Fly sprays for horses – chemical, fatty acid, or essential oils?


Fly season is coming up, which means we must declare war on flies right now. A trip to the feed store or tack shop will quickly get your head spinning about what fly spray to use… so here are the basic types of fly sprays.


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Chemical fly sprays for horses are designed to knock down and possibly kill flies.


  • Sometimes the chemicals that knock a fly down are strong enough to kill it, and sometimes not. Many larger flies of the horsefly family, like greenheads, are too large to be affected by the fly sprays out there.


  • You will commonly find pyrethrin as an ingredient in horse fly sprays. Derived from chrysanthemums, pyrethrins need to come into contact with a fly.


  • The pyrethrin then enters the bug’s nervous system to knock it off your horse. Often they are paired with synergists to keep the pyrethrins circulating in the bugs long enough to kill the bugs.


  • You will also find permethrin, another neurotoxic agent, in fly sprays. These chemicals are similar to pyrethrins but last a bit longer to kill the flies.


fly spray bottle with ingredients


Both permethrin and pyrethrins are broken down by sun and oxygen, so there’s little toxic risk to the environment, but other animals are at risk.


  • This also begs the question of how long they last on your horse….oh wait, just found the answer…. pyrethrins last an hour or two, maybe longer, depending on the other ingredients in the spray.


  • Pyrethrin is toxic to fish, bees, and birds, while permethrin is toxic to bees, cats, and fish.


  • Pyrethrins and pyrethroids, such as permethrin are downright toxic to cats and will kill them. Treatment is possible, but the entire process is heartbreaking and expensive. Do not even touch your barn cat if you have sprayed your horse or touched your horse after using fly sprays with these chemicals.


Fatty acids in fly sprays


  • These often funny-smelly sprays are designed to mask your horse’s location from flies that rely on a chemical trail to find your horse.


  • The fatty acids mimic your horse’s natural (and weak) bug-repelling smells to create a cloud of confusion around your horse.


  • Your horse is unbothered, and the flies MIGHT get to live. This type of fly spray won’t work against the flies that rely on a heat signature or sight to find a meal.


ecovet fly spray on horse's legs



You can also find fly sprays that are largely based on essential oils.


  • Lavender, peppermint, and lemongrass are popular essential oils for fly sprays.


  • The evidence for fly repelling abilities of these fly sprays are based on antidotes, not science, so it’s hard to say if they work or not, and if so, what flies they work on.


  • Many recipes also include vinegar, which for some bugs, like the many species of gnats out there, is actually an attractant. Some insects and flies use smell to locate their next landing spot, and essential oils definitely put off a smell.



  • You might be doing some research with your local agriculture extension service to find out about the flies in your specific area. Then you can create a plan and experiment with fly-repelling strategies.





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The ShooFly boots!

horse wearing sox for horses on mat

Sox for Horses – for any skin funk, fly problems, summer sore, stomping, etc.

Fly predators!

Another brand of Fly Predators! Let these wasps do the work.

This fly spray is weird but also great for certain types of flies

Fly traps, in case you want to buy them instead of making them.


A popular fly spray


Cashel Crusader Horse Fly Mask with Ears and Long Nose – select size


Cashel Quiet Ride Standard Horse Fly Mask with Ears for riding


Another style of long-nose fly mask for horses


How about some fringe?

                                                     This fly mask is also great for use under grazing muzzles to prevent rubs. 



Cashel Quiet Ride Bug Armor – 2 Piece Set


Amigo Mio Fly sheet – I love this one, the extra long tail prevents bugs up the butt, and the neckpiece is great. It’s also super light, which means it tears easily.

                                                                     Zebra prints are said to confuse flies.


Fly sheet belly guard



Thanks guys!