Watching your horse swish its tail constantly, stomp its feet, and develop raw, fly-bitten sores can feel like a special kind of helplessness. You’ve tried the sprays, the masks, the sheets, but the flies just keep coming back to their favorite breeding ground: your horse’s manure. That cycle of frustration is why a strategic, internal approach to fly control isn’t just a luxuryâit’s a cornerstone of modern, compassionate horse care.
Iâm Mo Mahin â the founder and writer behind Furric. My research for this guide involved deep analysis of veterinary safety data on insect growth regulators (IGRs), consultations with equine nutritionists, and evaluating thousands of real-world reviews from fellow horse owners battling everything from stable flies in Florida to face flies in the Midwest.
It’s a long-term investment in your horse’s peace and your sanity, but the payoff is a happier, healthier animal and a significantly more pleasant barn environment, which is why understanding the mechanism and commitment behind the best feed through fly control for horses is essential for effective season-long management.
How To Choose The Best Feed Through Fly Control For Horses
Choosing the right product isn’t about finding a magic bullet; it’s about understanding a biological process and committing to a proactive management strategy. Fly sprays treat the symptom (adult flies), while feed-throughs address the cause (larvae in manure). Your goal is to stop the next generation before it ever takes flight.
Understand the Active Ingredient: IGRs
The core of any effective feed-through is an Insect Growth Regulator (IGR), typically Diflubenzuron or Novaluron. These are not pesticides that kill adult flies. Instead, they pass through your horse’s digestive system unchanged and into the manure, where they inhibit the development of chitinâthe substance that forms a fly larva’s exoskeleton. Larvae cannot mature or hatch, breaking the reproductive cycle. This targeted action makes IGRs highly specific and considered very safe for horses, as mammals do not produce chitin.
Commitment and Timing Are Everything
This is not a “see flies, start feeding” solution. For the IGR to build up in the manure at effective levels, you must begin feeding the product at least 30 days before flies typically emerge in your region. Consistency is keyâfeeding must be daily throughout the entire fly season. Stopping and starting disrupts the cycle and reduces effectiveness. Think of it as a seasonal supplement, not a spot treatment.
Palatability and Feeding Ease
If your horse won’t eat it, the best science in the world is useless. Most feed-throughs are alfalfa or grain-based pellets designed to be highly palatable and mix easily with your horse’s daily grain ration. For picky eaters, starting with a small amount and gradually increasing can help. The easier it is to incorporate into your daily routine, the more likely you are to maintain the necessary consistency.
Integrate, Don’t Isolate
Feed-through control is most powerful as part of an Integrated Pest Management (IPM) plan. It should work alongside diligent manure management (regular stall cleaning and manure pile dispersal), physical barriers like fly masks and sheets, and targeted use of sprays for adult flies. The feed-through drastically reduces the population breeding on your property, making your other control measures far more effective.
Quick Comparison
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| Model | Type | Best For | Key Feature | Amazon |
|---|---|---|---|---|
| Formula 707 MultiFly 5lb | Pellet | Season-Long Barn Control | Novaluron IGR, 91 Servings | Amazon |
| Farnam SimpliFly 10lb | Pellet | Multi-Horse Barns | Diflubenzuron IGR, 160-Day Supply | Amazon |
| Absorbine UltraShield EX 128oz | Spray | Topical & Premises Spray | 17-Day Weatherproof, 70+ Insect Species | Amazon |
| Farnam Equitrol II 20lb | Pellet | Single Horse, Full Season | 320-Day Supply, Highly Palatable | Amazon |
| Formula 707 MultiFly 10lb | Pellet | Proactive Season Planning | Novaluron IGR, 182 Servings | Amazon |
| Farnam SimpliFly 3.75lb | Pellet | Trial or Small Barn | 60-Day Supply, LarvaStop Tech | Amazon |
| Wondercide Concentrate | Spray | Natural Premises Control | Cedar Oil Based, Pet-Safe | Amazon |
| Absorbine UltraShield EX 32oz | Spray | Effective Topical Spray | Award-Winning, Water-Based | Amazon |
| Horse Health Red Cell | Supplement | Vitamin/Iron Support | Yucca Flavor, Immune Health | Amazon |
| Farnam Repel-X 32oz | Spray | Multi-Purpose Spray | For Horses, Dogs & Premises | Amazon |
| Farnam Flys Off Ointment | Ointment | Wounds & Sensitive Areas | Targeted Protection, 7oz Tube | Amazon |
In-Depth Reviews
1. Formula 707 MultiFly Feed-Thru Fly Control Pellets (5 lb)
For horse owners seeking a powerful, proactive solution that tackles flies at their source, Formula 707 MultiFly stands out as our top recommendation. This feed-through pellet uses the next-generation Insect Growth Regulator Novaluron, which is celebrated for its 99.9% efficacy rate and safety profile, being free from organophosphates. It represents the ideal balance of proven science, equine safety, and practical value for a season-long battle.
