Our fleas and ticks became immune to the stand-by drops and I found Seresto. It's a product that absolutely works, and for eight months! We have six cats and flea and tick control gets expensive. It was worth it but it had to be planned for in advance. Now I've found Pet Bucket and save $20-$40 for each collar and no ticks or fleas, no trying to catch six cats once a month, trying to remember to do it, it's a win/win.