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Asian longhorned beetle

Learn here how to identify Asian longhorned beetle, where it is and how to help keep it from moving to new places. This pest is a serious threat to Wisconsin forests because it can attack many different tree species, even when the trees are healthy. Many types of trees affected by this beetle also line miles of neighborhood streets in urban areas.

Distribution

Asian longhorned beetle is found in many parts of the world

Asian longhorned beetle has not been found on trees in Wisconsin. It is a pest of maples and other hardwoods in China and Korea. It was discovered in Brooklyn, New York in 1996 and then in the Chicago area in 1998 and in northern New Jersey in 2002. The pest was found in Austria in 2001, and in 2003 was discovered in Toronto, Ontario and in Montpellier, France. Adult beetles have also been found inside warehouses in a number of locations around the country, but have not been found outdoors at these sites.

Asian longhorned beetle in the United States

The insect is believed to have entered North America inside wood packing materials used in the cargo industry and it was likely introduced several times. All of these infestations are believed to have been before regulations were put in place to require treatment of wood packing materials to eliminate hitchhiking insects and fungi.

Asian longhorned beetle is classified a prohibited species in Wisconsin under Chapter NR40.

Biology

A few facts about Asain longhorned beetle

Asian longhorned beetles, Anoplophora glabripennis, belong to a family of beetles known as "longhorns" or "longhorned beetles" because of the adults' long antennae. The adults are about 1 - 1.5 inches long, shiny black with white spots and have black and white horizontal stripes on their antennae. Several native beetles found in Wisconsin have a similar appearance [exit DNR] so specimens should be sent to experts for identification.

Types of trees attacked by Asian longhorned beetles

The preferred hosts are maples (Norway, sugar, silver and red) but the insect has also attacked birch, horse chestnut, poplar, willow, elm, ash and black locust.

Asian longhorned beetle life cycle

Adult beetles emerge from infested trees during the summer and are present from July through September. They may remain on the tree they developed in or they may fly short distances to infest new trees. Their eggs are laid on the tree, hatch and the larvae tunnel beneath the bark to feed just under the bark. Older larvae will burrow deeper into the wood. The following summer, adults will emerge by chewing a half-inch diameter exit hole through the bark.

Mature larva
Mature larva
Photo by Kenneth R. Law, USDA APHIS PPQ, from www.forestryimages.org

Adult Longhorned Beetle
Adult Longhorned Beetle
Photo by Kenneth R. Law, USDA APHIS PPQ, from www.forestryimages.org

Impact

Impact of Asian longhorned beetle on trees, forests and the economy

If Asian longhorned beetle became established and spread throughout much of North America, there would be serious environmental and economic impacts, primarily to maple forests and industries that use maple.

Asian longhorned beetle is a major threat to North American forests and urban areas because it can attack many tree species, even when the trees are healthy. The larvae’s tunnel causes branch death and canopy dieback and enough tunneling can kill the tree.

Tree Removal Before
Tree Removal Before
Photo by Thomas B. Denholm, New Jersey Department of Agriculture (from ForestryImages.org [exit DNR])

Tree Removal After
Tree Removal After
Photo by Thomas B. Denholm, New Jersey Department of Agriculture (from ForestryImages.org [exit DNR])

Tree removal in New Jersey
Tree removal in New Jersey
Photo by USDA ARS (from ForestryImages.org [exit DNR])

Forest Risk Map
Forest Risk Map
Photo by USDA Forest Service

Signs and Symptoms

Asian longhorned beetle - what to look for

Adults leave half-inch diameter exit holes in bark and small sawdust piles below where they have chewed their way out of the wood. Other symptoms of infestation include dieback of the leaves and branches at the top of the tree, tree death, darkened pits chewed into the bark where the female laid an egg and oozing sap at these pits (created by the tunneling larvae).

The beetles can only be found from July to September and are about 1 - 1.5 inches long, shiny black with white spots and have black and white horizontal stripes on their long antennae. Several native beetles found in Wisconsin have a similar appearance [exit DNR] so specimens should be sent to experts for identification.

Larval tunnels
Larval tunnels
Photo by Robert A. Haack, USDA Forest Service (from ForestryImages.org [exit DNR])
Adult emergence holes
Adult emergence holes
Photo by E. Richard Hoebeke, Cornell University (from ForestryImages.org [exit DNR])

Heavily infested tree in China
Heavily infested tree in China
Photo by Michael Bohne, USDA Forest Service (from ForestryImages.org [exit DNR])

Egg Pit
Egg Pit
Photo by Kenneth R. Law, USDA APHIS PPQ (from ForestryImages.org [exit DNR])

Boring Dust
Boring Dust
Photo by Robert A. Haack, USDA Forest Service (from ForestryImages.org [exit DNR])

Prevention

You can prevent the spread of Asian longhorned beetle

Asian longhorned beetle can easily hide in firewood so do not move firewood long distances.

Laws to prevent the spread of Asian longhorned beetle

The best way to manage Asian longhorned beetle is to eliminate it from North America. Regulations now require that wood packing materials be free of bark and treated to kill any insects in the wood. Cargo and shipping materials can be inspected in their country of origin and upon arrival in North America so that the pest is not reintroduced. In addition, quarantines are in place in the infested areas to stop the movement of potentially infested material into uninfested areas such as Wisconsin.

Management

Options for managing Asian longhorned beetle

Since the discovery of Asian longhorned beetle in 1996, more than $100 million has been spent to try to find this insect and get rid of it in North America. Finding and controlling the pest is labor intensive, as trees must be carefully examined for signs of infestation. Because the insect remains hidden beneath the bark for most of its life, the only practical way to eliminate it is to cut down infested trees and chip or burn them. Nearby trees may also be infested but not yet showing symptoms, so these trees are usually removed and destroyed, too. Thousands of trees have been removed in an attempt to eradicate the insect wherever it has been found. Infested areas are also quarantined to prevent the movement of potentially infested wood, nursery stock, firewood or other items that could carry the insect.

Tree Removal Before
Tree Removal Before
Photo by Thomas B. Denholm, New Jersey Department of Agriculture (from ForestryImages.org [exit DNR])

Tree Removal After
Tree Removal After
Photo by Thomas B. Denholm, New Jersey Department of Agriculture (from ForestryImages.org [exit DNR])

Tree removal in New Jersey
Tree removal in New Jersey
Photo by USDA ARS (from ForestryImages.org [exit DNR])

Last revised: Wednesday July 08 2015