Sweetgrass keeps biting bugs at bay, new research says. The news confirms what Native North Americans have long known. North American first nations people have always decked out their homes and themselves with fragrant sweetgrass (Hierochloe odorata), a native plant used in traditional medicine, to repel biting insects, especially mosquitoes.

Charles Cantrell, Ph.D., who investigates the components of plants used in traditional therapies, said:

“We found that in our search for new insect repellents, folk remedies have provided good leads."

Sweetgrass is a meadow grass that is a native to northern climates, Cantrell explains:

“It gives off a sweet aroma that repels mosquitoes."

Cantrell’s team at the U.S. Department of Agriculture, in collaboration with researchers at the University of Guelph and the University of Mississippi, carried out steam distillation on sweetgrass samples and evaluated its oil for the ability to deter mosquitoes from biting.

Using nuclear magnetic resonance spectroscopy and mass spectrometry, the researchers identified two chemicals in a sweetgrass extration which seemed to be responsible for putting off mosquitoes: phytol and coumarin.

Coumarin is an ingredient in some commercial anti-mosquito products, he adds, while phytol is reported to have repelling activity in the scientific literature.

Isolation and Identification of Potential Biopesticidal Compounds from the North American Insect Repelling Folk Remedy Plant, Sweetgrass, Hierochloe odorata 250th National Meeting & Exposition of the American Chemical Society

Photo: “Sweet Grass” by Kodemizer. Licensed under CC BY-SA 3.0

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