Fly Control 101

At Shade Haven, livestock comfort is our top priority—from providing mobile shade in the pasture to helping you reduce fly pressure. Special thanks to Dr. Sarah Slaby, D.V.M., for sharing her expertise for this article to help you protect your herd from fly infestations this grazing season.

Flies aren’t just an annoyance—they’re a costly threat to farmers and ranchers. For dairy and beef operations alike, unchecked fly populations can lead to significant losses in milk production, weight gain, animal health, and long-term productivity.

According to Dr. Sarah Slaby, a large animal veterinarian with over two decades of experience, fly control is crucial for both herd health and comfort. “Flies are pests to cattle. When something is biting at you and you’re constantly trying to swat it away, your normal routine is disrupted – for cattle that includes grazing, eating and drinking. Those are the main things we want cattle to be doing, so they can produce milk and gain weight.”

The most problematic flies include horn flies, stable flies, face flies, deer flies and house flies – each target cattle differently. Studies show the horn fly is responsible for $1 billion in losses annually for the beef industry. Additionally, dairy farmers can easily see a 5% drop in milk production if not properly managing flies.

“Heavy fly infestation can reduce weaning weight 10 to 15 pounds per calf,” adds Slaby. “In older calves that number is even higher.”

Disease Transmission

While flies reduce productivity, they also spread disease. Dr. Slaby identifies three common fly-borne illnesses she sees most in cattle:

• Pink Eye – Spread by flies carrying Moraxella Bovis bacteria.
• Mastitis – Transmitted by flies that carry Staph. aureus, often from one cow’s teat to another.
• Bovine Respiratory Disease Complex – Flies land on animals with compromised immune systems, transferring pathogens through eye and nasal secretions.

“Flies can be a significant stressor on the immune system,” explains Slaby. “When you observe a group of animals, you’ll find that those with the weakest immune systems attract the most flies. The insects can detect that these animals have a compromised immune response.”

A Systems Approach to Fly Control

Dr. Slaby recommends a multi-pronged approach to fly management, beginning with cleanliness. “Keep the farm as clean as possible, so flies don’t have a place to lay their eggs and reproduce more flies.”

A second strategy is the use of predators – small wasps that live off fly larvae. These are available through several retailers such as Spalding Labs. “It’s important that you use predators that are specific to your region,” Slaby advises. “It’s also important to start those predators early. Don’t wait until the flies are bad. That’s too late.”

Inviting natural predators – such as ducks, barn swallows, and purple martins – into your environment can also help keep fly numbers in check.

Other effective tools include fly tape, essential oils, and natural repellents, like Dr. Slaby’s own Shoo Fly formula. The Shoo-Fly repellent is a non-toxic, versatile solution. Unlike other products on the market, it can be mixed with water, oil or a combination of both, so you can adjust the formula as needed based on temperature and other conditions.

Shade Matters

Mobile shade systems like the Shade Haven can play a part in fly management. Moving the shade prevents manure build up and moves cattle away from the spot where the flies are laying their eggs.

Adding a fly control oiler/scratcher system to your Shade Haven provides another layer of protection. Shade Haven customers have reported success using Dr. Slaby’s natural Shoo Fly repellent in the oiler of our fly control system that is designed to fit both the SH600 and SH1200 mobile shade systems.

Final Tip

Dr. Slaby’s final recommendation? “Providing higher quality of nutrition, along with free-choice minerals and kelp, is beneficial for your animals, particularly during the stressful fly season”

For farms marketing their milk and proteins, managing flies not only boosts your bottom line – it demonstrates a commitment to animal welfare. That’s something important to today’s consumer. Slaby adds, “As a veterinarian, I want to know the milk or meat I’m consuming comes from animals that are treated humanely, and part of that is fly control.”