The Best Insect Repellents: Debugging Your Summer

Protect yourself against biting insects, including flies, mosquitoes, gnats, midges, and ticks, by choosing the best insect repellents.
By David Petersen
July/August 1989

Hikers should be especially careful to take protective measures against biting insects such as ticks, which carry Lyme disease.
PHOTO: ALLSTOCK/RICK MCINTYRE


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Nature writer Ann Zwinger has said that flies are the price we pay for summer. I would add mosquitoes, gnats, ticks, chiggers and biting midges to the bill. At one time or another, I've been driven from scenic campsites, lucrative fishing holes, vegetable gardens in need of tending and backyard barbecues by each of these little horrors.

And so, quite likely, have you.

This in spite of the fact that humanity began, thousands of years ago, slouching toward the development of defenses against our insect nemeses—including anointing one's body with urine or the juice of wild onions (Allium), smearing down with mud or bear grease, and building smudge fires and squatting in their choking, sooty smoke.

The trouble with these and other primitive tactics, aside from the fact that few of them worked, was that they tended to be more repellent to the users than to insects.

Only in the late 1940s did science finally devise an efficacious insect repellent, an oily liquid. But it would be a decade more before the advent of the Great Victory—the combination of effective chemical insect repellents and convenient aerosol sprays.

The aerosols were an instant commercial success. Never mind that their chlorofluorocarbon propellants were aiding the depletion of the earth's life-critical ozone layer—who knew beans about ozone back then? And never mind that they stained clothing, were oily and stunk. All of this we were willing to endure because we finally had a personal antibug weapon that worked. Most of the time. And it sure beat bear grease and smudge fires.

Today, while bothersome flies, mosquitoes, gnats, ticks, chiggers and biting midges (Ceratopogonidae: the infamous no-see-ums of the far north) are still very much with us, our repellents are more effective, less offensive and pose a significantly diminished risk to the environment (see the accompanying sidebar at the end of this article). We'll examine how to choose and use insect repellents in a moment. First, though, a look at the enemy.  

Flies

Earth is host to at least 60,000 and perhaps as many as 100,000 species of flies. Among the world's most adaptable creatures, flies have evolved to live almost everywhere, no matter how harsh the environment. The snow fly, for example, is active in cold as deep as 14 °F, while the larvae of Ephydridae can live in sulphur hot springs. For the average outdoors enthusiast or backyard recreationist, the most common and bothersome of the flies are the house, horse, deer, bot, blow, black and fruit varieties. (While mosquitoes, gnats and biting midges technically are flies, I think they rate separate billing.)

All flies develop via metamorphosis, undergoing a four-stage life cycle comprising egg, larva (those lovable maggots), pupa and adult phases. With some species, under favorable circumstances, the entire growth process, egg to adult, can be completed in one week. Over the three weeks that follow—the life span of the average adult fly—each female will lay hundreds of eggs. Most of these, within another week, will have become yet more adults laying yet more eggs. A hellish cycle it is.

To kill flies outright without endangering the health of your family and pets with noxious pesticides, there are flypaper, lure traps and the venerable and even sometimes entertaining hand-wielded swatter.

When outdoors, keep your body and clothing clean, seek out breezy campsites and, as necessary, apply an effective and safe insect repellent.

Mosquitoes, Gnats and Biting Midges

Of the world's 2,500 to 3,000 mosquito species, the contiguous United States know but 150 to 200. Plenty enough.

While male mosquitoes are content to dine on the nectar of flowering plants, females, in order to reproduce, must have fresh blood. To satisfy this Draculan craving, the "gentle" sex—of the mosquito and of various other biting fly types—is equipped with an elongated snout, or proboscis. At the tip of the proboscis is situated the mouth with its feeding implements—sharp blades called stylets. It's these tiny scalpels that pierce our skin and lacerate our superficial vessels so that blood can be drawn up through the strawlike labium.

Nasty business.

It's easy to understand why some veteran outdoors people, too often stuck and sucked, have developed vengeful approaches to mosquito control. For example: The West's most eloquent desert rat, Edward Abbey, when pressed by the necessity of thirst, used to swig water from slickrock potholes swarming with mosquito larvae. Abbey reported that the tepid organic soup had the sweet taste of revenge.

Amusing pastimes, perhaps—right up there with swatting flies—but perhaps too slow and demanding for some. Instead, people desperate or in a hurry to get rid of mosquitoes sometimes purchase expensive, noisy "bug lights" to zap flying pests en masse. This is a mistake. Not only are bug lights with their big blue eyes and loud poppings and sizzlings rude annoyances to neighbors, they've been shown to attract more mosquitoes than they kill, providing a net gain. Your loss.

