Using Fire to Manage Horn Flies on Cattle

Horn flies on a beef cow

Indigenous tribes of North America, Africa and Australia used fire for a variety of reasons including control of insects.  Commercial livestock operators have typically not recognized the impact of fire in reducing parasites on animals.  While the impact of fire on external parasites such as ticks has been documented, there has been little attention paid to how fire could be used to manage fly pests of cattle.  Horn flies are an external parasite of cattle that cause over $1 billion in economic losses each year.   Cattle serve as hosts for horn flies by providing blood meals and fecal pats that are used for laying eggs and overwintering pupa.  Given the fire prone ecosystems of North America, range scientists and livestock entomologists are evaluating the response of horn flies (a non-native pest from Eurasia) to fires.  The current trend in managing horn flies is with insecticides that are fed, sprayed or impregnated in ear tags.  Resistance to chemical active ingredients is a major problem and is now widespread.

Recent Findings

In 2011, cattle in Oklahoma and Iowa were evaluated for horn fly numbers.  Cattle were either on pastures that were patch-burned (a portion of the pasture burned each year) or on pastures that had not been burned in over two years.  All fires were conducted in March of that year.  Horn flies were counted during periods of peak activity and data was evaluated for location and treatment effects.  Cattle on pastures that were patch-burned had 41% fewer horn flies than cattle on pastures that had not been burned.  The accepted economic threshold for treatment of horns flies is 200 flies per cow, with 300 flies per cow causing behavioral stress. The unburned pastures had >400 horn flies per cow, while the patch burn pasture cows had approximately half as many horn flies.  It is thought that the application of fire is effective by two primary mechanisms: (1) cattle spend more time in the recently burned patch than unburned patches (as they are attracted to the highly palatable and nutritious plant regrowth after fire) and (2) fire in the dormant season (late winter and early spring) alters cow pats when pupa are overwintering in or below them.

Benefits of Fire Relative to Parasites

Using fire to manage horn flies is anticipated to have a number of positive impacts, including:  (1) reducing horn fly numbers is expected to result in a reduction of stress annoyance behaviors such as twitching, head throwing and swishing of the tail and ultimately an increase in grazing time, (2) reducing horn flies has been documented in numerous studies to have a positive impact on cattle performance, (3) the potential impact of fire on any parasite of cattle is an exciting alternative to the use of pesticides and a potential strategy to avoid the development of resistance to chemical treatments, (4) fly pests of cattle have been documented to vector diseases (horn flies are suspected of transmitting anaplasmosis and face flies are suspected of transmitting pinkeye).  Lastly, fire provides other benefits to pasture such as slowing woody plant encroachment and removing dormant plant litter and allowing for lush regrowth of grass. 

Influence of Fire on Cattle Forage Quality

Cattle grazing on a burn

Importance of Fire

Fire is an important driver of many North American ecosystems, particularly grasslands.  The influence of fire on the plant community is largely attributed to its removal of dead standing plant material, impact on forage quality, and the impact on grazing animals.  Cattle production in undisturbed tallgrass prairie can be low due to the accumulation of dead standing plant material.  However, fire can increase production over 75%.  Historically, large bison herds followed fire as they were attracted to the lush regrowth that emerged.  Today, managers use prescribed burning to capitalize on this change in forage quality for cattle production. 

Forage Quality

Forage quality is typically expressed as crude protein (CP) which is based on the nitrogen content of forage. This nitrogen content is critical for microorganisms in the rumen.  Other measures of forage quality include palatability (typically associated with texture and moisture content) and digestibility (largely based on fiber and lignin). The primary influence of fire on forage quality is the removal of standing, dormant plant material.  Forage quality is largely a function of time: as plants age (mature) they decrease in quality.  This decrease in quality is due to the increase in fiber and lignin content, resulting in reduced digestibility and animal consumption.  Prescribed fire remove dormant plant material, increasing the nutrition and digestibility of post-fire regrowth. While prescribed fires are commonly conducted during the late winter or early spring, growing season (summer) fires have the same effect and can boost forage quality during a period of the year where it is typically decreasing.  Furthermore, the interaction of fire and grazing will impact below ground plant growth by increasing nitrogen mineralization and plant nitrogen availability, and improving the root tissue quality.

Benefits of Higher Forage Quality

Forage quality is a critical component of cattle production including reproductive efficiency, rebreeding, calf production, animal growth and milk production.  Understanding the importance of fire to native rangeland plants and the potential benefits to cattle can be a useful tool for ranch managers. 

Livestock Weight Gain and Patch-burn Management

Achieving optimum livestock production on rangelands many times can conflict with wildlife conservation strategies that require lower stocking rates to maintain suitable habitat. Traditionally, livestock producers try to maximize gain per-acre by uniformly managing vegetation in pastures. Often this is achieved either by heavily grazing, burning the entire pasture, or both. This management strategy can create suitable habitat for some wildlife species, but poor quality habitat for others. 

