Invasive balsam woolly adelgid which threatens Michigan's Christmas tree industry spotted in state

Round, white hemlock woolly adelgid ovisacs are found on the undersides of branches near the base of the needles. (Photo: DNR)

A tiny invasive insect that feeds on fir trees and is considered a major threat to Michigan was spotted in a northern county recently.

It's the second time officials have reported finding balsam wooly adelgid in the state after it was first detected in 2021.

BWA is listed on Michigan's Invasive Species Watch List due to its ability to threaten trees' health and overtime kill some of the most common tree species in the state.

BWA was found on a residential property in Missaukee County, which is east of Cadillac in the lower peninsula. It was detected by a consulting forester who was working with the landowner, the Michigan Department of Agriculture and Rural Development said.

"We don’t known how balsam woolly adelgid was introduced to this site, but early detection is a fundamental component of successful response efforts," said Mike Philip, Director of MDARD’s Pesticide and Plant Pest Management Division. "MDARD and its partner agencies have begun survey work to determine the extent of the infestation."

The insect was first detected in Michigan when it was found at a site in Kent County, near Rockford. Efforts to contain the infestation have been ongoing since its discovery.

BWA appears as a tiny white wooly tufts that congregate on the trunks of several kinds of trees, as well as sometimes on large branches in the summer. One symptom of an infestation is swelling on twigs that experts call "gout."

If infected, the twigs will turn brownish-red before dying. 

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The insect likes to feed on sap produced by fir trees such as balsam, Fraser, and concolor. MDARD considers the insect a "significant threat" to the state because of its 1.9 billion fir trees, many of which feed the state's Christmas tree industry. 

If Michiganders suspect this invasive pest is damaging fir trees, they should take photos, note the location, and report it to the Midwest Invasive Species Information Network or MDARD at MDAInfo@michigan.gov or call 800-292-3939.