Better to adopt the organic approach. Drain any stagnant water on your property (perhaps the sole positive side effect of last summer's drought was fewer mosquitoes), keep a clean yard, apply pyrethrum (a relatively safe organic pesticide made from the dried flowers of the chrysanthemum) to problematic areas, put out the welcome mat for bats and skeeter-eating birds and, when possible, stay indoors during the dusk and dawn bug-happy hours.

When outside, dress in neutral colors, try to avoid working up a sweat (perspiration is an attractant) and, as necessary, apply an effective and safe insect repellent.

Ticks

While the tick's bite isn't generally painful, the little devil nonetheless is singularly disgusting in its proclivity for seeking out the warmest, moistest, fuzziest—and therefore the most personal and sensitive—parts of the human anatomy.

Ticks. They've always been a nuisance. But now, in some areas, they're a terror.

You probably already know about Lyme disease—caused by a tick-carried bacterium (Borrelia burgdorferi ) capable of producing severe skin rash and flulike symptoms including headache, nausea, coughing, sore throat, exhaustion, dizziness, chills, fever, and pain and stiffness in joints and muscles. It's capable also of causing ear, back and chest pain, as well as troublesome swelling of the lymph glands, testicles and spleen.

If left untreated, Lyme disease can lead to heart and nervous disorders and symptoms mimicking meningitis and rheumatoid arthritis. Although Lyme disease is not in itself a killer, in a rare few cases the complications arising from protracted infections have led to death.

Lyme disease. An unpleasant proposition and not at all uncommon these days. In fact, in some areas, especially coastal New England, Lyme disease has in recent years reached epidemic proportions. While prompt treatment with common antibiotics, such as penicillin and tetracycline, leads to total remission of symptoms in most cases, more advanced infections may require more extensive long-term care.

Better, obviously, to avoid contracting the disease in the first place by avoiding its vectors—deer ticks (Ixodes dammini in the eastern and central U.S., and its disreputable cousin I. pacificus in the West).

Deer ticks (now more often called Lyme ticks) are parasitic not only on deer, small rodents, humans and our pets, but infest more than two dozen bird species as well. This airborne transport makes them highly mobile. To date, thousands of cases of Lyme disease have been verified across some three dozen lower-48 states. The bad months are May through August, with the majority of infections occurring in July.

Ixodes, together with other species that carry Rocky Mountain spotted fever, Colorado tick fever, tick paralysis, relapsing fever and tularemia (rabbit fever), present a threat worth defending against.

When working or playing in infested areas, try to avoid contact with brush or tall grass; it is here that ticks like to lurk in ambush. Wear a wide-brimmed hat, a long-sleeved, collared shirt and full-length pants, their cuffs tucked into long socks. In particularly bad areas, douse clothing and skin around likely entry points (neck, waist, wrists and ankles) with a safe, effective repellent.

One repellent intended specifically for use against ticks is an aerosol called Permanone. Developed initially for the U.S. military, Permanone is now registered for over-the-counter sale in most states. The active ingredient is permethrin, which is said to be 100% effective when sprayed on clothing at likely tick-entry points. It smells faintly like cleaning fluid when applied but becomes odorless when dry, and is tenacious, claiming up to 48 hours' protection with one application.

The only good news about Lyme ticks is that they need eight hours or more to inject enough bacteria into your body to cause problems. This allows time to find and remove the ticks.

As soon as you come in from a foray through ticky woods, strip down and make a careful inspection of your entire body. Pay special attention to dark, damp, hirsute areas such as armpits and groin. If possible, have a (close) friend inspect your back, hair and anyplace else your eyes can't reach. Some ticks are large and obvious, but the Lyme tick is a mere pinhead, so search diligently.

Concerning tick removal—recent research has reversed traditional wisdom. The following excerpt from an Air Force directive to commanders and medical personnel, dated June 1987, while not the best example of English composition, nevertheless concisely summarizes current expert opinion on the how-to, and how-not-to, of tick extraction:

"Gentle tugging of the head of the tick with tweezers at the place where the tick has attached to the skin is the best method for tick removal. The application of petroleum jelly, nail polish remover, gasoline, lighter fluid, a lighted match or alcohol on the tick are not satisfactory means of tick removal. These methods do not usually work, are potentially dangerous, and may increase the risk of transmission of infection. Crushing of ticks should be avoided, as the contents of the tick may be infectious."

Once a tick is out, cleanse the puncture wound with rubbing alcohol or another antiseptic.

Choosing a Safe and Effective Insect Repellent

An "effective insect repellent" can be most any product containing DEET (N,N-diethyl-meta-toluamide). Or Rutgers 612 (2-ethyl-1,3hexanediol). Or citronella (a lemonscented oil extract of the Eurasian grass Cymbopogon nardus). And for those of us boycotting aerosols, several effective and convenient application alternatives are now available, including pump sprays, creams, liquids, sticks and towelettes.

