Adams Plus Flea and Tick Collar for Dogs will begin to kill fleas, flea eggs, flea larvae, and ticks immediately. Its full protection against harder to kill ticks will be built up within a few days after being placed on the pet. For continuous flea and tick protection, replace the collar every 7 months. The active ingredient works its way to the surface of the collar and is rubbed onto the fur of the animal. The active ingredient moves through the oils and from hair to hair to cover the entire body. Wetting will not impair the collar's effectiveness or the pet's protection.