I always had trouble with ants getting into my feeders, no matter what I bought or tried, so decided to give these window feeders a try, and would not go back to the other kind.  Not only do the ants stay away, the hummers love them.  Another perk is the fact that I can watch the birds as they feed, and that is nice.  I have had no problems with the  suction cups. I always moisten them before attaching them to the glass, and leave them attached when I remove the feeders in the fall.