There are so many claims made about various plants and essential oils that can repel mosquitoes and prevent bites that we decided to see what the research says. After all, if you can plant a few things in your garden or light some candles to keep from getting eaten alive, why not?
If you enjoy seeing what the science says about popular garden topics, also see Popular Garden Myths We’ve All Fallen For.
Which Mosquito Repellents Really Work?
Mosquito | Family: Culicidae
Small flying insects
• 3,500 species
• Development: egg to adult in 5 to 40 days
• Trivia: Antarctica and Iceland do not have mosquitoes
• Harm: Cause more deaths than any other animal group
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It’s the time of year where mosquitoes are a problem for some of us so I thought it would be good to see what the research says about various alternative repellents.
Keep in mind that I am sharing what the research shows. This is not advice for what to use. It is just a look at whether researchers have been able to substantiate any of the popular anecdotal claims.
How Good is Good Enough?
Before we dive in to some specific remedies, let’s think about the bigger question.
How effective does something have to be to be good enough?
There are some alternative repellents that reduce mosquito bites by 40%.
And, at first, that sounds good. We’ve probably all bought products because they do a 40% better job.
But with mosquitoes, what does that mean?
Instead of getting eaten alive, we’ll only get 60% eaten alive?
This may sound okay if you live somewhere where mosquitoes are considered an annoyance and not much more.
But, if you are allergic to bites like I am or find yourself somewhere mosquitoes spread deadly diseases like malaria or West Nile virus, getting any bites is potentially much more serious.
Along with limited efficacy, some alternative repellents may only work for a very limited time: 5, 10, or perhaps 30 minutes. After that, it’s open season.
So how effective do we need these things to be to recommend them?
Related: Are Epsom Salts Good for the Garden?
Mosquito Repellents Made from Essential Oils
Many essential oils don’t work at all, some work for a very short time, and a few are okay, but that’s about it.
Citronella, extracted from the plant citronella grass (Cymbopogon nardus), is perhaps the most popular essential oil associated with repelling mosquitoes.
And, while some may swear by it, the effectiveness is limited.
In a 2018 review of tests for repelling mosquitoes, Consumer Reports said:
“We advise skipping most products made with natural plant oils, such as those with citronella, lemongrass oil, cedar oil, and other ingredients. They did not perform well in our tests.”
The only oil with research to back it up is oil of lemon eucalyptus (PMD)—called Citriodiol in the UK, which you may have noticed in some commercial repellents in recent years.
Related: Is Vinegar Really a Good Anti-Weed Treatment?
For some people, a summer evening on the patio is not complete without mosquito-repelling candles burning in hopes of keeping those flying blood-suckers at bay.
But are the candles really reducing the bites?
Research from Science magazine (2017) says:
“Citronella candles are great for setting a mood, but they’re not so great for the very thing they’re advertised to do: repel mosquitoes.”
And logically, if mosquitoes are present, and an item repels them, how far away are they really going to go? Far enough to protect us bystanders from bites?
A better option may be to keep a fan blowing so the mosquitoes never reach you.
Related: Do Eggshells Really Help Plants Grow?
Mosquito Traps and Zappers
Traps that lure mosquitoes haven’t fared well in tests, partly because, if they do attract mosquitoes, not all of them end up in the trap.
In one study, some popular traps actually increased the number of bites people got.
Zappers, sonic devices, and wristbands? None of them got results.
One wearable that did got good results: Off makes a clip-on repellent with a built-in fan, and those did fine. The force of the blowing air is perhaps more helpful than anything else.
Eating garlic? Taking B1 supplements? Nope.
What about those plants that are supposed to keep mosquitoes away?
I’ve seen lemongrass, lemon balm, lavender, lemon thyme, catnip, basil, rosemary, garlic, marigolds, and citrosa all suggested and articles claiming their effectiveness are shared like crazy on Facebook.
But no, despite all the enthusiasm and wishful thinking, they are not the magical mosquito repellents we dream of.
And even if they could repel a mosquito, how will that help us?
Do we really think lemon thyme is going to provide a 10 or 30 or 50-foot mosquito-repellent force field that we can move freely in? Not happening.
At best it might mean the mosquito just moves on to flit around something else nearby. Or us.
Citrosa plants (Pelargonium ‘citrosum’)—one of the most popular recommendations—are specifically listed on Health Canada’s “Products That Don’t Protect Well” list.
Effective Mosquito Repellents
So where does this leave us?
In gardening as in life there are not always great solutions to common problems.
If preventing bites is a serious matter for you, these ingredients are shown to be most effective:
DEETPicaridin / icaridin (known by each name in different places)Oil of lemon eucalyptus (also known by its chemical acronym, PMD).
Be sure it is oil of lemon eucalyptus-PMD and not lemon eucalyptus (essential) oil which is not deemed effective. You can find all of them in sprays for topical use. Pay attention to the details: there are specific amounts needed to be effective and not all products have sufficient amounts.
That said, this is just a look at the research.
What you choose to trust and use is entirely up to you (of course).
References / Read More
DEET and PMD spray-on repellents most effective at repelling mosquitoes | Science DailyMosquito Repellents That Best Protect Against Zika
Ratings on Bug Sprays | Consumer ReportsWant to repel mosquitoes? Don’t use citronella candles | Science magazineInsect Repellents | Government of Canada7 Myths About Getting Rid of Mosquitoes You Need to Stop Using | Science AlertEWG Guide to Better Bug Repellents | Environmental Working Group (PDF format)Failure of the “Mosquito Plant”, Pelargonium x Citrosum ‘Van Leeni’ to Repel Adult Aedes Albopictus and Culex Qutnquefasciatus in Florida | ResearchGate~Melissa the Empress of Dirt ♛