You are never going to stop flies. They exist, and will be a nuisance no matter what. However, especially around livestock, precautions can be taken to significantly reduce the amount of flies.
There are several different kinds of flies. Biting flies are a painful nuisance, and often carry diseases. Face flies spread the pinkeye virus among animals. Stressed, sick or bothered animals become uncomfortable, and that will affect milk production. It is important to try and get a system in place to reduce the amount of flies before production is seriously affected.
Flies love manure, so keep pens cleaned regularly. Manage manure piles by composting or spreading on the field. When spreading on the field, try to spread in a thin, even layer. It will help to fertilize fields. It also helps to keep manure pile levels down. It can deter flies from being able to lay eggs and have them develop. If spreading manure in a field won’t work, try to rake or spread out manure so it can dry out. This makes the environment less friendly for flies to breed.
A great, natural way to get rid of flies is to get assistance from predators. Certain wasps, spiders, chickens, and ducks all love to eat flies. There are even certain parasites that will not affect humans or animals, but cause great disruption for flies. The parasites kill flies in their early maggot and pupa stages.
Traps or tapes are a fairly effective way to catch flies as well. Some attract flies by sight, and others use scent. Follow directions of the product and flies will be attracted to the trap or tape. Fans can be a great help for this type of method. Put fans in an area where cows walk daily and have the fans blowing on the animals. The flies will be bothered and fly up where they will be attracted to tape or a trap.
There are certain feeds that contain chemicals that help eliminate flies. While it doesn’t affect the animal, the feed will help prevent fly eggs from hatching in manure.
Ear tags with insecticides (fly tags) can be purchased and put on your cattle. The tags will not affect the animal, yet help prevent flies from bothering it, especially around the face. Dust bags or cattle rubs are another economical solution to put on the farm. Cattle will bump or rub against them, and the insecticide that is on these implements will transfer over to the cattle.
“Fly Control Strategies for Your Barn.” Tractor Supply Co.
Hilton, W. Mark. “5 Essential Steps for Fly Control on Cattle.” Beef Magazine
“Natural Methods for Cattle Fly Control.” Southern States