They have to use the cat door to go outside or come inside. Unless we're standing by the door. Or unless they're Charlie and jump at the screen and just hang there.
So many flies. Not so many when the screen doors and the garage door are shut.
A couple of the cats will not do the cat door. Phoebe. Ross. Bobby. I think pretty much all the other cats do it. Bobby surprises me, I'd think would have been the first one to learn it.