It’s a commonly held belief that citronella has insect-repelling properties, but to what extent does citronella repel flies and how effective is it?
Citronella oil-based formulas include creams that can be applied directly to the skin, citronella-infused candles that must be burned, or recipes that involve mixing the oil with other ingredients to make a home remedy insect repellant. The truth is, in all scenarios, it has to be used correctly to stand the best chance of success.
There is a lot more to unravel when it comes to the effectiveness of citronella. How does it work? What type of insects can it be used to protect against? How should it be applied, and are there any alternatives? In this article, I’ll be addressing all of these.
- What Is Citronella?
- How Does Citronella Repel Flies
- Other Insects That Citronella Can Keep Away
- How to Use Citronella Candles
- More Smells That Keep Flies Away
- Natural Fly Repellents
- Chemicals for Getting Rid of Flies
- How to Stop Flies from Coming Back
- Does Citronella Keep Flies Away Final Thoughts
What Is Citronella?
Citronella oil comes from the leaves and stems of the plant Cymbopogon nardus by way of extraction. Commonly known as Citronella Grass, this is a highly aromatic perennial that is native to Asia.
Citronella oil is an ingredient commonly added to insect-repellant formulas that are applied to the skin. It can also be burned in the form of a candle whereby the scented vapor repels insects. It is also used as an ingredient in disinfectants and soaps.
Some people can develop a reaction to the chemical compound that is responsible for the lemon-scented fragrance of citronella oil. This is particularly the case for people with skin conditions.
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How Does Citronella Repel Flies
According to a Johns Hopkins study, an ‘aversion response’ is triggered when the insect detects the smell of citronella. This then prevents the insect from landing on humans or getting near the air-borne vapor from a citronella candle. Scientists believe that protein-like pores on the body of insects absorb the scent of citronella, which then transmit signals to the insect’s brain warning them to avoid getting close to the scent.
Whilst there is a commonly held belief that citronella does repel insects, its effectiveness is questionable. This is because it is recognized that very high doses and repeat applications of this fragrant yet mildly-scented oil are required in order to maintain its insect-repelling properties. Furthermore, it is considered most effective for getting rid of flies on porches or patios i.e. when used in confined or small spaces.
Can Citronella Kill Flies
No, citronella is not an insecticide and cannot kill flies or other insects such as mosquitoes. It can harm humans if ingested.
Other Insects That Citronella Can Keep Away
Aside from mosquitoes, according to the National Library of Medicine, citronella can also repel head lice, body lice, stable flies, and leeches.
It is also thought that citronella may also repel other insects that primarily rely on their sense of smell to survive, but studies relating to this are yet to be concluded.
How to Use Citronella Candles
The glow and scent of a lit citronella candle is a popular sight on warm summer evenings, dotted around outdoor dining establishments and on domestic patio tables alike.
The truth is there is limited scientific evidence that backs the claim that candles containing citronella oil are effective at repelling insects. This is because there is simply not enough citronella scent released into the air for insects to detect. Plus, any scent that does become airborne, is quickly dissipated into the atmosphere.
Citronella candles, while they smell like citronella, simply don’t use enough citronella oil to have an effect on insects. The only time citronella candles can repel insects is when the concentration of citronella oil in the candle is abnormally high and when you light it up in an enclosed area.
Lighting a citronella candle on the patio or in the yard is unlikely to repel insects any more than other scented candles such as lavender or cinnamon.
When & Where To Use Citronella
Insect-repellent formulas that use citronella oil as their base repelling agent need to be applied directly to the skin. According to US guidelines, applications are required once an hour to maintain effectiveness.
These formulas can be used in all types of weather to keep insects at bay, but they are easily washed off by rain or when swimming and the solution can evaporate quickly at high temperatures. In addition, human sweat will also dilute the effectiveness.
In areas where mosquito numbers are high and where no other precautions have been taken against the possibility of contracting insect-transmitting diseases (such as malaria), it is recommended that alternative insect repellants are applied. Formulas such as Deet for example, have been proven to be more effective in this regard.
More Smells That Keep Flies Away
There are a number of smells that can seemingly overwhelm the senses of a fly, causing it to be repelled. Smoke, for example, is a natural repellent of all insects. The use of oil lamps or campfires that produce a lot of smoke is commonly used to repel mosquitoes and flies.
Flies are also deterred by some plants, as well as aromatic spices that let off a strong scent. Rosemary, mint, and catnip are the best examples.
It is also worth including lavender on this list, which can be grown as an outdoor insect-repelling plant but can also be used as an oil to repel flies.
Natural Fly Repellents
Later in this article, I’ll be covering store-bought options for repelling flies and explaining how to stop them from coming back into your home. For now, here is a look at the most popular natural, and homemade fly repellents.
1. Homemade Fly Repellent
Citronella oil not only repels flies, but it also repels other insects as well and can be used to make your own fly repellent.
Mix a cup of water and five drops of citronella oil in a spray bottle and spray it on fly-infested areas.
If the scent is strong enough, flies will evacuate the area and keep away until the smell subsides.
Keep in mind that this isn’t a fly killer, it’ll just deter them from wherever you apply it.
