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Latest Information on Invasive and Exotic Species in Michigan

MDARD Commission Water Soldier Order - 1-21-15 

Why we care:

This large, showy beetle was accidentally introduced into the U.S. on several occasions, probably in wood crating or pallets shipped from Asia.  Larvae feed in tunnels (called galleries) in the wood of tree branches and trunks.  The galleries can cause branches or trees to break and will eventually kill the tree.  North American trees have little or no resistance to infestation. 
Click here to read more about the Asian Longhorned Beetle.   

ASIAN LONGHORNED BEETLEAsian Longhorned BeetleJoe Boggs, Ohio State University Extension

Why we care:

These tiny insects secrete white wax as they feed on sap from hemlock shoots and branches.  Hemlock Woolly Adelgid (HWA) feeding can kill needles, shoots and branches.  Over time, growth slows as trees become less vigorous and trees may take on a grayish-green appearance.  Infested hemlocks, especially large, old trees, are often killed when other stress factors, such as drought, affect trees. Click here to read more about Hemlock Woolly Adelgid.  For quarantine information, click here.

HEMLOCK WOOLLY ADELGID Hemlock Woolly AdelgidElizabeth Willhite, USDA Forest Service,
Why we care:

Thousand Cankers Disease (TCD) involves an insect native to the southwestern U.S. and a newly identified pathogen.  It is a relatively new concern for black walnut trees.  When tiny walnut twig beetles feed on tree branches, they introduce a fungal pathogen that causes TCD in live trees.  The pathogen kills small areas of tissue, resulting in cankers.  As more cankers form, branches die and over time, the entire tree succumbs.  Click here to read more about Thousand Cankers Disease.  For quarantine information, click here.

Thousand Cankers Disease
Whitney Cranshaw, Col. State University
Why we care:

Balsam woolly adelgid (BWA) is a sap-feeding insect that attacks true fir trees, including balsam fir and Fraser fir.  Repeated attacks weaken trees, cause twig gouting, kill branches and, over the course of several years, cause trees to die.  Click here to read more about Balsam Woolly Adelgid.  For quarantine information, click here.

Balsam Woolly Adelgid image

William M. Ciesla, Forest Health Management International,

Why we care:

Oak wilt kills healthy red oaks. White oaks can also be affected but are more resistant and less vulnerable to mortality from the disease. Once a red oak becomes infected with the oak wilt fungus, the tree will die, and there is no treatment to save the infected tree. Once an oak wilt infection is confirmed, however, treatments are available to save surrounding oaks and stop the spread of this disease.  Click here to read more about Oak Wilt.

Oak Wilt image
Joseph O'Brien, USDA Forest Service, 

Why we care:

Beech bark disease (BBD) is caused by both asap-feeding scale insect and a fungus.  American beech trees are first infested with beech scale.  Scale feeding allows infection by the Neonectria fungus.  The fungus kills the wood, blocking the flow of sap.  Affected trees decline in health and eventually die.  Some infected trees break off in heavy winds before dying - a condition called "beech snap" (see photo).  The scales are covered with white wool, turning infested portions of the tree white. Click here to read more about Beech Bark Disease.

BEECH BARK DISEASEBeech Bark Disease image Joseph O'Brien, USDA Forest Service,
Giant Hogweed
Giant Hogweed was introduced into North America in the early 1900s.  Its native Central Asia, although now it occurs throughout the United Kingdom, Australia, Europe, parts of Canada and the United States.  It is suspected to have made its way into this country as ornamental.  Its size made it somewhat of an oddity and gardeners that wanted something unique imported it.  Click here to read more about Giant Hogweed. 

Man with Giant HogweedMan with Giant Hogweed


Giant Hogweed Flower with Pen
Giant Hogweed flower with pen