Found in grapefruit skin, it might be the first bug spray ingredient that actually smells good.

By Claire Gillespie
August 14, 2020
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If bugs are the bane of your life during summer, here's some good news: The Environmental Protection Agency (EPA) has approved a new ingredient, called nootkatone, for use in insecticides and insect repellents.

Nootkatone, which was discovered and developed by the Centers for Disease Control and Prevention (CDC), repels and kills ticks, mosquitos, and other biting bugs, and it can keep those pests away for several hours. Nootkatone is found in very small quantities in grapefruit skin and Alaska yellow cedar trees.

“According to the CDC, nootkatone kills pests in a unique and different way, which is very important for mosquito control operations,” David Brown, who has worked in mosquito control for more than 30 years and is technical advisor to the American Mosquito Control Association, tells Health. 

Mosquito control agencies essentially use two classes of pesticides, pyrethroids and organophosphates, to keep adult mosquito populations down. “These products disrupt the nervous system of the target insect, resulting in mortality,” Brown explains. “Nootkatone uses a different mode of action unrelated to pyrethroids and organophosphates, which will help reduce insect resistance to the products containing these active ingredients.” 

It’s not clear exactly how nootkatone repels insects, but experts believe that the biting bugs simply don’t like the smell or taste of the chemical. Nootkatone is responsible for the distinctive smell and taste of grapefruit, and it’s widely used in the fragrance industry to make perfumes and colognes.

“In some insects tested, areas treated with nootkatone were avoided prior to contact,” Karla M. Addesso, PhD, associate professor in the department of agricultural and environmental sciences at Tennessee State University, tells Health. “This suggests that they can smell the nootkatone, and that they don't like the smell. Other insects may need to contact the compound in order to detect it, and they may be repelled by the taste.”  

Nootkatone is also approved as a food additive and is classified as “generally considered safe” by the Food and Drug Administration (FDA). The EPA confirmed to The New York Times that it is considered nontoxic to humans and other mammals, birds, fish, and bees. 

While nootkatone is approved as an active ingredient in insect repellent, it’s unlikely nootkatone bug spray will be available before 2022, because any manufactured products containing the ingredient will also need to be tested and registered by the EPA separately.

Luckily, there are natural compounds that may work the same way nootkatone does when it comes to repelling bugs. Addesso suggests nootka oil and grapefruit oil, which are both available commercially. “The nootka oil has a cedar type smell, and the grapefruit oil is more citrusy due to the other compounds found in the oil,” she says. 

However, it’s not advisable to place any pure essential oil directly on skin, as it may cause irritation. “You can place drops of oil on clothing directly if you are not worried about staining them, such as a hat or gloves you use for gardening,” Addesso says. “You can also dilute the oils in a carrier like coconut oil to make lotions as you would any other essential oil. If you make candles with the oils, you can use them outdoors in place of citronella candles.”   

Another effective oil for repelling insects is oil of lemon eucalyptus, Brown says. For others, he recommends referring to the EPA’s list of ingredients registered as skin-applied insect repellents, which includes catnip oil and oil of citronella. 

“EPA-registered products have undergone studies to ensure they are safe for use, and they are effective when the label directions are followed,” Brown says. 

The fight against insect-borne diseases remains a priority for health officials. Per a 2018 CDC report, diseases caused by the bites of ticks, mosquitoes, and fleas have tripled in the US in the last 15 years. The threats include Lyme disease, anaplasmosis, and Rocky Mountain spotted fever from ticks; West Nile, dengue, Zika, and chikungunya from mosquitoes; and plague from fleas

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