MultiFly® Feed-Thru Fly Control

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We are temporarily backordered on 10# MultiFly. Please reach out to the office at if you'd like an estimated ship date.

Our MultiFly pellets provide safe and effective fly control for your barn. Simply feed once per day to break the fly life cycle. MultiFly is made with Novaluron, which is a completely safe Insect Growth Regulator and is 99.9% effective.

As existing adult flies die off, the overall fly population is significantly reduced within 2 weeks upon feeding MultiFly. Start feeding in spring before flies begin to appear. The product should be used as part of an integrated pest management program and should be used throughout the fly season. Novaluron is not an organophosphate, and can be safely used in a pest control program for horses and their environment.







The fastest way to enjoy fewer flies in your barn.

Flies are not only a nuisance, but can transmit diseases to your horses. MultiFly Feed-Thru Fly Control is one of the most effective fly control solutions on the market, at the cost of only $0.36 per day per horse. This safe, pelleted formula provides 99.9% efficacy at breaking the fly life cycle in the manure of treated horses. Simply feed to your entire barn, and watch the fly population quickly shrink.

Step 1: Give MultiFly to each horse in the barn daily with grain

It's important to feed every horse in your barn to see the best effects. Simply feed alone, or with grain. One scoop/day is sufficient for the average-sized horse.

Step 2: Horses eat MultiFly and expel it in their manure

The active ingredient in MultiFly, Novaluron, is a completely safe ingredient for horses. It is not absorbed by the horse, but rather is passed through the digestive tract, into the manure.

Step 3: Manure produced by horse is no longer a viable breeding ground for flies.

Fly eggs that are laid in treated manure will die before developing into flies.

Which fly species does MultiFly target?

MultiFly Feed-Thru Fly Control for Horses specifically targets the common types of flies that reproduce in manure, aiming to interrupt their life cycle and reduce their population. These flies include the housefly (Musca domestica) and the stable fly (Stomoxys calcitrans). It is important to note that certain species of flies, such as the horse fly and deer fly, do not reproduce in manure but rather lay their eggs near water sources or moist areas, like marshes or ponds. Many of our customers with water sources nearby use Fly Predators in tandem with MultiFly. These can help target flies that are reproducing in breeding sources that are not manure. MultiFly Feed-Thru Fly Control focuses on the fly species that rely on manure for reproduction, making it an effective solution for controlling these specific types of flies.

Loved by thousands of horses and their people.

Formula 707 is the trusted choice of thousands of horse owners globally. From various disciplines and all ages, our community values the special connection that horses and humans have. We prioritize the health and happiness of your horse by formulating our supplements in collaboration with experienced veterinarians. Produced in our equine-exclusive facility, our products are tested for purity and potency. With Formula 707, you're choosing proven quality for your equine partner.

Why use a feed-thru fly control?

1. Shrinks the overall fly population

While fly sprays can be useful, and we recommend them being used in conjunction with MultiFly, they don't tackle the root of the problem. MultiFly helps cut down the overall number of flies, lessening your dependence on fly sprays.

2. Reduces the risk of fly-borne equine disease transmission.

Using fly spray alone can be a pain to apply to each horse daily. Even fly sprays that are longer-lasting can be affected by sweat, water, and dirt. MultiFly is as simple as a scoop/day with your horse's normal grain.

3. Easy to administer.

Flies can carry dieseases such as Pigeon Fever and Equine Infectious Anemia (EIA). Fly control is an important piece of helping to protect your barn.

4. Makes a more enjoyable environment for you too!

No one like seeing their horse suffer from swarms of biting flies, but it's also not pleasant for you and anyone that is around your horses. MultiFly can help make your barn more pleasant for everyone who visits.

MultiFly breaks the fly life cycle so that adult flies can't form

What is in MultiFly?

Novaluron is the Insect Growth Regulator (IGR) used in MultiFly Feed-Thru Fly Control. All feed-thru fly control products on the market have an IGR. An IGR is an active ingredient that works to disrupt the normal life cycle of the insect.


Not all IGR's are created equal. Some IGR's used in feed-thru fly control products are organophosphates. Organophosphates are pesticides that are especially toxic to both mammals and insects.


Novaluron, on the other hand, is a minimal-risk IGR that is not an organophosphate. In a 2015 study, it was shown that Novaluron was 100% effective in preventing the development of house flies and stable flies in the feces of treated horses.

Manufactured in-house


99.9% effective at breaking the fly life cycle

Easy-to-feed pellets

No organophosphates

90-day satisfaction guarantee

This Product is Show-Safe

This product contains no ingredients that are listed as prohibited, and additionally has been used by customers in major federations without issue. (If you'd like to double check, please reach out to your respective federation!)

