How Do You Deal With Flies? | Advisor Panel
This article first appeared in the May 2026 issue of Graze. We're sharing it here in full to give you a taste of the practical content we offer in each issue of the magazine. For the full meal, subscribe today!
Our advisor panel writes in every issue sharing their perspective on a variety of topics and issues pertinent to grazing. They bring a variety of perspectives, since they come from different regions, have different species and farm sizes, and have different management styles. The panel encapsulates what makes the Graze community special: it's a gathering of different farmers sharing what works on their operations for readers to take ideas from.
By the Graze advisor panel
Jordan Settlage
Fly control has been one of the more challenging aspects of managing an organic dairy, especially when working within the limits of approved inputs. Over time we’ve developed a multi-layered approach that focuses less on any single “silver bullet” and more on stacking practices that work together.
Today, our fly control program combines several tools and management practices. We rely on natural repellents such as No-Fly from Crystal Creek and Pyganic as topical and area sprays. They help knock back fly pressure, especially during peak periods, but require consistent application to stay effective. Biological control also plays a key role, with predator wasps helping reduce fly populations at the source by targeting developing larvae in manure and bedding areas. We also run chickens behind the herd, which has the potential to be one of the more effective long-term strategies because they scratch through manure pats, breaking up breeding sites and consuming larvae. This helps interrupt the fly life cycle naturally. However getting the chicken system working well has been very difficult, not because it is ineffective, but because of heavy predator pressure. We deal with foxes, hawks, eagles, and coyotes, which makes it challenging to maintain a consistent and productive flock.
Earlier on, we experimented with a walk-through fly trap. In many ways it worked very well. It did an excellent job of removing flies from the cows themselves, giving immediate relief to the herd, but it was only moderately effective at actually trapping and killing flies. As our herd grew, the biggest challenge became throughput. The trap was designed as a single-lane system, which made it increasingly time consuming to run a larger number of cows through it. What worked well at a smaller scale eventually became a bottleneck as we expanded.
Even with a solid system in place, fly control remains a constant battle. Organic production limits the tools available, so success depends heavily on consistency, timing, and staying ahead of population buildup rather than reacting after flies are already a problem. Manure and bedding management are critical pieces, and weather can quickly shift the level of pressure, especially during warm and wet conditions.
Fly control in an organic dairy is not about finding one perfect solution but about building a system that layers multiple approaches together. By combining repellents, biological controls, and livestock integration, we have created an approach that is effective and fits within organic standards. It has been a long process of trial and adjustment, and while it is not perfect, each piece adds another level of control and helps keep fly pressure manageable.
Jordan Settlage milks cows on a certified organic dairy near St. Marys, Ohio.
Ben Beichler
“F” stands for flies — and also the grade I would give myself when it comes to fly management. Of all the things I dislike when it comes to farming, flies top the list. We have tried to mitigate flies in the past unsuccessfully and the only thing I can offer is our multi-prong strategy for this season.
Fly predators: We will be strategically placing fly predators at our hot spots like the manure stack, milking parlor, and calf barn. The objective is for the predators to kill the flies at the larva stage before they can fully mature and reproduce. We will additionally look at what we can do to reduce conducive environments for the flies to populate but will be relying on the predators to help where mitigation is limited. Last year we were feeding grain in the parlor, which was a major fly attractant, and I am hopeful we will see an improvement at the parlor since we discontinued that practice this year. I have heard great things about building birdhouses to attract certain birds that eat flies and want to give this a try, but building birdhouses didn’t make it to the top of the winter list this year.
Fans: Flies do not like high volumes of air. We will be placing fans in our shaded feed area to help cool the cows but also hopefully give fly relief as well. We have noticed a difference in the milking parlor where we already have fans placed and want to take that strategy to the feeding area.
Feed: A year ago we started paying attention to the fat content of our feed and increased it as part of an overall look at our energy sources. With the increased fat we gained production, body condition, and the cows had that nice slick look during the summer. As we all know, stressed cows attract flies and the improved energy also correlates with a reduction in fly pressure.
