Indoor Mosquito Repellent: What Works in Your Home

The best indoor mosquito repellent is a simple three-layer setup: keep mosquitoes out with screened windows and doors, keep air moving with a fan over the bed or sofa, and put a skin repellent with an active ingredient the CDC lists on exposed skin. Skip citronella candles, ultrasonic plug-ins and potted "mosquito plants."

That setup is what lets you leave the window open on a warm night, carry dinner from the patio to the living room without a whine at your ear, and sleep straight through. Below: each layer, what the research shows (with the source named), and a 10-minute evening room setup you can run tonight.

What actually repels mosquitoes indoors: the three layers

Layer 1: Keep them out. Screens on windows and doors, and air conditioning if you have it. Both come straight from the CDC's mosquito prevention guidance.

Layer 2: Keep the air moving. A fan over where you sit or sleep makes you much harder to find (more on the research below).

Layer 3: One skin repellent. The CDC lists these active ingredients for EPA-registered insect repellents:

• DEET
• Picaridin (called icaridin outside the US)
• IR3535
• Oil of lemon eucalyptus (OLE), plant-derived
• Para-menthane-diol (PMD)
• 2-undecanone, plant-derived

Scents and gadgets are supporting acts at best. When a 2017 Journal of Insect Science study compared wearable and spray-on products, all the spray-on repellents tested reduced mosquito attraction, while none of the bracelets did.

Keep them out first: screens, doors and air conditioning

The CDC's advice here is plain: "Use screens on windows and doors. Repair holes in screens to keep mosquitoes outdoors." It also says, "Use air conditioning, if available."

A quick walk around the house:

• Look for holes or tears in window and door screens, and patch them.
• Check that screens sit snugly in their frames, with no gaps at the edges.
• Notice the doors that get propped open at dusk, often the one to the patio.
• On sticky nights, run the air conditioning if you have it.

Once the screens are sound, you get the best part back: windows open and fresh evening air.

A fan over the bed or sofa

A fan is one of the easiest indoor wins. In a field study published in the Journal of Medical Entomology in 2003, Hoffmann and Miller found that fan-generated wind strongly reduced the number of mosquitoes caught in traps baited with carbon dioxide, across wind speeds from 0 to 3.7 meters per second. The authors concluded that wind works mainly by diluting the attractant, the plume of scent and CO2 that leads a mosquito to you, rather than by physically out-flying the insects. They recommended fans as a practical way to protect people in the backyard (study abstract).

In plain terms, moving air scatters the signal that says "dinner is here." Point a fan across the bed or sofa.

What to put in your bedroom for a bite-free night

The best mosquito repellent for a room or bedroom is not one product. It is a quick routine for the bedroom and the living room.

The 10-minute evening room setup

1. Screens shut and sound (2 minutes). Close any unscreened window.
2. Doors closed at dusk (1 minute). The patio door is the usual way in.
3. Fan on (1 minute). Aim it across the bed or sofa, where you will actually be.
4. Water check (4 minutes). Empty any standing water in the room: a vase, a plant saucer, a forgotten glass.
5. Skin repellent on exposed skin (2 minutes). Apply a repellent with a CDC-listed active to arms, legs, ankles and neck, exactly as the label directs.

Then open a book, put on a film, or fall asleep with the window cracked.

If you have little ones

Follow the CDC's guidance word for word:

• "Do not use products containing OLE or PMD on children under 3 years old."
• "Do not apply repellent to a child's hands, eyes, mouth, cuts, or irritated skin."
• "Cover strollers and baby carriers with mosquito netting."
• "Always follow label instructions."

Screens and a fan put nothing on anyone's skin, so they are an easy start for the whole household.

How to get rid of mosquitoes already in the house

If mosquitoes keep showing up indoors, they are getting in, growing in, or both.

Where they get in: open doors at dusk, torn screens, and unscreened windows.

Where they grow: standing water. The CDC says to "check for water-holding containers both indoors and outdoors," and to, "once a week, empty and scrub, turn over, cover, or throw out items that hold water," naming flowerpot saucers, buckets, toys and birdbaths among them. Indoors, look at:

• Saucers under houseplants
• Vases with water that has sat for days
• Pet water bowls (refresh and scrub them)
• Buckets or watering cans left in a laundry room or on a balcony

For the one already buzzing tonight, switch on the fan. The weekly water check stops next week's arrivals.

Plug-ins, traps and clip-ons: when they make sense

Plug-in vaporizers. These release an active ingredient into the room. Check the active on the label; common ones include transfluthrin, metofluthrin and allethrin, all synthetic pyrethroids. If you use one, use it exactly as the label directs. If you would rather not have a device running all night, a skin repellent plus a fan is a no-plug option.