The most powerful insect repellent is DEET. It confuses, irritates and repels flies, mosquitoes, gnats, fleas, ticks and biting midges. The percentage of DEET required to repel insects varies with the type and abundance of the pests, time of year (our local Rocky Mountain skeeters, for example, are far less robust and resolute early and late in the season) and personal attractiveness (it's probably not merely your imagination if bugs seem to prefer your flesh over that of your companions).

For most people in most short-duration outdoor situations, it doesn't take much DEET to get the job done. The prime example of this is Off! aerosol, which, with only 15% DEET, still manages to be one of the most popular repellents on the market.

At the other extreme, a demand has grown for full-strength (95%) DEET repellents, which many if not most manufacturers now offer in their product lines. While increasing DEET content beyond about 50% seems to offer only a slight boost in repellency, the stronger brews do stay on the job longer; most full-strength DEET products claim "up to 10 hours protection" from a single application.

While some people, especially children, can develop an allergy to DEET, and the stuff is poison if swallowed, it's generally safe for application directly to the skin.DEET's primary drawback is that it will melt plastics and watch crystals and will damage some paint finishes and synthetic fabrics (nylon, thankfully, is immune). Additionally, DEET tastes awful should you accidentally get a bit on lips or tongue, and, in concentrated form, stinks and feels unpleasant on the skin.

The leading brand containing Rutgers 612—an older repellent than DEET, and less effective—was long known simply as 6/12. Nowadays there's 6/12 Plus, the plus being a dash of DEET. Rutgers 612 gets the job done in most situations, is safe to apply to bare skin and provides a good alternative for those few individuals who manifest an allergy to strong doses of DEET.

Repellent products containing citronella—such as Natrapel—are neither as long-lasting nor as effective as those with DEET or Rutgers 612. However, citronella does help hold flies and mosquitoes at bay and is organic, pleasant smelling and safe. Citronella repellents are a good choice for infants, small children, the hyperallergic and pets, as well as for those who simply prefer organic substances over laboratory chemicals.

Since repellent effectiveness is a direct result of the type and amount of active ingredient a particular product contains, all brands having similar percentages of DEET are more or less equally effective. Smell, ease of use, and comfort on the skin, however, do vary considerably between brands. To help you narrow the choices, the chart below compares fourteen popular brands, giving type and percentage of primary active ingredient, plus some subjective comments.

One Beauty of a Bug Repellent

One effective insect repellent is marketed not as a repellent at all, but as a beauty product. A bath oil, to be exact. Avon Skin-So-Soft, to be precise.

Maybe you've already heard the story: Someone, most always a female someone, uses Skin-So-Soft after a bath or shower, ventures outdoors, is set upon by mosquitoes or gnats—and is amazed to see the little beasts turn proboscises and flee.

Pump-sprayed or rubbed on full strength, or cut by half with water, it doesn't seem to matter.

Unfortunately, Skin-So-Soft repels me as effectively as it does mosquitoes. It has a strong perfume fragrance, and perfumes turn me off. Of course, I realize that in this view I'm something of a "contrarian"; a great many people do like perfume—or at least prefer it to the smell of most insect repellents. Therefore, if you have an aversion to the smell or feel of "real" antibug products, give your Avon lady a call.

A Minimalist Approach to Using Insect Repellents

Since I raise a small garden, cut several cords of firewood a year, hunt, fish and am addicted to long evening walks in the woods surrounding my rural home, I'm outside during the buggiest hours on almost a daily basis. Through trial and error, I've come to favor a minimalist approach to the use of repellents.

Around home, hanging from hooks near the back door, I keep an old cap and a thin cotton long-sleeved shirt well pump-sprayed with a full-strength DEET repellent. As I head out to work in the yard or garden, I simply don the cap and pull on the shirt. One application of repellent every couple of evenings seems to maintain adequate protection in most situations.

On a typical evening walk, I'll go out dressed in jeans, a T-shirt and cap. In a fanny pack, along with other constant companions such as a compass and waterproof matches, I carry my "bug shirt" and two small containers of repellent—one low-powered and not unpleasant, the other packed with the punch of full-strength DEET.

My first line of defense is simply to move briskly, making it difficult for flying prospectors to land and drill. As the evening progresses, the air cools and the mosquito nuisance increases, I slip on the bug shirt. Most often, this is all the protection needed. If I decide to stop for a while in one place or happen to stray into a particularly buggy area, I'll apply a bit more repellent around the brim of my cap, along the top edge of my shirt collar and at the cuffs. Only in dire straits do I apply repellent directly to face, neck and the backs of my hands—and even then, except at the absolute very worst of times, I always limit myself to the low-strength formula.

