Never spray tropical ants, it just causes them to disperse into even more colonies. Maxforce is the quickest way to wipe out insects. Although if you live in a block of flats it won't be long before they're back again. Unless the whole block is treated it's a losing battle. We had ghost ants and I had to get my brother in NY to send me a supply of Maxforce baits as the stuff you can get in the UK is too weak and can take up to a year. Maxforce did the job in a few days.
I think it's the large sacks of rice and suchlike that some people buy that introduces them to flats.