Aside from being a nuisance, flies carry and spread diseases that you’d rather not share with your horses. And while you can take steps during fly season to reduce populations, the most effective way to manage flies is to practice early and ongoing prevention. By taking some pre-season measures, you eliminate many of the irritants you and your horse would otherwise deal with later. 

Keep Clean

Flies reproduce in shaded, damp areas, usually where there’s organic matter that they can feed on like trash or manure. Keeping flies out of your place from the start takes some diligence to keep your horse’s living environment clean and free of prime fly habitat. In early spring, before fly season begins, plan where you’ll dispose of manure. Aim to keep piles as far away as possible from your horse’s main living area. If it’s an option, haul it away completely. 

Before and during peak fly-breeding seasons, keep your horse’s stall and bedding areas picked up. Clean and muck stalls often. Remove wet or soiled shavings and apply odor-reducing, moisture-control products. PDZ and lime are two effective options, but be sure to re-lay enough bedding that it doesn’t come into contact with your horse’s skin and cause irritation.  

In and around the barn, take out trash often. If the can becomes wet or dirty, clean and disinfect the inside before putting another bag in. Keep tight-fitting lids on trash cans and feed and supplement containers, as these are attractive to flies. 

Want to learn more? Barn Fly Facts

Maintain Turnout Areas

Pastures and turnout areas should be maintained as well. Remove standing water in ponds and puddles, and slow-
moving ditches. If you can’t completely eliminate water on your property, manage vegetation. Mow and cut back grass, weeds, and bushes, which will also help keep mosquitos and ticks away. In non-grazing areas, spread manure so that it can dry out and reincorporate into the dirt quicker and not become home to fly larvae. (Note: non-composted manure shouldn’t be spread in the pasture as it contaminates the area.)

Shoo, Fly Schedule

While most tend to focus on the warmer months when flies are already out in full force, the best time to begin thinking about fly control is before they show up. Here’s a general seasonal timeline as you prepare. 

Spring

• Plan for manure storage
• Move existing manure piles
• Manage standing water
• Upgrade grain containers/trash cans if uncovered
• Clean garbage bins

Late Spring 

• Begin feed-through larvacide
• First round of predators 
• Use protective gear/methods

Summer/Fall

• Predators every four weeks
• Use protective gear/methods
• Spread manure
• Clean often

Cover Them Up From the Inside Out

As the weather heats up, flies will start laying eggs in any habitable matter. Since you’ll have prepped your horse’s space to make it less welcoming to flies, you should have fewer flies to contend with. For the ones you do have, your goal is to disrupt the breeding process to reduce populations.

Fly Predators, which are spread on manure piles, work to keep fly larvae from developing. The predatory wasps lay their eggs in fly pupae and kill fly larvae. They should be sprinkled on manure piles every three to four weeks during warm months beginning in spring.