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Most everyone hates flies. Cattle are no exception. Following our common theme, prevention will always be better than treatment, we talk types of flies and how to prevent them. Brad also loops us in on his research where he is vacuuming cows.
Hosted by members of the University of Minnesota Extension Beef and Dairy Teams, The Moos Room discusses relevant topics to help beef and dairy producers be more successful. The information is evidence-based and presented as an informal conversation between the hosts and guests.
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Joe: All right. Welcome to The Moos Room, everybody. OG three again. You're stuck with no guest. You're stuck with just us. We're talking today about fly control. We are in the middle of it. In the summer, we're dealing with flies all the time. I'm going to be perfectly honest with everyone. I am not a very good source of information on flies, so I'm here to ask questions today and find--
Emily: Wow. Something Joe doesn't know. I'm shocked.
Joe: I have little knowledge. It's not something we talk about in school, on the veterinary side, it's something that I relied heavily on producers to know and other experts. I just don't know a ton about it. Fortunately, Brad has done some research when it comes to controlling flies and preventing flies. Emily has written several articles to help us on this issue. I'm going to lean heavy on the co-host today. Brad's going to be talking a lot, so you get to be soothed by his dulcet tones.
Bradley: Yay.
Emily: Rude that you didn't say I'd be talking.
Joe: No, you don't get to talk.
Bradley: I didn't know much about flies either until I started in my research position. I took a veterinary entomology class in college in St. Paul University of Minnesota. We learned a little bit about that. Really, I had a good mentor, Roger Moon, University of Minnesota entomologist, Department of Entomology. He taught me all I need to know about flies and how to do that. It's too bad that Roger is retired now. I learned a lot from Roger and how to distinguish different flies and what works and what probably doesn't work.
Emily: He sounds like a character in a book.
Bradley: That's right. Oh, Roger's a wonderful guy if you don't know him.
Emily: I remember I got to interact with him briefly, Bradley, at one of your organic dairy field days. I remember he had a case with, I don't know what kind of fly or insect critter was in there, but he was very knowledgeable and excited about it.
Bradley: Roger was always the guy at the field day that brought his little trowel with and was out there scooping through manure pats and looking for pupae and going, "Ooh, yes, there's a stable fly. Ooh, there's a horn fly pupae." It was fun to see.
Emily: And dung beetles
Bradley: Dung beetles. I think he did his PhD on dung beetle research in California. Roger's quite known.
Emily: Coming soon, dung beetle episode.
Bradley: Oh, yes. Dung beetles.
Joe: Dung beetle episode. Why not? That's a good transition. We've already talked about manure a little bit here and scooping through it to find immature stages of these flies. Tell me about it. How does manure play a role in all of the fly control that we deal with on both dairies and beef operations?
Bradley: The biggest thing to do is trying to distinguish what flies you have first. I talk with a lot of producers on the dairy and the beef side, and most of the time it's like, "Well, how do I control this fly?" or "I got flies, what do I do"? It's like, "Well, okay, flies is a big word. There's so many different flies and how to control that." Really, it's about trying to distinguish what sort of pests you have first.
There's many different fly species, and they're found in many different things. During high fly times, we like to talk about filth flies, and those are the ones that you find in either manure or debris organic matter. The big four probably are houseflies. We all know what those are. I think those aggravate us everywhere. Then you have stable flies, horn flies, and face flies.
Those are really the four that are causing some issue. Three of them probably cause more issue with cows than another one. House flies where you find in the office, and I'm swatting them right now.
Emily: Or if you leave the windows of your car rolled down at a farm and when you leave.
Bradley: That's right. Those are houseflies coming in. Those are house flies.
Joe: For the most part, we call them filth flies because they use manure as a place to put their eggs?
Bradley: You're right, Joe. You are right.
Joe: I learned something, learned some stuff.
Emily: All I learned was something about flies being filthy.
