Resting places such as rafters, walls, and pen dividers should be sprayed. Insecticide baits should be placed in areas that pigs can not reach because most of these baits are sugar based and will be eaten by pigs. Without good sanitation, all of your other efforts will be wasted. Damp or spilled feed should be cleaned from around bins. This material is a food source for flies and will hurt your use of chemical baits.
Manure is an excellent breeding site for houseflies.
However, if the moisture content is below 30 percent or if the manure is liquefied, fly breeding is almost nonexistent. Manure should not be allowed to collect in or around barns. The following materials are cleared for use on swine to control mites, lice, and for use around barns to control houseflies. For complete application instructions, be sure to read the label before mixing and using an insecticide. Remember, label information can be helpful in controlling pests and preventing hazards to you and your livestock.