yep you need to drown them out right about now then use whatever treatment you can get to try and kill the nest there are a multitude of compounds around.

the long term is to have all pots sitting over a tray of water eg.,. a pot sitting in 3 or 4 pieces of broken paver to hold the pot above the water, in a tray with water continully in place and the ants can't get back into the pot, plus the ones in there will eventually starve out, be sure that none of the foliage or any part of the pot touches any other plant or surface, or the ants will form a bridge.

sounds like a lot of work but it is about the only way short of suspending all the pots from a frame then having an oil soaked rag around any uprights so the ants don't climb up to get to the pots. suspended you could suspend a wire framed shelf to hold many pots.

len

Cheap no-name talcum powder gets rid of ants. Someone told me about this years ago and I just sprinkled it around the affected area and left it for 24 hours and then, miraculously, no ants. They never came back. I don't know what it is, whether it is the actual talc or the smell but it works. Ants were mentioned in the gardening form about 12mths ago and other contributors suggested this as well. You may need to sit your pot in talc for a couple of days if they are embedded into the pot plant. Good luck.