How are Filth Flies Involved in Wasting Nitrogen?


Filth flies are species from the Diptera order associated with animal feces and decomposing waste. Beef cattle raised on open pastures are especially susceptible to two species of filth flies: Face flies (Musca autumnalis De Geer) and Horn flies (Haematobia irritans (L.))  because these flies develop exclusively in fresh cattle manure. Filth fly impact on cattle health is related not only to the loss of body weight but also to the transmission of diseases like pink eye and mastitis (Basiel, 2020; Campbell, 1976; Hall, 1984; Nickerson et al., 1995).

Nitrogen losses from cattle’s manure has been reported for domestic flies (Musca domestica) and bottle flies (Neomyia cornicina) (Iwasa et al., 2015; Macqueen & Beirne, 1975). Despite the regular presence of face fly and horn fly in pastures, their effect on the nutrient cycles is little known. The purpose of this study is to understand the relationship between filth fly’s presence in cattle manure with the nitrogen losses caused by an increase in ammonia and nitrous oxide emissions.

What Did We Do?

The study was conducted in four pastures in the Georgia Piedmont: two near Watkinsville and two near Eatonton during June, July, and August of 2021. Ammonia volatilization and nitrous oxide emissions were measured on days 1, 4, 8, and 15 following dung deposition. Manure samples were collected on days 1 and 15. A static chamber was sealed for 24 h on each sampling date to capture manure’s ammonia and nitrous oxide emissions. In each chamber, a glass jar with boric acid was used to trap ammonia, and gas samples were collected. The gas samples were analyzed for nitrous oxide with a Varian Star 3600 CX Gas Chromatograph using an electron capture detector.

The number of filth flies was determined using a net trap covered by a black cloth that was set after 1 min of manure deposition, allowing the flies to oviposit for 10 min. On the days in which ammonia was not measured, a net trap was set to avoid additional oviposits, and record the emergence of filth flies. On the 15th day, we collected the filth flies that emerged from the eggs deposited in the manure during the first day.

What Have We Learned?

We found that cattle’s manure nitrogen loss as nitrous oxide (N2O) and ammonia (NH3) emissions have a direct relationship with the number of horn flies and face flies in the dung, Figure 1. Eighty percent of the flies trapped were horn flies. Dung with less than 5 flies can emit as little as 0.11 mg of N/kg of manure per day, while cattle manure with more than 30 flies can increase this emission by more than 10 times.

Figure 1 Nitrogen emissions such as nitrous oxide and ammonia (mg/kg of manure) and number of filth flies.

Every extra filth fly in manure can increase N emissions by 0.03 mg per kg of manure per day. According to NRCS, 59.1 lbs. of fresh manure is produced by a cow (approx. 1 000 pounds animal) every day (NRCS, 1995). Considering an average of 85 % relative humidity, 4.03 kg of dry manure can be produced per cow day. The actual economic threshold for horn fly is 200 flies per animal (Hogsette et al., 1991; Schreiber et al., 1987), considering a 1 to 1 sex ratio during emergence (Macqueen & Doube, 1988) we are assuming 100 female flies. Since the capacity of horn flies is 8-13 eggs per day (Lysyk, 1999), 100 female horn flies can generate approximately 1,000 new flies every day.  Calculating the nitrogen emissions (4.03 kg of dry manure X 0.03 mg N kg manure x 1,000 flies per day) results in 121 mg of N loss per cow per day when assuming the number of flies is just at the economic threshold. In January of 2022, USDA released the Southern Region Cattle Inventory with a total of 91.9 million head, from which 30.1 million were beef cows (USDA, 2022). Considering the earlier numbers, the horn fly presence in the beef cattle of the Southern Region could be emitting 3,639 kg of Nitrogen to the atmosphere every day.

Future Plans

We will continue the study on ammonia and nitrous oxide emissions under the same conditions during another year to confirm the trends and accuracy of the results. Also, we will implement a study to analyze the effect of the introduction of a parasitic wasp Spalangia endius as a biological control on horn fly and face fly populations and therefore on the manure’s nitrogen losses.


Presenting author

Natalia B. Espinoza, Research Assistant, Department of Crop and Soil Science, University of Georgia

Corresponding author

Dr. Dorcas H. Franklin, Professor, Department of Crop and Soil Sciences, University of Georgia

Corresponding author email address or

Additional authors

Anish Subedi, Research Assistant, Department of Crop and Soil Science, University of Georgia

Dr. Miguel Cabrera, Professor, Department of Crop and Soil Sciences, University of Georgia

Dr. Nancy Hinkle, Professor, Department of Entomology, University of Georgia

Dr. S. Lawton Stewart, Professor, Department of Animal and Dairy Science, University of Georgia

Additional Information

Basiel, B. (2020). Genomic Evaluation of Horn Fly Resistance and Phenotypes of Cholesterol Deficiency Carriers in Holstein Cattle [PennState University]. Electronic Theses and Dissertations for Graduate Students.

