Because of the way they slow down the evaporation of the DEET, lotions always last considerably longer than sprays of comparable DEET concentrations. Sprays have the advantage of being able to be applied to clothing. Sprays remain effective much longer on clothing than on skin. Since repellents work as a 3″ barrier, clothing applications can often protect 6″ of exposed skin and significantly reduce your usage on skin. Our recommendation: DEET lotion on skin and Permethrin spray on clothing.