Bradley: Yes, that's right. Let's talk about the three different flies. One that probably you find in both. I've done a lot of work with pasture-based dairies, but one fly species that you find in both pasture dairies and confinement dairies is stable flies. Those are the flies that are on the legs of a cow. If you are in a barn or on pasture or see cows foot-stomping, those are stable flies that are really after cows.
Those are the ones that are on the legs of the cows, and that's really where you find them. You typically don't find the stable fly anywhere else. It's on the legs of a cow.
Joe: That's beef too. I see beef cows stamping away in the pasture.
Bradley: That's right. You find them in beef cows too. Stable flies are coming from organic matter debris. It's say beef cows, if you feed hay on pasture they're breeding in old hay, debris on the ground, or if you're in a barn, any spilled TMR that got wet, that's where stable flies are. Typically, old feed that got wet, you'll find stable fly pupae there.
You can find them in calves too. We forget about calves and flies, but if you've bedding calves with straw or sawdust, you'll find stable flies and that's what's going to bother the calves.
Joe: What about feed on the calf side? Especially if you're using a mob feeder or a bucket. I haven't seen a calf yet that doesn't spill water and/or milk into their starter. Is that an issue too?
Bradley: It can be. If the stable flies find a place to lay their eggs that's wet and dark, that's where they're going to lay it. You'll get way more stable flies than what you really wanted.
Joe: Brad, you said that causes stomping in these cattle, and that's one of the ways you can tell they've got biting flies on their legs. One of the few things I know about flies is that it causes cattle to bunch and group. We worry a lot about that because when it's already hot in the summer, it just causes them to get even hotter. I worry about it for heat stress and preventing heat stress. Is that the fly that causes them to bunch or is that some of the other flies we're talking about?
Bradley: It's both. I think when you see cows that are out bunching, it certainly depends where they're at. If they're outside bunching, yes. They're probably being attacked by stable flies and horn flies as well. That's the first defense that cows are going to do if they're being attacked by flies, is to start bunching to help ward off the flies from each other.
Emily: I know another thing they can do is feed tossing. I remember our cows doing that. They'll throw all their silage back.
Bradley: Yes, you're right. You see that in cows in freestyle barns or wherever. They're tossing feed on their back. That's a fly control mechanism to do that.
Joe: All right. We're getting a little ahead of ourselves. I'm asking these questions because I'm excited and I'm learning a bunch. We should probably go back to the discussion about the different types of flies. We got stable flies. We covered house flies briefly. Everyone knows what a housefly is. What are horn flies?
Bradley: Horn flies are flies that you will find on the backs of cows or calves, heifers, you name it. Horn flies are really only found in animals that are outdoors or on pasture. If you have a confinement barn that's, say a cross-ventilated barn that's locked up you don't have horn flies because horn flies actually breed on pasture. They're on the backs of the cows.
It's actually fascinating. You can watch this happen in cows. If a cow manure's on pasture, you'll see the flies fly off the back, come down and deposit eggs into the manure pile and then come back up to the cow. They're only laying eggs on pasture. Horn flies are also biting flies. They bite the cows and then they suck their blood. That's why those cows are pretty irritated as well.
Emily: See, we need a soundboard so you can put in a Dracula noise.
Bradley: That's right. That's right. True.
Joe: They're on their backs and--
Bradley: Backs of the cows.
Joe: Backs of the cows, okay. I've seen that, especially when we get bulls that come in. There'd be like a group of flies just sitting on their back and nowhere else and they're coming straight from pasture.
Brad: Those are horn flies.
Joe: Horn flies, stable flies and then we got one more, face flies.
Brad: Face flies, those are the flies, they're only pasture flies as well. They breed on pasture just like a horn fly does. They don't bite the cows, they're just annoying and they just fly around the face, in their nose or eyes. Really they're just looking for mucus to eat. That's what they're doing.
Joe: Face flies are looking for mucus and that's why they're concentrating on the face because they've got the nose, they got the mouth, they got the eyes right there.
Emily: So they're really just a nuisance fly.
Brad: They're just a nuisance fly.
Joe: Kind of, I hear about them because of pinkeye, right?