The alfalfa and wheat middlings base makes these pellets exceptionally palatable, eliminating the daily struggle of convincing a finicky eater. A single scoop mixed into the morning feed is all it takes to set up a defensive line in your horse’s manure. Community feedback from multi-horse barns consistently highlights a dramatic reduction in barn flies within weeks, with many reporting their farriers specifically asking what fly control program theyâre using due to the noticeable difference.
Starting this program in early spring is non-negotiable for maximum effect, but the payoff is a summer where flies are a minor nuisance rather than a constant torment. This mid-range option delivers premium results, making it the cornerstone of a sophisticated integrated pest management plan for the discerning horse owner.
Why we love it
- Highly effective Novaluron IGR breaks the fly life cycle with precision.
- Extremely palatable formula ensures consistent daily intake without fuss.
- Excellent value for the coverage, offering a full season for one horse.
- Made in the USA with a strong reputation for safety and quality.
Good to know
- Like all feed-throughs, requires a 30-day head start before fly season for full effectiveness.
- Does not kill adult flies; must be paired with sprays for immediate relief.
2. Farnam SimpliFly Feed Through Fly Control (10 lb)
If you manage multiple horses or simply want to secure a season’s supply in one go, the 10-pound bucket of Farnam SimpliFly offers outstanding value and convenience. Utilizing the trusted IGR Diflubenzuron, this product is a workhorse in the fly control world, preventing larvae development in manure to reduce populations by up to 97-100% according to brand data. The large bucket is a staple in well-organized tack rooms.
The pellets feature Farnam’s LarvaStop technology and are alfalfa-based for easy acceptance. The 160-day supply means one less thing to reorder during the busy summer months. Seasoned barn managers appreciate that this product performs consistently when used as part of a full program, noting a drastic decline in the time spent swatting flies during chores and a significant reduction in manure maggots.
For the price-conscious owner who doesn’t want to compromise on science-backed results, this bulk option is a smart, strategic purchase. It epitomizes the “ounce of prevention” philosophy, saving money and labor on reactive sprays over the long haul.
Why we love it
- Exceptional value per serving, ideal for multi-horse operations.
- Reliable Diflubenzuron formula with a long history of effective use.
- Convenient bucket packaging is easy to store and scoop from daily.
- Integrates seamlessly with sprays and masks for complete control.
Good to know
- The large bucket represents a higher upfront investment.
- As with all IGRs, it does not affect biting flies like horse flies or gnats that breed elsewhere.
3. Absorbine UltraShield EX Insecticide (128oz)
For the gold standard in topical and premises protection, the gallon size of Absorbine UltraShield EX is in a league of its own. This award-winning spray is a critical component of any IPM plan, offering robust, long-lasting repellency and knockdown for over 70 insect species. Its UltraBond technology provides up to 17 days of weatherproof protection, a claim that holds up even in challenging, humid environments.
Beyond just bugs, the formula includes sunscreen and coat conditioners, offering an extra layer of care during sunny summer rides. Equine enthusiasts in bug-infested areas describe it as “magic in a bottle,” with dramatic stories of immediate fly disappearance and notable relief for horses prone to sweet itch or insect-bite hypersensitivity. The water-based formula dries without greasiness and is safe for use on horses, dogs, and barn surfaces.
While not a feed-through, this premium spray is the perfect partner to one. Use it on your horse for immediate, long-lasting relief and around the barn to create a hostile zone for adult flies, while your feed-through product works silently to prevent the next generation.
