If you own livestock, you know that flies aren’t just an annoyance. They pose real health risks and challenges for cattle every season.
Whether you’re managing a large ranch or a hobby farm, knowing how to keep flies off cattle is key to ensuring the welfare of your herd. Flies cause stress, feed interruption, and skin discomfort.1 They can even transmit serious diseases like pink eye (infectious bovine keratoconjunctivitis).
We’ll walk you through everything you need to know about fly control: the types of flies most likely to bother your cattle, what they can cause, and our top tips for how to keep them at bay. We’ll also highlight how integrating wound care and pink eye products plays a vital role in comprehensive fly management and animal health.
Understanding the Problem: Common Flies and Health Risks
You likely encounter different types of flies buzzing around the barnyard, but only a few are true troublemakers when it comes to cattle health. Knowing which ones you’re dealing with can help you build the right defense system for your animals:
- Horn flies – Horn flies are one of the worst offenders. These blood suckers camp out on the backs and sides of your cattle. They breed fast in fresh manure and can have a serious impact on your cattle’s milk production and weight gain.2
- Face flies – While face flies don’t bite, they love to hang around the eyes and noses of cattle. Although this may sound harmless, these flies can spread the bacteria that cause pink eye.3 This painful and contagious eye infection can lead to blindness if left untreated.
- Stable flies – Like horn flies, stable flies bite. However, they usually go for the legs and belly, rather than the backs and sides.4 Their bites are painful, and cattle often stomp or bunch up in response, leading to stress and reduced feeding.
- House flies and barn flies – House and barn flies don’t bite, but they carry bacteria from manure to feed and water sources, contaminating everything along the way. This can have a direct impact on the health of your herd.
- Deer flies – Deer flies show up seasonally and can leave nasty wounds. They’re harder to control, but they’re part of the picture when you’re figuring out how to keep flies off cows in wooded or brushy areas.
- Screwworms and warble flies – These types of flies are rare in the U.S., but if you live in a southern state or are importing cattle, they’re worth knowing about. These flies lay eggs in wounds, and the larvae can cause severe infections—including fly strike in cattle, a condition where maggots feed on living tissue and rapidly worsen untreated wounds.
Ultimately, fly control isn’t just about comfort; it’s a critical part of herd health.
How to Keep Flies Off Cattle: A 10-Part Layered Approach That Works
No single fly control method works perfectly alone. The best strategy combines good hygiene, smart product use, and daily observation. Think of it as building layers of protection for your animals.
1. Maintain Cleanliness
Let’s start with the basics: Flies love manure, spilled feed, and standing water. For this reason, you should clean pens and pastures regularly and make sure drainage is solid. Even something as simple as keeping feed bunks clean and dry can make a big difference.
Spreading out manure or composting it away from the herd also helps break the fly breeding cycle.
2. Use Pour-Ons or Fly Sprays
Pour-on insecticides and sprays provide a quick and easy way to give your cattle a layer of defense.
These products typically last a few weeks, depending on the formula and weather. For best results, apply to clean animals and re-treat after heavy rain or if fly pressure gets high.
3. Add Insecticidal Ear Tags
These handy little tags slowly release insecticide right where flies like to land: around the face, neck, and shoulders.
One tag per ear usually lasts a few months. To prevent resistance, rotate the active ingredient each season.
4. Install Dust Bags or Back Rubbers
Set up dust bags or back rubbers where your cattle naturally gather, including by water tanks or mineral blocks, for example.
As cows brush against them, they’re treated with fly-killing dust or oil. It’s a passive but powerful form of protection.
5. Try Feed-Through Fly Control
Feed-through products contain insect growth regulators (IGRs) that pass through the animal and stop fly larvae from developing in manure.5
They’re ideal for bug herds and work best when everyone is eating the supplement consistently.
6. Encourage Natural Fly Predators
Birds like swallows, barn cats, and even parasitic wasps (which you can actually buy) can all help control fly populations. Even chickens scratching around the yard can help reduce larvae.
7. Watch for Wounds and Treat Them Fast
Open wounds are fly magnets. Keep a close eye on your cattle, especially after procedures like dehorning or castration.
Clean any injuries right away with Vetericyn® Antimicrobial Utility Spray. This non-toxic care product protects and moisturizes wounds to help them heal faster.
8. Set Up Fly Traps and Barn Sprays
Fly traps can reduce adult fly populations near barns, feeders, or loafing sheds. Barn sprays can be used on walls, windows, and ceilings. Just make sure animals aren’t present when spraying, and always follow label instructions.
9. Keep an Eye on Vulnerable Animals
Calves, post-calving cows, and injured animals need extra attention, as these cattle are most likely to get overwhelmed by flies.6 Checking them daily during fly season is one of the best steps you can take to prevent small problems from becoming big ones.
