Looking at the picture, the one problem I see with that product is that the minute your cat takes his/her paw right off the step the lid will snap shut right in front of your cat's face. That could be really annoying to the cat. I would get rid of the ants. I don't know how affective this is on ants but when I first moved into the condo where I live now I had a roach problem and I was told to buy some of those plug in devices from Home Depot that create a sound wave that people, dogs and cats can't hear but scares away roaches and other insects. I haven't had a single roach in my home since I've had these plugged into the walls. So perhaps after exterminating your ants you might try plugging these into the walls so they don't come back.