Real Support

Want help with your order, or have general questions? Our live, Colorado-based Customer Support team is here to answer any questions you may have. Simply email us at or call at 970-284-5575 (M-F, 8am-5pm MST). 

Customer Reviews

Based on 194 reviews
Tanya Reisinger

It actually works and works well! Easy and effective, what else is there? Certainly worth trying; you will not be disappointed.

Trisha Bordelon
Excellent product

Love this supplement. No flys at all in my barn


This product is the best I have found. Horses like it in their morning feed. Easy and efficient to use.

Dawn Montgomery
I will forever use this product!

There is a noticeable difference in fly activity since I started using this a few years ago! The first year, I started too late in the season. Last year, I started in March and definitely saw a drastic reduction in flies!! I have 8 horses at home and they are all on this product. I will always use this product. The benefit to my horses is tremendous!

Nancy Crutchfield
Fantastic Product!

I started using Multifly summer 2023 and within 1 week saw a huge decrease in fly activity. I’m feeding 2 horses and 2 minis. I think it’s a fabulous product and my horses love it! Highly recommend Multifly!

Gayle Decker
Fly congrol

I have found this to be a great product. This is my 2nd Summer with it. My horse eats it very well. I give it 2 thumbs up.

Can see a difference

I started using this about mid-fly season last year, which was obviously too late for full effect, but I still saw a difference in flies in and around the barn, especially the manure gnats. I also used predators, as I have been for over 10 years. Between the two of them I am able to keep my use of fly spray to a minimum (only when riding.) This year I started in early March and am expecting great things! Even my picky eaters eat this right up. Also very happy that Multifly is available in the larger bags now. I ran out of uses for the the little bucket and hate sending them to landfills.

Weather or Formula 707?

Just started using it about a month ago. The weather has been wonky so I don’t know if it’s the product or the weather being cold that there are less flies?
The horses have no problem eating it.
Will update when the weather warms up and I can determine if there really are less flies.

Frequently Asked Questions

Why is MultiFly less expensive than other feed-thru fly control products?

We manufacture MultiFly here in our own facility. Unlike other brands that have to pay a private manufacturer to produce their products, we are able to produce ourselves. The extra savings from this process are passed on to you! 

My dog eats manure. Will my dog be safe if he consumes manure when I am feeding MultiFly to my horses?

We have many MultiFly customers with pets that like to eat manure. However, we are not able to make any claims regarding safety/efficacy for any other animal other than horses. With that being said, Novaluron (the active ingredient in MultiFly) has undergone rigorous safety and efficacy studies, even for food-chain animals, and has been approved for commercial poultry operations. 

When is the best time of year to start feeding MultiFly?

It depends where you live. We recommend feeding a few weeks before you notice flies in the spring. You can start feeding it during fly season, but you may not see as dramatic of results.

Should I remove manure before I start using MultiFly?

Yes. We highly encourage customers to remove all manure from the premises. The goal is to eliminate any non-treated manure where flies could continue to breed. 

Is MultiFly safe for horses?

MultiFly is fully registered with the EPA and has undergone significant efficacy and safety studies in order to be approved by the EPA as a registered product that is safe for equines. 

Can I feed this to other species?

The active ingredient in MultiFly is Novaluron.  This ingredient is widely used in agriculture due to its high safety profile and low toxicity risk.  While this ingredient has been tested in non-equines (e.g., cattle, goats, etc.), we are not able to make any claims about safety/efficacy for any species other than equines.  We recommend that you contact your veterinarian before administering to any other species. 

What insects does MultiFly target?

MultiFly has been proven effective at breaking the fly life cycle of house and stable flies. 

How does this compare to garlic-based products?

Garlic-based supplements for fly control are targeted at only repelling the flies from the horse as its absorbed into the horse. They do nothing for reducing the overall fly population. It is also argued that garlic has insufficient efficacy claims.


MultiFly works by breaking the fly life cycle of flies in the manure of treated horses, thus reducing the overall population. MultiFly is not absorbed into the horse, and does not inherently act as a repellent to the horse itself.

I have a smaller/larger than average horse, how much should I feed?

For the average equine at 1100 lbs or less, feed 1 scoop daily. For especially small animals (e.g. 550 lbs or less) you may feed half a scoop. For equines over 1100 lbs, feed 2 scoops daily.

How does this compare to Simplifly®?

Both are nearly identical in efficacy and safety claims. The main difference is the Insect Growth Regulator (IGR) they both use. MultiFly uses Novaluron, and Simplifly uses Diflubenzuron. Both IGR's do the same thing - they stop larvae in manure from forming into adult flies. However, MultiFly is significantly less, at $0.36 per day, versus $0.46/day for a 10 lb bucket of Farnam Simplifly®.