Campbell, J. B. (1976). Effect of Horn Fly Control on Cows as Expressed by Increased Weaning Weights of Calves. Journal of Economic Entomology, 69(6), 711-712. 10.1093/jee/69.6.711

Hall, R. D. (1984). Relationship of the Face Fly (Diptera, Muscidae) to Pinkeye in Cattle – a Review and Synthesis of the Relevant Literature. Journal of Medical Entomology, 21(4), 361-365. 10.1093/jmedent/21.4.361

Hogsette, J. A., Prichard, D. L., & Ruff, J. P. (1991). Economic-Effects of Horn Fly (Diptera, Muscidae) Populations on Beef-Cattle Exposed to 3 Pesticide Treatment Regimes. Journal of Economic Entomology, 84(4), 1270-1274. 10.1093/jee/84.4.1270

Iwasa, M., Moki, Y., & Takahashi, J. (2015). Effects of the Activity of Coprophagous Insects on Greenhouse Gas Emissions from Cattle Dung Pats and Changes in Amounts of Nitrogen, Carbon, and Energy. Environmental Entomology, 44(1), 106-113.

Lysyk, T. J. (1999). Effect of temperature on time to eclosion and spring emergence of postdiapausing horn flies (Diptera : Muscidae). Environmental Entomology, 28(3), 387-397. 10.1093/ee/28.3.387

Macqueen, A., & Beirne, B. P. (1975). Influence of Some Dipterous Larvae on Nitrogen Loss from Cattle Dung. Environmental Entomology, 4(6), 868-870. 10.1093/ee/4.6.868

Macqueen, A., & Doube, B. M. (1988). Emergence, Host-Finding and Longevity of Adult Haematobia-Irritans-Exigua Demeijere (Diptera, Muscidae). Journal of the Australian Entomological Society, 27, 167-174. <Go to ISI>://WOS:A1988P906100002

Nickerson, S. C., Owens, W. E., & Boddie, R. L. (1995). Symposium – Mastitis in Dairy Heifers – Mastitis in Dairy Heifers – Initial Studies on Prevalence and Control. Journal of Dairy Science, 78(7), 1607-1618. 10.3168/jds.S0022-0302(95)76785-6

NRCS, N. R. C. S. (1995). Animal Manure Management. RCA Publication Archive(7).

Schreiber, E. T., Campbell, J. B., Kunz, S. E., Clanton, D. C., & Hudson, D. B. (1987). Effects of Horn Fly (Diptera, Muscidae) Control on Cows and Gastrointestinal Worm (Nematode, Trichostrongylidae) Treatment for Calves on Cow and Calf Weight Gains. Journal of Economic Entomology, 80(2), 451-454. 10.1093/jee/80.2.451

USDA. (2022). Southern Region News Release Cattle Inventory.

Livestock Waste Management For Protecting Water Quality

Does Siting Matter Relative to Cattle Feeding and Water Quality?

The site selection and management of cattle feeding facilities has a substantial impact on water quality in Kansas. Site location within the prevailing topography and management of cattle feeding pens is imperative to maintaining quality in the waters of the state. There are several factors which should receive consideration when selecting a site that cattle feeding pens will be constructed, as well as factors that demand attention when managing an existing facility.

What did we do?

Cattlemen planning to build a new cattle feeding facility, or perhaps expand an existing facility consider several aspects in relation to water quality. The number of the cattle that will be in the facility, and the size of those cattle are the first considerations. Feeding facilities that feed 300 animal units or more are required to register with KS Department of Health and Environment.. The amount of time cattle are in the pen is a major consideration. Many facilities will have cattle in the pens year-round, but some will only feed cattle for six months or less.

Other considerations when determining a cattle feeding facility include the slope of pen area, which is preferably 1 to 3 percent. The slope of the pen to soils designated as “flooded” is best if relatively flat, no more than 2 percent preferred. The greater the distance to the “flooded” soil, the better. The amount of rainfall and the rainfall intensity for the specific area of the state is noted, and all extraneous drainage should be diverted upslope of the pen area.

