Do Citronella Candles Work Against Mosquitoes?
Citronella candles work a little, close up, and not much more than any smoky candle. In a field trial in Ontario, people beside citronella candles got 42 per cent fewer bites than people with no candle, but a plain unscented candle cut bites by about a quarter on its own. Outdoors the effect fades within a couple of metres, and a 2017 wind tunnel test found a citronella candle had no measurable effect at all. For dependable protection, use an EPA-registered repellent on skin.
Citronella candles are one of the most popular mosquito products in America: in a 2018 online survey of 5,209 people, 43 per cent said they used them, nearly as many as used DEET spray (48 per cent). The research on them is unusually consistent, and it is worth knowing exactly what it says before you light one for a party.
What the trials found
Every controlled test of citronella candles has found either a modest effect or none, and every one that tested stronger alternatives found them better.
| Study | Setting | Citronella result | Comparison |
|---|---|---|---|
| Lindsay et al., University of Guelph, 1996 | Woodland, Ontario; people counting bites | 3 per cent candle: 42.3 per cent fewer bites | Plain candle reduced bites by about 24 per cent; citronella incense 24.2 per cent |
| Müller et al., 2008 (indoors) | High biting pressure, Israel; human landings | 5 per cent candle: 29.0 per cent repellency | Linalool candle 71.1 per cent; geraniol candle 85.4 per cent |
| Müller et al., 2008 (outdoors) | CDC traps 1 m from candles | 35.4 per cent fewer female mosquitoes | Linalool 64.9 per cent; geraniol 81.5 per cent; all dropped at 2 and 3 m |
| Müller et al., 2009 | Indoors and outdoors, commercial products | Candle indoors: 14 per cent | Citronella diffuser indoors 68 per cent; outdoors at 6 m, 22 per cent |
| Rodriguez et al., New Mexico State University, 2017 | Wind tunnel, person 1 m from mosquitoes | No effect: 90.95 per cent of mosquitoes still flew towards the person | 88.82 per cent with no candle; a PMD spray and a 98 per cent DEET spray cut attraction to about 30 and 34 per cent |
| Revay et al., 2026 | Field plots in Mali, traps 14 ft from device | Minimal or no measurable effect | Heat-activated transfluthrin devices cut catches sharply |
Do citronella candles really deter mosquitoes?
A little, at close range, and much of what they do is the smoke. The Guelph study is the clearest demonstration. Eight people sat at fixed positions in a woodlot and counted bites in five-minute blocks. With no candle they averaged 10.8 bites per five minutes, with a plain unscented candle 8.2, with citronella incense 8.2 and with a citronella candle 6.2. The citronella candle averaged fewer bites than the plain one, but the plain candle got roughly half of the way there on its own.
That matches the American Mosquito Control Association’s summary: citronella candles have a mild repellent effect but do not offer significantly more protection than other candles producing smoke. Smoke and heat interfere with the cues mosquitoes follow, which our guide to what attracts mosquitoes explains, starting with the carbon dioxide you breathe out.
The trials also show why results vary so much. A 3 to 5 per cent candle releases a small amount of oil into moving air. In Israel, the same researchers found geraniol candles about five times as effective as citronella indoors, and continuous-release diffusers far stronger than candles of the same oil. In the 2017 wind tunnel test the candle sat downwind of the person and mosquitoes came anyway.
How far away does a citronella candle work?
About a metre, on the best evidence. In the 2008 outdoor trial, citronella candles cut female mosquitoes caught in traps 1 m away by 35.4 per cent, and the repellency dropped significantly at 2 m and 3 m. Even the stronger geraniol candle lost most of its effect with distance. In the 2026 Mali field trial, with traps 14 ft from the device, the citronella candle showed minimal or no measurable effect.
Two practical consequences follow. A candle in the middle of a dining table protects the people nearest it, not the far end of the patio. And the Greater Los Angeles County Vector Control District points out that Aedes mosquitoes prefer to bite ankles and lower legs, away from candles set on a table top, and that any breeze removes the effect.