Patch Burning

Combining the spatial and temporal interaction of fire and grazing (patch-burning) a conservation-based approach to land management can be achieved. This practice can increase rangeland biodiversity by creating heterogeneous vegetation structure and composition that is beneficial to multiple wildlife species. However, for conservation strategies to be successfully implemented, they need to be both effective and economically sustainable. In both mixed-grass prairie and tallgrass prairie, cattle weight gain was compared in pastures with traditional fire and grazing management (continuous grazing, with periodic fire on tallgrass prairie and seasonal grazing without fire on mixed-grass prairie) and conservation based management (pyric-herbivory applied through patch burning), both at a moderate stocking rate. Stocker cattle weight gain, calf weight gain, and cow body condition score were comparable between the traditional and conservation based management at the tallgrass prairie site for the duration of the eight-year study, indicating that conservation management doesn’t decrease livestock production or profitability.

In the mixed-grass prairie pastures, stocker cattle gain was not different between traditional and conservation management for the first four years. However, stocker cattle in conservation based management out gained cattle in traditional management beginning in year five and remained 27% greater for the next six years of the study. Moreover, cattle weight gain under conservation management varied less year to year making profitability more consistent. Traditional management in mixed-grass prairie did not include fire, the process that improved range conditions and likely was associated with increased stocker cattle performance under conservation management. In conclusion, pyric-herbivory is a conservation-based rangeland management strategy that returns fire to the landscape without reduced stocking rate, deferment, or rest.         

Figure 1. Cattle weight gain on traditionally managed and patch-burn managed tallgrass prairie.


Figure 2. Cattle weight gain on traditionally managed and patch-burn managed mixed-grass prairie. An * indicates years when patch-burned managed cattle gained more than traditionally managed cattle.


Balancing Earth, Air and Fire In The Kansas Flint Hills

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Native Americans placed great value on the four elements of life,  earth, water, air and fire. They recognized, as we do today, that fire is the most powerful land management tool. The 4.8 million acre Flint Hills region of Kansas is the largest remaining expanse of tallgrass prairie in North America.   Prescribed fire is routinely practiced in the region to enhance livestock forage quality, control invasive species, provide grassland wildlife habitat and improve plant vigor.  But where there is fire, there is smoke, and there are public health concerns when excessive smoke is in the atmosphere.   Ground level ozone can have serious public health consequences and major cities adjacent to the Flint Hills, have recorded excessive ozone levels resulting from Flint Hills prescribed fire.   A collaborative effort including the Kansas Dept of Health & Environment, EPA,  K-State Research & Extension, Kansas Livestock Association and other groups completed the Flint Hills smoke management plan in December, 2010, with the objective of reducing health concerns from prescribed fire, while retaining it as a land management tool.  The plan established a  website of “best smoke management practices” and a comprehensive education and outreach effort for land managers was implemented, involving prescribed fire schools, news articles and radio airplay.   Results of the plan are positive, indicating  that Kansas has responded to the smoke issue appropriately and will retain prescribed fire as a management practice that maintains both the tallgrass prairie of the hills, and the air quality of adjacent metro areas.  The inter-relationships of earth, water, air and fire are continual, each impacting the other.   The Kansas Flint Hills now has a plan to ensure harmony of these essential elements of life.

A prescribed fire in the Kansas Flint Hills

Prescribed Fire in Tallgrass Prairie

The Flint Hills Smoke Management Plan is a collaborative effort designed to maintain the benefit of prescribed fire on the private grasslands of the Flint Hills, while also protecting the air quality of ajor metropolitan areas such as Kansas City and Wichita.   The Flint Hills have particular environmental implications, as they are the largest expanse of tallgrass prairie remaining in North America.

What Did We Do?

Kansas Department of Health and Environment wrote the plan, but embraced those involved with the issue, including K-State Research and Extension, the KS Livestock Association, Farm Bureau, Tallgrass Legacy Alliance, KS Prescribed Fire Council, Cities of Wichita and Kansas City, Natural Resource Conservation Service, KS Dept. of Wildlife Parks & Tourism to develop a plan that would address the goals of all those involved.   A website was developed to give ranchers day by day information regarding smoke emission and direction from a prescribed fire that day or the following day.

What Have We Learned?

Those that practice prescribed fire in the Kansas Flint Hills respect the health and environment of their city neighbors.   Conversely, those living in neighboring metropolitan areas understand the economic importance of prescribed fire as related to beef cattle production, and the role fire plays in preserving the integrity of the tallgrass prairie.   By engaging all entities involved, agreements can be reached, solutions can be found and advancements can be made.

Prescribed fire controls woody species, maintaining the integrity of the tallgrass prairie.

Future Plans

In the years ahead,  KS Dept of Health and Environment will continue monitoring smoke emissions due to prescribed fire in the Flint Hills.  Those practicing prescribed fire will be encouraged to use the best smoke management methods of prescribed fire.   This will be done through K-State Research & Extension prescribed fire schools, the KS Prescribed Fire Council workshops and the KDHE website.


Jeff Davidson  K-State Research & Extension Watershed Specialist      Kansas State University

Additional Information


K-State Research & Extension, Kansas Precribed Fire Council, Kansas Livestock Association, KS Dept. of Health & Environment,  Tallgrass Legacy Alliance, KS Dept. of Wildlife, Parks & Tourism, Natural Resource Conservation Service, Farm Bureau, Cities of Wichita and Kansas City.


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