How To Choose the Best Fly Spray for Horses

Flies, mosquitoes, gnats, ticks, and other biting insects are an annoyance to horses and humans alike. These common pests can also spread disease, and their pesky buzzing encourages horses to stomp their feet, increasing the chances of chipped hooves.  

Fly spray is part of a horse care routine that helps keep your equine partner comfortable and healthy. 

Why Fly Spray Is Essential for Horse Health

Bugs can spoil an enjoyable ride, ruin your performance, or interrupt your horse’s nap. Bug bites can cause welts, sores, and skin irritations, such as sweet itch, that require veterinary care. Insects can also carry diseases like:  

• West Nile Virus 
• Potomac Horse Fever 
• Equine Infectious Anemia  

Fly sprays for horses, especially when used in combination with veterinarian-recommended vaccines, good barn management practices, and fly gear like sheets, masks, and boots, help reduce the risk of disease transmission. These products also help your horse feel more comfortable, as well as more focused during work. 

Types of Fly Sprays for Horses

To choose between the types of fly sprays for horses, start with understanding formulations and ingredients.  

Chemical Fly Spray 

Chemical fly sprays typically use two types of active ingredients: 

• Pyrethrins, which are derived from chrysanthemums, provide a speedy knockdown, killing insects quickly. However, they break down quickly in sunlight. Additional ingredients in a formulation can prolong the effectiveness of pyrethrins. 
• Pyrethroids are synthetic pyrethrins, with the most common including permethrin, cypermethrin, and resmethrin. Sunlight doesn’t break down pyrethroids as quickly, allowing them to remain effective for several days.  

Chemical formulas such as Tri-Tec 14 are strong, fast-acting, and long-lasting.  

The tradeoff is that they can irritate sensitive-skinned horses and can raise environmental concerns. 

Chemical fly sprays come in two different formulations: oil-based and water-based. 

Oil-Based Fly Spray 

Oil-based formulations like Pyranha Wipe N’ Spray tend to work fast and last longer, but they also attract more dust.  

They also magnify the sun, increasing the chance of sunburn in sensitive areas.  

Water-Based Fly Spray 

Water-based formulations like UltraShield EX can be less irritating to horses with sensitive skin. These sprays don’t attract as much dirt but do require more frequent applications.  

Natural Fly Spray 

Natural fly sprays, like this one from Absorbine, use essential oils such as citronella, eucalyptus, cedarwood, geranium, and lemongrass.  

Natural ingredients are more eco-friendly and often better tolerated by sensitive horses. However, they generally require more frequent reapplication, especially in hot or humid conditions, and are more heavily scented.  

Alternative Applications 

There are multiple fly repellent application methods. These four are good options for targeted use and application around sensitive areas: 

• Spot-on products like Equi-Spot are applied similarly to feline and canine flea and tick treatments, and offer protection against ticks and other insects. 

• Roll-on products like Fly Bye! have a roller ball, making it easy to apply around the nose, ears, mouth, and wounds. 

• Manufactured wipes like these from Manna Pro make applying fly repellent to the face easier.  

• You can also apply fly spray to a rag and wipe it on or use an ointment like Swat, which is useful in ears and on belly areas or around small wounds to minimize infection from these pests. 

• Fly collars like this one from ALZOO can repel ticks and insects for up to three to four weeks.  

Although they look like dog tick collars, be sure not to use any product marketed for dogs on horses. 

5 Key Factors to Consider When Choosing a Fly Spray

Choosing the right fly spray for your horse can feel overwhelming. These five factors can help you make the best choice. 

1. Effectiveness Against Specific Insects 

Choose a fly spray formulated to target the insects most common in your area. Even within a geographic area, insect populations vary. For example, ponds and other standing water are more likely to have mosquitoes than dry areas, so check product labels to find a fly spray that’s most effective on mosquitoes and flies. 

2. Duration of Protection 

Some fly sprays are designed for daily use, while others offer multi-day or sweat-resistant protection. Long-lasting fly sprays for horses are helpful for turnout, trail riding, or competition days. 

3. Horse Skin Sensitivity 

Horses with sensitive skin benefit from alcohol-free, hypoallergenic, or natural formulas. Look for manufacturers that make fly sprays for sensitive horses, and always spot-test a new product before a full body application. 

4. Weather and Riding Conditions 

Sweat, rain, and humidity can break down fly sprays quickly. Consider water-resistant formulas for riding or extended turnout during peak insect season. 

5. Scent Strength 

Strong scents may deter insects but they can also bother riders and sensitive horses. Choosing between scented and unscented fly sprays depends on your preference and your horse’s reaction. 

Fly Spray Ingredients to Look For (or Avoid)

All fly repellents must include a label that lists the ingredients. Look for effective ingredients and ones to steer clear of.  

Effective Ingredients 

Pyrethrins and permethrin are widely used for their proven insect-killing power. Natural ingredients like citronella, cedarwood, geraniol, peppermint, lemongrass, and clove oil can be effective repellents for some horses when reapplied consistently. 

Ingredients to Avoid 

Harsh alcohols can dry out skin and worsen irritation, especially with frequent use. Horses with allergies may also react adversely to certain essential oils or synthetic additives. 

How To Apply Fly Spray Safely and Effectively

Always read a product’s label for application instructions. The “For Use” section explains proper use, including the distance from the horse and application frequency. 

Once you’ve read the label: 

• Brush off any dirt and debris from your horse 

• Shake the bottle 

• Hold the spray bottle 8–12 inches away from your horse 

• Spray a consistent mist from your horse’s poll to their rump and down their legs 

• Avoid spraying products around the eyes, nostrils, and wounds 

• Reapply as needed and based on label instructions 

Insects can become resistant to pesticides. Alternating products formulated with different ingredients can help maintain fly spray effectiveness.