The most effective bug repellents are skin-applied products containing DEET, picaridin, or oil of lemon eucalyptus, all of which work by interfering with the insect’s ability to smell you. But repelling bugs goes well beyond sprays. Treated clothing, fans, spatial repellent devices, and certain essential oils all play a role depending on the situation.
How Bug Repellents Actually Work
Mosquitoes, ticks, and biting flies find you primarily through smell. They detect carbon dioxide from your breath and chemical signals from your skin. Effective repellents block the insect’s olfactory receptors, essentially jamming the signal so they can’t lock onto you as a target. DEET, the most widely studied repellent ingredient, inhibits specific odor receptors that insects rely on to detect human skin. It doesn’t kill bugs or create a force field. It makes you invisible to their sense of smell.
Synthetic Repellents: DEET and Picaridin
The EPA registers seven active ingredients for skin-applied insect repellents. Of those, DEET and picaridin are the most popular and best supported by research.
DEET at 10% concentration protects for about two hours. At 30%, protection extends to roughly five hours. There’s no benefit to going above 50%, as higher concentrations haven’t been shown to extend protection further. DEET is available in more than 500 registered products.
Picaridin offers comparable or better protection with less of the oily, chemical feel that some people dislike about DEET. A 5% picaridin product protects for three to four hours, while a 20% product can last up to 12 hours. That makes high-concentration picaridin one of the longest-lasting options available.
Other EPA-registered options include IR3535 (found in about 45 products) and 2-undecanone, though these are less common and have fewer product choices on shelves.
Oil of Lemon Eucalyptus: The Best Plant-Based Option
Oil of lemon eucalyptus contains an active compound called PMD, derived from the Australian lemon-scented gum tree. The CDC endorsed it in 2005 as an effective repellent. In lab testing, a 20% PMD product reduced biting by 90 to 95% for up to eight hours. In real-world field conditions, it provides around six hours of protection, putting it in the same range as DEET at similar concentrations.
This is the only plant-derived repellent ingredient that performs close to synthetic options. It should not be confused with pure lemon eucalyptus essential oil, which is a different product with shorter protection times.
Essential Oils: Short-Lived Protection
Many essential oils do repel mosquitoes and ticks, but their protection fades fast. In a study testing 20 oils formulated as 10% lotions, clove oil and cinnamon oil provided the longest protection, lasting just over one hour against mosquito bites and tick crossings. Peppermint, geranium, lemongrass, and citronella oils provided protection for roughly 30 to 60 minutes. Garlic oil and spearmint oil lasted about 30 minutes.
The rest of the oils tested performed no better than unscented lotion. If you prefer natural products but need reliable, hours-long protection, oil of lemon eucalyptus is a far better choice than any common essential oil. If you do use essential oil products, expect to reapply frequently.
Treated Clothing With Permethrin
Permethrin is an insecticide applied to fabric rather than skin. You can buy pre-treated clothing or spray your own gear. Factory-treated clothing maintains its repellency for up to 70 washes. In a study of outdoor workers wearing permethrin-treated uniforms, tick bites were reduced by 82% over an entire year.
Permethrin works differently from skin repellents. Instead of masking your scent, it kills or disables insects on contact with the treated fabric. Combining permethrin-treated clothing with a skin-applied repellent on exposed areas gives you the most complete protection, which is the standard recommendation for people in tick-heavy environments.
Fans and Wind
A simple fan is one of the most underrated ways to keep mosquitoes away from a patio or outdoor seating area. Mosquitoes are weak fliers, with flight speeds between 0.9 and 3.6 miles per hour. Wind speeds that approach those numbers make it physically difficult for them to navigate toward you. Even a moderate breeze of about 1.3 miles per hour (0.6 meters per second) at your position can significantly reduce landings. A large box fan or oscillating outdoor fan pointed at your seating area creates a zone that mosquitoes struggle to penetrate, with no chemicals involved.
Do Repellent Plants Work in Your Garden?
The idea of planting citronella, lavender, or basil around your patio to keep bugs away is appealing but mostly overstated. Studies on potted repellent plants show modest results at best. Potted basil plants reduced mosquito landings by about 38 to 40% in field and semi-field studies. Lantana plants offered around 27 to 32% protection. These numbers mean bugs are still biting, just somewhat less often.
Fresh plants hung indoors performed better in some cases. Basil hung inside a dwelling in one field study in Eritrea reduced the number of mosquitoes entering the space by 53%. But this involved large quantities of fresh-cut plant material, not a decorative pot on a windowsill. The volatile oils that repel insects evaporate from intact, undamaged leaves at levels too low to create a meaningful barrier in open air. Crushing the leaves or burning dried plant material releases far more of these compounds, which is why people in tropical regions have burned plant matter as fumigants for centuries.
What Doesn’t Work
Ultrasonic Devices
Despite aggressive marketing, ultrasonic pest repellent devices have no scientific support. No published study has demonstrated that ultrasonic sound effectively repels any arthropod pest. Testing has found them ineffective against mosquitoes, ticks, cockroaches, fleas, bed bugs, and ants in both lab and field conditions. Some products claim to emit sound waves between 5 and 20 kHz to repel mosquitoes and even rodents, but these claims are not backed by evidence.
Vitamin B1 and Garlic Supplements
The belief that taking vitamin B1 (thiamine) or eating garlic makes your skin repellent to mosquitoes is persistent but wrong. A scoping review of all available research concluded that thiamine cannot repel insects at any dosage or by any route of administration. Reports of it working are anecdotal and based on uncontrolled trials that used bite symptoms, not actual biting rates, as their measure. Controlled experiments found no reduction in insect landing or feeding.
Safety for Children and Pregnancy
For children under six months old, insect repellents containing DEET should not be used. Between six months and two years, limit DEET use to one application per day. Children aged two to twelve can use DEET up to three times per day, with concentrations of 10% or less. Picaridin and oil of lemon eucalyptus are alternatives, though oil of lemon eucalyptus is not recommended for children under three.
Pregnant and breastfeeding women can use DEET-based repellents. Studies tracking pregnant women who used DEET found no adverse neurological, gastrointestinal, or skin effects in the mothers, and no effects on survival, growth, or development in their babies at birth or at one year of age. The CDC specifically advises pregnant women to use DEET-based repellents to reduce the risk of mosquito-borne infections. No human studies have examined first-trimester exposure specifically, but the overall safety profile is reassuring.
Matching the Repellent to the Situation
For a quick evening on the patio, a fan and a citronella candle may be enough. For a few hours of yard work, a 10 to 20% DEET or picaridin spray handles most situations. For a full day of hiking in tick country, layer permethrin-treated clothing with a 20% picaridin or 30% DEET product on exposed skin. For international travel to areas with malaria or dengue, the combination of treated clothing and a high-concentration skin repellent is the standard approach.
Concentration determines duration, not strength. A 30% DEET product doesn’t repel bugs more effectively than a 10% product in any given moment. It just lasts longer before you need to reapply.