Photo of Cattle Feeding PenA buffer down-slope of the pen area is essential to managing water quality. The buffer area should be on permeable soils and covered with dense grass. The buffer size should be more than equal to the footprint of the pen, and it is preferred that it be twice the area of the pen. Size of the buffer is influenced by the soils, The more permeable the soil, the greater the infiltration rate, reducing the need for increased size of the buffer area.

Groundwater is carefully protected in Kansas, and livestock feeding facilities must be located in areas that are not deemed “ground water sensitive.” Depth to groundwater of all facilities is recorded as well as distance to any existing wells.


The management of the feeding pen system is imperative to maintaining quality water. Pens need to be cleaned regularly to reduce solids leaving the pen and to ensure buffer vegetation is vigorous and free of weeds. The buffer should be hayed to remove nutrients from the system. The pens should be designed and maintained so that runoff leaving pens should flow evenly into and across the buffer to avoid channeling.

The management of livestock waste in cattle feeding facilities deserves the same attention to detail as ration formulation and health protocols.

What have we learned?

The Kansas Center for Agricultural Resources and the Environment, a department of Kansas State Research and Extension, employees a team of five Watershed Specialists who assist cattle producers who routinely keep cattle confined. These specialists work closely with the producer, K-State and the Kansas Department of Health and Environment to make sure cattle facilities are designed in a water quality responsible manner. In addition, these specialists provide educational outreach, design and promote “off stream” water development, encourage restricting cattle from ponds, and advise on proper grazing management of forage resources.

In the past 4 years, these specialists have consulted with 805 livestock producers, affecting over 34,000 animal units. From their efforts, Kansas waterways have seen a reduction in each year of 211,000 pounds of nitrogen, 88,000 pounds of phosphorus and 346 tons of sediment.

Future Plans

Continue educating cattle producers about the importance of properly sited and managed livestock feeding facilities, and helping them achieve water quality responsible goals.


Jeff Davidson, KSU Watershed Specialist

Ron Graber, KSU Watershed Specialist

Additional information

Jeff Davidson,

Ron Graber,


EPA 319 funds are a major contributor to this program

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Effect of Feeding Distiller’s Grains on Reduced Sulfur Emissions

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Why Study Sulfur Emissions and Manure from Animals Fed Distillers Byproducts?

Odorous reduced sulfur compounds are produced during manure decomposition and emitted from confined animal feeding operations.  Feeding high-sulfur distiller’s byproducts may increase the emission of these compounds.  The objectives of a series of feedlot pen studies was to (i) determine if emissions of reduced sulfur compounds from fresh manure and from the feedlot surface where affected if cattle were fed varying levels of distillers byproducts, and (ii) determine the areas within a pen that emit greater amounts of reduced sulfur compounds.

Study #1–Relative emission of redued sulfur compounds from fresh feces. Cattle fed diets containing 0%, 20%, 40%, and 60% WEGS.

What Did We Do?

Three studies were conducted to evaluate the relative impact of feeding high-sulfur wet distiller’s grain plus solubles (WDGS) to beef cattle.  In the first study, beef cattle in sixteen small-scale pens were fed varying amounts (0%, 20%, 40%, and 60%) of WDGS, and the relative emissions of reduced sulfur from fresh feces were measured using a laboratory wind tunnel chamber.  A follow up study in eight production-scale feedlot pens also examined the effect of feeding 0% or 40% WDGS on fresh manure emissions.  A third study in ten production-scale pens examined emissions from the pen surface when cattle were fed 0% and 40% WDGS diets over two production cycles.

Study #2–Relative emission of reduced sulfur compounds from feces of cattle fed 0% or 40% WDGS. P values above bars indicate the significance of the difference between emissions on the four dates.

What Have We Learned?

The relative emission of reduced sulfur from fresh feces was significantly greater (4 to 22-fold) when 40% (or greater) WDGS was fed in the initial study.  The follow up study confirmed this finding, but found the relative emission to be lower (2 to 4 fold higher for WDGS) in the production-scale feedlot.  In the final study examining the relative emission from the whole feedlot pen surface (mixed soil and aged feces) over many months, emissions principally came from the wetter edges of the pen when animal were fed higher levels of WDGS in their diet.  For the six study periods, the relative emissions from WDGS pens ranged from 0.3 to 4-fold higher than a standard ration.  Consistent results from these three studies indicate that reduced sulfur emissions increase when animals are fed higher levels of WDGS.

Study #3–Relative concentration of total reduced sulfur (TRS) in the chamber for each of the seven study periods. An asterisk above the bars indicates a significant difference (P < 0.05) between diets.

