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Feed Type Fly Control For Beef Cattle

May 17, 2024

Mike Jarosz

Pasture Feed and Tubs Product Manager

Uncontrolled flies can cost cow/calf producers an estimated 13 lb. Campbell, 1976) of weaning weight at a potential loss of $32.50/head ($2.50/lb) or feedlot cattle with an estimated loss of $34/head ($1.70/lb.) at 20 lb. (Taylor et al., 2012) less gain.  The average feed through fly treatment program would cost ~$4/head for 150 d feeding (prices vary by year and location).


Horn Fly:

  • Egg to adult ~21 days-starting with two adult flies untreated, in 30 days fly numbers could reach 1700 adult & 26,000 immature.
  • Only leave host cattle to lay eggs in fresh manure and commonly return to the same animal.
  • Not strong fliers, lessening chance to spread from neighboring herds.
  • Bite and take blood at a nutrient loss to the host.

Face Fly:

  • Live and breed in pastures
  • Need fresh undisturbed manure to reproduce
  • Feed on secretions around nose, eyes, & mouth
  • Economic concern—Disease spreading such as pinkeye

House Fly

  • Live in and around buildings and feed bunks
  • Females lay eggs and mature in animal manure, wet organic mater, spilled feed, compost piles, etc.
  • Prolific around feedlots as mainly nuisance and disease spreaders.

Stable Fly

  • Live in and around buildings and feed bunks
  • Piercing mouthparts penetrate the skin of their hosts to obtain blood meals
  • Five flies or more per front leg results in lost performance (Campbell, 1976).
  • Eggs and Larvae need moist organic mater to survive, such as manure piles, soiled straw, silage, old bale feeding sites, etc.



  • Economic threshold is a target of 200 flies/animal or fewer for grazing.

EPA regulated additives, S-Methoprene-Altosid® or Diflubenzuron-ClariFly®.

  • Begin feeding 30 days prior to average spring temperatures reach 65 oF.
  • Stop feeding 30 days after the last frost in the fall.
  • Compounds need consumed daily at recommended level to maintain adequate concentration in the manure.


  • 0.76-1.5 mg, or average of 1.13 mg/cwt body weight/day
  • Pasture cattle
  • Horn Flies only
  • Cattle consume a feed containing Altosid®, which passes through the digestive tract and is deposited in the manure.
  • Female flies lay eggs in fresh manure.
  • Altosid® stops the larvae from developing into a Pupa and it dies.
  • Not approved for horses.


  • 0.0454 mg/lb. body weight/day.
  • Confinement feeding, or pasture conditions when other than horn flies present.
  • Stable, Horn, House, & Face Flies
  • Cattle consume a feed containing ClariFly®, which passes through the digestive tract, deposited in the manure, getting mixed in with other organic material such as straw, dirt, decaying manure, etc.
  • Female flies lay eggs in treated manure and other mixed organic matter.
  • ClariFly® kills the larvae stopping the development of adult flies.


  • Clarifly® is approved for horses.
  • 0.15 mg/lb. body weight/day Diflubenzuron.


  • Stable, Horn, House, & Face Flies
  • Limited data under controlled studies.  2-year study in Canada did measure ~47% decrease in the number of flies on cattle when feeding garlic powder vs. not (Durunna & Lardner, 2020).
  • Garlic organosulfur compounds are absorbed into the blood creating odors presented through the skin and other organs helping repel flies.
  • Organosulfur content is not standardized, making it a challenge to interpret data on garlic.
  • Many garlic powders fed at 1-2 g/hd/d.
  • Potentially works with pasture and confined cattle.

®Altosid and Clarifly are registered products of Wellmark International.







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