Mosquito Repelling Crew Socks are the newest weapon in the ground war against mosquitoes. Made of a Nylon/Polyester/Spandex blend, they’re treated with invisible, odorless Permethrin, the active ingredient in Insect Shield. The Permethrin repels mosquitoes (including those carrying West Nile virus and malaria), ticks, ants, flies, chiggers and midges (no-see-ums) and lasts for 70 washings. Available in Black, sizes S/M (Women’s 4-7.5), M/L (unisex design, fits Women’s 8-10.5 / Men’s 7-10) and L/XL (Men’s 10.5-13).