Future Plans

The level of sulfur in WDGS varies depending upon source and production method.  Feeding lower sulfur WDGS should reduce the relative emission of odorous reduced sulfur compounds.  Production of the reduced sulfur compounds may also be related to water quality—some water sources high in sulfur may enhance the emission of reduced sulfur from animal production sites.  Further research into the mechanism of reduced sulfur production may provide new insights into controlling the emissions of these odorous compounds.


Daniel N. Miller, Research Microbiologist, USDA-ARS, Lincoln, NE,

Mindy J. Spiehs, Research Animal Scientist, USDA-ARS, Clay Center, NE

Bryan L. Woodbury, Agricultureal Engineer, USDA-ARS, Clay Center, NE

Additional Information

Miller, D. N., V. H. Varel, B. L. Woodbury, and M. J. Spiehs.  2010.  Enhanced reduced sulfur emission from manures of beef cattle fed distiller’s byproducts.  International Symposium on Air Quality and Manure Management for Agriculture Conference Proceedings, 13-16 September, Dallas, Texas.  711P0510cd.


The authors would like to acknowledge the technical expertise of Todd Bowman, Alan Kruger, and Ryan McGhee.  Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.  USDA is an equal opportunity provider and employer.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Greenhouse Gas Emissions from Livestock & Poultry

Agriculture is both a source and sink for greenhouse gases (GHG). A source is a net contribution to the atmosphere, while a sink is a net withdrawal of greenhouse gases.  In the United States, agriculture is a relatively small contributor, with approximately 8% of the total greenhouse gas emissions, as seen below.  Most agricultural emissions originate from soil management, enteric fermentation (the ruminant digestion process that produces methane), energy use, and manure management.  The primary greenhouse gases related to agriculture are carbon dioxide, methane, and nitrous oxide. Within animal production, the largest emissions are from beef followed by dairy, and largely dominated by the methane produced in during cattle digestion.

U.S. GHG Inventory

U.S. greenhouse gas inventory with electricity distributed to economic sectors (EPA, 2013) 

Ag Sources of GHGs

U.S. agricultural greenhouse gas sources (Adapted from Archibeque, S. et al., 2012)

Greenhouse gas emissions from livestock in 2008 (USDA, 2011)

Soil Management

Excess nitrogen in agriculture systems can be converted to nitrous oxide through the nitrification-denitrification process. Nitrous oxide is a very potent greenhouse gas, with 310 times greater global warming potential than carbon dioxide.  Nitrous oxide can be produced in soils following fertilizer application (both synthetic and organic).

As crops grow, photosynthesis removes carbon dioxide from the atmosphere and stores it in the plants and soil life. Soil and plant respiration adds carbon dioxide back to the atmosphere when microbes or plants breakdown molecules to produce energy.  Respiration is an essential part of growth and maintenance for most life on earth. This repeats with each growth, harvest, and decay cycle, therefore, feedstuffs and foods are generally considered to be carbon “neutral.”

Some carbon dioxide is stored in soils for long periods of time.  The processes that result in carbon accumulation are called carbon sinks or carbon sequestration.  Crop production and grazing management practices influence the soil’s ability to be a net source or sink for greenhouse gases.  Managing soils in ways that increase organic matter levels can increase the accumulation (sink) of soil carbon for many years.


The next largest portion of livestock greenhouse gas emissions is from methane produced during enteric fermentation in ruminants – a natural part of ruminant digestion where microbes in the first of four stomachs, the rumen, break down feed and produce methane as a by-product. The methane is released  primarily through belching.

As with plants, animals respire carbon dioxide, but also store some in their bodies, so they too are considered a neutral source of atmospheric carbon dioxide.

Manure Management

A similar microbial process to enteric fermentation leads to methane production from stored manure.  Anytime the manure sits for more than a couple days in an anaerobic (without oxygen) environment, methane will likely be produced.  Methane can be generated in the animal housing, manure storage, and during manure application. Additionally, small amounts of methane is produced from manure deposited on grazing lands.

Nitrous oxide is also produced from manure storage surfaces, during land application, and from manure in bedded packs & lots.

Other sources

There are many smaller sources of greenhouse gases on farms. Combustion engines exaust carbon dioxide from fossil fuel (previously stored carbon) powered vehicles and equipment.  Manufacturing of farm inputs, including fuel, electricity, machinery, fertilizer, pesticides, seeds, plastics, and building materials, also results in emissions.

To learn more about how farm emissions are determined and see species specific examples, see the Carbon Footprint resources.

To learn about how to reduce on-farm emissions through mitigation technology and management options, see the Reducing Emissions resources.

 Additional Resources

Additional Animal Agriculture and Climate Change Resources

Author: Crystal A. Powers, UNL