As any backpacker or outdoor enthusiast knows, swarms of mosquitoes and wee biting flies can manage to spoil the best of summer fun. When you feel as though you're the entrée on the hungry-insect menu, what options do you have besides using chemical repellents or seeking refuge inside? Try herbal essential oils, a great natural way to make yourself less appetizing to summer's peskiest little creatures.

Many synthetic insect repellents contain DEET, or N,N-diethyl-meta-toluamide, which, despite its ability to damage plastics, synthetic fabrics, leather, and painted or varnished surfaces, is deemed safe by the U.S. Environmental Protection Agency for use as a topical insect repellent. Because DEET can sometimes cause serious side effects, the EPA recommends "great caution" when using DEET on children and urges that it be applied sparingly to exposed areas and washed off after use. Possibly unaware of its toxicity, some 30 percent of Americans use DEET every summer.

The truth is, you don't have to resort to such high-stakes chemical deterrents. Herbal essential oils provide gentler solutions. For example, researchers at Iowa State University report that nepetalactone, the essential oil in catnip (Nepeta cataria), is ten times more effective than DEET at repelling mosquitoes (American Chemical Society annual meeting, August 2001). The reason it works, however, is unclear, according to entomologist Chris Peterson, PhD. (Also unknown is whether you'll attract cats while trying to repel bugs.)

Michael Vertolli, RH, clinical holistic herbalist and director of Living Earth School of Natural Therapies in Toronto, Canada, says that many herbal repellents are nearly as effective as synthetics. The main difference is that natural oils need to be applied much more frequently. How frequently depends on the blend and prevailing insect conditions, but hourly is a good guideline. If you are pregnant, speak to an herbalist before using any essential oils.

Herbal Allies
Besides catnip, several aromatic herbs fall into the insect-repelling category, including basil (Ocimum basilicum), camphor (Cinnamonum camphora), clove (Syzygium aromaticum), eucalyptus (Eucalyptus globulus), geranium (Pelargonium graveolens), lavender (Lavandula spp.), mint (Mentha spp.), and rosemary (Rosmarinus officinalis). Evergreen herbs, such as cedarwood (Cedrua atlantica), cypress (Cupressus sempervirens), fir (Abies alba), hemlock (Tsuga mertensiana), and pine (Pinus sylvestris), repel insects, as do lemony herbs, including citronella (Cymbopogon nardus), lemon balm (Melissa officinalis), lemongrass (Cymbopogon citratus), and lemon thyme (Thymus citriodora).

According to Vertolli, the essential oils of these plants help in various ways. "First, they disguise our scent," to which many bugs are naturally attracted, he says. "For this reason, the same combination of essential oils will not work for everyone. It depends on the interaction between the scent of the oils and the scent of the person's skin. Second, essential oils change the taste of a person's skin. Again, this effect depends on the natural taste of a person's skin. Finally, essential oils contain many constituents that are actually toxic to insects."

You may have to endure some bites, but the best way to find a winning blend of essential oils is to try a few. "Each person really needs to experiment and see what combination works for them," Vertolli says. "I usually use a combination of three or four essential oils."

Different herbs also repel different bugs. "I have yet to come up with a combination that works for all biting insects equally," Vertolli says. "I usually use a couple of combinations at different times of the year, depending on what insects are most prevalent."

For mosquitoes, Vertolli combines lemony citronella with an evergreen herb and an aromatic one, usually eucalyptus or camphor. His recipe for repelling blackflies and deerflies contains basil, lavender, and geranium.

Bug-free Zone
Here's how you can blend a topical repellent that keeps you bite-free—and that you won't mind wearing. Start by making a base to which you will add essential oils; the goal is something that won't sweat or wash off your skin too easily. For an oil base that's not too heavy and that penetrates the skin, Vertolli recommends a 50:50 blend of olive and almond oils. If this feels too oily, he suggests adding enough pure ethanol (grain alcohol) to comprise 20 percent of the base. To every ounce of oil, add the contents of a 400 IU vitamin E capsule to help preserve the mix. "You can also make a nonoily base by using 50 percent vodka, 40 percent water, and 10 percent vegetable glycerin," he says.

To the base you'll add essential oils. "This active part of your insect repellent should make up about 5 percent to 10 percent of the finished product," he says (see "Recipe for Relief").

With a little experimentation, you'll have a safe and effective natural insect repellent that lets you skip the chemicals and dodge the biting insects this summer.

Dena Nishek is a freelance writer and editor.