Trees & Ravines

Asian Long-Horned Beetle

Trees Under Threat
The Asian Long-horned Beetle in Greater Toronto

Asian Long Horned Bettle on branch of Maple treeExplore:

Unwelcome Guest, Unwanted Pest
Alien Invader
What's at Risk
A Bug's Life - A Tree's Death
Being a Good Host is Deadly
Recognizing Adult Beetles and Infested Trees 
Battling the Beetle 
What You Can Do
Renewing the Urban Forest
Information Sources for the Asian Long-horned Beetle

Update on the Asian Long-Horned Beetle

The Canadian Food Inspection Agency (CFIA) issued a Ministerial Order on December 3, 2013, which identified a new Asian Long-horned Beetle (ALHB) infestation and Regulated Area located in Mississauga and Toronto. This new infestation comes after a previous ALHB infestation located in Toronto and Vaughan had been successfully eradicated after ten years of intensive survey and the removal of roughly 28,000 trees.  After preliminary analysis of the age, extent and location of the new detections, it is suspected that this new infestation is un-related to the previous one.

The Ministerial Order prohibits the movement of any woody material of the twelve genera of ALHB hosts and firewood of any species outside the Regulated Area without authorization from CFIA.  Solid Waste Management Division of the City of Toronto has information for residents and businesses on the disposal of regulated articles located within the Regulated Area.  Click here for more information.

The City of Toronto was a partner with CFIA in the previous eradication program and will continue to work closely with CFIA on this new infestation.  Surveys and mapping are presently being conducted to determine the scope and extent of the infestation.  A decision regarding any control program will be made in due course and more information regarding the ALHB infestation in Toronto will be made available as it arises.

Click here for more information on ALHB from the Canadian Food Inspection Agency.

Unwelcome Guest, Unwanted Pest

Extreme Close up of the head of the Asian Long Horned BeetleThe Asian long-horned beetle (Anoplophora glabripennis), a serious forest pest in its native Asia, has been found in Canada for the second time.  An ALHB infestation is one of the most difficult and complex forest health issues facing our urban forest and forests throughout southern Ontario and beyond.

The beetle is not a threat to human or animal health. It does, however, pose a great risk to Canada's hardwood forests and shade trees as a killer of multiple hosts. With no known natural predator in North America, the ALHB poses as a serious threat with the potential to destroy up to 70 per cent of the trees and canopy of the urban forest and the natural forests of Ontario and Canada. In the City of Toronto, 42% of our street trees are the preferred host species for ALHB, with 33% being maples that are particularly susceptible to ALHB infestation.  As a result, the potential for a devastating impact on Toronto's forest canopy from this pest is very real.  Our hardwood forests have already lost tree species - elm, chestnut, butternut, beech and now ash - due to successive attacks of introduced pests. The additional impact caused by Asian long-horned beetle would be devastating, if allowed to establish, especially to maples.

Led by the Canadian Food Inspection Agency (CFIA), all levels of government are working to contain and eradicate the beetle before our trees and forests are decimated. An informed and active community is a critical element in this battle against the beetle. This brochure introduces the Asian long-horned beetle and addresses:

  • how the beetle got to Canada, and what's at risk in this country
  • which trees are attacked by the beetle, and how it kills
  • how you can identify the beetle and infested trees
  • what you can do to halt the spread of the beetle
  • what government agencies are doing in Canada to combat the beetle.

For other updates on the Asian long-horned beetle,, visit,,  and If you think you've found an adult beetle or an infested tree, call the CFIA toll-free at 1-800-442-2342.

Alien Invader

Asian Long Horned Beetle resting on extended handGlobal trade is responsible for bringing the Asian long-horned beetle to North America. For decades, the beetle has attacked poplar and willows growing in plantations and windrows in agroforest landscapes in China. Infested wood from these plantations was turned into crates, pallets, spools and dunnage - cheap packing material for cargo carried by ships to overseas markets. Thus, infested cargo is the pathway by which this beetle came to North America.

The Asian long-horned beetle was first detected in the U.S. and Canada at ports and inland warehouses in the early 1990s. To date, at least 15 U.S. states and two Canadian provinces (British Columbia and Ontario) have reported interceptions at these locations.

