Summertime equals mosquito time. If you’re like us, you’re always searching for natural and easy ways to repel mosquitoes. We’ve searched all over for solutions. We’ve even found an article that advised us to sleep with a pig in the room. There are little things you can do to minimize the mosquito population in your yard, such as removing standing water or building a bat house to attract bats. However, we also like to go with plants to beautify while we fortify our yard.
Many plants produce strongly aromatic compounds that are distasteful to critters that would otherwise eat them
Some of those compounds also have (just by chance) mosquito repellent activity. Not all repelling plants are equally effective, of course. Our botanical allies do not all share a single mode of action. Scents from some plants mask the chemical signals you send out, making it harder for the skeeters to locate you. Other plants smell or taste bad to the mosquitoes, so they tend not to bite. Still others are actually toxic to mosquitoes. There is not a lot of information about how each specific repellent acts on a target insect. And, of the almost 3500 different species of mosquitoes, not all will react the same to a specific repellent. Bottom line: If the foliage of a plant is highly aromatic, it just might be effective at warding off those pesky skeeters.
There are several kinds of plants that produce chemicals that are repellent to mosquitoes
In some cases, just brushing against the foliage may release biologically active volatile compounds that repel mosquitoes. Two recent studies in Africa, where mosquito borne diseases are endemic, show that West Indian Lantana (Lantana camara) and Hoary Basil (Ocimum americanum) reduce the incidence of mosquitoes when merely inside or at the doorway entrances to native huts. Mosquito incidence inside the huts cut down by a third to a half. The effect probably was because people, coming and going, brushed against the plants, releasing the volatile chemicals that repel mosquitoes.
The best way to use plants as mosquito repellent, however, is to extract the essential oils and formulate a lotion for applying to the skin. Extracts from a number of fragrant plants have been tested and several have been found to repel mosquitoes. But this is only after the active ingredients are extracted, concentrated, processed, and applied directly to the skin. The effectiveness of most of these extracts is short term, usually just two hours or less. By comparison, low concentrations of DEET (diethyltoluamide, the compound in most commercial mosquito repellents) are effective for 6-8 hours. Extracting essential oils is an elaborate process that involves specialized knowledge and fancy laboratory equipment. If you want to try making your own essential oils, here is a site that tells how: http://www.essential-oil-mama.com/make-your-own-essential-oil.html.
Merely crushing the aromatic leaves of certain plants releases volatile phytochemicals (biologically active compounds found in plants) that can be repellent to mosquitoes
Bruised and crushed foliage can be tied into a sachet and hung in doorways or placed where people might brush against it. Certain aromatic plants can be burned to produce a fumigant that may drive mosquitoes away. Rubbing the skin with the leaves can offer some short term protection from skeeters, and might be less toxic than DEET, but is nowhere near as effective as the oils from the plants. (Before rubbing your skin with the crushed leaves of any plant, you should first do a patch test on a small area of your forearm and watch it for a couple days to be sure you don’t get a rash.)
Here are some plants that are useful for repelling mosquitoes. (The so-called “mosquito plant” (Pelargonium ‘Citrosum’) apparently does not repel mosquitoes at all, even when its foliage is crushed, and is not included here.)
West Indian lantana (Lantana camara), originally a native of South America, is now a widespread weed throughout much of the world. In a recent study of several potential mosquito repelling plants in Africa, lantana turned out to be the best. On the downside, the lantana plants multiplied rapidly and became troublesome weeds in the vegetable gardens. Brushing against the foliage of lantana releases a stinky odor that reduces the incidence of mosquitoes in the immediate vicinity. Crushing the leaves and rubbing on the skin is even more effective.
Lemon Eucalyptus (Corymbia citriodora) is a large tree that hails from Australia. Highly refined essential oils derived from lemon eucalyptus have been shown to repel mosquitoes, and lemon eucalyptus may in fact be the most effective natural mosquito repellent yet discovered.
Lemon thyme (Thymus x citriodorus) has fragrant foliage that contains phytochemicals that repel mosquitoes. Rub bruised leaves on your skin to repel mosquitoes for an hour or two. Some people develop a rash from the oils in thyme, so before coating yourself with it, you should test your tolerance first with a patch test. Studies have shown that rubbing the skin with the crushed leaves of lemon thyme reduced mosquito bites by 62%, compared to using DEET, which reduced them by 90%.
Citronella grass (Cymbopogon nardus) yields a chemical, citronella oil, that is an insect repellent. The oil is extracted from the plant and mixed with other vegetable oils, then applied to the skin for an insect repellent. Candles and incense made from citronella oil are less effective. In fact, to keep mosquitoes away, you would have to burn so many candles that the smoke would be almost intolerable. Some people get a skin rash from citronella oil and inhaling the fumes may increase heart rate for some.
