The Best Fly Control Strategy Starts Before Fly Season Does
It happens every year. Winter ends, the focus shifts to spring turnout, and somewhere between thawing water buckets and evaluating blanket damage, fly season quietly arrives. By the time the problem is visible, the fly population is already established and playing catch-up is harder than getting ahead of it.
The good news is that a well-planned barn fly program, started early and maintained consistently, can dramatically reduce fly pressure throughout the entire season. The key is understanding how flies reproduce, which products address different parts of the problem, and how to layer control methods so no single approach is doing all the work alone.
In the Mid-Atlantic region, the program should be in place by March 1st.
Why Feed-Through Fly Control Works
The foundation of an effective barn fly program is attacking the problem at the source rather than the symptom. Flies reproduce in manure. Every adult fly that lands on a horse was once a larva developing in a manure pile. Feed-through fly control interrupts that cycle before it starts.
SimpliFly Feed-Thru Fly Control is the most widely used feed-through option for horses and is the only equine feed-thru fly control product to receive EPA Reduced Risk Pesticide status. It contains an insect growth regulator (IGR) that passes through the horse's digestive system into the manure, where it prevents house fly and stable fly larvae from developing into adults. The result is a measurable reduction in the fly population emerging from treated horses throughout the season.
Two details make or break the effectiveness of a feed-through program:
Start early. The IGR needs to be in the manure before flies begin emerging in spring. Starting by March 1st in the Mid-Atlantic region ensures the barrier is in place when fly pressure begins. Starting in May after flies are already present reduces the impact significantly.
Treat all horses in the barn. Untreated horses continue contributing to the fly population regardless of what treated horses are receiving. For the program to deliver its full benefit, every horse on the property should be participating. SimpliFly is a highly palatable top-dress that most horses accept readily.
For a broader comparison of feed-through IGR options including Altosid and ClariFly, The Mill's guide to controlling flies with feed-through additives covers which products work best in different management situations.
On-Animal Fly Sprays and Repellents
Feed-through products manage larval populations. They do not repel or kill the adult flies that are already present. On-animal fly sprays and repellents are what protect horses directly from the biting, irritation, and disease transmission that flying adults cause.
The Mill carries a range of fly spray options suited to different preferences and use situations.
Absorbine UltraShield EX Fly Spray is one of the most comprehensive on-animal sprays available, killing and repelling over 70 species of flies, ticks, mosquitoes, and gnats. Its UltraBond Technology makes it weatherproof and sweat-resistant, with up to 17 days of protection per application. It includes aloe, lanolin, and sunscreens that condition and protect the coat alongside the insect control.
Repel-X Insecticide and Repellent Spray is a ready-to-use, water-based formula that kills and repels six fly species, mosquitoes, gnats, fleas, and ticks. It can be applied as a spray or wiped on, making it versatile for sensitive areas of the face and legs where spray application is not always practical. A concentrated version, Repel-X pe Emulsifiable Concentrate, is available for operations that prefer to mix their own spray at a more economical per-application cost.
Pyranha Wipe N' Spray is a pyrethrum-based formula that is a consistent favorite among show horse owners. It provides effective fly and mosquito protection while imparting a high shine to the coat when brushed out. Citronella-scented with lanolin as a coat conditioner, it requires only 2 ounces per head per application.
Nature's Defense Natural Fly Repellent is a botanical-based option for horse owners who prefer to avoid synthetic insecticides. It combines citronella with clove oil, mint oil, and thyme oil to repel five types of flies, mosquitoes, and gnats without preservatives, additives, or artificial colors.
SWAT Fly Repellent Ointment is a targeted ointment for use around wounds, abrasions, and sensitive areas where spray application is not ideal. It keeps flies away from problem spots that attract them most, which reduces secondary infection risk and allows healing tissue to remain undisturbed.
Physical Barriers: Fly Masks, Sheets, and Boots
On-animal sprays provide broad body protection, but the face, eyes, and lower legs are the areas flies target most aggressively and the areas where spray application is most limited. Fly masks, sheets, and boots fill this gap by creating a physical barrier that keeps flies off the most vulnerable areas entirely.
Fly masks protect the eyes and face from face flies and gnats, which are responsible for spreading pinkeye and causing the kind of persistent irritation that drives horses to rub their faces on fencing and stalls. Fly sheets cover the body and are particularly valuable for horses that react severely to fly bites or that have skin sensitivities that are aggravated by topical sprays. Fly boots protect the lower legs from stable fly biting, which causes the leg stomping and behavioral agitation that disrupts grazing and turnout.
Browse The Mill's selection of fly masks, sheets, and protective equipment in the Horse Health and Stable Supplies collection.
Barn Management: Reducing the Environment Flies Need
Every fly that emerges from a manure pile is a fly that chemical products will have to address. Reducing the breeding habitat available in and around the barn is the most permanent and cost-effective part of a fly control program.
Practical barn management steps that make a measurable difference:
- Remove manure from stalls, paddocks, aisles, wash stalls, and run-in sheds frequently and consistently throughout fly season. Daily stall cleaning reduces the window of larval development significantly.
- Keep feed rooms swept and store open feed in sealed, pest-resistant containers. Spilled grain and exposed feed attract and sustain fly populations.
- Remove uneaten feed promptly rather than leaving it in buckets or feeders where it becomes a fly attractant and breeding site.
- Manage wet bedding and organic matter accumulation around water troughs and high-traffic areas, as moist, decaying material is prime stable fly habitat.
Fly Traps, Strips, and Fly Predators
Adult fly populations inside the barn can be reduced further with supplemental control tools that work alongside the feed-through and on-animal program.
Fly strips and bait stations provide passive control, capturing or killing adult flies that have already emerged. They work best in enclosed spaces like feed rooms, tack rooms, and stall areas where fly concentration is highest. Follow product instructions for placement and replacement timing to maintain effectiveness.
Fly predators are a natural, non-chemical option that targets flies at the pupal stage in manure and organic matter. These tiny, parasitic wasps lay their eggs inside fly pupae, preventing adult flies from emerging. They are harmless to horses, humans, and other animals and are a valued part of a low-chemical barn management approach. For best results, release fly predators around manure storage areas and high-concentration zones before fly season peaks, and continue releases throughout the season.
Ventilation: Simple, Effective, and Overlooked
Flies prefer warm, still, humid air. Good air circulation through the barn disrupts that environment and forces flies to seek conditions they prefer. Installing barn-safe fans in stalls, aisles, feed rooms, and run-in shed overhangs reduces fly activity in those areas and provides a secondary benefit of cooling during hot summer weather.
This is one of the simplest and most cost-effective improvements a barn can make for fly management, and its benefits compound every other product and practice being used.
Building a Complete Fly Control Program
No single product or method controls all fly species equally well across an entire season. The programs that deliver the best results combine multiple approaches that address different fly species, life stages, and management situations simultaneously.
A complete barn fly program typically includes:
- Feed-through IGR to interrupt larval development at the source
- On-animal fly spray applied consistently throughout the season
- Physical barriers including fly masks for face and eye protection
- Barn management practices that reduce breeding habitat
- Supplemental traps, strips, or fly predators for adult population management
- Ventilation improvements that make the barn a less hospitable environment for flies
For more detail on equine insect control options including fly spray chemistry and product selection by situation, The Mill's Beat the Bugs equine fly control guide is a thorough companion resource.
Find Fly Control Products at The Mill
The Mill carries a full selection of feed-through fly control, on-animal sprays, physical barriers, and barn management supplies for every phase of the fly season. Visit any local The Mill store or browse online at themillstores.com to find the right combination of products for the barn.
