U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Agricultural Research (March 2013).


A little monkey business is revealing a few clues about natural remedies that animals use to protect themselves against biting insects and arthropods.

Certain species of animals, such as monkeys and birds, anoint themselves with citrus, other plants, and creatures like millipedes. To find out more about this behavior and to determine if any chemicals in the anointing substances effectively deter ticks and mosquitoes, scientists are examining responses to natural compounds.

Scientists at the Agricultural Research Service Henry A. Wallace Beltsville [Maryland] Agricultural Research Center (BARC) and the Smithsonian Conservation Biology Institute (SCBI) at the National Zoological Park in Front Royal, Virginia, compared the effects of citrus compounds on lone star ticks and yellow fever mosquitoes. They also investigated compounds found in millipedes.

Citing Citrus Effects

“We tested a number of components known to be abundant in all citrus extracts, not just lemons, limes, and oranges, but all the fruits that are used in anointing— including citrus leaves,” says SCBI researcher Paul Weldon.

Of the more than 20 citrus compounds they evaluated, the scientists found that 10 deterred ticks and/or mosquitoes, and 9 impaired basic tick behavior.

Weldon used a feeding membrane module that he developed to test citrus compounds against mosquitoes. Some compounds were very effective. But the same compounds were not effective at all when mosquitoes were exposed to them in a wind tunnel module by chemist Ulrich “Uli” Bernier, in the Mosquito and Fly Unit at the ARS Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Florida.

“We viewed the results of the wind tunnel as being more authentic,” Weldon says. “The compounds didn’t affect mosquitoes that much, but mainly affected ticks. It was a step forward in pinpointing what we believe is the reason that animals anoint themselves with citrus substances.”