Farms, especially those with animals, attract flies. This can be a real challenge for agritourism venues, especially in food areas where flies try to get on the guests' food.
On a recent trip to consult for a farm south of St. Petersburg, FL, Randy, our CEO, stopped at Mullet's Fish Camp for dinner. There he discovered "fly fans" that the waitstaff promptly brought to his table when the meal arrived that had fish as the entrée, a fly magnet. He says the fan really worked. There wasn't a single fly invasion of his food, although there were plenty of flies around. He also highly recommends Mullet's Fish Cam p if you are ever in the area.
Fly fans are available from many national retailers, including Amazon.