Why we love it
- Unmatched, long-lasting repellency and knockdown power.
- Multi-benefit formula includes sunscreens and coat conditioners.
- Versatile for use on animal coats, stalls, fencing, and kennels.
- Consistently top-rated by equestrian publications and professionals.
Good to know
- Premium tier investment for the gallon size.
- Some users note the sprayer mechanism can be prone to leaking; many transfer to their own sprayer.
4. Farnam Equitrol II Feed-Through Fly Control (20 lb)
For the dedicated single-horse owner who desires the ultimate in convenience and a “set it and forget it” approach for an entire year, Farnam Equitrol II delivers. This massive 20-pound bucket provides a staggering 320-day supply, effectively covering one horse for a full fly season and then some. Its primary appeal is eliminating the need for multiple orders and ensuring you never run out at the peak of summer.
Reviews from owners with horses on pasture highlight its effectiveness when fed consistently, even if not daily. Many share that after establishing the program, they noticed a stark increase in flies within two weeks of stopping, which is the most real-world proof of efficacy you can get. The pellets are reported to be highly palatable, with horses readily eating them straight from the hand or mixed with feed.
This is an investment in uninterrupted, consistent control. Itâs perfect for the owner who values planning ahead and wants to provide their equine partner with steady, internal protection from the spring thaw to the first hard frost.
Why we love it
- Unbeatable convenience of a full season’s supply in one purchase.
- Proven to significantly reduce house and stable fly populations in manure.
- Horses generally find the taste very appealing.
- Builds a reliable foundation for your barn’s fly management program.
Good to know
- The highest upfront investment of all feed-through options.
- Large bucket requires adequate storage space.
5. Formula 707 MultiFly Feed-Thru Fly Control Pellets (10 lb)
This is the larger-volume sibling to our top pick, offering the same superior Novaluron formula for owners with two horses or those who simply prefer to buy in bulk. The 10-pound bag provides 182 servings, making it a cost-effective choice for small barns wanting to standardize their fly control program with a highly-regarded product. Itâs the choice for the planner who buys for the entire season at once.
The consistent feedback here mirrors the smaller bag: noticeable results when started early, happy horses who eat it willingly, and a profound reduction in the frustration of fly-ridden manure piles. Barn managers report that this product, when combined with good sanitation, can transform a buggy barn into a much more pleasant workspace within a single season.
Choosing this size demonstrates a commitment to a science-backed, preventive health strategy for your herd. Itâs a decision that pays dividends in horse comfort and reduced labor spent on constant topical applications.
Why we love it
- All the benefits of the 5lb bag with greater value per serving.
- Ideal for small barns with two or more horses.
- Builds a consistent IGR level in manure for sustained population control.
- Trusted, non-organophosphate ingredient safety profile.
Good to know
- Requires a commitment to daily feeding for several months to utilize fully.
- Effectiveness is cumulative and not instantaneous against existing adult flies.
6. Farnam SimpliFly Feed Through Fly Control (3.75 lb)
New to the concept of feed-through fly control? The 3.75-pound bucket of Farnam SimpliFly is the perfect introductory size. It offers a 60-day supply, giving you ample time to evaluate its effectiveness in your own environment without a major commitment. This allows you to witness firsthand the reduction in larvae in your manure piles and gauge your horse’s acceptance of the pellets.
First-time users often express pleasant surprise at how simple it is to integrate into feeding time and how quickly they observe a difference in fly activity around the barn, noting that the flies seem “less aggressive” or concentrated only near waste buckets rather than on the horses themselves. This size is also excellent for horse owners who only need coverage for the peak summer months or for a single horse on a trial basis.
Think of this as your proof-of-concept purchase. It provides all the technological benefits of the larger SimpliFly buckets, empowering you to make an informed decision about investing in a larger supply for the following season.
Why we love it
- Low-risk way to trial feed-through technology with your horse.
- Perfect size for covering the height of summer fly season.
- Easy to store and handle, with a manageable bucket size.
- Features the same reliable Diflubenzuron IGR as the larger sizes.
Good to know
- Higher cost per serving compared to the larger bulk sizes.
