I haven't yet seen ants on these flowers. If I a correct this one is a Dhalia. We also have a Peony which can look somewhat similar that atracts a lot of ants. Grrr, Imrahil
Oooh yeah, I get those two plants mixed up a lot. All I know is my mother always had the one in the front yard when I was a kid and they were always swarming with ants.