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Summer fun is easily ruined by insects.

Ask any dermatologist or military commander what to do to avoid mosquito bites and you'll be told that DEET is the answer (New England Journal of Medicine, July 4, 2002).

The U.S. military developed DEET in the 1940s to protect its personnel from diseases carried by mosquitoes, biting flies, other insects and ticks. Such critters intensely dislike the smell of DEET and avoid it.

The trouble is that many people also dislike DEET. It can irritate the skin and has a greasy feel.

Questions have been raised about neurotoxicity, especially when combined with permethrin, used on clothing to repel insects (Pharmacology, Biochemistry and Behavior, February 2004).

Nonetheless, a 33 percent DEET cream made by 3M (Ultrathon) is the standard-issue insect repellent for the military.

Other ingredients have been tested and are approved by the Food and Drug Administration for deterring insects.

Picaridin is apparently about as effective as DEET, but there have been fewer skin reactions reported. It is used to repel ticks, chiggers, fleas, biting flies and mosquitoes.

Another compound, IR3535, has been used in Europe for decades and is classified as a biopesticide because it is closely related to the amino acid alanine. In the U.S., it is found in Avon Skin So Soft Bug Guard products as well as BullFrog's Mosquito Coast.

Other natural approaches include products containing oil of lemon eucalyptus (Off! Botanical, Repel Oil of Eucalyptus, Fite Bite) or citronella (Buzz Away, Green Ban, Herbal Armor, Natrapel), derived from lemon grass.

A product combining soybean oil, coconut oil and geranium oil (Bite Blocker) works longer than citronella but does not work against ticks.

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Readers' tips

They say these things work for them:

"I have used the 'Dirt Doctor's' (Howard Garrett) formula for mosquito repellent with great success: Mix 8 ounces water with 2 teaspoons vanilla extract and 1 teaspoon orange oil. Spray this on liberally. It gives me about six hours of protection."

In a similar vein, a reader remarked: "My daughter made me an herbal insect repellent that I found very effective. It doesn't work for everyone, but it does for me. Mix 3 ounces distilled water, 1 ounce almond oil, 10 drops peppermint oil and 10 drops lavender oil. Shake before spraying it on skin.

"Unlike the commercially prepared herbal insect repellent I have tried, this does not give me a rash."

Another reader has a different approach: "I take odorless garlic gel caps every day to help my circulation, and mosquitoes stay away while biting everyone else! There is no odor with these gels, so it's just another benefit of garlic that I didn't plan on."

Such remedies don't work for everyone.

One woman wrote, "I started applying coconut milk, thinking it might help my skin from a lot of sun exposure during yard work. A side effect I noticed was that the mosquitoes were not biting me. Neither did ticks, though they'd been a serious problem before. My neighbor says it doesn't help her, though I'm not sure why."

You'll find more stories from readers about natural mosquito repellents at

Joe Graedon is a pharmacologist. Teresa Graedon holds a doctorate in medical anthropology and is a nutrition expert. They answer letters from readers via their website: