Pyrethrins are natural insecticides produced by certain species of the chrysanthemum plant. Pyrethrins are fast acting and extremely effective against cold blooded insects such as fleas and ticks. Piperenol Butoxide is a synergist to the pyrethrin and adds additional effectiveness. After use, this product will leave a small amount of residual insecticide in and on the ear for a few days or until the animal is bathed, because it's based on the natural derivitive of the chrysanthemum. It is safe for use on puppies and kittens, 12 weeks and older.