Just read the Countryside article, "Portable Fly Control: (and its environmentally friendly!)," and it was great! (Vol 94, No 3) It is about the Epps Biting Fly Trap, invented by cattleman Alan Epps. Flies are attracted to the sillouette of animals, so these large, part dark and part transparent sheets attract flies. They fly into the clear plastic which mimics the underbelly of an animal, and bounce off of it into a tray of water. You put 8 drops of soap in the water of any kind (LOC is drinkable by livestock), which breaks the surface tension of the water so the flies sink rather than float. It will catch about a pound of flies a day (gross!), and clear an area 2-4 acres of them. You replace the clear plastic sheets for $8 every few years, but that is much better than the chemical approach, which many insects eventually develop resistance to anyway. Even the lightweight, portable aluminum version can withstand 90 mph winds (held down by 2 sandbags), so the trap can be moved every time cattle switch pasture. The portable trap goes for $299, and can be gotten from
www.horselineproducts.com