Speaker 1: Kelli Anderson, NDSU Ag Communication Specialist
Speaker 2: Gerald Stokka, NDSU Extension Veterinarian and Livestock Stewardship Specialist

Kelli: This is Sound Ag Advice, a weekly feature presented by NDSU Extension. I'm Kelli Anderson and I'm joined this week by Dr. Gerald Stokka, NDSU Extension veterinarian and livestock stewardship Specialist. Today we're going to be talking about some of the options beef producers have for controlling flies. So Dr. Stokka, why is it so important to control flies?

Dr. Stokka: Flies bring us into a realm of economic issues, they really do. Too much fly pressure cause behaviors in cattle that doesn't contribute very well to their productivity. If there's too many flies, they spend less time grazing and the calves don't grow as well as they should be. So that's a direct economic impact from flies themselves. The other part is their role not only in the behavior part, but also in transmitting disease.

When there's too many flies, the fly populations are too high. And we really deal with three different types of flies out on pasture, we deal with horn flies, which is tends to be on the back and on the shoulders, we deal with the face flies, which like their name is around the face, then we deal with stable flies that want to be on their bellies and on their legs. Really, the stable flies tend to bring us the most problem regarding behavior, because there gets to be a lot of congregation of the herd itself that crowd together, that same mechanism for them to maybe protect some that are in the middle, I'm still not sure why they crowd together so much, but they do. And that crowding produces conditions that can lead to bacterial infections like foot rot and pinkeye.

So for example, if we talk about foot rot, which is an infection of the soft tissue between the toes, if this congregation or this crowding is occurring in wet areas, maybe a stock pond or near creek or even around a tank water tank itself, then it becomes muddy conditions, it leads to a greater susceptibility of the tissue between the toes to allow that bacterial entrance. And once that bacteria gains entrance into that skin, then you have a condition in some cases that we call foot rot. Flies aren't directly involved with that, but it leads to behavior in cattle, that can make them more susceptible to this foot rot condition.

The same holds true somewhat for pinkeye. Cattle that are crowded closer together allow greater transmission of some of those bacterial pathogens that the fly in this case, the face fly, can carry from animal to animal. So, flies can have a big impact on us, not only from a behavior standpoint in the cattle, but also from allowing greater susceptibility or greater risk of getting pinkeye and foot rot.

Kelli: I know that there are multiple methods to controlling flies. How should we be using multiple methods to control the different types of flies?

Dr. Stokka: You know, we can ignore it and just let nature take its course and have as many flies as you want. But you can see the discomfort in cattle. And so, there are many different ways that you can deal with this issue. One of the ways that, that we try and deal with it, that kind of/sort of works, and that's rotating pastures. If you take cattle from pasture they've been in, they've left their manure behind and gone to a brand-new fresh pasture, the fly pressure should be less now, that doesn't mean flies can't fly to a new location because they can. But if it's some distance away, the fly pressure should be less, at least for a while. We can also use things like pour-ons that maybe last for 10 days or so, or we can use dust bags that are kind of hung over the mineral feeders, we can use fly sprays, where you can go out and spray the entire herd. Spraying is fine. It's just that cattle aren't sure about what you're doing when you come out there with the sprayer on a four-wheeler or something they kind of tend to want to move away from you and it takes time too, but they can all be effective, but usually it's fairly short term.

And then there are some things that we can feed to cattle that inhibit the development of the larvae that are developing in the manure patties. And they can decrease the fly population. But we will never get to zero flies. And I don't think we want to, but we just want to reduce the number that are making the lives of these cattle miserable at times.

Kelli: Dr. Stokka, where can producers go if they want more information on the best ways to control flies?

Dr. Stokka: The best thing to do when you're trying to find out information on fly control, go to your veterinarian. Many veterinary clinics carry products that are labeled and be used in fly control. Your Extension agent should know a fair amount about flight control. Even your animal health distributors will have fly-control products. There should be somebody there that knows about fly control. And of course, we here at Extension have publications that deal with fly control as well.

Kelli: Thank you to Dr. Stokka for his time today. This has been Sound Ag Advice, a weekly feature presented by NDSU Extension.