Spraying: We have tried several organic fly sprays and have been disappointed in their efficacy. They will provide temporary relief but the marginal benefits don’t justify the cost. We are not certified organic so we have used permethrin if the fly pressure is too high, but I try to stay away from conventional products as much as possible. We don’t use any feed additives because of the potential harm they pose to soil life.
We would love to have a fly vacuum, but since Spalding discontinued making them they have been hard to find. We are a handy and creative bunch so we are looking at building our own if we get the time this spring! Overall, I am hopeful that our renewed focus on mitigation and control will yield better results than in the past and that the cows and we will experience a less annoying summer.
Ben Beichler milks cows for a raw milk herdshare near Middlebrook, Virginia.
Aaron Helmick
I hear people say things like, “When I get to heaven, I’ll fish all the time, or eat this every day, etc.” I’m the kind of person who wants to ask questions when I get there.
As an example, this month’s topic of flies…why do we need them? (I am sure there is a good reason). Or when cattle are hot, why do they bunch? I know if I’m hot, don’t touch me, and please don’t stand near me. That’s as much for your benefit as it is mine, as the “fresh as a daisy fragrance“ becomes “what’s that smell?” very quickly!
Flies, we’ve gone full circle. Treat, prevent, treat, prevent, mechanical, I think we have tried them all. Conventionally we have used pour-ons, rubs, tags, etc. Organically, we’ve added sulfur, an Agri-Dynamics product, a fly vac, etc. All of these things are tools in a tool kit that help. I want to be clear on the following: the current iteration we are in, and have been for a while, is the simplest, cheapest, and most effective.
So, let’s climb back to 30,000 feet and look down at the big picture. What are your goals? And how do you want to achieve those? We believe in our operation that we need to be gentle as possible to achieve our overall goal of stewardship. What follows is our approach to flies not in any order, but only as they come to me in thought.
Genetics: Some livestock seem to be more resistant to flies. However, this depends on your goals. If you buy stockers in the spring and sell in the fall you have little control over genetics, whereas a seedstock producer could cull out animals that don’t fit.
Environment: What’s the livestock pressure in your area? If you have livestock bordering your farm your flies may be worse than if there is no livestock close. Can we control that? Sure, but do you want to take care of the neighbor’s livestock as well? However, we can’t ignore the added pressure.
Pasture management: To quote Logan Pribbano, “If grazing isn’t the answer, you’re asking the wrong question.” We see that rotation and management play a large role in controlling fly breeding grounds.
The biggest thing we utilize is the Steve Campbell approach and doing our best to keep animals in an alkaline state. We achieve this with sea salt, sodium bicarbonate, and/or apple cider vinegar. These are done in particular order. Steve can be found on several podcast talks, etc. and is a wealth of information. Also at tailormadecattle.com. This system is the cheapest and most effective we have used in our operation, especially when paired with grazing management.
Finally, I will add that on our conventional livestock we are doing pour-ons once or twice, more for ticks than flies, but it does offer some fly protection.
I really find it valuable to consider the 30,000-foot questions before adopting any one program.
Aaron Helmick grazes near Greenville, West Virginia.
Michael Dolan
Dealing with flies is a problem every farm faces and many farmers use different strategies to combat them. Since we are organic, I will only discuss our practices for dealing with flies. Number one is having a good pasture rotation and integrated pest management. Moving livestock frequently is crucial to combat the impact of flies on the herd. Managing the land to maintain perennial cover increases biodiversity, which brings more birds onto the land and helps control fly populations. Therefore we have installed some bird houses around the property to promote that.
Also we have been big proponents of using fly predators spread in our pastures and now maintain a healthy population of fly predators on our farm, which keeps the fly population in check. We can certainly tell the difference between our home farm and rented farms where we haven’t used fly predators. However, one of the biggest concerns for cattle producers is that flies can spread pinkeye like wildfire. So we really try to focus on combating face flies during the summer.
