Feedback on new bark and ambrosia beetles in Michigan

Dave<smitley@msu.edu> Smitley, Michigan State University Extension, Department of Entomology -

Two cases of black stem borer and ambrosia beetle were found in Michigan.

I received two quick responses to the article on new bark and ambrosia beetles recently found in Michigan written in May. In the first case, a nursery in southern Michigan reported extensive damage to young apple trees 2 to 2.5 feet in diameter. Beetles collected from the dead and dying trees were sent to MSU where Dr. Anthony Cognato identified them as Xylosandrus germanus, the black stem borer (Photo 1). Frass tubes the diameter of pencil-lead were also found protruding from infested apple trees (Photo 2).

Black stem borer
Photo 1. The black stem borer. Photo credit: Steve Valley, Oregon Department of Agriculture.

Frass cloumn of black stem borer
Photo 2. Frass column of black stem borer protruding from entrance tunnel. Photo credit: G. Keith Douce, University of George, Bugwood.org

In the second report, photos were sent by Guerin Wilkinson, owner of GreenStreet Tree Care (Photo 3). Wilkinson found frass tubes protruding from some large Norway maples in Ann Arbor that were definitely made by an ambrosia beetle. These trees are declining for unknown reasons. At this time, we have not identified which ambrosia beetle it is or if the decline of these trees is due to the ambrosia beetles or other factors.

Frass tubes protruding from Norway maple
Photo 3. Tiny (diameter of a pencil lead) frass tubes protruding from a Norway maple in Ann Arbor. Photo credit: Guerin Wilkinson, GreenStreet Tree Care.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

Did you find this article useful?

You Might Also Be Interested In

Tag List
  • landscaping,
  • msu extension
  • follow us on youtube
  • follow us on linkedin
Michigan State University
  • Spartans Will.
  • © Michigan State University

MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential.

Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.

The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707.

We comply with the Federal Trade Commission 1998 Children’s Online Privacy Protection Act (COPPA).