10. Time Your Procedures Wisely
Try to schedule procedures like dehorning, castration, or tagging during cooler months when flies aren’t as active. Once fall rolls around, remember to remove fly tags to prevent resistance and reset the clock for next season.
Fly activity ramps up when temperatures rise and humidity increases—especially after periods of rain. By tracking weather patterns, you can anticipate fly surges and apply treatments before populations explode.
If a warm front or rainstorm is on the way, consider applying pour-ons or recharging fly traps early. Similarly, keep a closer eye on wound-prone cattle during heat waves, as flies become more aggressive and persistent. Aligning your fly control efforts with the forecast adds a proactive layer to your management plan.
What to Do If Flies Bite or Wound Cattle
Even with the best prevention strategies, you might still find the occasional fly bite or irritated wound. If this happens:
- Clean the area – Gently flush the wound with clean water. Then, apply an Antimicrobial Utility Spray to safely and effectively remove dirt and impurities from the wound to promote faster healing.
- Cover or shield the wound if needed – In some cases, especially with larger wounds, a light wrap or breathable dressing can help keep flies off. Just be careful not to trap moisture or cause irritation.
- Watch for infection or pink eye – Swelling, heat, discharge, or a foul odor are signs of infection. If you see tearing, squinting, or cloudiness in the eyes, pink eye might be starting. A gentle spray can help soothe pink eye in livestock and stop bacteria in their tracks.
If you notice maggots in a wound, swelling that gets worse, or pink eye that doesn’t improve, it’s time to call your veterinarian. They may recommend antibiotics or other treatments.
Why Pink Eye and Flies Go Hand-in-Hand
As mentioned, face flies are a major culprit in the spread of pink eye in cattle. These flies often land on one cow’s infected eye area and carry bacteria to the next. Dust, UV light, and grass can also irritate the eye and make infection more likely.1
Fly control should be your first line of defense against pink eye. However, if pink eye does pop up, treating it quickly is crucial. Vetericyn® Pink Eye Spray is designed for exactly this situation. It’s easy to apply, doesn’t sting, and helps keep the eye clean while reducing irritation and bacteria.
Catch pink eye early, and you may be able to avoid antibiotics and more serious damage.
Fly Control for Big Ranches vs. Hobby Farms
The size of your operation may also influence your fly control strategy. On larger ranches, you’ll likely use ear tags, feed-through larvicides, and back rubbers to cover a lot of animals efficiently. Scheduling herd-wide pour-on treatments and rotating pastures can also help keep fly pressure down.
For smaller farms, you might take a more hands-on approach, using fly sprays and portable traps and keeping a close eye on individual animals. Small-scale sanitation (like cleaning pens and rotating paddocks) can also go a long way.
Regardless of herd size, the basics remain the same: Prioritize clean surroundings, treat wounds quickly, and stay proactive when it comes to fly prevention.
Protect and Care for Your Herd with Vetericyn
Flies may be tiny, but their impact on your herd can be significant. From spreading pink eye to creating painful wounds, they’re a constant threat during the warmer months. But with a little planning and a lot of consistency, you can get ahead of them.
By combining sanitation, smart use of fly control products, timely wound care, and daily observation, you can give your cattle the best chance at a comfortable and productive season. And, if things get tricky, Vetericyn’s trusted livestock care solutions can help.
Shop our collection today to ensure you’re always prepared to support your herd’s well-being.
Reviewed by C. Scott Van Winkle
Scott has been with Innovacyn for the past 11 years and has been working within the Burlingame portfolio of companies for the past 23 years. Scott brings a diverse background to Innovacyn. With an upbringing as the 5th generation on his families cattle ranch, Scott has a passion for animal health and the continuous improvement surrounding agricultural practices. Scott earned marketing and business management degrees from the University of Idaho and holds an Executive MBA from Pepperdine University.
Sources:
- Texas A&M University. Shoo Fly! Keeping Cattle Comfortable and Healthy. https://vetmed.tamu.edu/news/pet-talk/protect-cattle-by-controlling-flies/
- Central Life Sciences. Understanding Horn Flies and Their Impact on Cattle. https://www.altosidigr.com/blog/horn-flies-impact-on-cattle/
- Montana State University. Face Flies on Cattle. https://apps.msuextension.org/montguide/guide.html?sku=mt201701AG
- Texas Farm Bureau. Fly control important for livestock health. https://texasfarmbureau.org/fly-control-important-for-livestock-health/
- ScienceDirect. Insect Growth Regulator. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/insect-growth-regulator
- Michigan State University. Protect newborn calves from fly strike. https://www.canr.msu.edu/news/protect_newborn_calves_from_flies_during_fall_calving
- Prevent Blindness. Eye Inflammation and Inflammatory Eye Disease. https://preventblindness.org/eye-inflammation/