Clip-on fan devices. Products such as OFF! Clip-On (metofluthrin) are made for outdoor seating. Follow the label, which for OFF! Clip-On has said "For outdoor use only" and "Do not use indoors or in enclosed spaces." A 2016 outdoor field study by Florida's Anastasia Mosquito Control District found its effect reached about 0.3 meters (1 foot) from the device. So it belongs on the patio chair, not the nightstand.

Traps. We did not find indoor research on traps we would stand behind, so they stay off our graded table.

What smell do mosquitoes hate?

One study is worth knowing here. Müller and colleagues, writing in the Journal of Vector Ecology in 2009, tested candles and diffusers indoors. Their repellency results:

• Citronella candles: 14%
• Geraniol candles: 50%
• Citronella diffusers: 68%
• Linalool diffusers: 93%
• Geraniol diffusers: 97%

In that study, diffusers did far better than candles. It is one study, so treat scent as a pleasant extra layer, not a replacement for a repellent on your skin.

If scent matters to you, see our guide to repellent that smells good.

What does not work indoors

Ultrasonic and electronic repellents. A Cochrane review (Enayati, Hemingway and Garner, 2007) looked at 10 field studies and found no evidence of any repelling effect. Cochrane marks the review "no update intended" (summary).

Citronella candles. In the 2009 Journal of Vector Ecology study, citronella candles gave 14% repellency indoors. Lovely for atmosphere, not a plan.

Potted "mosquito plants." Extension entomologists say a plant sitting on a patio or sill has no measurable effect. Iowa State Extension, UF/IFAS Extension and NC State Extension all land in the same place, and most research tests extracted oils, not living plants. Keep the lavender for how it looks and smells. More in our guide to mosquito repellent plants.

Wristbands and bracelets. In the 2017 Journal of Insect Science study from the Hansen lab at New Mexico State University, none of the repellent bracelets reduced mosquito attraction. The full breakdown is in do mosquito bracelets work.

Indoor mosquito control, compared

We graded each option on the strength of its source, not on opinion.

Where a plant-based skin repellent fits

Superbloc co-founder and formulator Cassidy Huang and I spent two years working with a Taiwan-based chemist to develop a plant-based PMD spray we would happily use on the patio and then carry inside.

Bloc Off spray uses 8% plant-based PMD (para-menthane-3,8-diol) derived from lemon eucalyptus, with 6+ hours of lab-tested protection against mosquitoes, ticks and other biting insects. It is DEET-free, alcohol-free and water-based, with aloe vera and chamomile, in a 4 oz (118 ml) bottle for $15. Shiso (perilla), a traditional East Asian botanical, rounds out the formula with a clean herbal scent; the protection itself comes from the PMD.

Indoors, it covers the moments the other layers miss: moving from the yard to the sofa, or a screen you have not patched yet. Apply it to exposed skin as the label directs.

Bloc Off Wipes come as 10 individually wrapped wipes, with top notes of lemon and eucalyptus finishing with pine and cedarwood, for $13. For a whole household, the Family Mosquito Protection Pack bundles 2 sprays and 2 wipe packs for $51.

Superbloc has been featured in goop and Harper's Bazaar. For the bigger picture on plant-based options, see our natural mosquito repellent guide.

FAQ

What repels mosquitoes indoors?

Screens on windows and doors, a fan moving air over where you sit or sleep, and a skin repellent with an active ingredient the CDC lists, such as PMD, picaridin or DEET. Candles and gadgets add very little.

What smell do mosquitoes hate the most in your house?

In one 2009 indoor study in the Journal of Vector Ecology, geraniol diffusers gave 97% repellency and linalool diffusers 93%, far ahead of citronella candles at 14%. Treat scent as a supporting layer; a repellent on your skin does the main work.

How do I get rid of mosquitoes in my house fast?

Switch on a fan and empty any standing water (vases, plant saucers, pet bowls). Then patch torn screens and keep the patio door shut at dusk.

Can I use bug spray indoors?

A skin repellent, yes: apply it to exposed skin indoors exactly as its label directs. Area foggers and outdoor-only products are a different category. If the label says outdoor use only, keep it outside.

Do mosquitoes breed inside the house?

They can, wherever water sits. The CDC says to check for water-holding containers indoors and outdoors, and to empty, scrub, turn over or cover them once a week.

Written by Tanya Lee, Co-Founder of The Superbloc, with formulator Cassidy Huang. Sources: CDC, Preventing Mosquito Bites (cdc.gov/mosquitoes/prevention); Hoffmann and Miller, Journal of Medical Entomology 40(5), 2003; Müller et al., Journal of Vector Ecology 34(1), 2009; Enayati, Hemingway and Garner, Cochrane review CD005434, 2007; Rodriguez et al., Journal of Insect Science 17(1), 2017; EPA-filed OFF! Clip-On label and Bibbs and Xue (Anastasia Mosquito Control District) field study via Entomology Today, 2016; Iowa State, UF/IFAS and NC State Extension.