Fly and Insect Control for Livestock

Why do flies matter for livestock?

Flies irritate animals, causing them to bunch up, stop grazing and burn energy swatting and stamping. Some spread disease such as pinkeye, and some bite and draw blood. Heavy fly pressure lowers weight gain and milk production and bothers everyone nearby, including neighbors.

Different flies behave differently, so the right control starts with knowing which kind you have. Your county extension office can help you identify them.

Fly season also affects people on the farm. Stable flies bite, house flies spread germs on food and manure, and heavy populations can lead to complaints from neighbors or conflicts with local nuisance rules. Check with your county about nuisance regulations that may apply.

How do I cut down breeding sites?

Most flies breed in wet manure, spilled feed, damp bedding and standing water. Removing these before flies can complete their life cycle is the single most effective step. Clean pens and barns on a regular schedule, keep bedding dry, fix leaking waterers and spread or compost manure properly.

Good drainage around buildings matters. Low, muddy spots near tanks are fly nurseries.

Manure management is worth a deeper look. Fresh manure is where many flies lay eggs, and a pile that stays moist and undisturbed is a hatchery. Spreading it thinly so it dries quickly, or composting it properly so it heats up, breaks the cycle. Ask your extension office for methods that suit your climate.

• Clean out wet bedding and manure regularly.
• Fix leaks and drain standing water.
• Clean up spilled feed.
• Keep manure piles away from the barn and managed according to local rules.

What other non-chemical options exist?

Fly traps, sticky tapes, fans for air movement, and encouraging natural enemies such as predators or beneficial insects can lower numbers. Some producers use natural predators of fly pupae, though results vary with weather and management. Shade and airflow reduce fly worry for animals themselves.

Combine several methods, because no single one is enough in a heavy season.

Fans in barns, open sides for airflow and shaded loafing areas help animals tolerate flies that remain. Animals in comfortable, airy spaces are less stressed and less likely to bunch and burn energy.

When are insecticides appropriate?

Sprays, pour-ons, ear tags and feed additives can help, but flies develop resistance, and overuse harms beneficial insects, pollinators, fish and people. Use only products labeled for your species and the type of fly, follow the label exactly and keep them away from water sources.

Some products have waiting periods before animals go to slaughter or milk is used. Your veterinarian or extension agent can help you choose and your state department of agriculture can answer rule questions. Store chemicals securely, away from feed, children and pets.

Rotate the active ingredients you use if you rely on chemical products, since using the same one repeatedly speeds resistance. Ask your veterinarian or extension agent how to rotate in a way that fits your animals and the labels.

How do I protect animals' eyes and skin?

Pinkeye spreads on flies and can cause pain and blindness. Keep an eye out for squinting, tearing and cloudiness in the eye, and call your veterinarian quickly. Fly masks and sheets help some animals, as does keeping pastures mowed to reduce irritants.

Check wounds regularly in fly season. Flies lay eggs in open wounds, and infestation can follow quickly.

Flies in the barn are also a sign that moisture or manure is building up. Treat them as feedback on how well your cleaning routine is working.

How do I plan across the season?

Start before the season, not in the middle of it. Clean up in spring, get traps out before numbers build and review your plan in early summer. Keep track of when the problem begins each year so you can act earlier next time.

Talk with neighbors, since fly populations move between properties. A shared effort works better than one farm acting alone.

What should I keep in mind for people and pets?

Insects can bother people too, and some carry disease. Use repellents as directed, wear protective clothing and check for ticks. If someone develops a fever or rash after bites, they should talk to a doctor. The CDC has general guidance.

Keep pesticide containers and treated animals away from children, and read the label before every use.

Dispose of empty containers as the label directs and keep a list of what you apply and when. A simple written log helps you avoid repeating treatments too soon and keeps you within label limits.

Last reviewed: November 12, 2026. Written by the Rural Farm Life Editorial Team. See our editorial policy.