Must be the recent spell of good weather. They were mad busy and the winged ants were swarming (wrong term I'm sure but you get the gist) both at our house and at the mother in law's at the weekend.
I had to close all the windows as these flying ants were everywhere last evening. Horrible things, a few still managed to get in to the house, looking for somewhere to set up a nest I suppose. Although it is amazing that some people don't notice them.
A leisure centre that I worked in years ago had an ant problem. We doused them with water & domestos. Followed it up with putting down powder. Problem solved, they were never seen again.