Citronella candles vs diffusers
Diffusers that release oil continuously did consistently better in the Israeli trials. Indoors, a citronella candle repelled 14 per cent of mosquitoes against 68 per cent for a citronella diffuser. Outdoors, with diffusers 6 m from the traps, citronella cut female mosquitoes by 22 per cent, linalool by 58 per cent and geraniol by 75 per cent, and catches fell further when the diffusers were moved to 3 m.
So the oil does something; the candle is simply a weak way to deliver it, and citronella is the weakest of the three oils tested. None of these devices is on CDC’s list of recommended repellents.
Citronella oil on skin
Does citronella repel mosquitoes when it is applied directly? Briefly. In the 2002 New England Journal of Medicine comparison by Fradin and Day, carried out under controlled laboratory conditions, the botanical repellents tested, including the citronella-based products, protected for a mean of less than 20 minutes. A 23.8 per cent DEET product protected for an average of 301.5 minutes, a soybean oil product for 94.6 minutes, and an IR3535 product for 22.9 minutes.
| Repellent (Fradin and Day, 2002) | Mean complete protection |
|---|---|
| DEET 23.8 per cent | 301.5 minutes |
| Soybean oil based | 94.6 minutes |
| IR3535 based | 22.9 minutes |
| Other botanicals, including citronella based | Under 20 minutes |
| Repellent wristbands | No protection |
A 2011 review in Malaria Journal by Maia and Moore puts citronella’s protection at about two hours against host-seeking mosquitoes and explains why it is short: the oils evaporate rapidly, leaving the user unprotected. Either way, it falls well short of DEET.
Is citronella EPA registered?
Yes, and that is easy to misread. EPA first registered oil of citronella in 1948, as a repellent for gnats and mosquitoes applied to skin and clothing, and describes it as a biopesticide with a non-toxic mode of action. But since 1996, citronella and citronella oil have also been on EPA’s list of minimum risk ingredients, which means products meeting that list’s conditions are exempt from federal registration. EPA does not review exempted products. A citronella candle on a supermarket shelf may therefore never have had its repellency claims assessed by EPA at all.
Indoors, flies and wasps
Do citronella candles work indoors?
Modestly. Indoor trials found 14 per cent repellency for a commercial candle in one study and 29.0 per cent in another, in a closed room with no breeze. That is better than outdoors but still far below a diffuser or a repellent on skin. Indoors, window screens in good repair do more, and CDC lists them among its core steps.
Do citronella candles work on flies?
There is little direct evidence for house flies. The one biting fly tested in the candle trials, the sand fly, was reduced by 15.4 per cent at 1 m outdoors and 24.7 per cent indoors, less than mosquitoes.
Do citronella candles work for wasps?
We found no controlled trial of citronella candles against yellowjackets. UC IPM explains that yellowjackets turn up at picnics and barbecues in late summer and fall because colonies need sugar, and its advice is to keep food and pet food covered, cover drink cans so wasps cannot crawl in, and keep rubbish sealed. Our data below show yellowjacket records peaking in October, later than mosquitoes. For nests, see our wasp and hornet identification guide.
When candles are being asked to do the most work
Our analysis of US iNaturalist research-grade records shows the mosquito family at 147 on our index in July, 168 in August and a peak of 182 in September, nearly twice its yearly average share of what people record. The Asian tiger mosquito peaks even more sharply, at 236 in September. UF/IFAS describes it as a daytime feeder whose feeding peaks in the early morning and late afternoon, so an evening candle meets it only at the tail of its biting window. Yellowjackets climb to 208 in September and 251 in October. These figures reflect when people photograph and identify insects, not bite counts, but they show that late summer is when outdoor protection matters most.
What works better
- A repellent on skin. CDC recommends EPA-registered products containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone, used as the label directs, and advises against OLE or PMD on children under 3.
- Moving air. Michigan State researchers found fan-generated wind strongly reduced mosquito catches at carbon-dioxide-baited traps and recommended fans for backyards.
- Removing standing water weekly, which stops the next generation rather than masking the current one.
- Treatment for a specific evening if mosquitoes are heavy; our guide to mosquito control for events covers timing, and our mosquito control cost guide covers prices.