Brad: You're right, pinkeye. They're not really sure but we think that that's a vector for pinkeye is the face fly. If an animal has pinkeye and then flies over to another one, more than likely it's spreading pinkeye that way. Flies are a big pinkeye spreader.
Joe: Why do we need to know the difference, Brad? We've got the big three. Actually, you need to know what a housefly looks like as well but why do I need to distinguish between the three?
Brad: The big thing is probably for prevention. If you want to be able to treat your animals, if you are conventional and you can use insecticides or whatever or want to use those, you want to know what's the correct one to use. If you're maybe a pasture-based herd or a beef herd that's grazing, you can utilize different ways to alleviate the flies on those.
A fly is not just a fly, there's different ways to control them, and some you can't control like a face fly, they're really hard to control. There's not many things that work for the face flies. We always think about wanting to use insecticides or pesticides or something else to control the flies. That's what we always go right towards.
Emily: Chemical control.
Brad: That's right. Maybe there's some other alternatives that we can use and that is cleanliness. In my book, cleanliness is number one to help reducing your fly population. That's cleaning up the spilled TMR on the ground or hay debris, spreading it around. Obviously, there's a lot of things that you can't prevent if you have calves out in hutches. Maybe you need to change their bedding more often or if you wean some calves out of a hutch, maybe you should clean it up that day or the next day because those are prime grounds for fly breeding.
If you just let it sit there, the stable flies are going to invade and then 10 days or two weeks later, you're going to have this whole brand new group of stable flies running all over the place. In my mind, cleanliness and sanitation are the biggest factors to controlling your population. Yes, there's other ways to do it but I think you'll get more control from keeping things clean. We all know that's hard.
Joe: It's an easy thing to say and there's always a lot of things going on in the farm but we are back to this, something we talk about all the time, whether we're talking about prevention being better than treatment. It definitely holds true right now too with flies, If you can prevent it from being an issue and stay ahead of it, you're in way better shape than trying to treat it after it's already a problem.
Emily: Yes, and just by keeping it clean you prevent so many different things, not just one. Cost-benefit analysis is pretty good on this one.
Brad: I agree, it's all about economics. It's how you can make your farm more profitable and how you can do that. There's many different ways to do it but I think in my mind, cleanliness is the key. I'll give you an example. Last week, my students and I, we cleaned out a feed bunk because we were putting a few animals in there and there was some old haylage that was there for just maybe five days that hadn't been cleaned up and it got rained on. We cleaned out the feed bunk and there were so many maggots, so many eggs from stable flies there that would have been thousands of new stable flies that were infiltrating our farm here if we didn't clean that all up.
When you expose those maggots and pupae to sunlight, they pretty much die, they're done. We helped prevent all these flies just by cleaning out a little bit of space in the feed bunk. It wasn't much, I'm talking 10 feet of a feed bunk and we were going to have a lot of stable flies bothering us. You just don't know how many flies are until you actually dig through that stuff and see what's there.
Joe: That's pretty cool. I didn't realize.
Emily: Not all heroes wear capes. Wow, Bradley.
Joe: It was similar along that same line. There's a lot of guys that scrape or rake a silage pile and then there's stuff that you don't feed because it either has mold or it's not properly fermented in whatever way, could that be an issue too? If you leave that pile sitting there in the bunker, there's lots of guys that have that bunker fairly close to calf hutches and other facilities, is that an issue?
Brad: Sure, can be. If it gets wet, gets rained on or flies find their way to it and start laying their eggs and you can generate that. You talked about things being right next to each other, sometimes these flies can go a long distance. They found horn flies can fly a mile away. Sometimes you might not be able to prevent flies from coming to your farm because maybe the neighbor is generating all the flies for you and your farm. That can be an issue as well, that some of these flies, just because they lay an egg on your farm doesn't mean that they don't go somewhere else.
They are going to find the cattle, the species that they want to, especially a horn fly, and they're going to fly till they find what they need to survive.
Emily: Girls got to eat.
