June 24, 2015
The deadliest insect on Earth, a mosquito is a formidable opponent that’s had 200 million years to perfect its game. Here’s how to win with natural and non-toxic approaches to bug repellents.
Hiking and enjoying the outdoors should not be a bloodletting affair. Getting a serious blood-borne disease is even worse. Along with sunscreen and poison ivy barrier lotions, mosquito repellents are essential. (We’ll get to chigger repellents another time.)
The female mosquito needs blood to grow her egg brood and is determined to get it. She sucks blood from birds, mice, squirrels, deer and more, in the process spreading diseases. Malaria, encephalitis, dengue and yellow fevers in the tropics, while in Texas it’s the West Nile virus from bird to human. Meanwhile, the male is like a butterfly, drifting about sipping flower nectar and sweet tree saps, waiting for eggs to fertilize.
Mosquitoes lack a sense of smell. Strong aromas do not deter them. They locate potential victims through the carbon dioxide of their exhale. So what a mosquito finds repellent is highly specific, hence strange chemicals like DEET (N,N-diethyl-m-toluamide), which can cause neurological damage in high doses. Your skin must become so unappetizing they won’t bite there. That means a thorough application is important. Aroma won’t cut it. It must be a physical barrier.
Right, courtesy of InsaneScouter.org.
Lucky for us, there are options. Those based on plant oils and essential oils continue to improve. New on the scene are non-toxic synthetic repellents, some of them plant-derived, that are non-toxic and do not damage fabrics, plastics or other materials like DEET does.
Botanical repellents work fine for most backyards and light nature excursions.
To make your own natural repellent, dilute essential oils into a base before applying. Soybean oil and castor oil sticks to your skin a long time, resists sweat and is unpleasant to bugs. But other plant, nut and seed oils or vegetable glycerin will do. Thin these with witch hazel, isopropyl alcohol or cetyl (drinking) alcohol, or a combination, to create a spray that must be shaken very well before using.
Mountain Rose Herbs has a great do-it-yourself approach for a sprayable light repellent based on a catnip hydrosol or alcohol tincture. While they swear by catnip for repelling mosquitos, this is a problem in my household. To moderate the cat-attracting qualities and increase the bug-fighting oomph, Mountain Rose recommends adding some of these essential oils: cedarwood, citronella, eucalyptus, lavender, lemongrass and rosemary. Include some witch hazel extract to make your skin happy. If the catnip proves irresistible to your felines, use witch hazel astringent as a base. Directions are at their blog.
Above, catnip essential oil from Mountain Rose Herbs.
The biggest problem with botanicals is that they evaporate quickly, from 30 minutes if you’re sweating in the sunlight to two hours if you’re cool, shady and non-sweaty. Apply thoroughly and thickly. Commercially made potions contain natural fixatives that help them last longer.
Here are some essential oil-based products:
• Bug-Bouncer by Bug-Bouncer
A base of 23 percent soybean oil and 10 percent castor oil, with 0.5 percent wintergreen for a nice smell. Shake well before using. Super oily, hassle to use, not very effective. Available in pump spray.
A base of 11.5 percent soybean oil, with beeswax and vegetable glycerin. A hefty 10 percent of citronella, plus smaller amounts of cedar, geranium, lemongrass and peppermint essential oils. Effective and sticks to you. Available in pump spray, aerosol-like Eco-Spray.
A base of soybean oil, 10 percent castor oil and vitamin E, plus 6 percent geranium essential oil. Available in pump spray.
A base of beeswax, coconut oil, vegetable glycerin, 8 percent castor oil, and 3 percent soybean oil, with alkalizing baking soda. Essential oils include citronella, cedarwood, geranium, lemongrass and peppermint. Effective and sticks to you, but only the Extreme version. Available in pump spray, wipes.
Base of soybean oil, 10 percent castor oil and vitamin E, with small amounts of cedar, citronella, clove, geranium, lemongrass and peppermint essential oils. Wimpy. Available in pump spray.
Based on geraniol, which is extracted from geranium and other plants. Small drawback: geraniol attracts bees. Otherwise not very natural, loaded with sodium laurel sulphate and other chemmies, with only a smidge of soybean oil. Both get very mixed reviews.
The current rock star among plant-derived repellents is oil of lemon eucalyptus (Corymbia citriodora) that is refined to create p-menthane-3,8-diol (PMD). This is similar to how orange oil is refined to create the natural orange-oil herbicide. When studies refer to the bug-fighting ability of oil of lemon eucalyptus, it is this refined version, NOT the essential oil version.
Right, lemon eucalyptus tree, courtesy of Wikipedia.
According to the Center for Disease Control, a 10 percent concentration of PMD is good for short excursions; 30 percent is effective up to 6 hours. Concentrations of 20 to 25 percent are equal to 15 to 20 percent DEET. Not as effective on sand gnats, biting midges and other 'no-see-ums.'
The Center for Disease Control advises against using lemon eucalyptus oil on children under three years of age.
May cause a reaction on sensitive skin at any age.
Here are some PMD-based products:
•Botanical Lotion Insect Repellent by Off!: 10 percent PMD. Available in lotion, wipes.
•Lemon Eucalyptus Natural Insect Repellent by Repel: 30 percent PMD. Available in pump spray.
•Lemon Eucalyptus Insect Repellent by Cutter: 30 percent PMD. Available in pump spray
•Mosquito Coast Insect Repellent by Bull Frog: 20 percent PMD. Synthetic base with aloe vera. Available in aerosol-like Eco-Spray, wipes, and with sunscreen.
Picaridin (pih-CARE-a-den), more accurately icaridin, is known to cosmetic chemists as 2 hydroxyethyl isobutyl piperidine carboxylate. Also termed KBR3023, Bayrepel or Saltidin, it has been Europe’s DEET-replacement for many years. It is almost free of color and odor and has low oral, dermal and inhalation toxicity.
The longest-lasting repellent, according to the Center for Disease Control, a 20 percent picaridin concentration protects for up to 8 hours, outlasting DEET. A 5 to 10 percent concentration is good for short-term protection. Also works well on sand gnats, biting midges, and other 'no-see-ums.'
Here are some picaridin-based products:
•Skin-So-Soft Bug Guard by Avon: 20 percent picaridin. With aloe and vitamin E. Available in pump spray and with sunscreen.
•Tick Defense by Repel: 20 percent picaridin. Available in aerosol spray.
•Natrapel 8-Hour Insect Repellent by Adventure Medical Kits: 20 percent picaridin. Available in aerosol-like Eco-Spray, wipes.
Permethrin is applied only to clothing and gear. It can even kill ticks, another disease carrier. The neurotoxin acts like natural pyrethrum extract from chrysanthemums. Except for one big drawback: cats that inhale permethrin fumes may undergo hyperexcitability, tremors, seizures, or even death, though it’s said to be safe once dried. Like pyrethrum, it is also dangerously toxic to fish. Not effective when applied to the skin.
Caution: Permethrin can be toxic cats and fish.
Fabric sprayed with permethrin can be washed a half-dozen times before becoming ineffective. Commercially treated clothing can go through ten times as many washes and the permethrin is sealed into the fabric for cat safety. REI, Cabela’s and other outdoor sports stores carry permethrin clothing, including hats and neck and ankle gators. A treated long-sleeved shirt, even just worn open as an over-shirt, is essential in high infestations.
Here is a permethrin-based product: