2012 Highlights: UC IPM Annual Report

Pheromone-baited funnel trap used for detecting walnut twig beetles.Pheromone-baited funnel trap used for detecting walnut twig beetles. Photo by S. Seybold.

UC IPM publishes national detection guidelines for walnut twig beetle


  • Trapping guidelines were developed to track beetle spread.
  • Fifteen eastern states are using the guidelines to detect the beetle’s presence.

The tiny walnut twig beetle carries Geosmithia morbida, the fungus causing thousand canker disease, which has killed many black walnut trees in wild areas and landscapes in California and other western states. Commercial English walnut orchards are beginning to see losses as well.

In 2010, the disease and beetle were discovered for the first time in the eastern United States, where it threatens black walnut forests harvested for wood, an industry valued at $500 billion.

UC IPM Entomologist Mary Louise Flint is part of a team—which includes USDA Forest Service Entomologist Steve Seybold, UC Davis post-doctoral scholar Paul Dallara, and graduate student Stacy Hishinuma—in developing better ways to detect the beetle as it invades new areas. The research has resulted in the discovery of an aggregation pheromone that greatly improves trap catches.

In spring 2012, UC IPM published the team’s trapping guidelines with instructions for building traps and placing and checking them in the field plus photographs to distinguish the walnut twig beetle from similar beetles caught in traps. Online videos illustrate the entire process.

Fifteen eastern states are using the guidelines to track the beetle’s spread; so far the beetle has been confirmed in Tennessee, Virginia, and Pennsylvania. The protocols are also being used in California for research to learn more about the biology of this insect pest and potential management strategies.

Find the guidelines, videos, and much more.

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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