Dr. Ted Wiseman, OSU Extension ANR Educator, Perry County
(Image Source: Intermountain Farmers Association (IFA))
As summer temperatures rise, so does the pressure from biting and nuisance flies on livestock operations. According to university research, fly infestations cost U.S. producers an estimated $700 million to $1 billion annually in lost performance. With today’s strong livestock markets, minimizing these losses through effective fly control is more important than ever.
Understanding the Impact of Flies on Livestock
Flies reduce productivity by interfering with feeding, causing stress, and transmitting disease. The primary culprits include:
- Horn Flies (Haematobia irritans): These blood-feeding pests remain on the backs of [livestock] feeding 20–40 times per day. Economic thresholds are reached at 200 flies per animal. Females lay eggs exclusively in fresh manure, and the life cycle can complete in as little as 10 days under warm conditions.
- Stable Flies (Stomoxys calcitrans): Also blood feeders, stable flies target the legs and bellies of livestock. Their painful bites lead to foot stomping, bunching, and water-seeking behavior. They breed in moist, decaying organic matter—especially hay mixed with manure in feedlots or winter-feeding areas.
- Face Flies (Musca autumnalis): Though non-biting, face flies feed on secretions from the eyes, nose, and mouth. Their activity can damage eye tissue and increase the risk of pinkeye. Like horn flies, they lay eggs in fresh manure.
Other pests such as horse flies, deer flies, ticks, and mosquitoes also contribute to stress and disease transmission but are less economically significant.
Integrated Fly Management Strategies
Universities emphasize Integrated Pest Management (IPM) as the most sustainable approach. Key components include:
Sanitation
Cleanliness is foundational. Removing or managing breeding sites—especially wet organic matter and manure—reduces fly populations at the source. This is particularly critical in feedlots, barns, and around hay feeding areas.
Larval Control
Larvicides can be applied directly to breeding sites or administered through feed additives and mineral mixes. These products disrupt the fly life cycle before adults emerge.
Adult Fly Control
Correct identification of fly species is essential before choosing a control method. Options include:
- Insecticide ear tags
- Pour-ons and sprays
- Dust bags and back rubbers
- Walk-through traps
- Insecticide capsules (projectile-based systems)
Self-application devices should be placed in high-traffic areas—such as near water or mineral sources—to ensure consistent use.
Resistance Management
Rotate insecticide classes annually and avoid under-dosing to prevent resistance. Always follow label directions, including withdrawal times for meat and milk.
Final Thoughts
Fly control is not a one-size-fits-all solution. It requires a season-long, multi-pronged approach tailored to your operation. Consult your local Extension office or land-grant university entomologist for region-specific recommendations and product guidance.