Lemongrass repels mosquitoes, house flies, stable flies, and ticks. Its essential oil contains compounds that interfere with how these insects detect human hosts, making it a popular natural alternative to synthetic repellents. The oil is also used in gardens to deter whiteflies and other small pests. However, lemongrass works very differently depending on whether you’re using the extracted oil or simply growing the plant nearby.
Insects and Pests Lemongrass Repels
The strongest evidence for lemongrass as a repellent involves mosquitoes. Multiple species of disease-transmitting mosquitoes respond to lemongrass oil, and it’s already used as an active ingredient in commercially available repellent products. Beyond mosquitoes, lab studies have confirmed repellent effects against common house flies and stable flies, the biting flies often found around livestock and rural properties.
Lemongrass oil also shows promise against ticks. Research on blacklegged ticks (the species responsible for transmitting Lyme disease) found that lemongrass essential oil significantly disrupted the ticks’ ability to detect butyric acid, a chemical compound found in human sweat that ticks use to locate hosts. Two key compounds in the oil, citral and geraniol, both independently produced this effect. In a garden setting, lemongrass is sometimes planted as a companion crop to help deter whiteflies from nearby vegetables and herbs.
How It Works
Lemongrass oil doesn’t kill insects. Instead, it overwhelms or blocks their ability to sense the chemical cues they use to find you. Mosquitoes and ticks rely heavily on detecting carbon dioxide, body heat, and specific compounds in sweat. The volatile oils released by lemongrass, primarily citral and geraniol, appear to jam those signals. In tick studies, exposure to these compounds stopped both lab-reared and wild ticks from responding to the attractant chemicals they’d normally follow straight to a host.
This mechanism is similar in principle to how DEET works, though the two differ significantly in staying power and strength.
How Long Protection Lasts
This is where lemongrass falls short of synthetic options. Lemongrass oil evaporates relatively quickly because the active compounds are volatile, meaning they disperse into the air and fade. A cream formulation containing lemongrass oil provided roughly 3 hours of mosquito protection at a lower dose and up to 5 hours at a higher dose. Concentrations above 3% generally offer about 3 to 4 hours of bite protection.
Compare that to DEET: a product with about 24% DEET provides roughly 5 hours of complete protection against mosquitoes. But the gap widens when you consider that many botanical repellents tested in a New England Journal of Medicine study provided less than 20 minutes of protection. Lemongrass performs better than most botanicals, but it still can’t match DEET for duration or reliability in high-risk environments where mosquito-borne diseases like malaria or dengue are a concern.
Reapplication is key. The repellent vapor fades as air currents carry it away, so if you’re relying on lemongrass oil outdoors, plan on reapplying every 2 to 3 hours for consistent protection.
Growing the Plant vs. Using the Oil
A potted lemongrass plant on your patio won’t create a mosquito-free zone. The repellent compounds are locked inside the leaves and stems. Unless you crush, bruise, or break the foliage, the plant releases very little of its essential oil into the surrounding air. The research supporting lemongrass as a repellent is based on extracted oil applied to skin or surfaces, not on intact plants growing in pots.
That said, growing lemongrass in a garden can serve a dual purpose. You’ll have a fresh supply of leaves to crush and rub on skin when you’re working outdoors, and the plant may offer some mild companion-planting benefits by deterring whiteflies from nearby crops. Just don’t expect the plant itself to act as a perimeter defense against mosquitoes.
Regulatory Status in the U.S.
Lemongrass oil is not an EPA-registered insect repellent active ingredient. Products containing it typically fall under the EPA’s “minimum risk pesticide” exemption, meaning they can be sold without the same testing and registration process required for DEET, picaridin, or oil of lemon eucalyptus. This doesn’t mean lemongrass is unsafe, but it does mean the EPA hasn’t independently verified efficacy claims on the label the way it has for registered repellents.
Safety Around Pets
Lemongrass is toxic to dogs, cats, and horses. The ASPCA lists it as a concern due to its essential oils and cyanogenic glycosides. Dogs and cats that ingest lemongrass typically develop stomach upset, including vomiting and diarrhea. In horses, the risk is more serious, with potential symptoms including difficulty breathing and weakness. If you’re using lemongrass oil as a repellent around the house or yard, keep concentrated products away from areas where pets eat, groom, or rest. Diffusing lemongrass oil in enclosed spaces with cats is a particular concern, since cats lack the liver enzymes needed to efficiently process many essential oils.