Invasive bug found near Rockford a threat to Christmas tree industry

Kent County

A photo shows the tiny white, cottony tufts of a balsam woolly adelgid on the trunk of an infested tree. Photo courtesy of Jerald E. Dewey, USDA Forest Service,

ROCKFORD, Mich. (WOOD) — An invasive bug that’s a potential threat to Michigan’s Christmas tree industry has been discovered in Kent County.

The Michigan Department of Agriculture and Rural Development announced Monday it had confirmed the state’s first detected case of the balsam woolly adelgid near Rockford.

MDARD said the homeowner noticed several Fraser firs in their yard were declining and contacted an arborist, who spotted the infestation and alerted the state.

It’s unclear how the bug reached Michigan or how long it’s been in our state, but MDARD Director Gary McDowell said it’s “plausible” the invader arrived on trees shipped to a nursery.

The resurgence in camping and hiking also increases the risk of spreading balsam woolly adelgid.

“Human movement is one of the most common ways non-native species spread. When traveling, remember to leave firewood at home and buy it locally at your destination,” said Rob Miller, the invasive species prevention and response specialist for MDARD’s Pesticide and Plant Pest Management Division. “Balsam woolly adelgid cannot travel far on its own but may be carried by wind, wildlife or infested wood.”

The Balsam woolly adelgid has been on Michigan’s Invasive Species Watch List for years. Like the hemlock woolly adelgid, this sap-sucking insect damages trees, weakening or killing them over the course of many years. However, the balsam woolly adelgid feasts on true fir trees, including balsam, Fraser and concolor (white) fir — not hemlocks.

“This invasive insect is a threat to the nearly 1.9 billion balsam fir trees in Michigan’s forests,” Miller stated in Monday’s news release. “And, as the third largest Christmas tree-growing state in the country, Michigan produces nearly 13.5 million fir trees each year, which are susceptible to balsam woolly adelgid.”

The balsam woolly adelgid is tiny, measuring 1-2 millimeters. It appears on the lower trunk of a tree or large branches in the spring and summer, and looks like white woolly tufts.

Red flags of a potential balsam woolly adelgid infestation include:

  • Swelling and distortion of the twigs, commonly called “gout.”
  • A branch or branches turn brick red and die.
  • Tree crowns that become narrow and misshapen with few needles.
(Swollen tissue in tree twigs, called gouting, is a sign of a balsam woolly adelgid infestation. Photo courtesy of David McComb, USDA Forest Service,

Anyone who suspects they have a balsam woolly adelgid infestation is encouraged to take photos, document the location and report the possible case to the Midwest Invasive Species Information Network or MDARD by emailing or by calling 800.292.3939.

The MDARD says the balsam woolly adelgid likely hitched its first ride to the United States on imported nursery stock from Europe more than a century ago, triggering fir tree infestations in other portions of the country over the decades.

In 2014, MDARD began balsam wooly adelgid quarantine, regulating the movement of trees from other areas in North America with known balsam woolly adelgid infestations.

MDARD’s Pesticide and Plant Pest Management Division will now survey trees in the Rockford area to see if the bug has spread.

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