We frequently get asked about what we do for fly control. We try to take a multi-faceted approach and do things that actually work versus doing things that don’t really have much effect. As an example I don’t consider daily fly spray a very useful form of fly control. I’ve tried every fly spray on the market, from the all natural ones to Pyranha. I’ve even tried making my own fly spray using essential oils. The bottom line is they’re all largely worthless. 
Sure, I’ll use some fly spray when a horse is seeing the vet or farrier and is doing a lot of tail swishing, or I’ll put fly spray on before I ride my horse.  I have one horse that I’m spraying daily as they are currently something of a fly magnet due to a health issue. It doesn’t help the horse for long but it makes me feel better. But by and large I find fly sprays mostly useless. All of those claims the various fly sprays make about how many hours they last? What a joke. At best you get thirty minutes, maybe an hour with the Pyranha, of reasonable usefulness from any of them. I haven’t found any sprays that deter ticks. I’ve tried Spot-On on many horses as I’ve often heard it is good for keeping ticks off. I can’t say that I found that claim to be true in my trials. 
I think the Pyranha works the best out of any of the sprays (which still doesn’t mean I think it has any long lasting effects). However I’ve seen enough horses have irritated skin from Pyranha that I don’t keep it on the farm anymore. Plus, I’ll admit I don’t like pumping a bunch of insecticide into the environment, or inadvertently on myself. I find it ironic that some horse people will talk about all the horrible environmental damage farmers do using chemicals on their crops as they buy gallon after gallon of insecticide. Double standard much?
So outside of situation-specific uses I don’t consider fly spray a very useful tool for fighting flies. In my view the more flies I can keep from reproducing, the better. The three main lines of defense I use against flies are fly predators, large biting fly traps, and small sticky traps.
The fly predators only work against certain types of flies and it is important that they be spread in the appropriate locations. We started using fly predators 3 or 4 years ago and saw enough of a difference from the fly predators that we are still using them a few years later. We order ours from Spalding.
We also use large fly traps that are designed to attract biting flies like horse flies and deer flies. We use the Horse Pal trap that can be found at www.bitingflies.com. We started with just one trap to see if it actually trapped any flies. It did, and now we have four traps around the farm. I’ll probably add another one next year. The first couple of years we trapped a lot more flies than we do now. Between the fly predators, the Horse Pal traps, and sticky traps we’ve put a pretty decent dent in our fly population so we simply don’t have as many flies to trap from year to year. That being said I don’t think it is possible to ever trap too many flies, so much to Jason’s chagrin he’ll probably be assembling his fifth Horse Pal fly trap next year.
Horse Pal fly trap
The Horse Pal trap works by using a large target, a swinging black ball, to attract the flies. Then the trap takes advantage of a the natural response from these flies which is to continue to go up. The flies eventually wind up in a plastic jar at the top of the trap where they are killed by heat build-up in the jar.  We’ve found that the key to these traps is placement, just as described on the website. They need to be placed in an area that is open and in the sun all day for maximum effectiveness. We use a strand of electric tape around the traps to keep the horses from bothering them.
In addition to the large fly traps I also use sticky traps as well. I hang these down low, about 3 – 4 feet (about a meter), off the ground.  I was a little skeptical about these so I only bought two first and hung them up to see what would happen.  One fly buzzed over and got stuck to one as I was hanging the first one up, and they continued to get covered up with flies over a period of a couple of weeks. Now I order a dozen at a time and hang them up in various places around the farm. I change them out and put new ones up about once a month. I have a sick side that enjoys watching the traps fill up with flies. I check them almost every day to see how many more flies have been trapped, and I do the same with the Horse Pal traps. I know, there’s something a bit off about that.
one of the sticky traps
I like that the fly predators, Horse Pal traps and sticky traps are on the job 24/7. I like that they don’t involve spraying gallon after gallon of insecticide that has a very short window of usefulness into the environment. And I like that every fly I keep from producing means I have made a tiny but permanent dent in the fly population. I read somewhere that one female fly can produce up to 900 flies. I don’t know where the term breeding like rabbits came from, it needs to be breeding like flies. 
Of course there are other things that play a role in fly control as well, with manure management being a big one. We do a lot of composting and harrow as appropriate as well.  Mitigating, and when possible eliminating, areas of standing water is also important. However there will always be flies around, and of course depending on what your neighbors are doing or not doing you may have to deal with their flies as well. 
There is no 100% perfect solution, but this approach seems to work the best for us. 
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Kennedy’s typical look when he’s napping
B-Rad and Alex
Johnny, Sam and Sebastian
Silky looking sleepy
a happy turkey family
George and Asterik
Cocomo and Gus
Romeo and Lotus
Remmy
Slinky and Lightning
River and Rocky
Jason’s early morning view from the tractor
some of my early morning views the last couple of days