Rake around feeders and waterers every day removing the moist feed that has been dropped. Pick up grass clippings, keep grass and weeds mowed, and pick up trash regularly. Be sure there is proper drainage in all stalls, pens, paddocks, and pastures. Repair leaking faucets, hydrants, hoses, and waterers. Eliminate wet spots in stalls and pens by clearing the bedding away, liming the stall floor, and letting the ground dry out.
Barn designs that allow sunshine to dry the floors are best.
If possible have an extra stall or pen so you can rotate a horse out of his regular stalls for a day or two each month to let his stall dry. Feeding your horse an oral larvicide daily can prevent the development of flies in the manure. However, the chemical that kills the larvae also kills beneficial microorganisms such as the ones necessary for decomposing manure. Several brands of oral larvicide are available. The approximate 1 ounce daily dose costs from 4 to 30 cents per day, depending on brand and amount purchased.