Frontline plus for cats is a fast-acting waterproof flea and tick treatment proven to kill adult fleas flea eggs flea larvae chewing lice and ticks. Approved for use in cats and kittens this month-long treatment is made for cats eight weeks or older weighing 1.5 pounds and greater. This treatment breaks the flea life cycle by killing adult fleas as well as the eggs and larvae preventing further infestation.