Relieving Bug Bites

In spite of our best efforts, we'll all get bitten this summer. No big deal, though, since several products are now available for near-instant relief. I've tried three: Sting Eze comes in a small, dropper-type bottle and relies on camphor as its primary active ingredient. After Bite—in a pen-type applicator—and Hy-Grade lotion (which, like Skin-So-Soft, is marketed as something other than a bug product) both contain ammonia as their primary active ingredient. All three work well to relieve the pain and itching of a wide range of bites and stings.

Biting Insects: In Defense Of The Enemy

Why, it's fair to wonder, do biting insects exist at all? What mysterious niche in nature did they evolve to fill?

There are, of course, explanations for the presence of specific species in specific biomes. But a broader and more satisfying justification is this: Noxious insects—some of them vectors of horrid diseases, others merely unbearable nuisances—help to slow the anthropocentric despoliation of Planet Earth.

How? By making some areas unfit for human settlement and exploitation, or at least delaying both.

To paraphrase environmental philosopher Christoph Manes: The mosquitoes, chiggers, ticks, scorpions, fire ants, hornets—all the little things that God in his wisdom put on this earth as a last defense against Industrial Man—have saved more wilderness than the 10 biggest environmental organizations combined.

In that respect, I say Amen and more power to them.  


Aerosol Propellants: A Repellent Concern

According to the Environmental Protection Agency (EPA), you needn’t worry overmuch about depleting the ozone with your can of bug spray. In the U.S. the villains—the chlorofluorocarbons (CFCs) once widely used as aerosol propellants—are a thing of the past.

While some manufacturers voluntarily discontinued the use of CFCs some two decades ago, substituting hydrocarbon propellants such as butane and propane, others made the switch only in 1978, when CFCs were banned jointly by the EPA and the Consumer Product Safety Commission. (Now, if only we could get the rest of the world to follow suit!)

Even so, aerosols aren’t out of the woods yet. While the new hydrocarbon propellants don’t attack the ozone, they do contribute to urban pollution and the greenhouse effect—albeit in a relatively small way: In a given year, all the aerosol cans in an entire city probably don’t put out an amount of hydrocarbon pollution equal to that belched by a mere handful of automobiles. Still, no matter how slightly, hydrocarbons do pollute. That’s one strike against aerosols.

Hydrocarbon propellants are also highly flammable. Strike two.

Finally, aerosols are inefficient and wasteful. Not only do aerosol repellents cost more per ounce than creams and liquids, but not all of what they spray lands on your skin and clothing. And in order to achieve maximum effectiveness, you still have to rub the stuff in, so your hands get repellent on them either way. Strike three—but a long way from out.

As long as lazy consumers demand the convenience of the push-button spray, I’m afraid the minor evil of aerosols will remain with us. 

 


A Guide to Insect Repellents: DEET Content

Ben’s 100: pump spray or squeeze bottle (mild chemical smell; oily)—95% DEET.

Cutter: cream (lime-scented; rubs in like a hand lotion)—33.25% DEET

Cutter Original: aerosol (almost no odor)—26% DEET

Cutter Evergreen Scent: aerosol (mild pine scent)—26% DEET

Muskol Original: aerosol (very mild chemical smell)—25% DEET

Muskol Maximum Strength: aerosol (mild chemical smell)—40% DEET

Natrapel: pump spray (pervasive citrus scent; organic)—10% citronella

Off!: aerosol or pump spray (mild chemical smell with a hint of citrus)—25% DEET

Off! Deep Woods: aerosol or pump spray (mild citrus smell)—25% DEET

Off! Deep Woods: towelettes (each 7 3/8” x 5 1/2” towelette comes in a sealed foil packet and has coverage for an adult’s face, neck, arms and hands; citrus scent over mild chemical smell; towelettes are clean and handy, but present a strong temptation to litter)—30% DEET

Off! Maximum Protection: pump spray (mild chemical smell; oily)—95% DEET

Repel Sportsman’s Formula: pump spray or squeeze bottle (very mild chemical smell)—52.25% DEET

Repel 100: pump spray (mild chemical smell; oily)—95% DEET

To summarize, repellents with low percentages of DEET generally are less offensive to the nose and more comfortable on the skin than those containing higher percentages. They just don’t repel as well or last as long. Therefore, probably the best approach is to select the lowest strength of formula that will get the job done given your area and circumstances—then hedge your bet with a small container of a full-strength DEET repellent for those unexpected situations when nothing less will do.


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Post a comment below.

 

Donna_42
4/1/2007 6:10:40 PM
We need to Know what Lime dust would do to ticks and other yard pests if it would help or not.








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