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).
PASTURE FLIES
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
CONFINEMENT FLIES—Feedlots
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.
FLY CONTROL COMPOUNDS
NO FLY CONTROL PROGRAMS ELIMINATE 100% OF THE FLIES.
- 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.
S-Methoprene/Altosid®:
- 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.
Diflubenzuron/ClariFly®:
- 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.
Horses:
- Clarifly® is approved for horses.
- 0.15 mg/lb. body weight/day Diflubenzuron.
Garlic:
- 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.