Have you noticed the creamy white bot eggs ‘glued’ to the animal’s hair during late summer and early autumn.  These eggs can be found anywhere in the horse’s body but will be mostly on the hair of the forelegs, shoulders and around the lips. 

 

Have you ever wondered where they come from and why they are there?  You probably wonder why they show up again the next day when you just removed them all.  Maybe you wonder why your horse has bot eggs when you've always been current with your Deworming program and you thought that alone solved the problem.  

Once the eggs are laid, they will hatch in 5-7 days either spontaneously or as a result of stimulation through licking and self grooming by the horse.  The larvae crawl or are transferred to the tongue during this licking.  They burrow into the tongue and cheek tissue and live here for about one month after which they pass to the stomach. 

    

Once they enter the stomach, they attach to the stomach’s lining or pass into the small intestine and attach there.  The attachment to the tissue creates a mild irritation which results in irritation in the site.  The larvae develop for about a year before they are passed out of the body with the horse’s manure.  Occasionally horse owners claim to see the bot fly larvae in their horse’s manure.  In 1-2 months adult bot flies will emerge from the developing larvae and the cycle will repeat.  

What is the significance of bot infestation to the overall health of the horse?  Adult flies are an annoyance as they lay their eggs. Most horses show no effects from having the bots attached to the stomach lining.  

 

Deworming with a boticide after autumn frosts or during the winter months will eliminate an infection.  In milder climates, additional treatments are needed in eliminating bot flies.  Removal of the bot eggs is important and easiest done with a bot knife or stone. Deworming with an approved product though is the only method that will rid a horse of bots that have already reached its mouth.