Please do not kill ants. They are sentient beings like you and me. Do not kill.I have this problems too, until I found out something, after I took time, following their trails. When you have ants, appearing out of nowhere & then everywhere..even you killed quite many, even by spraying insecticide or try all sorts of killing methods, they still appear!!.
They have a nest or nests nearby, find that & destroy it...the problem will be gone.
Instead, keep your environment clean, free of food crumbs or droppings. This will discourage them and they will move away without you killing them. Good for your karma too.
Amituofo.