Steps have been taken to prevent the re-entry of the beetle. Canadian officials imposed stringent entry requirements in 1999 for wood packing materials originating from China and Hong Kong, but the current infestation likely began before these measures were implemented. All non-manufactured wood must undergo kiln drying, fumigation or treatment with preservatives prior to export. In 2004, these conditions will apply to all countries except the U.S., which has similar rules in place.

The beetle is not new to North America - it has long been on the move. Infested trees were found in New York City and on Long Island, NY, in 1996, followed by Chicago, IL, in 1998 and Jersey City, NJ, in 2002. By October 2003, over 7,700 infested trees had been cut down in these areas.  Presently, there two major ongoing infestations of ALHB in Massachusetts and Ohio.

Like many alien forest pests, the Asian long-horned beetle has no known natural predators in North America that can control its spread.

What's at Risk?

Community quality of life: A significant percantage of Toronto's street trees are maples - one of the beetle's preferred host species. These and other threatened hardwoods provide shade and beauty, shelter birds and animals, help filter air pollutants, produce oxygen, and increase property values.

Path leading through forest displaying fall coloursThe forest-based economy: Canada's commercial hardwood forests produce $11 billion in wood products annually. The maple syrup industry is worth another $100 million each year. Healthy forests also support tourism and recreation.

Ecological dynamics: Broad-leaved deciduous trees are a vital component of healthy woodlands in southern Canada. Many of Canada's endangered and threatened species are found in Ontario hardwood forests. Forest health and biodiversity are at stake.

If the Asian long-horned beetle goes unchecked, much of the fall colour in Toronto's parks and southern Canada's forests could be erased.


A Bug's Life - A Tree's Death

Unlike most other Canadian long-horned beetles that feed on dying or dead trees or cut timber, the Asian long-horned beetle attacks and kills apparently healthy trees. A look at its life cycle reveals how the beetle larvae kill trees and how the adult beetle and infested trees can be identified. In its native range in East Asia, the beetle has either a one- or two-year life cycle. Southern Canada's climate is well-suited to the beetle; our harsh winters do not pose a problem. Insulated by wood, the beetle overwinters either as an egg, larva or pupa.


Diagram of teh lifecycle of the Asian Long horned Beetle.
Life cycle of the Asian long-horned beetle.
Photo Credit: Michael Bohne, University of Vermont

Click to enlarge



  • each egg is deposited on the inner bark with one egg per pit
  • eggs develop in 1-2 weeks (if laid in summer),
  • or several months (if laid in late fall)


  • young larvae generally feed for about 20 days in the sappy, green inner bark (cambium-phloem interface), thereby reducing nutrient and water transport within the tree
  • older larvae (up to 5 cm in length) bore into the sapwood and heartwood, chewing tunnels through the trunk and branches, thereby structurally compromising the tree


  • mature larvae pupate in the wood in early spring - the stage between larva and adult


  • adult beetles chew and emerge through exit holes in the bark, likely beginning in late June in Toronto
  • female beetles undergo a sexual maturation period of 10-15 days, during which they disperse and feed; mating may occur during this period, but few eggs are laid
  • female beetles chew egg pits (oviposition sites) through the bark of the host trees, deposit or inject a single egg within the cambium and plug the egg deposition channel
  • adults cause external damage by feeding on young shoots, petioles, leaves and bark
  • populations peak in July-August

Larval tunnels within an infested tree.
Larval tunnels within an infested tree.
Photo Credit: Charles Harrington, Cornell University

Being a Good Host is Deadly  

Maples (Acer spp.) are among the preferred host species for the Asian long-horned beetle. Some of the infested trees found in Greater Toronto have been under attack for several years, as indicated by the presence of branch dieback and dead trees.

Beetles affect hardwood trees serving as hosts in various ways: (1) foliage may drop prematurely because adult beetles feed on leaf petioles and the leaves themselves; (2) eggs may be laid but fail to hatch; or eggs may be laid and hatch, but larval development fails to occur, thereby limiting damage to oviposition pits on trunks, branches or exposed roots; or (3) all stages of the beetle's life cycle are completed, and adults bore their way out of infested trees. Repeated attacks of this latter type can cause tree death in as little as two to five years depending upon beetle density and tree health before the attack.

