When I was little, I grew up in the country down in south west Florida. It's hot there, and fleas are a major problem. I was allowed to adopt stray cats, and had a few outside kitty friends. Fleas were a serious SERIOUS issue, however we went to the vet and got Advantage, drops that went on the back of their necks. It was a miracle cure. Not one flea on them, ever, unless we were late in re-application (one vial per month.)