One way we do that is by adding a face fly treatment to our mineral feeders. We use a fly deterrent from Crystal Creek mixed with mineral oil. This works great as the cows consistently hit the salt/mineral block, treating themselves. However to be honest there were times when the flies got just downright terrible, usually after extended periods of rain and hot weather. In some extreme cases when this happens we load a fogger with a water-based fly repellent from Crystal Creek and drive around the herd spraying them with the solution. Implementing this method requires significant work because you need to attach the fogger to the tractor and fill it with water. But when it is hot and the cows are bunched up this can give them some relief to the heat and flies.
In the past we also pulled a batch of laying chickens following the mob of cows. This proved effective because the chickens would scratch in the cow patties and eat the fly larvae. However, it required significant work, as it added an extra step to moving the cows and also shutting in the chickens at night was not my favorite chore. Eventually predators took most of the chickens that we had working on fly control.
Lastly I would argue that having good genetic cattle is the most important method of fly control. The genetic trait that deters flies in cattle is determined by blood thrombin levels. The higher the level of blood thrombin, the lower the amount of flies. This can be a tough trait to determine without blood sampling but spring is generally the easiest time to tell. Animals that shed their winter coat first, appearing sleek and shiny are usually the most genetically well-adapted to resist flies.
Building a herd with this trait takes time and attention to the animals but most importantly, it requires starting with a good herd of cows. This is always the most important thing I state when advising people looking to start a herd. For us, that means starting with high-quality Murray Grey genetics. They are well adapted to grass operations, are a very docile and calm breed, and have been thriving for us here in southwestern Wisconsin.
Michael Dolan grazes livestock near Spring Green, Wisconsin.
Martin Fox
Our fly management starts with cleaning out and spreading all our winter bedded packs after first cutting to greatly reduce fly breeding areas. Our weak point, though, is the earthen lagoon and the pit underneath the slatted floor in the barn, which sits half full the whole summer. I use pit treatment to reduce the crust on the pit, which is prime fly-breeding territory.
For the last two years we used fly parasites around the manure pit to hopefully reduce fly proliferation. How much it actually helped I don’t know, neither have I decided yet if I will be using fly parasites this year or not!
On the mechanical control side, our biggest hit is sticky fly tape along the holding area, feed bunk, and through the parlor. In peak fly season we may need to rewind the tape every day or two. If my calculations are correct, a 1,000-foot sticky tape roll can hold up to 100,000 flies! I typically use 3-4 rolls in one summer.
Once summer heat and fly pressure intensifies, we switch our milking times to 7:30 a.m. and 5 p.m. instead of our usual 6 a.m. and 6 p.m. schedule. I keep the cows in the barn under fans through the hot daytime hours (the 9.5 hours between morning and evening milkings), and they still have a long enough night on pasture (14.5 hours) to harvest at least 60% of their dry matter intake from pasture.
The original farmstead has an old abandoned bank barn that teems with barn swallows every summer. We do not own or use this barn but definitely benefit from the fly control factory that occupies that structure! We also have a few birdhouses throughout the farm that are usually occupied with bluebirds or tree swallows, if we get around to doing the upkeep that it takes to keep the open sign out for them.
I feed Sea-90 garlic salt from mid-April to September. We have noticeably fewer horn flies since using garlic salt, though it has only marginal effect on face flies.
Finally, if all the above has not brought fly pressure down to an acceptable level, we use fly repellent mixed with water and/or mineral oil. I use either Dr. Sarah’s Shoofly, Martin’s Agri Supply’s EcoShield (formerly Agri-Dynamics Ectophyte), or Crystal Creek’s fly repellent. This is applied with a backpack sprayer when the cows are in the holding area or when locked into the headlocks.
A popular mix we use is a 15-gallon recipe from Lancaster Ag: 1 gallon Shoofly concentrate, 1 pint Pyganic 1.44, 4 gallons mineral oil, and enough water to make 15 gallons total. This mixture needs to be mixed well before and while using. I often just mix half a batch to fill a 5-gallon jug, using less water. The ideal mix would replace all water with mineral oil, but it is more expensive and doesn’t go through the sprayer as well.
