No surprises - they are attracted by food.
One day this summer I was at the large pool and noticed an army of ants marching along under my sun bed in the joint between the tiles.
I followed the trail for about 10 meters. The ant trail led along to the pool life guard's lunch bag. They were stealing his lunch !!
I alerted him to his plight.
These were dark, almost blacks ants.
Later that day on my balcony I noticed some smaller red ants. These were few and randomly roving about. But I guess if they discovered food
on the balcony they would be soon an army of them.
You can buy ant powder down at the 'hardwear store in Sabi - near the roundabout.