The most effective way to repel insects is to apply a skin-based repellent containing one of a handful of proven active ingredients, treat your clothing with permethrin, and minimize exposed skin. That combination covers the vast majority of situations, from backyard evenings to deep-woods hiking. The details matter, though, because protection times vary enormously depending on what you use and how you use it.
How Insect Repellents Actually Work
Biting insects find you primarily by smell. Your skin releases carbon dioxide, lactic acid, and other compounds that mosquitoes, ticks, and flies track through specialized smell receptors. Repellents like DEET work by blocking those receptors, essentially masking the odors that make you detectable. The insect lands on or near your skin but can’t recognize it as a blood meal, so it moves on. This is why repellents don’t kill insects. They make you invisible to them.
Proven Active Ingredients
The EPA registers seven active ingredients for skin-applied insect repellents. The four you’re most likely to encounter on store shelves are DEET, picaridin, oil of lemon eucalyptus (OLE), and IR3535. Each has a different protection window, and choosing between them mostly comes down to how long you need coverage and who’s using it.
DEET
DEET has been the gold standard since the 1950s and appears in more than 500 registered products. At concentrations of 25 to 40 percent, it provides 2 to 8 hours of protection depending on the formulation and conditions. Higher concentrations extend duration rather than strength, so 30 percent DEET doesn’t repel “more” insects than 10 percent, it just lasts longer. Products above 50 percent offer the longest protection times available in any repellent.
Picaridin
Picaridin performs comparably to DEET at the same concentration, with some evidence suggesting it persists slightly longer on skin. At 10 to 20 percent concentrations, it provides roughly 3 to 10 hours of protection. The maximum concentration in current picaridin formulations tops out below 30 percent, so if you need the absolute longest-lasting option and a 50 percent DEET product is available, DEET has the edge. For most everyday situations, though, picaridin and DEET are interchangeable. Picaridin has a lighter feel, doesn’t damage plastics or synthetic fabrics the way DEET can, and has almost no odor.
Oil of Lemon Eucalyptus
OLE is the strongest plant-derived option, providing 2 to 5 hours of protection at 30 percent concentration. It contains a compound called PMD that genuinely repels mosquitoes and some ticks. One important distinction: “oil of lemon eucalyptus” is not the same thing as “lemon eucalyptus essential oil.” The essential oil has very low PMD levels and does not offer meaningful protection. Look for the specific term “oil of lemon eucalyptus” or “PMD” on the label.
What About Essential Oils?
Citronella, peppermint, and other essential oils do have some repellent effect, but the protection is short-lived. Most essential oil sprays last between 30 minutes and 2 hours under ideal conditions. In one direct comparison, citronella provided complete protection for about 10 minutes against mosquitoes, while DEET lasted 360 minutes. If you’re sitting on a porch for 20 minutes, a citronella candle or spray might take the edge off. For anything longer or in an area with disease-carrying insects, they’re not a substitute for EPA-registered repellents.
Treating Clothing With Permethrin
Permethrin is not a skin repellent. It’s a treatment you apply to clothing, shoes, gear, and tent fabric. When an insect contacts permethrin-treated fabric, it becomes disoriented and falls off or dies. This is especially valuable against ticks, which crawl up from ground level and spend time on your pants and socks before reaching skin.
You can buy aerosol permethrin sprays and treat clothing yourself, but this method requires reapplication after every wash or two, and studies show most people don’t keep up with it. Factory-treated clothing is more reliable. Commercially impregnated garments maintain their repellency for up to 70 washes, which can mean an entire season or more of regular use. Several outdoor brands sell pre-treated shirts, pants, and socks, or you can send your own clothing to a treatment service.
The most effective approach combines permethrin-treated clothing with a skin repellent on exposed areas. This gives you two layers of defense: one for the fabric insects land on first, and another for any skin they reach.
How to Apply Repellent Correctly
A good repellent applied poorly won’t protect you. Spray or rub the product evenly on all exposed skin. Insects will bite any patch you miss, so pay attention to ankles, the backs of hands, and the neck. Don’t apply repellent under clothing, as it’s unnecessary and increases skin absorption without adding protection.
If you’re also wearing sunscreen, apply the sunscreen first and let it absorb, then apply insect repellent on top. Using them in the wrong order reduces the effectiveness of both. Combination sunscreen-repellent products aren’t ideal because sunscreen needs reapplication every two hours while repellent typically lasts longer, leading you to over-apply the repellent or under-apply the sunscreen.
For your face, spray repellent onto your hands first, then rub it on. Avoid the eyes, mouth, and any cuts or irritated skin. When you come indoors, wash treated skin with soap and water.
Repelling Insects in Your Yard
Spatial repellent devices, like clip-on fans and portable diffusers, release vaporized chemicals (often metofluthrin or allethrin) into the air around you. These can reduce biting in a small radius and work best in calm air. In one lab study, metofluthrin deterred 72 to 81 percent of ticks from climbing toward a host. Wind reduces their effectiveness significantly, so they’re better suited for a patio than an open field.
Reducing mosquito breeding sites around your home makes a real difference. Mosquitoes lay eggs in standing water, and they don’t need much. Empty saucers under flower pots, clean gutters, flip over unused containers, and change birdbath water at least once a week. Eliminating even small pockets of stagnant water cuts down the local mosquito population within a couple of weeks.
Fans also help. Mosquitoes are weak fliers, and a box fan or oscillating fan on a porch creates enough airflow to keep them from landing. This costs nothing and works immediately.
What Doesn’t Work
Ultrasonic repellent devices, the plug-in or wearable gadgets that claim to emit high-frequency sounds insects avoid, have no scientific support. Controlled studies have found no effective repellency against mosquitoes, ticks, fleas, cockroaches, or bed bugs. One study testing nine commercial ultrasonic devices against ticks found that while some showed minimal deterrence in a confined lab arena, the effect was far too small to offer any real protection. These devices cannot be recommended for bite prevention.
Vitamin B1 supplements, garlic consumption, and wristbands infused with repellent also lack evidence. Wristbands may create a small zone of reduced biting right around the wrist, but they leave the rest of your body unprotected.
Protecting Children
DEET and picaridin are both recommended for children two months and older. For children, DEET products should contain no more than 30 percent concentration. Apply the repellent to your own hands first, then rub it onto the child, avoiding their hands (since children touch their mouths frequently). Oil of lemon eucalyptus should not be used on children under three years old.
For infants under two months, skip chemical repellents entirely. Use mosquito netting over carriers and strollers, and dress the baby in lightweight long sleeves and pants. Permethrin-treated clothing is another option since it doesn’t contact skin directly.
Choosing the Right Strategy
- Backyard dinner or short outdoor event: A 15 to 25 percent DEET or picaridin spray covers 3 to 5 hours comfortably. A fan pointed at the seating area helps too.
- Hiking or camping in tick country: Permethrin-treated pants, socks, and shoes combined with a skin repellent on exposed areas. Tuck pants into socks. Do a full-body tick check afterward.
- Travel to areas with mosquito-borne disease: Use 25 to 50 percent DEET or 20 percent picaridin for maximum duration. Reapply as directed. Sleep under a treated bed net if screens aren’t available.
- Prefer plant-based options: Oil of lemon eucalyptus at 30 percent is your best bet, offering 2 to 5 hours of protection. Reapply more frequently than you would with DEET or picaridin.