We have indoor\/outdoor cat who I put Advantage II on every month, sometimes every 3 weeks. The medecine worked great. But we also were getting fleas in the house, and the fleas would bite my 3 year old grandson who is so very allergic to flea bites. His mom found these, got us one and it worked. I ordered 3 more, one for each bedroom and living room. They stay on all of the time. I was surprised at the number of fleas that got on these traps. I have had these traps about 6 months now and need to replace the sticky paper for the first time. (the sticky paper is covered with fleas). I was embaressed at the number of fleas, but then I noticed that the cats had no fleas on them and I have not used Advantage II on them in 3 months. I comb them occassionally for fleas and do not find any and the cats are not scratching either. I think they still bring the fleas into the house, and then the fleas leave the cats for the sticky paper. And my grandson does not get bitten by fleas when he is at our house. It is almost April and the flea will get worse with the warm weather. I hope these traps continue to attract the fleas from our cats in really warm, humid weather like we have here in the Southern U.S.