Joe: Girls got to eat. Let's talk some economics, just to convince people that it really matters. How much does it matter when we're talking economics?
Brad: That's a good question. Sometimes we don't really know how much fly control or reducing flies can help alleviate, but it's probably a couple pounds of milk. We did a study here on pasture-based herds and we did some back-of-the-napkin type calculations. If we could get two to three more pounds of milk, which we did by using some fly control methods for our organic herd on pasture, we got three pounds more milk out of those cows by just using our cow vacuum.
Three pounds of milk per cow per day times 100 cows over the summer, that's real money that can be lost if we don't think about fly control as well.
Joe: I'm just doing some calculations like you said back of the napkin. Maybe like 5%, 6%, 7% production depending on how much you're milking?
Brad: That's right. Maybe 5% milk. We talked about it from the milk side but it also affects average daily gain in beef animals. If you have beef in a open feedlot or something like that, you might suffer on average daily gain if you're not able to control the flies or using some sort of method to control flies. It can affect a gain as well.
Emily: With calves too, can it stress them, so then they may become immunosuppressed and then they're just always sickly? Those cows that don't get a good start don't become good cows.
Joe: Yes, absolutely.
Emily: How do you even put a value on that too?
Joe: That's really hard to put a value on and stretch that economics output. 5%, that's no joke on average daily gains. If you're looking at a calf, let's talk beef side for a second. Looking at a calf or a heifer or a growing heifer on the dairy side, if you're looking for 2 pounds a day of growth and you've got a 5% reduction, that's a 10th of a pound every day that you're missing out on. That's a big deal.
Brad: We see reduction in average daily gain is because there is a reduction in feed intake or water intake. Those animals that they're bunching, whether it be on pasture or open locked or things like that, if they're in a group bunching, they're trying to avoid flies and they're not at the feed bunk eating or they're not drinking water. That's where you see the reduction in either production or gain is really reduced feed intake from not eating when they're trying to get rid of flies.
Joe: We talked about stuff getting wet and decaying organic matter, what about around that water? How do you keep that clean? That's going to be tough to do.
Brad: It is a tough one. How do you keep that clean?
Joe: Concrete?
Brad: Concrete, yes, that's right. That's a tough one.
Emily: Atomic blast.
Brad: Exactly. On pasture, they're going to create a mud hole so that basically, they're trying to help get rid of stable flies but if there's other debris around feed debris or something around the feed around the water trough, cleaning it up and making sure because that'll breed flies like crazy if there's a bunch of spilled TMR around a water tank, it's going to create flies.
Joe: I think we're going to stay away from talking about treatment methods, just because it's such a huge topic when we talk about insecticides and chemical control and things like that. Prevention is the key, but there's other treatments that you can use. Brad's done some research. He already mentioned the Cow-Vac. What is that? That sounds kind of space-age to me. Why are we vacuuming cows?
Emily: I imagine just like a Dustbuster
Joe: It's just one person that you hire with a little Dustbuster to wander around and vacuum all the cows.
Brad: That's right. It's actually kind of a neat contraption. It was developed at North Carolina State University. A long time ago, me and Roger, we went to NC State to view this and then it was commercialized and we got one up here. Actually, I've had four of them up here to do research with, but it's kind of a chute.
The cows walk through it and there's a fan that blows the air across the belly on one side and sucks them the other side. Then there's also some fans that suck the flies from the top of the backs of the cows. It sucks in the flies off the top.
Emily: Is it solid sized or how--
Brad: It is, yes. There's some tarps on the sides.
Emily: I guess not just open air.
Brad: Yes, there's some tarps on the sides that you can use. It works out quite well and we can reduce fly population by 40% to 50% on our pasture cows by using the cow vacuum.
Emily: What happens to the flies that are sucked up by the vacuum? They just live there forever or what?
Brad: We capture them so they're caught in a mesh net so that's the problem. You got to capture the flies, otherwise, if it just sucks the flies off cows, they go back into the environment and breed more flies. We actually capture them and collect them.
