8 Products for Controlling Barn Flies and Pests

The low buzz starts in May, a minor annoyance that quickly swells into a deafening, swarming nuisance by mid-summer. Flies descend on the barn, tormenting livestock, contaminating surfaces, and turning simple chores into a frantic, swatting battle. Winning the war against barn pests isn’t about finding one magic bullet; it’s about building a smart, layered defense with the right tools for each part of the job.

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An Integrated Approach to Barn Pest Management

Before you buy a single product, understand the strategy: Integrated Pest Management (IPM). This isn’t just a buzzword; it’s a practical framework for controlling pests by combining different methods to achieve the best results with the least environmental impact. Think of it as a four-front war. The first front is cultural control—changing your environment by managing manure and moisture to make it less hospitable for pests.

Next comes biological control, where you enlist nature’s own army, like predatory insects, to target pests at their source. The third front is physical or mechanical control, which involves using physical barriers and traps to capture or kill pests directly. This includes everything from sticky traps to bait stations.

Finally, there is chemical control, which involves the targeted use of insecticides, larvicides, and baits. This is the most powerful weapon in the arsenal, but it’s also the one that requires the most care and responsibility. A successful IPM program doesn’t rely on just one of these pillars; it strategically combines all four for season-long effectiveness.

Start with Manure and Moisture Management

The single most effective step in any fly control program costs nothing but labor. Flies lay their eggs in decaying organic matter, and their number one nursery is a combination of manure and moisture. If you don’t control the breeding grounds, you will be fighting a losing battle, no matter how much you spray or trap.

Your primary task is rigorous manure management. This means cleaning stalls daily and moving the manure to a compost pile or off-site location far from the barn. If you compost, ensure the pile is actively managed—turned regularly to generate heat that kills fly larvae. Pay equal attention to moisture. Fix leaky faucets and water troughs, ensure proper drainage around the barn, and remove wet or soiled bedding promptly. A dry barn is an uninviting barn for flies.

Biological Control – Spalding Fly Predators

Biological control is your silent, background defense, working 24/7 to stop flies before they even hatch. The strategy is to introduce beneficial insects that prey on fly pupae, disrupting their life cycle. This is a proactive, preventative measure that reduces the number of adult flies that ever emerge.

For this job, Spalding Fly Predators are the industry standard. These are not flies, but tiny, gnat-sized wasps that do not sting or bite humans or animals. You receive a shipment of parasitized fly pupae, which you sprinkle around "hot spots"—manure piles, under water troughs, and along fence lines. The predators hatch and immediately seek out and destroy developing fly pupae in the soil or manure.

Spalding operates on a subscription model, automatically sending you a new batch every few weeks, timed perfectly for your climate zone. This is crucial because you need a continuous population of predators to keep up with the flies. This solution is not for immediate knockdown of an existing adult fly problem. You must start releasing them in early spring, before flies become numerous, and continue through the first frost for them to be effective.

Feed-Through Larvicide – Farnam SimpliFly

Another powerful preventative tool is a feed-through larvicide, which turns your animal’s manure into a fly-free zone. The product passes through the animal’s digestive system and, once excreted in the manure, prevents fly larvae from developing into adults. It’s a highly targeted way to stop the fly life cycle at the source.

Farnam SimpliFly with LarvaStop is a top choice for horse owners. It’s a palatable pellet that you add to your horse’s daily feed, making it easy to administer. The active ingredient, diflubenzuron, is an insect growth regulator (IGR) that specifically targets the fly larvae’s ability to molt, without affecting the horse.

Before using, understand its limitations. SimpliFly only treats the manure of the horses consuming it, so all horses on the property must be on the product for it to work effectively. It won’t stop flies breeding in other organic matter or those flying in from a neighbor’s property. Like fly predators, this is a long-term strategy that should be started in the spring before the fly season begins.

