Homemade Fly Spray For Horses With Permethrin

Last Updated on March 8, 2022

It’s easy to pick up a bottle in any tack shop, but to avoid nasty chemicals or add your own ingredients, try a homemade fly spray for horses with permethrin. Making your own fly spray is also one way to save money. Let’s take a look at insect-busting permethrin and how you can make your own bug repellents.

Protect Your Horse From Biting Insects

As soon as the weather warms up after winter, the bugs come out to irritate people and horses alike. Flies and mosquitos can spread disease and make horses uncomfortable, even driving sensitive horses crazy.

What Is Permethrin

Permethrin is a type of pyrethroid insecticide. While it is not a natural insecticide, it is quite similar to pyrethrum. Pyrethrum is a natural bug killer derived from chrysanthemum plants.

Pyrethroids are more stable than pyrethrum. While pyrethrum breaks down with exposure to sunlight and only protects for a couple of hours, permethrin lasts much longer, even days. It is one of the most effective fly sprays for horses and the least toxic.

Protect Your Horse From Biting Insects

Permethrin is effective on several types of bugs including, flies, ticks, and mosquitoes. The doses used in insect control don’t negatively affect people, but it is not completely safe. To avoid any of the effects, which usually only occur with exposure to high doses, stay inside when spraying property with it.

Is Permethrin Safe For Horses

Permethrin is toxic to flies and other insects. When they come into contact with it, it affects their nerves, leading to paralysis and death. However, it is considered safe for horses.

Safe Use Of Fly Spray For Horses With Permethrin

While fly spray will not eliminate insects on your property, it will deter them from landing on your horse and biting them. Insects are attracted by your horse’s body heat, and unfortunately, there is nothing you can do to stop this. However, if you use fly spray, the insect will avoid contact when exposed.

Always read product labels thoroughly before using them. Permethrin is sold in varying strengths, and sometimes it is combined with other products. Make sure when using a homemade fly spray for horses with permethrin, you use the recommended dilution. 


Even though it is rare, some horses experience sensitivity to permethrin. The most commonly seen issue is a skin reaction. If this occurs, give the horse a bath with a gentle shampoo and rinse thoroughly. 

Another side effect of permethrin use on horses is coat loss. This is usually due to the use of a highly concentrated product, such as a spot on. Always take caution to avoid contact with your horse’s eyes and nose.

Homemade Fly Spray For Horses With Permethrin

One alternative to purchasing commercially produced insect control is to create your own homemade fly spray for horses with permethrin. You won’t have trouble finding a recipe to make your own but we will help you get started with a couple of suggestions that include permethrin.

The first ingredient you need regardless of your recipe is a bottle of 10% permethrin concentrate. Make sure the version you buy is labeled safe for horses and other animals. The best place to find the right kind of permethrin is a tack shop or your local farm supply store.

Homemade Horse Fly Spray Recipes

1. Mix the following ingredients in your spray bottle.

  • 30ml of permethrin concentrate
  • 1 tablespoon of lemon dish soap
  • 2 cups of apple cider vinegar (ACV)
  • 2 teaspoons eucalyptus oil
  • 1 teaspoon cedarwood oil

Bayer Permectrin II Insecticide, 32-Ounce

Add all the ingredients to your spray bottle and give it a good shake. Fill the remainder of the bottle with water and shake again.

2. The next natural fly spray for horses with permethrin comes from Dr. Twilla, a vet at Brandon Equine Medical Center in Florida. Mix the following ingredients in a spray bottle.

  • 2 ounces of Skin So Soft
  • .75 ounces of permethrin 10%
  • 4 ounces of white vinegar
  • 1 teaspoon of citronella
  • 6 ounces of Healthy Hair Care
  • Water

Simply add all of your ingredients into your spray bottle and shake well to mix it up.

DIY Horse Fly Spray Without Permethrin

If you prefer to keep your fly spray as natural as possible, you can make your own without adding permethrin. However, keep in mind this will greatly reduce effectiveness and likely only last for a short period of time.

Saddle Box has shared this budget-friendly fly spray for horses. Just add all the ingredients together in a 32-ounce spray bottle and shake it up.