I had a grad student once we went around to seven farms and collected all these flies and across the summer we had a whole garbage bag full of flies from all these farms.
Emily: That is disgusting.
Joe: That's pretty gross.
Brad: It was an interesting project. We figured there was way over maybe a million flies that we had captured that summer that we did the study on.
Joe: Wow.
Brad: Kind of crazy.
Joe: That's so gross. It's good to know that that's an option. The cows walk through it just fine?
Brad: They walk through it just fine. It takes us maybe a couple days to get them used to it, but it really only works for horn flies. That's really what it's meant for and it's an adaptation of the old walkthrough traps that you see on a beef grazing farm or beef cattle that are outdoors. They've used some of these old traps to capture flies.
This is just mechanical ways to get them off. Whether you're pasture based or conventional, I think we can control the horn flies a lot better because you could use insecticides, or there's different alternative methods like the fly sucker that we can use but stable flies can be a little more difficult to control because they can breed in many different places.
Yes, you can use insecticides or pour-ons, but they're tough to control as well. I think in my mind, the horn fly is a little bit easier to control, but you're pretty much a pasture herd beef or dairy to have those flies.
Joe: I have one specific situation in my mind that's coming up and it's pink eye-related and it's pinkeye in calves and you said that face flies are only on pasture, right?
Brad: They only breed on pasture.
Joe: Okay. They only breed on pasture. This situation, it's like semi confinement I guess. You've got some cattle that are confined, it's a mono slope building and then the older calves had access to pasture.
Brad: That's right.
Joe: You're saying if I couldn't control my face fly problem by just locking the gate and keeping everyone in the mono slope because the flies are going to breed on pasture but they're going to make it to the rest of the calves in the mono slope.
Brad: That's right. If you got cattle on pasture, that's where the face fly is and they're depositing manure on pasture, that's where the face flies are coming from.
Joe: I could control my face flies if I locked that gate and they couldn't go outside, they weren't ever on pasture, but because they were on pasture, there's manure out there and there's a place for them to breed and then I have face flies.
Brad: Right. I think you can control them. It's not going to be zero, so you're never going to have no flies. Like I said, pinkeye could be-- we think that it's face fly, but frankly, house flies could probably, or stable flies might spread pink eye as well. We just don't know what the real vector is for that but we think it's face flies, but there could be other ways to do it too.
It's not going to be zero. I think you can prevent them by not having animals on pasture but we know that's not a reality. That can be pretty tough. If you have the space and you don't want to waste it, then you're going to put your animals on pasture.
Joe: All right. I guess the takeaway is the first step in fly control is looking at your cattle, figuring out where the flies are on the cattle, and deciding what fly you have. That can target what you need to do on the prevention side and then also what you need to do if you are going to choose a treatment to make sure that it's targeted.
Brad: You are right. Trying to figure out what fly you have is the number one thing to figure out and how to prevent them.
Joe: Well, I think we've got a bunch of ideas for following episodes where we get either more into flies and maybe have an entomologist on from Extension or someone who has a specific interest. We've also got a big topic of treatment and all that kind of thing. I think there's a pink eye episode somewhere in here that we need to cover as well.
Brad: Sounds like it.
Joe: We keep coming back to it.
Emily: We got our work cut out for us.
Joe: There's a bunch to do. Fortunately, we're still stuck at home and we've got a bunch of time to podcast, so we'll keep bringing it to you. Thank you for listening, everybody. If you have questions, comments, concerns, or scathing rebuttals, send them to themoosroom@umn.edu.
Emily: That's T-H-E-M-O-O-S-R-O-O-M@umn.edu.
Joe: You can also check us out on our website, extension.umn.edu, and on Facebook @UMNDairy and @UMNBeef. Thanks again for listening. We'll catch you guys next week.
Emily: Bye.
Joe: Bye. I love that we're having a fly episode and I can see Brad just swatting.
Emily: Yes. Flies.
Brad: They're everywhere. Freaking house flies.
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