Herbs vs. Bugs

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

Turning away from the laboratory to the plant world for alternatives gives us few definitive answers; much is still uncharted territory. Volumes of anecdotal evidence and historical accounts exist on the repellent properties of many herbs, but few well-designed scientific experiments have been performed to test these claims. Research on this subject, much of it done in Third World countries, often has been only preliminary or has yielded inconclusive results, or the statistics don’t hold up to today’s standards. However, evidence suggests that herbal repellency is a subject offering promise for future research.

Herbal Possibilities

Please remember that herbs carry their own set of dangers and warnings. “Natural” does not mean “harmless”. I have several shelves of books about plants that are poisonous on ingestion or contact with skin. Herbal preparations should not be consumed or sprayed directly on skin unless they’re known to be safe. If applied to clothes instead of bodies, the repellency lasts longer anyway.

When asked what herbal insect repellents I can recommend, I must say that I’m a conservative: I stick to those plants and chemicals that are generally recognized as safe by the U.S. Food and Drug Administration. If they’re OK to eat, then I feel safe applying them to my skin and clothing. I avoid using, either internally or externally, any plants that are questionable. At the same time, I’m not willing to enhance my own body odor with some stinky formulation, bugs or no bugs.

For The Herb Companion, I have devised an herbal formula designed to repel mosquitoes, ticks, flies and fleas. It is a fragrant combination of the oils of basil, juniper, palmarosa, citronella, rose geranium, rosemary, myrrh, cedarwood, pine and lemon mixed into a base of grain alcohol. The formula is based on personal experience and a review of the scientific literature on insect repellency; its effectiveness has not been extensively tested. I’d be interested to know about readers’ experiences with this or any other natural substances they find useful as insect repellents.

Let’s look at these herbs, as well as other possibilities from the garden, and how we might put them to use against pests.

Mosquitoes

Mosquitoes are the most thoroughly studied insects in the search for repellents because these bloodsuckers transmit numerous diseases, including malaria and yellow fever. Citronella (Cymbopogon nardus), several species of basil and juniper have been shown to be effective against mosquitoes. Rose geranium, rosemary and several species of cedar all have shown promise in preliminary testing.

The oil of citronella, a fragrant grass of southern Asia, has long been used as an insect repellent and is often sold in candles that are burned on the patio in hopes of driving away mosquitoes in the evening. I use citronella candles myself, although I also question how effective they are: it seems to me that year after year and dollar after dollar I still scratch as much. A more effective way to use the repellency of citronella is to apply the oil to skin or clothing. The biggest drawback to the use of citronella oil on skin, however, is that the repellency fades fairly rapidly as the oil evaporates, and so it must be reapplied often. One experiment showed the maximum protection time of citronella oil against the yellow-fever mosquito to be only 1 hour and 18 minutes.

RSS | Comments | E-mail | Print