Less can be more with repellents
"The more, the merrier" and "seeing is believing" are both mistakes when applying insect repellent.
"For best results, you really do need to cover every square inch of exposed skin and clothing," said Ludek Zurek, entomologist with Kansas State University Research and Extension. "A mosquito can hone in on an unprotected spot that's dime-size.
"At the same time, though, you should apply repellent sparingly. Saturating your skin or clothes does nothing to increase product effectiveness."
This year's new clip-on, fan-distributed repellent sounds like an easy way to achieve coverage without a direct application. TV ads for the product have reinforced that view.
Based on its own instructions, however, the product has several serious short-comings, Zurek said.
"They include the suggestion that you clip the product to your waistband," he explained. "Yet, they also provide a string of precautions--including that you avoid contacting the product with your skin, eyes or clothing. You're also supposed to avoid breathing the product's fan-distributed vapor and keep it away from food.
"Besides, the product doesn't seem to be very practical unless you're basically going to stay in one place. The instructions say that whenever you move, you have to allow a few minutes for the unit to rebuild its protection. That would be a problem if you were mowing, playing touch football or using a swing."
Applying other products evenly on skin is easiest with towelette, stick, liquid or creams repellents--although sprays can be evened out if spread by hand, he said. For good coverage on clothing, however, aerosols or pump sprays always work best.
When selecting among products, however, content can be more important than form, Zurek added. Repellents can contain different active ingredients and different percentages of the same active ingredient.
The percentages have nothing to do with how well the products work. They indicate how long the products will provide protection.
"Even the manufacturer of DEET--the most proven repellent you can buy--recommends that you select on the basis of how long you'll be outside," he said. "Depending on the weather and your activity level, a 7 to 10 percent concentration of DEET is good protection if you're just going outside for a little while. A 30 percent product can protect you for four to five hours.
"No matter its percentage, though, you reapply only if the mosquitoes start biting because you've stayed out longer than you planned or sweat your first application away."
Zurek pointed out four important exceptions to these rules:
--Spraying plastics, leather or rayon with repellent can cause surface damage.
--Protection from ticks requires at least a 20 percent-concentration product.
--No matter what, follow label directions exactly--for example, on how many separate times you can reapply the product safely. --And, wash off the repellent as soon as you return indoors.
In most cases, combination sunscreen-repellent products aren't a good idea. If you reapply them as often as you need more sunscreen, you can end up with too much repellent too soon.