black stem bore

 Xylosandrus germanus (Blandford)

Xylosandrus germanus is a recent arrival to Oregon and has now been trapped in nursery production areas. Despite its name, this scolytid beetle originated from Asia and now has dispersed to many new regions including North America where it can be found in areas in the Northeast (reports from CT, MD, NJ, RI) South and Southeast (AL, OK, GA, MS, TN, TX), , and Pacific Northwest (OR, BC). The Long Island area is the site where X. germanus is thought to have been first introduced into the US in 1932. (Gill et al. 1998).

The borer is of concern as it has a reputation for attacking apparently healthy plants. This ambrosia beetle is also known for its toothpick-like frass tubes (also produced by the Asian ambrosia beetle), present under the right conditions when wind and rain do not disturb them.

The borer is reported to attack over 200 speciesof plants. Hosts include: beech, birch, holly, honeylocust, elm, linden, maple, oak, planetree, sweetgum, tulip tree, and willow. Japanese silver bell trees (Gill); apple, ash, black cherry, black walnut, cedar, dogwood, grape, pear, pecan, pine, plum, poplar, and rhododendron (ODA 2005); boxwood, fig, hazelnut, and hornbeam.

Research in Tennessee showed that ambrosia beetle attacks began about the time of dormancy break (noted by swelling and color change of the buds) which occurs in April. They report that the progeny of X. germanus. began emergence on May 24, peaked from late May to mid-June, and was 95% completedbyJuly 14. X. germanus averaged 55 days from first tree attack to emergence of the progeny. Their work also showed that tree attacks correlated to collections in ethanol-baited Lindgren traps although the ratio of borers species in the trap did not correspond to actual tree attacks. Although lower in number in the trap catches, X. germanus was found more often than other species in the indicator trees, Chinese chestnuts (Oliver and Mannion, 2001).

Beyond the quality loss from the direct damage, there is concern that X. germanus is responsible for carrying Fusarium fungus into trees as they tunnel into the wood.



Gill, S., Blessington, T. and E Dutky. May 28, 1998. Greenhouse Weekly IPM Report From Maryland Central Maryland Research and Education Center Ellicott City, Maryland

Oregon Department of Agriculture. Pest Alert: Black Stem Borer.

Oliver, J.B. and C. Mannion. 2001. Ambrosia Beetles Collected From Ethanol-Baited Traps
and Chinese Chestnut in Middle Tennessee. SNA RESEARCHCONFERENCE- VOL.46 - 2001.

Mandelshtam, M. 12/10/2001. Two new bark beetle (Scolytidae) pests in fauna of Russia.

There are several websites about this borer that might be of interest to nursery producers.

The Imported Japanese Scolytid beetle Xylosandrus germanus - EMPA in Switzerland. This site has good pictures of the galleries with an adult and frass tubes from conifers.

Featured Creatures - Black twig borer, Xylosandrus compactus (Eichhoff). University of Florida and Florida Department of Agriculture and Consumer Services, Division of Plant Industry. This site has a good discussion of Xylosandrus species with limited information about X. germanus.

Asian Ambrosia Beetle - University of Arkansas Cooperative Extension. Although this website is about the Asian ambrosia beetles it has lots of good information about monitoring and control of ambrosia beetles.


Page last modified 5/14/07