Neem (Azadirachta indica), is a tree in the mahogany family, Meliaceae. Extracts from neem leaves have varying effectiveness in repelling mosquitoes, and have not been approved by the EPA for use as a topical insect repellent. Most noteorthy that neem leaves also possess immunomodulatory, anti-inflammatory, antihyperglycaemic, antiulcer, antimalarial, antifungal, antibacterial, antiviral, antioxidant, antimutagenic AND anticarciogenic properties.
Catnip or Catmint (Nepeta cataria), is a member of the mint family and contains the essential oil nepetalactone, which is responsible for its distinctive scent. Nepetalactone proves to repel mosquitoes and other insects, although it is not as effective as DEET. Furthermore, this plant seems to have repellent properties, not only for the mosquitoes, but also ants, flea beetles, mice and cockroaches. There’s even some evidence that catnip can effectively kill flies. Just be careful planting it in your yard because Catnip grows like crazy.
Common thyme (Thymus vulgaris) also has some efficacy in repelling mosquitoes. A study published in a 2005 issue of the Journal of the American Mosquito Control Association found that compounds extracted from the essential oil of Thymus vulgaris act as a repellent. As with lemon thyme, the essential oils in common thyme can be irritating to the skin of some people.
Lavender (Lavandula sp.) is loved by humans all over the world, but mosquitoes hate it! We’ve heard that if you add a drop of lavender to a ribbon and place around open windows mosquitoes will think twice before entering. You can also create a skin lotion by adding 30 drops of lavender essential oil to two tablespoons of vegetable oil – such as olive oil – and rub onto exposed skin. Not only will you smell beautiful, but it will stop mosquitoes from landing on you. Much like Catnip, Lavender could take over your yard, so keep an eye on it or plant it in a pot.
Hoary Basil (Ocimum americanum), despite its Latin name, is a native of Africa and Asia. The various basils contain essential oils that can be extracted and used as a spray to repel mosquitoes. Basil plants emit their aromas without actually crushing the leaves, so you can grow basil in a pot to ward off mosquitoes as you brush against it. Rubbing a handful of crushed basil leaves on your skin will help repel mosquitoes, too. There are a couple dozen species and varieties of basil, but the strongest aromatic fragrances seem to come from hoary basil, lemon basil,cinnamon basil and Peruvian basil.
Lemon Balm (Melissa officinalis) is an herb in the mint family that has a variety of uses including flavoring in herbal teas. Make a quick mosquito repellent, by crushing a handful of leaves and rubbing on your exposed skin. Grow them in the garden for easy access when you need them.
Lemon Grass (Cymbopogon citrates) contains citronella, a natural oil that repels mosquitoes. Lemon grass is used in Southeast Asia to flavor foods. In India, it is an anti-inflammatory medicine. Lemongrass has a wonderful aroma so that it is in perfumes and other toiletries. Rub some of the crushed leaves on your skin to repel mosquitoes.
Lemon Verbena (Aloysia citrodora) is best in your garden, doorways, and windows to repel mosquitoes as it makes contact. This South American native has an aromatic, fresh lemony scent and is used as a medicine, to flavor foods and to ward off bugs.
Mexican Marigold (Tagetes lucida) the scent of Mexican marigold is offensive to many people and to mosquitoes. You can grow it in your yard or cut the flowers off and keep them around the house where they might reduce the incidence of mosquitoes.
Wormwood (Artemisia absinthium), native to the Mediterranean region, is a very poisonous plant if ingested. However, it has many uses in medicine and beverage flavoring (think absinthe). Some say that the stinky foliage repels mosquitoes. Try crushing wormwood leaves and distributing around your outdoor living area.
You may assume that “natural” plant based repellents are safer than DEET, but this is not necessarily so
DEET has been widely used for decades and has a good safety record. Some “natural” products (think poison ivy, or pyrethrum, for example) may not be as safe . Mosquitoes are pretty persistent, and most natural repellents just seem like a very temporary roadblock. Since they generally only protect for a short while, it’s best not to rely on these plants for hours on end. Rubbing some homemade lemon thyme based anti-mosquito lotion on your skin will not keep you safe for long. You need to re-apply, botanical repellents up to 4 times more often than products containing DEET. Still, plants known to have mosquito repellent characteristics can be nice additions to the garden and home.
Potential plant-based mosquito repellents are being studied by scientists all over the world. Someday we may have alternatives to DEET that are safer to use and just as effective. Until then, all we can do is continue to hope that someone around us will attract the mosquitoes more than we do!