The cotton blend ExOfficio BugsAway Targa Sock provides long lasting, effective and convenient insect protection, and wicks moisture to keep your feet dry and cool. They also have arch support construction. Permethrin, the active ingredient in Insect Shield, is invisible, odorless, and tightly bonded to the fabric fibers, and lasts the expected lifetime of the garment 70 washes. It repels mosquitoes including those carrying West Nile virus and malaria, ticks, ants, flies, chiggers and midges no see ums. Insect Shield repellent lasts 70 washings.