Adams Plus Flea & Tick Collar for Dogs begins to kill fleas, ticks, flea eggs, and flea larvae immediately. Its full protection against ticks will be built up within a few days of placement on dog. Provides protection for up to 7 months. Wetting will not impair the collar’s effectiveness. Do not use on puppies under 6 weeks of age. If used on pregnant or nursing dogs, do not replace collar until puppies are at least 6 weeks of age. Contains 14.55% tetrachlorvinphos and 1.02% s-methoprene.