- A 60-day supply may not be sufficient for full season control in many climates.
7. Wondercide Outdoor Pest Control Spray Concentrate
For horse owners prioritizing natural ingredients and seeking a safe premises spray for use around paddocks, patios, and barn entrances, Wondercide’s concentrate is a standout. Powered by cedarwood oil and other essential oils, this formula kills and repels a wide array of pests on contact and creates a protective barrier. It’s a conscious choice for those managing organic facilities or with concerns about chemical runoff.
Users love the fresh, woody scent and the peace of mind that comes from using a product safe for kids, pets, and beneficial insects like bees and butterflies when used as directed. It’s particularly favored for spraying perimeter fencing, around stall doors, and in outdoor sitting areas to create a more comfortable zone for humans and horses alike. Many note its effectiveness against fleas, ticks, and mosquitoes in addition to flies.
While not a feed-through or a direct substitute for a long-lasting equine coat spray, Wondercide is a powerful tool in the natural horse keeper’s arsenal. It allows you to treat the environment thoroughly without synthetic pesticides, complementing other management practices beautifully.
Why we love it
- Plant-powered, natural formula derived from essential oils.
- Safe for use around animals, gardens, and children with no re-entry wait.
- Pleasant cedar scent instead of a chemical odor.
- Versatile concentrate can be mixed for various sprayer types.
Good to know
- Protection duration is shorter than synthetic residuals, often requiring more frequent application.
- Not designed or tested as a direct spray for horses’ coats; use on the environment only.
8. Absorbine UltraShield EX Insecticide (32oz)
The quart size of Absorbine UltraShield EX brings the legendary performance of this spray into a more accessible, ready-to-use package complete with a sprayer. It’s the go-to for riders who need reliable, long-lasting protection for trail rides, shows, or daily turnout. The formula’s reputation for effectiveness in humid, bug-prone areas is well-earned, making it a trusted staple in many grooming totes.
Equine caretakers dealing with insect-bite allergies or sensitive-skinned horses frequently report this spray as a game-changer, preventing the painful welts and sores that can develop from fly bites. The inclusion of sunscreen is a valued bonus for horses with pink skin or thin coats. The water-based nature means it won’t gum up coats or leave a heavy residue, which is appreciated during busy summer training schedules.
This is the tactical weapon you use for direct defense. When you need your horse to be comfortable and focused, not distracted by swarming pests, a few sprays of UltraShield EX provide the high-performance barrier you can count on.
Why we love it
- Delivers the same premium protection as the gallon in a convenient size.
- Comes with a sprayer, ready for immediate use.
- Highly effective for horses with fly allergy or sweet itch.
- Water-based and non-greasy, with added sunscreen benefits.
Good to know
- The sprayer unit can sometimes be less durable than the product itself.
- While long-lasting, it still requires reapplication, especially after sweating or rain.
9. Horse Health Red Cell Liquid Supplement
It’s crucial to clarify that Red Cell is not a fly control product; it’s a premier vitamin, iron, and mineral supplement designed to address nutritional gaps and support overall health, including immune and circulatory function. A healthy horse is better equipped to handle the stresses of summer, including insect annoyance and the potential for allergic reactions. We include it here as a reminder that foundational wellness is part of any holistic care plan.
This yucca-flavored liquid is a classic in the equine world, often recommended by veterinarians for anemic, debilitated, senior, or heavily worked horses. Owners of performance animals note improved bloom and energy levels, while those nursing rescues back to health rely on it to help rebuild strength. It can be easily dosed via syringe or mixed into feed, though some picky eaters may detect its distinct flavor.
Think
Think of Red Cell as part of your horse’s foundational health protocol. By supporting robust blood cell health and metabolic function, you’re helping your horse maintain the vitality needed to thrive, which indirectly supports their ability to cope with seasonal stressors like heat and insects.
Why we love it
- Trusted formula for supporting iron levels and overall vitamin/mineral intake.
- Yucca flavor enhances palatability for many horses.
- Easy to administer via dose syringe or mixed in feed.
- Ideal for senior, performance, or recovering horses.
Good to know
- This is a nutritional supplement, not a fly control product.
- Some horses may be sensitive to the taste or smell; mixing and letting it dry can help.