Knowing which tree species are attacked and killed by the beetle is essential to any program of survey and treatment. Hardwood species in the Greater Toronto urban forest that are suitable for the full development of the Asian long-horned beetle are listed below. This list is based on field studies and laboratory research in China and the United States. Work is underway to determine the suitability of other hardwood species that are found in Greater Toronto, but not in China or in the infested areas of the United States.

Greater Toronto hardwoods suitable for full development of the Asian long-horned beetle

Common Name Scientific Name


Maple (sugar, silver, red, Manitoba, Norway, Schwedler, Japanese, etc.)



Horsechestnut (common and red

horsechestnut; Ohio buckeye, etc.)



Elm (white, Siberian, etc.)



Birch (white, yellow, etc.)



Willow (golden weeping, crack,

pussy, etc.)

Poplar (balsam, Lombardy, Carolina and European white poplar; trembling and largetooth aspen; eastern cottonwood, etc.) Populus
Sycamore/London plane-tree Platanus
Hackberry Celtis
Mountain ash Sorbus
Katsura Cercidiphyllum
Goldenrain tree Koelreuteria


It is strongly recommended that no trees belonging to the above genera be planted within 400 metres of any known infested area until the beetle has been eradicated.

Coniferous (i.e., evergreen) trees are not attacked by the Asian long-horned beetle and are never hosts. The beetle is not a structural pest - unlike termites, it does not attack construction wood in residences. The beetle will bite people only if threatened (such as when held in the hand and squeezed).

Recognizing Adult Beetles and Infested Tree

Being observant is the first line of neighbourhood defence against the Asian long-horned beetle. Because larvae and pupae are hidden inside infested trees for more that 10 months, focus your search on adult beetles.

Adult Beetles: Identification

1) Body

  • glossy black with from 0 to 20 irregular white spots on the back (giving rise to the beetle's Chinese name, translated as "starry sky beetle")
  • bullet-shaped
  • length - 1.7 to 3.5 centimetres, with females generally larger than males

2) Antennae (there are two antennae)

  • long (1 to 1.3 times the body length in females, 2.5 times the body length in males)
  • 11 black segments with whitish-blue base

3) Legs (there are six legs)

  • black with bluish-white tinge

Female (top) and male (bottom) adult Asian long-horned beetles, shown at actual size. Both can be confused with other species like the white-spotted sawyer, which is common in Ontario


Female (top) and male (bottom) adult Asian long-horned beetles, shown at actual size. Both can be confused with other species like the white-spotted sawyer, which is common in Ontario. For information about look-alikes, see and

Photo Credit: USDA, Forest Service

How to Look:

A good pair of "bird-watching" binoculars with a wide field of view and good light-capturing ability is best. Such binoculars enable you to see deeper into a dark canopy than you can with the naked eye, even at close range. Looking with the sun at your back is best.

Where to Look:

In the Landscape:

  1. street and backyard trees;
  2. isolated or open grown trees in parks and cemeteries; 
  3. hedgerows; 
  4. edges of woodlots or ravines.

In Trees:

  1. male beetles either rest or wander throughout the tree in search of female beetles and thus can been seen anywhere on the tree; 
  2. female beetles rest, chew egg pits and lay eggs on branches and the trunk (more than 5 cm in diameter), or feed on shoots, petioles or leaves. The location of females in trees attacked for the first time will depend on tree size: in large trees, female beetles can be seen laying eggs on higher branches, whereas in small trees (less than 16 cm diameter at breast height), females can be found lower on the trunk. When a tree has been attacked for several years, female beetles are found laying eggs lower on the trunk of even large trees because preferred oviposition sites have been used-up.

When To Look:

Based on U.S. experience, and on a mathematical model predicting adult emergence that uses our temperature records, adults are likely active in Greater Toronto between late June and early November. Their peak months for flying and mating are probably July and August.

Infested Trees

Hardwoods of any age or size are attacked - check young saplings with stems over 5 cm as well as mature trees, focusing on the tree species (list). Do not check evergreens like pine, hemlock, spruce or cedar, as they are not host species for the Asian long-horned beetle.