Homemade Fly Spray For Horses Without Permethrin
  • 1 cup of white vinegar
  • ½ cup of spray-on sunscreen
  • 50 drops of citronella oil
  • 25 drops of lemongrass essential oil
  • 25 drops of peppermint essential oil
  • 20 drops lavender oil
  • 2 tablespoons Dr. Bronner’s liquid soap
  • 2 cups water 

For another great homemade fly spray for horses that don’t use permethrin check out this detailed helpful video from Budget Equestrian.

Essential Oil Must-Knows

When choosing an essential oil to add to your homemade fly spray for horses, take extra care. For example, citronella oil comes in two types, one of which is very dangerous. You want to pick the essential oil citronella, not the type that is used for tiki torches.

All essential oil is highly concentrated, so you only need to use small amounts. Check that the oil actually pure, only containing compounds of the plant. Watch out for solvents and synthetic essential oils.

Essential Oil Must-Knows

Fly Spray For Horses That Really Works- Conclusion

Making your own homemade fly spray for horses with permethrin is easy, economical, and even fun. Ensure you use a safe concentration of permethrin on your horse and only add essential oils that are non-toxic for them. If your horse gets a reaction to your fly spray that doesn’t resolve with a bath, don’t hesitate to get in touch with a vet.

In addition, to fly spray, you can use fly masks and fly sheets to protect your horse from insects. These are particularly good to use if you have a horse that is sensitive to insect bites.

One important thing to note, with regards to permethrin use, is to avoid using it on or near cats, as they are more sensitive to it and susceptible to neurotoxicity.

How long does horse permethrin last? 

Permethrin is an efficient and economical insecticide with proven effectiveness against a broad range of insects. It’s safe to use on livestock and can as well be used to treat premises. The residual activity lasts for up to 28 days which means you only need to apply it once per month. With an average of just pennies a horse, Permethrin can be used to treat your entire herd for an affordable price. 
As with any insecticide, if you have concerns about the safety of Permethrin you should contact your veterinarian or your local government health department. Permethrin is safe for horses, however there is some risk of toxicity in certain circumstances. To help reduce this risk, please follow the instructions provided with your product and keep in mind that these products are intended to be used as part of a complete control program. 

Does permethrin kill horse flies?

Horse flies are annoying pests that can make your summer more of a headache than you’d prefer. Luckily, there are ways to get rid of horse flies. So, if you’re an outdoorsy person who spends most of your time in nature with your horse trying to avoid horse flies, you may want to get your horse treated with permethrin. Permethrin isn’t a miracle cure for horse fly bites; it’s merely a repellent. When used correctly it’s not harmful to the horse or to you, but it does provide some relief from horse flies while out on the ride.

Can you spray permethrin 10 on horses?

10% Permethrin can be applied to your horse’s skin in a spot treatment or as a spray but never as a pour-on. However, you must dilute 8 ounces of the product in 50 gallons of water first. This will ensure that your horse is safe while using the product and at the same time still protected from ticks, flies, mosquitoes and other insects.

How much Permethrin is safe for horses?

Studies has shown that the use of 3.6% permethrin appears to be safe for horses. The pour-on method used in this studies is considered to be safe and effective for controlling flies on horses. The treatment should be applied prior to turnout to ensure maximum effectiveness.
However, the pour-on method used in this study was different from the way the product is typically applied to horses. The pour-on method involved applying the product by pouring it directly onto the skin of the horse. In contrast, the conventional method involves spraying the product into a hand-held sprayer that is then held against the horse’s skin. The difference between the pour-on and conventional methods is important because the pour-on method can’t be safely used with higher concentration of permethrin. 

How does permethrin work on flies?

Permethrin is one of the most effective pest control products available. It works by overstimulating the nervous system of insects, eventually causing the insect to die. It’s a broad-spectrum insecticide that works on a wide range of pests, such as fleas, ticks, cockroaches, flies, and mosquitoes.
Permethrin belongs to Pyrethroids pesticide class. They are the most widely used pesticides as they are fast acting and remain active for long periods of time even in extreme conditions.