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The Green Foxtail Fungus

Green Foxtail Weedimage of Foxtail: rollingroscoe via

Scientists at the Department of Agricultural Chemistry at Tottori University in Koyama, Japan may have finally found an effective stink bug repellent derived from a fungus that thrives in the green foxtail plant. Where conventional pesticides have failed, this fungus may succeed thanks to its symbiotic, host-protecting nature.

The fungus, prevalent in Japanese foxtail plants, appears to repel the white-spotted stink bug, a close relative to the brown marmorated version that has invaded the United States in recent years. In tests conducted by Hiromitsu Nakajima and his colleagues comparing an extract from the fungus to naphthalene (the active ingredient in mothballs), the fungus was equally as effective, repelling up to 90% of stink bugs. With modifications, the extract proved even more effective -- nearly double -- in additional tests.

Green Foxtail Weedimage of Foxtail: Anita Rust via

A Fungus Among Us

Thought of as mostly an invasive weed, the green foxtail (or Setaria viridis) can be found throughout moderate climates all over the United States, blooming primarily as a summer annual. Its early grasses grow in clumps, later giving rise to stalks of around 12 inches or more with a fuzzy, erect seedhead. In Japan, the plant is just as prevalent, as are stink bugs, which have taken their toll on rice plants for decades.

Green Foxtail WeedI took this picture in a park near my house! No attribution required, ya'll.

Unfortunately, as of this writing, a commercial solution utilizing Nakajima's extracted fungus is unavailable. Testing for efficacy across the species along with safety and deliverability could take several years, as is typical with many pesticides. Until then, be sure to check out how to Stop Stink Bugs Now using traditional and hardware-store methods.

See the previous article, "Homemade Solutions" »

Sources used in the research for this article:
Image: Art Cushman, USDA; Property of the Smithsonian Institution, Dept. of Entomology,
Image of Foxtail: rollingroscoe via
Image of Foxtail: Anita Rust via

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At a glance

The Green Foxtail Fungus Repellent:

  • Developed in Japan.
  • Uses a fungus from the Green Foxtail weed.
  • The weed can be found in the U.S.
  • An extract is not yet available.