Other patio favourites fare no better. Zappers kill almost no biting mosquitoes, as our look at whether bug zappers work shows, and potted citronella plants and other mosquito repellent plants release even less oil than a candle. Keep candles for what they are, a pleasant light that may trim bites for the person sitting next to one.
Frequently asked questions
What is the best thing to put on to keep mosquitoes away?
An EPA-registered repellent with one of the active ingredients CDC recommends: DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone. In a 2017 New Mexico State test, sprays containing DEET or PMD worked best. Follow the label for how much and how often, and do not use OLE or PMD products on children under 3. Ask a doctor or pharmacist about anything specific to your health.
Do dryer sheets keep mosquitoes away?
There is no good evidence that they do. The Greater Los Angeles County Vector Control District says dryer sheets have not been scientifically tested as an insect repellent. A Kansas State University study found dryer sheets repelled fungus gnats in laboratory containers, but it did not test mosquitoes. Tucking a sheet in a pocket is not a substitute for a registered repellent.
Are citronella candles worth buying?
Only as a minor extra. The best result in a field trial was 42.3 per cent fewer bites, and a plain candle achieved about 24 per cent in the same test. Outdoor protection fades beyond about 1 m, and one wind tunnel test found no effect. If bites matter, especially where mosquito-borne disease is reported, a registered repellent on skin is the dependable option.
Is a citronella diffuser better than a candle?
In the Israeli trials, yes. Indoors a citronella diffuser repelled 68 per cent of mosquitoes against 14 per cent for a citronella candle. Diffusers of geraniol and linalool did better still, at 97 and 93 per cent indoors. Outdoors at 6 m, though, a citronella diffuser cut catches by only 22 per cent, so distance and wind still limit any device that works through the air.
Sources
- Lindsay, L.R. et al. Evaluation of the efficacy of 3% citronella candles and 5% citronella incense for protection against field populations of Aedes mosquitoes. Journal of the American Mosquito Control Association 12(2): 293 to 294, 1996. University of Guelph.
- Müller, G.C. et al. Indoor protection against mosquito and sand fly bites: a comparison between citronella, linalool, and geraniol candles. Journal of the American Mosquito Control Association 24(1): 150 to 153, 2008.
- Müller, G.C. et al. Ability of essential oil candles to repel biting insects in high and low biting pressure environments. Journal of the American Mosquito Control Association 24(1): 154 to 160, 2008.
- Müller, G.C. et al. Efficacy of the botanical repellents geraniol, linalool, and citronella against mosquitoes. Journal of Vector Ecology 34(1): 2 to 8, 2009.
- Rodriguez, S.D. et al. Efficacy of some wearable devices compared with spray-on insect repellents for the yellow fever mosquito. Journal of Insect Science 17(1): 24, 2017. New Mexico State University.
- Revay, E.E. et al. Performance of different spatial repellents against vector mosquito species in Mali, West Africa. Frontiers in Insect Science 6, 2026.
- Moore, E.L. et al. An online survey of personal mosquito-repellent strategies. PeerJ 6: e5151, 2018.
- Fradin, M.S. and Day, J.F. Comparative efficacy of insect repellents against mosquito bites. New England Journal of Medicine 347: 13 to 18, 2002.
- Maia, M.F. and Moore, S.J. Plant-based insect repellents: a review of their efficacy, development and testing. Malaria Journal 10 (Suppl 1): S11, 2011.
- US Environmental Protection Agency, R.E.D. Facts: Oil of Citronella, EPA-738-F-97-002, 1997; Conditions for Minimum Risk Pesticides; 40 CFR 152.25(f).
- American Mosquito Control Association, Frequently Asked Questions.
- Greater Los Angeles County Vector Control District, Insect Repellent Myths.
- Hoffmann, E.J. and Miller, J.R. Journal of Medical Entomology 40(5): 607 to 614, 2003. Michigan State University.
- UF/IFAS EDIS EENY319, Asian Tiger Mosquito; UC IPM Pest Notes: Yellowjackets and Other Social Wasps, Publication 7450.
- Kansas State University, fabric softener dryer sheets and fungus gnats, HortScience, 2010.
- Centers for Disease Control and Prevention, Preventing Mosquito Bites.
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.