For horse owners who are currently using Simplifly®and would like to switch over to MultiFly, it is safe to do that immediately.

What if I don't see the results I was looking for?

If you aren't happy with the results of MultiFly, simply reach out to us, and we will be more than happy to make it right with our 100% 90-day satisfaction guarantee.

How do I get free shipping?

To get free shipping, spend $100 or more in a single purchase, and it will automatically be applied!

If I sign up for a subscription, can I change or cancel anytime?

Yes - you can change or cancel your autoship anytime by logging into your account, or reaching out to us.

Is Novaluron a urea? Is it the same urea that's found in cattle feed?

Novaluron is a benzophenyl urea, which is not chemically similar to urea found in cattle feed.

Will my horse test if drug tested at an event?

MultiFly contains an Insect Growth Regulator, Novaluron. Novaluron's sole purpose in agriculture is to stop flies from forming their exoskeleton - and thus breaking the life cycle. There are no known sedative effects of novaluron.

We always urge customers to reach out to their respective association if they would like to check. We have many customers in different associations that show while on this product and have never had a reported issue.

Will this affect dung beetles?

The active ingredient in MultiFly is novaluron, which works as a chitin synthesis inhibitor. The exoskeleton of all insects contain chitin. Insects that reproduce directly in manure will likely be affected. 

Will this affect bees?

The active ingredient in MultiFly is Novaluron, which works as a chitin synthesis inhibitor. The exoskeleton of all insects contain chitin. Insects that reproduce directly in manure will likely be affected. Since bees reproduce in their hives, bees are unlikely to be affected.


Novaluron is also not systemic - meaning that it cannot be absorbed by plants. Bees and other pollinators will not ingest novaluron through plants.

Can I garden with manure that has been treated with MultiFly?

The active ingredient in MultiFly is Novaluron. Novaluron is not systemic, meaning that it is not absorbed by the plant from the soil. Plants that are exposed to novaluron (in the soil, compost, etc.) will not have any novaluron content present in leaves, stems, etc. Manure treated with MultiFly is safe for vegetables, fruits, and other vegetation. Novaluron itself is widely used in U.S. agriculture for food crops.


In regards to organic gardening - we ask that you reach out to the USDA for clarification for your operation.

Is MultiFly toxic to aquatic life?

The active ingredient, Novaluron, is moderately toxic to fish and very toxic to aquatic invertebrate organisms (e.g. shrimp, crawfish).


Care should always be taken to prevent manure from entering aquifers and bodies of water - regardless if the manure has been treated with a feed-through fly control product. We'd recommend you reach out to your state extension office for guidance on manure management.

Is MultiFly safe for metabolic horses?

A single-serving of MultiFly is very small at about just 0.88 oz. The pellets are low in nonstructural carbohydrates.


We'd recommend you reach out to your veterinarian if you're concerned. We know of many metabolic horses that have been on the product per their vet's recommendation.

My neighbors also have horses and aren't feeding MultiFly. Will it still work?

The best results are when the entire facility and adjacent facilities are on MultiFly - as it stops flies from producing in all manure. It can be tough when your neighbors aren't on the product, as flies can and do travel between farms. Dependent on their proximity and their manure management, you will likely still see a difference in the fly population, albeit not as much as if you were the only one for miles! 

I have one horse in a boarding facility. Is MultiFly worth feeding?

Unfortunately, MultiFly works best when all horses on the premises are on the product. Since flies would still be able to reproduce in the manure of other horses at the barn, it will be unlikely to make a difference.


Speak to your barn manager about getting a whole-barn program started!

Does MultiFly repel flies from my horse?

No - MultiFly is ineffective towards existing adult flies. MultiFly is not a fly repellant - rather it is an Insect Growth Regulator that stops flies from reproducing in manure.

Is MultiFly carried in retail stores?

Since MultiFly is a newer product, it isn't in a lot of brick & mortar stores - yet. Feel free to let your local store know if you'd like to see the product on the store shelves! They can apply to become a retailer by reaching out to us at

How quickly will I start seeing results with MultiFly?

Some of our customers start seeing results in as little as three days, but most people see significant results in two to four weeks, since that is around the average lifecycle of a fly.

Can I use this in conjunction with fly predators?

Yes! Fly predators attack the pupal stage of the fly and do not eat the manure themselves, so they are unaffected by MultiFly in the manure. For customers that have wet, marshy areas - fly predators can be a great compliment to MultiFly - since MultiFly is only passed through the manure.

Is MultiFly safe for pregnant & nursing mares?

Many of our customers feed MultiFly to pregnant/lactating mares. However, we would recommend getting the opinion of your veterinarian first! 

Is MultiFly safe for breeding stallions?

We'd recommend consulting your veterinarian before feeding MultiFly to breeding stallions.

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