Essential Oils for Bugs: What the Research Shows

Search for the best essential oil for bugs and you will find tidy rankings and confident recipes. The research behind them is more interesting, and more modest, than the lists suggest. A few careful laboratory studies tell us which oils are worth watching, and they also explain why a bottle of oil is not the same thing as a repellent.

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The study everyone should know about

The most useful recent comparison is a 2023 study in Scientific Reports that tested 20 active ingredients from EPA's minimum risk pesticides list. Researchers made each into a 10% lotion emulsion and measured how long it gave complete protection, using yellow fever mosquitoes in an arm-in-cage assay and blacklegged ticks in an EPA-recommended procedure. Clove oil and cinnamon oil gave the longest protection against both mosquito bites and tick crossings, and the authors concluded that specific ingredients in a 10% emulsion can protect for longer than one hour.

Those are encouraging results and also very specific ones. They describe a controlled lotion at a stated strength, tested in a laboratory, and not an oil dabbed from a bottle in a garden. Our take is that the study is a good map of which oils deserve more research, and a poor recipe card.

Why a lab result does not travel

A 2024 review in Emerging Infectious Diseases makes the same point about ticks. Products exempt from EPA registration, often built on botanical oils, are multiplying, and their effectiveness can differ a great deal from one product to the next. Evaluations tend to focus on individual ingredients rather than the finished, multi-ingredient products people actually buy. In other words, knowing that an ingredient did well in a test says little about the bottle on a shelf.

EPA frames it from the regulatory side. Citronella oil is among the ingredients used in repellents sold without registration, because EPA determined in the 1990s that they pose minimal risk to human health. EPA adds that products made from them have not been evaluated for effectiveness. A registration number, by contrast, signals that the product was evaluated for human safety and effectiveness when used as directed. Older work shows the gap well: the 2002 New England Journal of Medicine comparison found that DEET products gave the longest complete protection, a soybean-oil-based repellent averaged 94.6 minutes, and the other botanical repellents tested averaged under 20 minutes.

Where lemon eucalyptus fits

Lemon eucalyptus has a genuine repellent story, and it belongs to a refined material. PMD is a spent product of the distillation of the leaves of the lemon-scented gum, and registered products built on oil of lemon eucalyptus (OLE) or PMD are on CDC's list of recommended active ingredients. A wind-tunnel study found the DEET and PMD sprays had the highest efficacy among eleven repellents it examined. CDC also says it does not recommend using "pure" oil of lemon eucalyptus, an essential oil that is not formulated, as a repellent. We sell that essential oil for fragrance in diffusers, soap and candles, and we say so plainly so that nobody buys it expecting protection. Our comparison of OLE and the essential oil and our DIY spray explainer go into why we do not offer recipes.

Natural is not the same as gentle

A review of plant-based repellents in Malaria Journal notes that these products are often perceived as safer than long-established synthetic ones, sometimes mistakenly, and that too few studies follow standard testing guidelines. Poison Control adds that dilution in a carrier is needed before skin use, that damaged skin should be avoided, that children's thin skin and immature livers may make them more susceptible to toxic effects, and that oils should be kept locked up away from children and pets. Concentrated botanical oils are wonderful materials, and they deserve the respect you would give any concentrated ingredient. See our piece on natural versus synthetic repellents for more.

What we would do with this

For fewer bites, choose a product with an EPA registration number, and use EPA's Find the Repellent that is Right for You to compare.
For a child under 3, CDC says not to use OLE or PMD products, so ask a pediatrician.
For scent, choose the oil that you love to smell. Our guide to lemon eucalyptus and citronella covers two familiar outdoor aromas.

How to read a recipe online

When you meet a confident bug-spray recipe, a few questions sort the careful ones from the hopeful ones:

Does it point to a study, and does the study describe the same oil, strength and test?
Does it state a concentration, or just say "a few drops"?
Is there an EPA registration number anywhere on the product?
Does it promise protection for a set number of hours with nothing behind the number?

If the answers are mostly no, treat the recipe as a craft idea and not a plan for keeping bites away.

The science on essential oils and insects is moving, and the clove and cinnamon results show why researchers keep looking. In the meantime the sensible split is simple: registered products for the bites, and good oils for the pleasure of the scent.

There is real joy in essential oils: the first lift of a citrus oil when the cap comes off, a small project that smells like a good afternoon. Enjoying that does not need a promise about bugs, and we think the oils are better loved for what they are.