I have had an ant epedmic this year. And then they started aphid farming on my plants - you will probably notice them carrying tiny eggs up into the leaves. My advice is to get a reel of double-sided sticky tape and make some little collars out of cardboard, covered with the sticky tape and put them round the main stem. You need to refresh the sticky tape occasionally and check that there are no other points of access for the ants to climb up the plants e.g. remove the lower leaves and make sure the plant's leaves are not touching the window or other things the ants could crawl up.
You could probably do with spraying the aphids with horticultural soap (fatty acids), then putting the collars on. When I did this, I found that the "scout" ants would get stuck on the collars - warding the rest off. The ants continued to live on the honeydew excreted by the aphids though, as it falls in a mist from the leaves and onto the table. So the horticultural soap is the best idea, otherwise you will find the ants live on. And they won't eat any poison you put down for them until you get rid of the honeydew.
Its a tricky old business. I never had this problem last year, for some reason there were fewer ants. This year it got out of control quickly. Next year, I will pay more attention to getting rid of the ants and using the sticky tape and poison before the plant is infested with aphids.
Oh, the other thing I tried was vaseline round the rim of the plant pots. Pretty useless, so don't bother with that!
Hope that all makes sense. I might take a photo of one of the collars to show you.