Signs of beetle damage on host trees include:

1) Egg-pits (created by adult females laying eggs)

  • oval or round pits, 10-15 mm in diameter
  • found on the trunk, branches or exposed roots (more than 5 cm in diameter)

Asian Long Horned Beetle laying eggs

Adult beetles and egg-laying sites.
Photo Credit: Kenneth R. Law, USDA, APHIS

2) Leaking sap

  • dark spots on trunk and branches around egg pits created by adults, or near cracks or holes created by larvae wasps, ants, flies, scarab beetles, butterflies and other insects are attracted by the sap and may be

    seen around these spots

Egg-laying sites leaking sap
Egg-laying sites leaking sap.
Photo Credit: CFIA

3) Frass (mixture of wood and dung created by larvae boring in wood)

  • short slivers or strands of wood fibres (1-1.5 cm long)
  • found either at bark crevices, at tree joints (where branches meet the main trunk), or around the base of infested trees

Frass (mixture of wood and dung created by larvae boring in wood)  in the joint of a tree branch      Close up of Frass (mixture of wood and dung created by larvae boring in wood)  in the joint of a tree branch

(left) Frass in a tree joint.
Photo Credit: CFIA

4) Exit holes (created by adult beetles emerging from inside tree)

  • large round holes, 10-15 mm in diameter
  • typically found near egg-laying sites
  • irregularly distributed - holes in a horizontal line are likely the work of woodpeckers

Asian Long Horn Beetle exit hole in tree bark with Canadian ten cent coin beside to show comparative size, bore hole is slightly smaller.

A pen or pencil will fit easily into an exit hole.

5) Yellow or drooping leaves and premature leaf drop

  • premature leaf drop, specifically where the base of the leaf petiole has been chewed on or scarred, where the outer tissue of the petiole has been chewed off, or where portions of main leaf veins or tissue has been removed by feeding adults

6) Branch dieback

  • an advanced sign of attack
  • typically begins at the top of the tree

When To Look
The search for evidence of infested trees can take place year-round.

Battling the Beetle

Eradicating the Asian long-horned beetle is a long, difficult and expensive process requiring significant resources and commitment. Eradication of the previous Canadian infestation in Toronto and Vaughan took 10 years of hard work.  Elsewhere, the American experience is instructive. For example, Federal, state and city officials adopted a US$365 million plan in 2000 to eradicate the beetle by 2009 in New York City and Chicago.

Research to find more effective detection, control and eradication methods is ongoing and success requires co-operation and co-ordination among many partners. Moreover, battling the beetle is not the work of government alone - support from residents, tenants, property owners, employees, arborists, landscapers and naturalists is essential.

What You Can Do

Alert and observant citizens - not pest specialists - first discovered the Asian long-horned beetle in New York City, Chicago, Jersey City and Greater Toronto. All community members, including tree-care and landscape professionals, can help beat the beetle through an 8-step program:

1) Learn to recognize what adult beetles and infested trees look like. Know the beetle's host tree species.

2) Alert your family, friends and co-workers to the threat posed by the beetle.

3) Watch for signs of infestation on public and private property. Check trees along streets, in backyards, and in parks, ravines and valleys. Binoculars will help.

4) Report any suspected sightings of adult beetles or infested trees to the Canadian Food Inspection Agency (CFIA) at 1-800-442-2342. If you catch a beetle, let the CFIA know immediately. Be careful that you do not risk letting the beetle escape to a new location. Report the exact location where the beetle was found. For infested trees, report the exact location, type of damage, and site of damage on the tree.

5) Know if your property lies within the Regulated Area. This area is roughly bounded by Highways 427, Finch Avenue West, Martin Grove Road and  Highway 401. Click here for a map of the new Regulated Area

6) Don't remove any restricted woody material from the regulated area. This includes firewood of all tree species along with nursery stock, trees, logs, lumber and wood with bark attached, wood chips or bark chips from trees identified as hosts for the Asian long-horned beetle. This material can accidentally spread the beetle to un-infested areas. Click here for more information.  Leaf and yard waste in the regulated area of Toronto Solid Waste Management and transferred to a designated facility. Call 311, click here for the collection calendars for residential single family homes or here for more information on disposal of regulated articles.

For information on approved disposal sites for the tree-care industry, call 311 at the City of Toronto or the City of Mississauga

7) If you own property in an infested area, expect several visits from CFIA inspectors. They will survey all known and potential host trees, likely on several occasions. They may remove infested and potentially infested trees. 

