Q & A

The Economics of Horn Fly Control

Q. What is the economic impact of horn flies on cattle production?

A. Horn flies are the number-one economic ectoparasite in North American cattle production, causing an estimated $1 billion loss annually. Compare this to the estimated loss due to bovine respiratory disease at $600 million or pinkeye at $100 million.


Q. How can I tell if I have a horn fly problem?

A. Horn flies are an ectoparasite of cattle and tend to stay on the backs and sides of animals throughout the day. Despite their name, horn flies do not congregate on the horn and head area. Horn flies are about half the size of the common house fly and lay eggs exclusively in fresh manure.


Q. How do horn flies affect cattle?

A. Horn flies cause cattle stress. Under stress, cattle will not feed as freely and may move to areas in or near water to escape fly pressure. A moderate horn fly population (500 per animal) will suck 7 cc of blood per day. Typical weight loss is estimated at 15 to 50 pounds per yearling. Also, a 10- to 15-pound weaning weight advantage results when good horn fly control is used.*


Q. What’s the best way to control horn flies?

A. Most horn fly control strategies require you to either gather cattle on a regular basis for treatment or replenish the various systems that dispense products for horn fly control (dust bags, backrubbers, etc.). While these methods are labor-intensive, an insect growth regulator (IGR) allows you to provide horn fly control right in your feed or minerals, letting cattle do the work.


Q. How do I know if my horn fly problem is worth treating?

A. University research indicates the economic threshold for horn flies is 200 per animal and, for dairy cattle, may be as low as 50 flies per animal.


Q. How do I calculate the cost of horn fly control?

A. The cost per animal will vary and can be measured on a return-on-investment (ROI) basis. For ear tags, you should also consider the cost of labor to determine the real cost per animal. An economic calculator is available  here.

* Source: NebGuide, University of Nebraska Cooperative Extension Service.

An IPM Approach to Horn Fly Control

Q. I had horn fly pressure last summer. Should I assume I’ll have the same problem next summer?

A. It’s a good bet that if you had the problem last season, you’ll have at least some insect pressure next spring. Horn fly pupae overwinter under manure and emerge when temperatures begin hitting the upper 60’s and lower 70’s during the day.


Q. If I see horn fly populations growing fast, is it too late to get economical control?

A. No. While it’s best to begin implementing your horn fly control program before you see adult emergence, it’s not too late to get economical control. By using an adulticide spray, like Prolate/Lintox-HD™, you can effectively knock down adult flies while you start a feed-through program.


Q. I’m concerned about exposing my family and workers to pesticide products. Are there equally effective alternative strategies for horn fly control?

A. Pesticides are, by nature, “economic poisons” and should always be used according to label directions. Because horn flies lay their eggs only in fresh manure, delivering the pesticide directly in the manure is highly efficient and reduces potential exposure to farm and ranch personnel. Products that are highly specific for insect control, like insect growth regulators (IGRs), offer a less toxic approach to horn fly control.


Q. The surrounding ranches do not use any type of horn fly control. What kind of results should I expect if I’m the only one on an IGR program?

A. Reducing the impact of horn flies on your cattle alone generally results in positive ROI. While you may see some migration of insects from surrounding areas, the majority of the insect pressure you see is from “local” horn fly populations. Consider talking with your neighbors about your experience with horn fly control strategies and their results.


Q. I have more fly problems than just horn flies. What can I do to create a more general fly control program?

A. Knowing which target insect is causing you the most economic loss is critical in prioritizing your control strategies. Regular sanitation procedures to minimize moisture and organic matter (manure, straw) should help reduce fly pressure in general. Visit www.starbarproducts.com for suggestions and product offerings to implement an effective Integrated Pest Management (IPM) program.

Feed-Through Programs For Horn Fly Control

Q. I generally feed mineral supplements. Can these be integrated into a feed-through program?

A. Yes. By combining horn fly control with your mineral supplementation, you eliminate the additional labor needed to administer other types of control programs (backrubbers, dust bags, sprays or ear tags).


Q. Does my feed-through product control flies other than horn flies?

A. Fly biology indicates the active ingredient may not be present when these other flies make use of manure. Altosid® IGR has an approved claim for horn fly larvae control.


Q. Are there beneficial insects that exist in manure?

A. Yes, dung beetles are one such insect. When Altosid® IGR is fed at approved rates, there is no impact on dung beetles.


Q. How long does is take to see results from a feed-through program?

A. To effectively break the horn fly life cycle, a feed-through program using Altosid® IGR Feed-Thru requires 3 to 4 weeks for significant reduction in adult horn fly numbers. Greatest overall success is achieved when the feed-through program is started 30 days before adult horn fly emergence.


Q. What’s the average return on investment of a feed-through program?

A. Using Altosid® IGR Feed-Thru typically costs 3.2 cents per 1,000 lb. animal per day of control. Basically, for every dollar spent on Altosid® IGR, a return of $6 to $10 is typical. This fact is based on well-established university economic parameters on weight loss or lost milk production. This return on investment makes Altosid® IGR an excellent value.


Q. I’ve got a horn fly problem right now. Will a feed-through program get rid of the adults?

A. Feed-through products only control larvae and will not impact adults. A spraying program, using products such as Prolate/Lintox-HD™, may be needed to knock down adult flies when you begin your feed-through program. Visit www.starbarproducts.com to learn more.


Q. I’ve used ear tags for several years with good results. Why should I consider changing practices?

A. Ear tags have proved an excellent tool in horn fly control, but they do have drawbacks compared to other methods. Resistance to insecticides in ear tags has reduced their efficacy in many areas. They also require labor to install and remove, and they may not last through the entire horn fly season.


Q. With all the insecticide resistance problems out there, won’t the feed-through products eventually cause resistance?

A. Because Altosid® IGR mimics biochemicals naturally produced by insects, resistance is unlikely. In fact, in more than 25 years of use, there has never been a single documented case of horn fly resistance to Altosid® IGR.


Q. How does Altosid® IGR Feed-Thru work?

A. Horn flies lay eggs in manure. After the eggs hatch, larvae (maggots) must molt as they grow. During this growth process, insects produce biochemicals that aid in this process. As the final growth stage, the pupal stage, occurs, the IGR provides a jolt of extra biochemical that interrupts the growth process. As a result, adult flies never come out of the pupal stage.


Q. Can I use an IGR with other horn fly control products?

A. Yes. A complete program should include face fly control, along with adulticide products, depending on the level of initial infestation.