The most reliable way to repel biting insects is to apply a skin-based repellent containing an EPA-registered active ingredient, wear treated clothing, and reduce exposed skin. A product with 20% or higher concentration of DEET or Picaridin will protect most people for several hours against mosquitoes, ticks, and other common biters. Beyond that core strategy, the details matter: what you choose, how you apply it, and what doesn’t actually work despite popular belief.
How Repellents Actually Work
Biting insects find you primarily through smell. Your skin releases carbon dioxide, lactic acid, and other chemicals that mosquitoes and ticks follow like a scent trail. Repellents disrupt this process in two ways. At a distance, they interfere with the insect’s odor receptors, either scrambling the signal from your skin chemicals or triggering an avoidance response, similar to how a foul smell makes you turn away. On contact, repellents activate a separate set of chemical sensors that cause the insect to back off before it bites.
Scientists still debate which of these mechanisms matters more. One leading theory is that DEET essentially jams the insect’s ability to detect you, making you invisible to its nose. The other is that insects perceive repellents as a noxious odor and actively avoid it. In practice, both effects likely contribute, which is why repellents work best when applied evenly across exposed skin rather than dabbed in a few spots.
Choosing the Right Active Ingredient
The EPA registers seven active ingredients for skin-applied insect repellents. The four most widely available and well-studied are DEET, Picaridin, IR3535, and Oil of Lemon Eucalyptus (OLE). Each has trade-offs in protection time, feel on the skin, and availability.
DEET is the oldest and most tested option, with over 500 registered products. Concentrations range from 5% to nearly 100%. Higher concentrations don’t repel better, but they last longer. A 20–30% product covers most outdoor situations for several hours. Products above 50% offer extended protection that can be useful in high-exposure settings like tropical travel or all-day hikes.
Picaridin performs comparably to DEET at the same concentration, with some evidence it lasts slightly longer per application. It’s odorless, doesn’t feel greasy, and won’t damage plastics or synthetic fabrics the way DEET can. Products typically max out around 20–30%, which provides solid multi-hour protection. If you’ve avoided repellent in the past because you disliked the feel or smell of DEET, Picaridin is worth trying.
IR3535 is common in Europe and available in about 45 products in the U.S. It’s effective but generally found in lower concentrations, so reapplication may be needed sooner. Oil of Lemon Eucalyptus is a plant-derived option that performs reasonably well, though it typically needs more frequent reapplication than DEET or Picaridin at comparable concentrations. It should not be used on children under 3 due to the risk of allergic skin reactions.
Less common registered ingredients include catnip oil, oil of citronella, and 2-undecanone. These have far fewer products on the market and generally shorter protection windows.
Why Essential Oils Fall Short
Citronella candles, peppermint oil bracelets, and other plant-based options are popular, but they provide dramatically less protection than registered repellents. In controlled testing, a 10% citronella oil solution offered no measurable protection from mosquito bites. Even at 50% concentration, citronella protected for only about 50 minutes, and a pure citronella solution lasted around two hours.
Other essential oils fare worse. Thyme, cedarwood, soybean, and rosemary oils at 10% concentration in lotion provided less than 20 minutes of protection. Peppermint, geranium, and lemongrass did slightly better, reaching about 30 minutes. Compare that to a standard DEET or Picaridin product that lasts four to eight hours, and the gap is clear. If you’re sitting on a patio for a few minutes, an essential oil might be fine. For a hike, yard work, or travel to an area with disease-carrying insects, it’s not enough.
Treating Clothing With Permethrin
Repellent on your skin handles exposed areas. Permethrin handles everything else. This insecticide is applied to clothing and gear, not skin, and it kills or repels ticks, mosquitoes, and other insects on contact. The CDC recommends using 0.5% permethrin solutions to treat items like pants, socks, boots, and tent fabric.
You can either buy pre-treated clothing or spray your own gear. Sprayed items need to dry completely before wearing. Treated clothing remains effective through multiple washes, often lasting six weeks or more depending on the product. For anyone spending time in tick-heavy areas, permethrin-treated pants and socks are one of the most effective layers of protection available.
Application Tips That Affect How Well It Works
Even the best repellent underperforms if applied poorly. Spray or rub it on all exposed skin, not just your arms. Ankles, the back of your neck, and your ears are common bite zones people miss. Don’t apply repellent under clothing, as it’s unnecessary and wastes product. For your face, spray it on your hands first, then spread it, avoiding your eyes and mouth.
If you’re also wearing sunscreen, apply the sunscreen first and let it absorb before adding repellent on top. Avoid combination sunscreen-repellent products. Sunscreen needs reapplication every two hours, while repellent lasts longer, so a combo product forces you to over-apply repellent or under-apply sunscreen. Using separate products lets you reapply each on its own schedule.
Sweating, swimming, and toweling off remove repellent faster. If you’ve been active and notice bites starting, it’s time to reapply. There’s no need to reapply on a fixed schedule if you’re sitting still indoors with air conditioning.
What Doesn’t Work
Ultrasonic repellent devices, whether plug-in units, wristbands, or pet collars, have been tested repeatedly and consistently fail. In the most thorough study to date, nine commercial ultrasonic devices produced less than 20% repellency against ticks, meaning more than 80% of ticks were completely unaffected. Separate testing found the same devices ineffective against mosquitoes, fleas, cockroaches, and bed bugs. No published study has demonstrated that ultrasonic sound effectively repels any biting arthropod. These products are not a substitute for chemical repellents.
Citronella candles and torches create a mild deterrent effect in the immediate area but don’t prevent bites reliably, especially in any breeze. Garlic supplements, vitamin B patches, and various smartphone apps have no scientific support. Bug zappers kill large numbers of insects, but mostly beneficial ones rather than mosquitoes.
Reducing Bites Beyond Repellent
Repellent is the most important tool, but simple behavioral changes add meaningful protection. Mosquitoes are most active at dawn and dusk, so timing outdoor activities around those windows helps. Wearing long sleeves and pants in light colors makes it harder for insects to land and bite. Dark clothing attracts mosquitoes more than light colors.
Around your home, eliminating standing water removes mosquito breeding sites. A single bottle cap of water can produce mosquitoes, so empty plant saucers, clogged gutters, old tires, and pet bowls weekly. For outdoor gatherings, a portable fan aimed at seating areas disrupts mosquitoes’ weak flight ability more effectively than most candles or coils.
For children under 2 months old, no repellent is recommended. Instead, use mosquito netting over strollers and carriers. For older infants and children, DEET and Picaridin are considered safe at any concentration, though most pediatric guidance suggests sticking with 10–30% products. Adults should apply repellent to their own hands and then transfer it to a child’s skin, keeping it away from the child’s hands to prevent contact with eyes and mouth.