8) Plant either conifer trees or hardwood trees suggested in the following chart. Use the chart as a guide for appropriate species and planting locations. For more advice, call your municipal forestry office. Once the beetle has been eradicated from Greater Toronto, you will be able to plant other hardwood species.

Trees Suggested for Planting in Greater Toronto Infestation Areas



Planting Location*

    street backyard ravine within 100 m of a natural area
Serviceberry Amelanchier spp. yes yes yes
Blue-beech Carpinus caroliniana yes yes yes
Hickory Carya spp. yes yes yes, if native
Catalpa Catalpa spp. yes yes no
Katsura-tree Cercidiphyllum japonicum yes yes no
Redbud Cercis canadensis yes yes yes
Turkish hazel Corylus colurna no yes no
Beech Fagus spp. no yes yes, if native
Ash Fraxinus spp. no** yes** yes, if native**
Ginkgo Ginkgo biloba yes yes no
Honey-locust Gleditsia triacanthos yes yes no
Kentucky coffeetree Gymnocladus dioicus yes yes yes
Hibiscus Hibiscus spp. no yes no
Black walnut/butternut Juglans spp. yes yes yes, if native
Tulip-tree Liriodendron tulipifera yes yes yes
Apple Malus spp. no yes no
Dawn redwood Metasequoia glyptostroboides no yes no
Ironwood Ostrya virginiana yes yes yes
Amur corktree Phellodendron amurense yes yes no
Cherry/plum Prunus spp. yes yes yes, if native
Pear Pyrus spp. yes yes no
Black locust Robinia pseudoacacia no yes no
Japanese lilac tree Syringa reticulata yes yes no
Basswood Tilia americana yes yes yes
Little-leaf linden Tilia cordata yes yes no
Crimean linden Tilia X euchlora yes yes no
Oak Quercus spp. yes yes yes, if native
Conifers (e.g., pine, hemlock, cedar, Abies spp. fir, spruce) Tsuga spp.,Thuja spp., Pinus spp., and others no*** yes yes, if native

* Suitability of a species to a site is also determined by environmental factors such as soil drainage, texture (sand or clay content) and shade. For planting tips, including a list of species native to Toronto, see Trees and Ravines.

** Not recommended due to the threat posed by the emerald ash borer, an alien forest pest that has recently infested southwestern Ontario. The City of Toronto has adopted a policy of not planting ash trees along streets or in parks until further notice. Find more information on Trees and Ravines and visit

*** Unless the tree is more than 5 metres from curb.


Some residential trees suggested for planting in Greater Toronto infestation areas:
Canada red chokecherry in late spring
(Prunus virginiana cultivar)
Canada red chokecherry (Prunus virginiana cultivar)
Shagbark hickory
(Carya ovata)
Shagbark hickory (Carya ovata)
(Ostrya virginiana)
Ironwood (Ostrya virginiana)
Turkish hazel
(Corylus colurna)
Turkish hazel (Corylus colurna)
Kentucky coffeetree
(Gymnocladus dioicus)
Kentucky coffeetree (Gymnocladus dioicus)
Redbud with spring flowers (Cercis canadensis) Redbud with spring flowers (Cercis canadensis)

Photo Credit: Toronto Parks, Forestry & Recreation

Renewing the Urban Forest

Even if the Asian long-horned beetle's attack can be limited to those areas currently infested in Greater Toronto, the removal of thousands of trees will dramatically change the urban forest and the appearance of many neighbourhoods. Will anything positive emerge from this devastation?

As a clear and present danger to the urban forest, the beetle has underscored the need to improve tree care in cities. Renewing the urban forest means many things. It means planting more trees, and a greater number of tree species, to expand and diversify the forest canopy. It means ensuring that trees have an adequate growing environment, including soil, space and water. It means controlling invasive, non-native species that undermine the local ecology.

Youth volunteers planting young saplingRenewing the urban forest means that we all must think seriously about the needs and the benefits of city trees, and then develop and implement a plan of action. This is not a job for government alone - as the beetle battle has demonstrated, success requires the support and participation of an active and aware community.

Community stewardship is essential to renewing the urban forest and responding to threats like the Asian long-horned beetle.

Photo Credit: Parks, Forestry & Recreation

Information Sources for the Asian Long-horned Beetle

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