Your Fly Control Program Starts with Feed Additives

Dr. Erika Nagorske

Jun 13, 2023

As summer approaches, it’s a good time to start thinking about adding fly control solutions to your nutrition program. No matter how much you don’t want to deal with pesky flies, they simply won’t disappear on their own.

Ignoring the problem can have a significant impact on both your herd’s health and your operation’s finances. Fly counts of 200 flies per animal will require a systematic plan to eradicate the infestation.

Having a good understanding of the different types of flies can help you get started. While there is no one single way to deal with fly control, the best strategy is to tackle the issue with a multifaceted approach.

When budgeting for your fly control program, plan to proactively spend most of your budget in April, May, and June.

Start with a Clean Space 

Whether you’re dealing with feedlot, cow calf, dairy cattle, or a swine operation, the first step to any fly control program is to clean up areas where your livestock congregate — and where flies likely breed.

Removing stock-piled manure or spilled feed and silage on a weekly basis is a simple preventative measure that will help keep flies from becoming a problem for your animals.

It’s also a good idea to cut or mow vegetation to less than five inches to prevent flies from overtaking your livestock.

Feed Additives for Fly Control

While cleaning is the first step to a good fly control program, there are many other ways to deal with the issue. Incorporating feed additives is a smart and effective way to curb fly infestations.

Start including fly control additives in your feeding program early in the spring, usually about 30 days before the average daily temperature reaches 65℉ or when flies begin to appear.

From this point, it’s key to continue using fly control in your feed until 30 days after the first frost in the fall. Continuing treatment in the fall is just as important as starting early in the spring. Proactive treatment later in the year will help control the next year’s fly population by preventing horn fly larvae from hibernating and surviving the winter (also known as overwintering) below manure pattie before later developing into adult flies.

How Do Feed Additives Work? 

There are two main types of fly control feed additives: 

  • Insect growth regulators (IGR) 

  •  Larvicide products

Both are particularly effective in controlling face and horn flies. If you are considering using either type of additive, check to ensure that these products are also labeled as being effective against stable flies and house flies.

Insect Growth Regulators

IGR products with the active ingredient methoprene are fly control feed additives that deal specifically with horn flies. When fed to cattle, IGR products can disrupt horn fly larvae from developing in the manure of the treated animal. (There is no risk to the animal because the IGR isn’t actually absorbed but instead passes through the animal’s manure.) By stopping the flies developing into biting adult flies, you’ll prevent a potentially expensive impact on your herd. Luckily, methoprene is a very cost-effective fly control approach, costing as little as 2 to 4 cents per animal per day.

ClariFly® Larvicide Premix 0.67% is an effective IGR and is available on the FBN® Animal Health Store


Larvicide products with the active ingredient diflubenzuron are another popular feed additive form of fly control.

Diflubenzuron works by interrupting a fly’s life cycle instead of killing it outright. It targets a fly’s ability to develop an exoskeleton, which means they’re not able to survive into adulthood. 

Similar to IGR, consider adding a larvicide like Rabon™ Oral Larvicide to your animal’s feed as a cost-effective way to control flies without a lot of additional work or effort.

Is Garlic Effective? 

Some farmers have found success by adding garlic to their loose mineral or tubs to help repel flies. While research on this strategy is still being developed, early results look promising. 

Unlike IGR or larvicide, garlic does not prevent or kill flies; instead, it functions as a natural repellent. As with all fly control programs, it’s best to use garlic in conjunction with other fly control measures such as fly tags and pour-on insecticides.

Be Proactive About Fly Control

By cleaning the areas where your animals feed and congregate, as well as where flies breed, you’ll be able to better control and proactively address flies before they negatively impact your herd this season. 

Find a diverse selection of fly control products, including feed additives, sprays, ear tags, baits and traps, on the FBN Animal Health Store to get started with your proactive fly control program.


The above is provided for information purposes only and should not be used for the diagnosis or treatment of any condition. This information does not cover all possible variables, conditions, reactions, or risks relating to any topic, medication, or product and should not be considered complete. Certain products or medications may have risks and you should always consult your local veterinarian concerning the treatment of your animals.

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Dr. Erika Nagorske

Jun 13, 2023

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