How about simply killing them, Lucky? I don't know why they would be attracted to your plumeria. I have dozens of plumeria and have never noticed any ants on them. If I did, I would put a pinch of Orthene Fire Ant killer on the top of the media. This stuff quickly kills the ants and won't harm your plants. It works in hours for me. I occasionally have to use it on my orchids and staghorn ferns that are outside.