On-Animal Fly Spray – Absorbine UltraShield EX

While preventative measures work on the next generation of flies, you need something to give your animals immediate relief from the biting, swarming adults that are present now. A high-quality, long-lasting on-animal fly spray is a non-negotiable tool for animal welfare during fly season. It repels and kills pests on contact, reducing stress and preventing insect-borne diseases.

Absorbine UltraShield EX is the go-to for a reason. It’s a powerful, multi-ingredient formula designed for the toughest conditions. Its combination of permethrin and pyrethrins provides a fast knockdown and a residual effect that, thanks to its weatherproof and sweat-resistant formula, can last for days, not hours. It also includes sunscreens and coat conditioners, making it a comprehensive grooming aid.

This is a potent insecticide, so responsible application is critical. Always follow the label directions, avoiding the animal’s eyes and mucous membranes. It’s wise to test the product on a small patch of skin first to check for any sensitivity. UltraShield EX is for providing comfort to your animals; it is not a tool for reducing the overall fly population in your barn.

Premise Spray – Permethrin 10% Insecticide

Treating your animals is only half the battle; you also need to treat the barn itself. Premise sprays create a residual barrier on surfaces where flies land and rest, like walls, ceilings, and rafters. When a fly lands on a treated surface, it picks up the insecticide and dies, significantly reducing the population inside the structure.

A bottle of Permethrin 10% Insecticide concentrate is one of the most versatile and cost-effective tools for this job. This is a broad-spectrum insecticide that you dilute with water in a pump sprayer according to the label instructions. The 10% concentration allows you to mix it to the appropriate strength for different applications, from a general premise spray to treating specific pest problems.

Safety is paramount when using a premise spray. All animals must be removed from the barn before application. Wear appropriate personal protective equipment (PPE), including gloves and a mask. Spray surfaces to the point of runoff and allow the barn to ventilate completely until the spray is dry before allowing animals to return. A well-applied premise spray can remain effective for several weeks.

Disposable Fly Trap – Rescue! Big Bag Fly Trap

Sometimes you just need to remove a massive number of adult flies from an area, and for that, nothing beats a disposable bag trap. These traps use a powerful, non-toxic attractant to lure flies in, where they become trapped and drown. They are a simple, set-and-forget tool for dramatically reducing the adult fly population around your barn.

The Rescue! Big Bag Fly Trap is legendary for its effectiveness—and its smell. The trap consists of a durable plastic bag and a powdered attractant. You simply add water to activate the attractant, hang the trap, and let it work. It can catch and hold up to 40,000 flies, making it ideal for properties with a heavy fly load.

The key to using these traps is placement. The attractant is extremely pungent and designed to smell like decaying matter, so you must hang these away from your barn, house, and outdoor living areas. The goal is to draw flies out of the spaces you use, not into them. Hang them along a perimeter or near manure piles, at least 20-30 feet from doorways. When full, the entire bag is disposable.

Sticky Fly Trap – Starbar Fly Stik Sticky Fly Trap

For controlling flies inside enclosed spaces like the barn, tack room, or feed room, a sticky trap is an excellent non-toxic option. Unlike sprays or baits, they work silently and continuously without chemicals. They are perfect for catching the flies that inevitably make their way indoors.

The Starbar Fly Stik Sticky Fly Trap is a significant improvement over old-fashioned fly ribbons. Its large, cylindrical design provides a massive surface area for catching flies and is less prone to curling or tangling. It uses a combination of a bright, reflective surface and a pheromone attractant to lure flies to the glue.

These traps are simple to use: just hang them and you’re done. However, placement is everything. Hang them vertically in areas where flies congregate, such as near windows or doorways, but well out of reach of animals, children, and your own hair. They will eventually become covered in flies and dust, so they need to be replaced when they are no longer sticky or are full.

