Military uniforms and mosquito nets are treated with permethrin, a repellent and insecticide used for personal protection against biting flies, mosquitoes, and other disease-carrying insects. Vector-borne diseases such as malaria, leishmaniasis (a parasitic infection spread by sandflies), Zika virus, West Nile virus, Lyme disease, and more can be diminished if treated nets or clothing containing the proper amount of permethrin are utilized. Washing and wear depletes the insecticide on the material, eventually rendering it ineffective. Currently, there are no commercially available colorimetric (color-changing) tests available to gauge the amount of permethrin left in fabrics after use and repeated washes. CDC researchers developed a rapid and simple technique using a reagent to quantify the amount of permethrin in the treated fabric. The low cost colorimetric spot test yields color intensity proportional to the permethrin concentration levels and has been adapted into a prototype for field testing. The technology provides a rapid means to evaluate permethrin-treated materials, such as military uniforms, outdoor gear, mosquito nets, and curtains.