As fall settles in and cooler weather begins to ease fly pressure, feedlot operators can reflect on another season of managing one of cattle’s most persistent stressors — flies. Beyond being a nuisance, flies have a measurable impact on comfort, feed efficiency, and overall performance.
Flies are hidden stressors that quietly drain productivity. Recognizing how they affect feedlot cattle — and using sanitation, monitoring, and targeted control — helps protect animal health and profitability heading into winter and the next production cycle.
The Hidden Cost of Flies
Cattle spend valuable time and energy avoiding flies — stomping, tail switching, bunching, or standing in water rather than feeding. Those defensive behaviors translate directly into lost gains.
Studies indicate that horn fly infestations can reduce weight gain by 0.3 to 0.5 pounds per day, and cattle protected from flies may gain 15 to 50 pounds more over a grazing season than untreated animals (Nebraska Extension). Flies also spread disease: face flies transmit Moraxella bovis (pinkeye), and stable flies can mechanically spread other pathogens. These small irritants can quickly become costly threats to feedlot performance.
Know the Enemy, Target the Source
Different fly species thrive in different places — and knowing where they breed is key to managing them.
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Stable flies bite and feed on blood, breeding in wet bedding or spilled feed.
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House flies rarely bite but reproduce quickly in manure and organic debris.
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Horn flies are pasture pests, clustering on cattle and breeding in dung pats.
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Face flies feed on secretions around the eyes and nostrils, transmitting pinkeye pathogens.
Understanding where each species lives helps producers target problem areas more effectively.
Cleanliness Comes First
No matter the species, sanitation is the cornerstone of every fly management plan. Flies depend on moist, organic matter to reproduce, so removing breeding sites is the most effective control measure.
Clearing manure, rotting hay, and spilled feed limits fly emergence. Even in late fall, regular scraping and composting can reduce overwintering pupae and set up the next season for success. Clean pens also improve animal comfort and reduce other stress factors.
Smart Scouting and Targeted Control
Monitoring fly populations helps determine when to intervene. Watch for signs such as increased tail switching or bunching and inspect moist areas for larvae or pupae.
Sticky traps, bait stations, and fly counts per head help track activity. When chemical control is needed, rotate insecticide classes annually to minimize resistance.
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For stable and house flies, use premise sprays or baits in combination with sanitation.
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For horn and face flies, ear tags, dust bags, and back rubbers work well if placed correctly and rotated each season.
No single method works alone — the best results come from integrated programs that combine several tools.
Biological Allies
Biological control adds sustainability to the mix. Predatory beetles, parasitic wasps, and even poultry in yard systems can help disrupt fly lifecycles by feeding on larvae or pupae.
These methods are most effective when used with sanitation and minimal insecticide overlap. Planning biological control zones carefully helps preserve beneficial insect populations.
Late-Season Payoff
As temperatures drop, fly activity slows, but the management decisions made now shape next year’s starting point. Cleaning pens, managing manure, and improving drainage all help reduce overwintering populations. Feedlots that finish the year with clean conditions and active monitoring enter spring with fewer pest pressures and stronger performance potential.
At the Feed Bunk
Flies may be small, but their impact on cattle is anything but. By treating them as both parasites and stressors, feedlot operators can reduce irritation, improve comfort, and protect gains. Even late in the season, integrated management — sanitation first, monitoring second, and targeted control as needed — keeps cattle on feed, on track, and performing at their best.