Fly Bait Scatter – Starbar QuikStrike Fly Bait

For targeted, rapid knockdown of adult flies in specific problem areas, a fly bait is an invaluable tool. Baits use a combination of attractants and a fast-acting insecticide. Flies are drawn to the bait, consume it, and die quickly, helping to break infestation cycles in high-density areas.

Starbar QuikStrike Fly Bait is exceptionally effective due to its multiple attractants, including a fly sex pheromone. The active ingredient, dinotefuran, provides a rapid kill, often within a minute of feeding. This makes it ideal for use around dumpsters, the perimeter of feed rooms, or near manure piles where flies gather in large numbers.

This is a poison and must be used with extreme caution. It should never be scattered in areas accessible to livestock, pets, or wildlife. The safest way to use it is inside a dedicated, enclosed bait station. This prevents accidental ingestion by non-target animals while still allowing flies to enter. Always read and follow the label directions precisely.

Rodent Bait Station – Protecta EVO Express

Flies aren’t the only pests in a barn. Rodents contaminate feed, chew through wiring, and undermine structures. Effectively managing them requires a secure method for deploying rodenticide, and that’s the job of a bait station. A good bait station protects the bait from weather and, most importantly, prevents non-target animals from accessing it.

The Protecta EVO Express is a professional-grade, tamper-resistant bait station built for the rigors of a farm environment. Its heavy-duty plastic construction and locking mechanism ensure that only rodents can get to the bait. It can hold bait blocks on vertical or horizontal rods, accommodating different bait types and rodent behaviors.

Remember, the station itself is just the box; the rodenticide bait must be purchased separately. Place stations along walls, behind equipment, and in other areas where you see signs of rodent activity, as rats and mice prefer to travel along established pathways. You must check the stations regularly to monitor bait consumption and, critically, to find and dispose of any deceased rodents to prevent secondary poisoning of predators like owls, hawks, or barn cats.

Safety First: Applying Products Responsibly

Using any pest control product, from a "natural" spray to a powerful insecticide, comes with a responsibility to use it safely. The single most important rule is to read and follow the entire product label before you open the container. The label is the law, and it contains critical information on application rates, safety precautions, and proper storage and disposal.

Always wear the recommended Personal Protective Equipment (PPE). For mixing and applying premise sprays or handling baits, this typically means chemical-resistant gloves, long sleeves, and eye protection. When spraying, a mask or respirator is often advised to avoid inhaling mist.

Be mindful of your surroundings. Prevent sprays and baits from contaminating feed, water troughs, and hay. Pay attention to wind direction when spraying outdoors to avoid drift. Understand that broad-spectrum insecticides can harm beneficial insects like bees and your fly predators, so apply them surgically rather than blanketing an entire area. Store all pest control products in their original containers in a locked cabinet, away from children, pets, and livestock feed.

Combining Methods for Season-Long Control

No single product will solve a serious pest problem. The key to a peaceful, low-pest barn is layering these tools into a comprehensive, season-long strategy. Your foundation is always manure and moisture management. Without this, everything else is a temporary fix.

In early spring, start your preventative layers: begin your Spalding Fly Predator shipments and put your horses on Farnam SimpliFly. As temperatures rise, deploy your perimeter defense with Rescue! Big Bag Fly Traps to intercept flies before they reach the barn. Inside, use Starbar Fly Stiks for ongoing, silent capture.

Use your reactive tools as needed. Provide daily comfort to your animals with Absorbine UltraShield EX. When fly populations spike, treat the barn structure with a Permethrin 10% premise spray for residual control. For flare-ups in specific spots, use Starbar QuikStrike Fly Bait in secure stations. All the while, keep your Protecta EVO Express rodent stations baited and active. This integrated approach means you are always one step ahead, managing the pest life cycle from every angle.

Controlling barn flies and pests is a constant chore, not a one-time fix. But it doesn’t have to be an overwhelming battle. By combining good management practices with a toolbox of smart, effective products, you can keep populations in check, ensure your animals are comfortable, and make your barn a more pleasant place to be all season long.