My favorite spray for the stable and horn flies in the parlor is Pyganic and mineral oil with a little fly repellent sprayed on the belly and legs of the uneasy, tail-swishing, feet stomping, and kicking cows bothered by flies. A mist of Pyganic knocks the flies off and the cows quiet down making milking time much more pleasant.
Everything taken into consideration though, our best war on flies is having the cows in the barn underneath fans for the short daytime period between milkings. Happy cows make for a happy farmer.
Martin Fox milks cows on a certified organic dairy near Penn Yann, New York.
Matt Moyer
Fly control continues to evolve somewhat for us. For years we relied on pour-on products such as Cylence particularly on the lactating cows. The cows were the easiest to apply because they were coming through the parlor. The calves and heifers sort of got neglected, and we didn’t do much with them. If it worked out logistically we would apply Cylence to young stock, but it wasn’t done very regularly. We dealt with a decent amount of pinkeye and dead quarters and damaged teat ends when heifers would calve and come into milk. We blamed that on horn flies biting teat ends.
We also played around with feed additives that were supposed to prevent fly larvae from hatching and therefore reduce the fly population. Whether or not it actually did what it was supposed to do, I don’t know. What I do know is that it didn’t seem to have much impact at the cow level.
Eventually we started seeing less and less of a response to the pour-on products. For example, Cylence was labeled to only be applied every 3 weeks. We were fortunate to get a week to 10 days out of one application. And it didn’t seem to matter if we changed the product: at some point it was less effective than it was originally.
Somewhere along the way, probably about 10 years ago, we purchased a Cow Vac. Essentially, the cows walk through a big vacuum as they exit the parlor that sucks the flies off the cow. That has proven to be quite effective. The key is to start them going through pretty early in the season, before flies are a problem. It does not eliminate the fly problem, but over time it really does help with the fly load.
There is usually a couple-week period through the summer when it seems that the Cow Vac isn’t keeping up. But that doesn’t last too long. Sometimes as farmers we will purchase something and at some point wonder if it was worth the money. This is one purchase that I can say was worth the money! We have only used Cylence once or twice since we have had the Cow Vac.
Unfortunately the manufacturer has quit making them and they cannot be purchased anymore.
Fortunately we found a used one a year or two after purchasing the first one, so we have one at both farms now. That one is set up for the cows to walk through as they enter the parlor holding area, which is the way they recommended it to be set up. In Manns Choice we didn’t have a good way of having them walk through before milking, so we had to settle for after milking.
Around the same time as we started using the Cow Vac, we started using the Y-Tex insecticide ear tag rotation on calves and heifers. There are four or five different tags they manufacture, and each is treated with a different chemical. The idea is to prevent the flies becoming resistant to a particular tag. That program worked quite well and we used it pretty exclusively until last year.
After talking with some other farmers and hearing some concerns about the products on the insecticide tags killing dung beetles, I decided to look for another option.
For a year or two we had been offering free choice Sea-90 sea salt to the lactating cows. And I knew the company offered a garlic salt as well. Apparently garlic is a natural fly repellent.
So we decided to give it a try on the yearling heifers. We figured if the flies got too bad, we could always run them through the chute and put tags in later. We replaced our previous mineral with free-choice Sea-90 garlic salt. We never worried about it all summer. We saw very little fly pressure on the heifers. And we didn’t have the stress of working them through the chute and putting in the tags. So the plan is to do the same this year with the heifers. Hopefully we are as happy this summer as we were last year!
We did continue with the insecticide tags on the calves last year. They receive grain that has salt and mineral included. So I didn’t feel, when free-choicing, they would get enough consumption of the garlic salt to make a difference. I am going to see if perhaps we could get the regular salt in the grain mix replaced with the Sea-90 garlic salt. Not sure if that is an option yet, but I’m going to try.
Matt Moyer grazes and milks cows for a conventional market near Manns Choice, Pennsylvania.
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