We tested a total of 10 formulations: Four of citronella, three of DEET (N,N-diethyl-meta-toluamide) and one each of oil of vanilla, soybean oil and prickly pear extract. Only three of the products provided more than one hour of protection with a single application: They were the 2 percent soybean oil (1.6 hours of protection), 4.75 percent DEET (2 hours) and 6.65 percent DEET (2.1 hours). One of the DEET products, a wristband with 9.5 percent DEET, had the shortest protection time (15 seconds), a result that emphasizes the importance of proper application. DEET works best when it is applied as a lotion, spray or cream directly to the skin, or when clothing, such as a mesh sweatshirt, is impregnated with it. DEET does not work as well when it is applied in small areas, even in a relatively strong form as on a wristband. This summer encapsulated DEET will be available in the form of a slow-release lotion which is supposed to prevent absorption of the repellent into the skin and make an application last longer.