It is also worth noting that repellents will quickly evaporate or get washed away by rain. So, you need to reapply often.
This is why a repellent, be it homemade or store-bought isn’t a long-term solution.
2. Vinegar And Dish Soap Solution
A homemade solution of vinegar and dish soap is a great deterrent for fruit flies and one that I highly recommend.
Take a jar or cut a plastic bottle in half and mix a teaspoon of dish soap with half a jar of apple vinegar. Simply leave it to rest near the flies and watch them drown.
Since apple vinegar smells like rotting fruit to them, flies are naturally attracted to the solution. Dish soap makes the solution sticky and heavy, dragging the flies down to the bottom when they touch the surface.
While this will most likely kill all the flies in the area, it still won’t prevent new flies from coming in.
3. Planting Herbs
Growing powerfully scented herbs such as mint, rosemary, lavender, and thyme in an area frequented by flies can help to control their numbers and naturally deter them from a specific location.
However, this solution isn’t absolute and it depends on many factors. Firstly, scent-based repellents are less effective outdoors because the wind aerates the area quickly.
Secondly, different varieties of these plants release scents of different strengths and you will need to plant a lot of herbs for this method to be effective.
Lastly, if you’re growing herbs indoors to deter flies, know that the flies will likely just move to another room in your home.
This is a good way to keep flies away from the kitchen, but not necessarily from the entire house.
Chemicals for Getting Rid of Flies
Here are the most popular chemical and mechanical practices used to get rid of flies.
Insecticides are chemical solutions sprayed directly onto the insects, killing them instantly. They’re usually perfectly effective and will kill 100% of insects they come in contact with.
However, they’re not a long-term solution and they won’t stop new flies from appearing.
2. Bug Zappers
Bug zappers can be highly effective when it comes to keeping flies out of your home. Insects are attracted to their glow, which they then get electrocuted and fry to death when they come into contact with the zapper.
If you place zappers outside (out of the reach of pets and kids), they’ll most definitely kill insects and draw their attention away from your home.
They’re not recommended as long-term solutions, though. The light may begin to attract more insects than there would normally be around your home, while the killed insects could spread disease if not removed from the zapper device.
3. Hanging Fly Traps
Fly traps are similar to electric bug zappers, but they don’t fry the bugs. These traps hang from the ceiling, where they are covered with a sticky, often toxic substance that smells like an attractant to flies.
Flies naturally come to investigate, get stuck in the trap, and die there.
These traps are very effective in barns, garages, sheds, and partly open areas (porches, gazebos, etc.), but they shouldn’t be used inside the home unless windows and doors can be kept open at all times when in use to sufficiently ventilate and disperse the toxic fumes.
How to Stop Flies from Coming Back
The most important part of insect control is prevention – once you get the flies out of your home, here’s how to stop them from ever returning.
1. Seal Access Points
Simply put, if there’s no clear path for a fly to get into your home, it won’t be able to invade it. The most common way a fly enters the home is through open windows and doors.
Install window and door screens so that you can keep them open during warm weather without flies coming in.
Aside from that, flies can get it through cracks and gaps, which will need to be patched, covered, and sealed.
2. Remove Standing Water
Standing water is an attractant for two reasons – it accelerates vegetation decay, which flies need to feed and breed, while some flies feed on nutrients found in standing water (drain flies, for example).
If there’s any standing water in your yard, you can expect flies to converge on it. Removing that water as soon as possible will deter the flies.
3. Clean Surfaces and Floors
Flies feed on decomposing materials and many things found on the floor of your house can be food to them. Cleaning your home is part of integrated pest management and it will help keep flies away.
4. Replace Compost and Rubbish Bin Lids
Garbage bins are very attractive to flies because they contain their favorite food – rotting meat, fruits, and vegetables. This is a problem with many mammals too, such as raccoons and skunks.
Prevent this problem with airtight lids and washing the outside of trash cans regularly, which minimizes the scent let off by the rotting garbage.
5. Grow Scented Plants That Flies Hate
There are some plants that naturally deter flies because of their powerful scent. Grow lavender, mint, thyme, and rosemary near fly attractants, such as your garbage bins or your kitchen.
6. Change Lighting
It’s been found that yellow light and halogen lights attract flies less than blue and green lights, so changing the bulbs in your lights could attract them less. This is especially important if flies are attracted to a seating area or porch outside.
7. Improve Ventilation
Insects are incredibly light animals and in the wild, they’re thrown about by the wind mercilessly. This is why they like enclosed areas and still evenings. One of the simplest ways of showing flies they’re not welcome is by opening windows and creating a draft. Alternatively, try blowing them away with a fan.
Does Citronella Keep Flies Away Final Thoughts
Citronella oil is a commonly used ingredient in many insect repellants and when applied to the skin correctly, can be safely used to keep irritating flies and non-disease-carrying insects away.
The jury is still out on the effectiveness of citronella candles, which are considered – by many- to be less effective since the scented vapor is dissipated into the atmosphere quickly.
The best way to keep flies away for good, though, is by closing all access points and keeping your home tidy – this way, they won’t be attracted to it and they won’t be able to get inside.