10. Farnam Repel-X Insecticide & Repellent (32oz)
A classic in the equine world since 1957, Farnam Repel-X is a versatile, cost-effective option for those seeking a single product for horses, dogs, and barn surfaces. This ready-to-use, water-based formula kills and repels six common fly species along with mosquitoes, gnats, and ticks. Its multi-purpose nature makes it a handy all-in-one solution for the homesteader with various animals.
The formula is designed to leave minimal greasy residue, which is appreciated when spraying stalls or kennels. Dog owners in particular have shared remarkable stories of using it to protect their canine companions during camping trips or outdoor activities, noting an immediate “force field” effect against bugs. For the horse owner on a budget who needs a reliable, no-fuss spray for general use, Repel-X has stood the test of time.
While it may not have the extended residual power or sunscreen additives of more premium sprays, it delivers solid, effective repellency. It’s a testament to the idea that a straightforward, well-formulated product can remain a staple in barns for generations.
Why we love it
- Excellent value for a multi-purpose insecticide and repellent.
- Can be used safely on horses, dogs, and premises like stalls and kennels.
- Water-based and non-greasy, easy to apply and clean up.
- A proven, trusted formula with a long history of reliable use.
Good to know
- Sprayer mechanisms have been reported by some users to malfunction or leak.
- Protection duration may be shorter than more modern, technology-driven sprays.
11. Farnam Flys Off Fly Repellent Ointment
When flies relentlessly target specific areasâlike the edges of wounds, rubbed-raw sores, tender ear tips, or the udderâa broad spray isn’t the right tool. Farnam Flys Off Ointment is designed for this precise, targeted protection. Its thick, adherent formula creates a long-lasting, physical and chemical barrier over sensitive spots, providing relief and allowing healing to occur without constant insect harassment.
Dog owners with breeds prone to fly-strike on their ears consider this product a lifesaver, reporting that a single application can protect for several days and finally allow painful lesions to heal. The ointment’s consistency means it stays put through light rain or dust, offering persistent protection where it’s needed most. It’s a staple in many first-aid kits for both equine and canine care.
This is not a whole-body solution, but a specialized one. Having a tube of Flys Off on hand is a smart move for any animal caretaker. It addresses those acute, localized fly problems that other methods can miss, ensuring your animal’s comfort during recovery or in particularly vulnerable areas.
Why we love it
- Provides targeted, long-lasting protection for wounds and sensitive areas.
- Thick formula adheres well and doesn’t wash off easily.
- Highly effective at stopping flies from aggravating existing injuries.
- Small tube is convenient for travel or to keep in a tack box or barn first-aid kit.
Good to know
- For spot treatment only, not suitable for full-body application.
- The thick, ointment texture can attract dirt and dust in very dry, dusty environments.
Safety & Care Tips
Start Before You See Flies
The single most common mistake is waiting until flies are swarming to begin a feed-through program. Insect Growth Regulators (IGRs) work preventatively by building up in the manure. Begin feeding at least one month before flies typically emerge in your area. This head start ensures the manure is “treated” when the first eggs are laid, stopping the first generation before it starts.
Maintain a Multi-Pronged Approach
No single product is a silver bullet. Combine your feed-through supplement with daily manure management (remove and compost manure piles away from barns), use physical barriers like fly masks and sheets, and apply a quality topical spray as needed for immediate adult fly relief. This Integrated Pest Management (IPM) strategy addresses flies at every life stage and from every angle for maximum control.
FAQ
How long does it take for feed through fly control to work?
Is feed through fly control safe for all horses?
Will feed through pellets control horse flies or gnats?
Can I stop feeding the pellets once flies are gone?
Final Thoughts: The Verdict
For most pet parents, the best feed through fly control for horses winner is the Formula 707 MultiFly 5lb Pellets because it marries next-generation Novaluron technology with excellent palatability and strong real-world results, offering the best balance of efficacy and value. If you want the most cost-effective bulk option for a multi-horse barn, grab the Farnam SimpliFly 10lb Bucket. And for immediate, long-lasting topical protection to pair with any feed-through program, nothing beats the Absorbine UltraShield EX 128oz Spray.