The Right Way to Apply Bug Spray

The most effective insect repellents include one of these active ingredients: DEET, picaridin, the chemical IR3535 or oil of lemon eucalyptus. "DEET, picaridin and IR3535 confuse an insect's sense of smell," says Kathy Cearnal, senior director of research and development for Spectrum Brands, which includes Repel and Cutter. "If a bug can't smell you, it doesn't know to bite you." Oil of lemon eucalyptus, on the other hand, acts as a true repellent, she says: "Insects don't like the smell, so they simply won't come near treated skin." The general rule is that the higher the concentration of the active ingredient, the longer the protection. For one to two hours outdoors, use a low level (5 to 10 percent) of picaridin or DEET; for a longer period (eight to ten hours) or a buggier situation, like a hike in the woods, use 20 percent or higher picaridin, IR3535 or DEET. Most products with oil of lemon eucalyptus come in a 30 percent concentration, which works well for up to six hours.