I've met these guys before. I feed Zorro & Stanley on the patio and on one rare occasion (they always eat the last bit) there was 1 tiny piece of dry food left. So, I go out for a smoke. Yes, bad habit. But its out there for all to know! (Haven't done it in the house for 7 years). I look down and there they are. All over this bit of food. The troops are a coming n' a going. Its a remarkable site. So I sit there watching and realize that they are doing something that we, the free willed, would probably not do. They have a route that they do not waver from a fairly straight line. Some are circleing the bowl, others are on their way back, passing others on their way in. Next time I'm out there not a soul in site.
I think these teeny tiny ants show up once a year. I've never paid attention to when they come so this entry will help me next year! I'll be armed and ready.