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Your Fly Control Program Starts with Feed Additives

Dr. Erika Nagorske

Apr 22, 2021

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 economic impact and can adversely affect your animals’ health. 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, it’s good to tackle the issue with a multifaceted approach.

When it comes time to start budgeting for your fly control program, plan to spend most of your budget in April, May, and June in order to be proactive.

The first step to fly control is cleanliness

Whether you’re dealing with feedlot, cow calf, dairy cattle, or swine operation, the first step to any fly control program is to clean up areas where your livestock congregate and where flies 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 5 inches to prevent those pesky flies from overtaking your livestock.

Adding 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 degrees or when flies begin to appear.

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 in the fall will help control the next year’s fly population.

This prevents horn fly larvae from hibernating and surviving the winter (aka overwintering) below manure patties. It also stops them from developing into adult flies (which would cause a nuisance for you come spring).

How feed additives work

There are two main types of fly control feed additives: insect growth regulators (IGR) and larvicide products.

Both are particularly effective to help control face and horn flies. It is recommended that 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, it disrupts 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 dead in their tracks from developing into biting adult flies, you’ll prevent a potentially expensive impact on your herd.

Luckily, Methoprene is a very cost effective way to control flies and can cost as little as 2 to 4 cents per animal, per day.


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, add larvicide to your animal’s feed where it then passes through the animal and ends up in their manure.

Again, this is where flies lay eggs and the larvicide prevents them from maturing into adults. It’s a cost-effective way to control flies without a lot of additional work or effort .

What about garlic?

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

Unlike IGR or larvicide, Garlic is not preventing or killing flies; rather functioning as a 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

Your first step to fly control is to clean the areas where your animals feed and congregate as well as where flies breed. Good manure management will help reduce flies but will never eliminate them.

That’s why it’s good to swat the problem before it gets out of hand by incorporating fly control feed additives into your program.

Get started on your proactive fly control program with FBN® today.


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

Apr 22, 2021