They are chasing after the grubs. Get rid of them, they'll leave. I've heard that Preen works, but any insecticide should get rid of them. I'm not sure who to recommend talking to. If I was looking for granular insecticide, I'd go to the local Farm Service, (FS, but I don't know if they are in your area). Local farmer, anyone who deals in agricultural chemicals. If your lucky, you won't need a chemical license to purchase. If you do, get a farmer to buy it for you. Or, maybe a local turf/lawn care specialist. Local golf coarse greens manager too.
