The bottom line on bots and horses!


Well, bots are one of the many pests that can bother and potentially harm your horse. Bots are a variety of fly, and even though they live part of the life inside your horse, they are not a worm. Parasite, yes, worm no.


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  • The adult female botfly makes it her mission to lay about 500 eggs on your horse. She will aim for legs, neck, and mouth area and will glue her eggs to your horse, mule, donkey, or zebra. For some reason, she doesn’t like cows, which is good to know if you have them. And by glue, I mean it. Those eggs are not coming off voluntarily!


So how does the bot fly life cycle work?


  • The adult fly places the eggs on your horse. Your horse rubs his legs with his nose, or maybe he rubs his buddy during mutual grooming.


  • Bot fly eggs are horribly sticky, and almost look like yellow flecks of pollen on your horse’s legs, which is where they typically are laid. You might also find some on your horse’s neck.


  • Bot fly eggs are really hard to see on gray horses.


  • When your horse rubs his legs or any other area where the eggs are with his face, those eggs end up in his mouth.


  • It’s in your horse’s mouth that they hatch into larvae and burrow in his cheeks and tongue. They live there for a bit, then they migrate to his stomach and attach themselves there, also as larvae. This is fairly gross. Ok, it’s totally gross.

yellow bot eggs on a horse knee

Those little yellowish dots are bot eggs. They are super sticky!


Larvae do not lay eggs, so having a fecal egg count won’t tell you if your horse has bots in his stomach.


  • Once in the stomach, they like to attach themselves to the stomach lining and wait out the winter.


  • Come spring, the larvae are passed with manure into the soil or manure pile and become pupae, eventually emerging as adult flies to mate and lay more eggs.


bot knife on a table

A handy dandy bot knife will take care of removing eggs from your horse!


In many parts of the country, you have weather on your side.


  • Frost will kill any stages of bot that are not in your horse, so this is the time to join forces with your veterinarian to administer anti-bot medication.


  • This assures your springtime manure pile won’t be full of bot pupae. If you don’t have weather on your side, talk with your veterinarian about a bot plan of attack.


pumice stone grooming block

Grooming blocks (like the one above) and bot knives remove the eggs from your horse’s legs, neck, etc so they won’t end up in his mouth and continue the bot life cycle.





  • You should also know that bots have been linked to weight loss, colic, indigestion, and other ailments of the GI system in horses. Don’t take chances here!


  • How can you manage bots year-round while you wait for the first frost? First, manure management is key. Bot pupae like to mature into adults in manure, so keep it picked up and composted and/or removed.



  • Remove the eggs daily from your horses with a bot knife or bot comb, an inexpensive and handy tool.



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Farnam Slick 'N Easy Horse Grooming Block
$5.49 $4.24

Good for grooming, shedding, and bot egg removal

06/13/2024 02:53 am GMT


Thank you!