If anyone has ever been around cattle in the summer, one thing that can be overwhelmingly noticeable is the amount of flies on the bodies and faces of the cows. Most commonly, there are 2 types of flies that cattle deal with- horn flies and face flies. Horn flies bite and feed on the blood of the cattle, while face flies feed on the mucous secretions of the face, nose, mouth and wounds. Both are a major nuisance! They cause stress to the animals and can potentially transmit diseases, such as pinkeye throughout the entire herd. The conventional approach to the fly issue is the frequent use of insecticides either sprayed directly on the cattle or administered through a pour-on or oral drench. These methods are certainly effective in killing flies and minimizing fly related issues but they also have their downsides. Over time, flies will become resistance to the insecticide, thus requiring multiple insecticides to be used and used more often. Most insecticides are only effective for a few weeks at a time and then require another application, creating the need to round up the herd again creating stress and the possibility of injury to both animals and people.
The more you treat cattle with chemicals to address issues, the more you suppress the natural genetic predisposition of the animal to deal with external and internal parasites on its own. If you walk through any herd of cattle and observe fly numbers, you will notice that certain animals have a lot less flies than others. These animals are better equipped to repel flies naturally; This is a characteristic that can be bred into cattle over time. The biological effect of the chemicals on cattle can be argued but it really doesn't answer the fly issue as a whole either way.
At the end of the day, its important to limit stressors in order for the cattle to be healthy and perform well. I've seen many "organic, natural" farm operations that didn't want to use any chemicals, but their cattle were infested with flies and most of them had pinkeye, which can lead to the permanent loss of sight. I don't tolerate the suffering of an animal for the sole purpose of living up to a purist ideology. Trying to raise animals insecticide free takes active management and strategies that need to be adjusted and constantly improved upon to be able to ensure animal health and well-being. While no practice is 100% effective in eliminating flies, what we do at Harmon Creek Farms controls the fly populations to a manageable level without the use of chemicals.
The life cycle of the horn fly begins with adult flies laying eggs in fresh cow manure, the eggs hatch to become maggots by day 3 and then become adults by day 10-20 depending on the weather, and then living for about 3 weeks. The key to controlling flies is to disrupt this cycle. The more cows are forced to stay in the same pasture and poop in the same area, the more they are subjugated to a growing fly population
Here at Harmon Creek Farms, we do a number things through everyday management to disrupt the life cycle. Moving our cattle to new pastures frequently is an effective way to put distance in between them and their manure. We move our cattle to fresh pasture often.
The other management tool we use is to encourage populations of fly predators. For us, that's primarily birds and dung beetles.
With a healthy population of dung beetles, who live and feed on cow manure, a fresh manure pat can be totally utilized and almost disappear within a week, thus eliminating the fly egg habitat. Increasing dung beetle populations is a long process but is primarily done by ceasing the use of cattle de-wormers, which kill fly larvae but also kill dung beetles. By moving cattle frequently to new pastures we break the internal parasite life cycle, making de-worming unnecessary.
We encourage populations of fly eating birds, such as swallows and purple martens by building birdhouses and placing them throughout the pastures. Certain times of the day you will see hundreds on birds in with the cattle, sometimes even perched on the cows heads, eating flies directly off their faces.
We've also tried adding garlic into their mineral supplement, this practice shows promise, but we haven't done it long enough to verify how effective it is.
We will continue to find natural ways to combat flies WITHOUT the use of insecticides.