Well I have had fruit flies, or what every they are. The best way to get rid of them, a few simple steps I take, number one put all fruits away. Number 2 either set out a small glass of sugar water, or wine. They like the smell of sweet things so sugar water will draw them to it, once they get in there they wont be able to fly out. I know there are a few other tricks but I can't remember them.

As far as your cat(s) go, I am not sure about that. I know my cat loves to catch flies. I let one in one time while I was on the balacony and he loved it. He stood by the slider as if trying to tell me to let more in. But with fruit flies or what ever they are, I don't think they would do any harm to your cat(s). Maybe you should call your vet in the morning and find out.

Katie

P.S. I hope this helps.