You think ants are bad you try box elder bugs, pincher bugs or the japanese beetles we get here every fall in Wisconsin. You will find them everywhere and there is really nothing you can do about it. At lease with ants you can cut off their scent trails that they leave and you will cure 90% of the problem. By the way I am with the rest of the crew that thinks something was spilled there at one point maybe not by you or it could even have been tracked in.