the focus to prevention.

From egg hatch to adult emergence, Asian longhorned beetle is hidden in galleries and chambers within the tree, protected from both environmental and management options. This makes both detection and treatment difficult. In China, where the beetle is an indigenous pest, topical and systemic insecticides are widely used. Pesticides registered for use against Asian longhorned beetle under specific situations may change from year to year. Therefore, please search Health Canada’s Pesticide Product Information Database for currently registered pesticides and product information for use against this insect. The application of any registered product should be based on population size and applied only when necessary and against the approved life stage. It is also recommended to consult a local tree care professional. Pesticides may be toxic to humans, animals, birds, fish, and other beneficial insects. Apply registered products only as necessary and follow all directions and precautions noted on the manufacturer’s label. In some jurisdictions and situations, only a licensed professional can apply pesticides. Consulting relevant local authorities to determine local regulations that are in place is recommended.

Pest management strategies for a particular pest vary depending on several factors. These include:

• the population level of the pest (i.e., how numerous the pest is on the affected host[s]);
• the expected damage or other negative consequences of the pest’s activity and population level (either to the host, property, or the environment);
• an understanding of the pest’s life cycle, its various life stages, and the various natural or abiotic agents that affect population levels;
• how many individual host specimens are affected (an individual tree, small groups of trees, plantations, forests);
• the value of the host(s) versus the costs of pest management approaches; and
• consideration of the various silvicultural, mechanical, chemical, biological, and natural control approaches available and their various advantages and disadvantages.

Decisions about pest management strategies require information about each of these factors for informed decision-making. These various factors should then be weighed carefully in terms of costs and benefits before action is taken against any particular pest.

Selected references

Haack, R.A.; Hérard, F.; Sun, J.; Turgeon, J.J. 2010. Managing invasive populations of Asian longhorned beetle and citrus longhorned beetle: a worldwide perspective. Annual Review of Entomology 55: 521–546. https://doi.org/10.1146/annurev-ento-112408-085427

Kimoto, T.; Duthie-Holt, M.; Dumouchel, L. 2006. Exotic forest insect guidebook. Canadian Food Inspection Agency. Ottawa, Ontario. 120 p. https://publications.gc.ca/site/eng/9.689640/publication.html [Accessed April 2024]

Meng, P.S.; Hoover, K.; Keena, M.A. 2015. Asian longhorned beetle (Coleoptera: Cerambycidae), an introduced pest of maple and other hardwood trees in North America and Europe, Journal of Integrated Pest Management 6(1): 4. https://doi.org/10.1093/jipm/pmv003

Pedlar, J.H.; McKenney, D.W.; Yemshanov, D.; Hope, E.S. 2020. Potential economic impacts of the Asian longhorned beetle (Coleoptera: Cerambycidae) in eastern Canada. Journal of Economic Entomology 113(2): 839–850. https://doi.org/10.1093/jee/toz317

Smith, M.T.; Turgeon, J.J.; Groot, P.; Gasman, B. 2009. Asian longhorned beetle Anoplophora glabripennis (Motschulsky): lessons learned and opportunities to improve the process of eradication and management. American Entomologist 55(1): 21–25. https://doi.org/10.1093/ae/55.1.21a

Turgeon, J.; Smith, M.T. 2013. Anoplophora glabripennis (Motschulsky), Asian longhorned beetle (Coleoptera: Cerambycidae). Pages 82-92 in P. Mason and D.R. Gillespie, editors. Biological control programmes in Canada 2001-2012. Commonwealth Agricultural Bureau International (CABI). Oxfordshire, United Kingdom. 504 p.  https://doi.org/10.1079/9781780642574.0082

Turgeon, J.J.; Smith, M.T.; Pedlar, J.; Fournier, R.E.; Orr, M.; Gasman, B. 2022. Tree selection and use by the polyphagous xylophage Anoplophora glabripennis (Coleoptera: Cerambycidae) in Canada. Canadian Journal of Forest Research 52(4): 622–643. https://doi.org/10.1139/cjfr-2021-0244

Cite this fact sheet

Photos

An adult Asian longhorned beetle (dorsal view).

Donald Duerr, USDA Forest Service, www.forestryimages.org

Larva of Asian longhorned beetle exposed in the wood of its host.

Steven Katovich, USDA Forest Service, www.forestryimages.org

Round exit hole created when the adult Asian longhorned beetle emerged from the trunk or branch of its host. The bark has been removed.

Larry R. Barber, USDA Forest Service, www.forestryimages.org