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How to Remove Bot Fly Eggs from a Horse

Updated: Nov 26, 2021

What are the yellow specs on my horses Leg?

Those very small yellowish specs you see on your horses legs are eggs in late summer and fall, are laid by a bot fly. The bot fly looks like a honey bee and it’s purpose is to start a new life cycle.

The bot fly lays its eggs on the horses hair in areas like the fore leg, chest, shoulder and sides of the body. When the horse rubs and licks itself, the eggs enter the horse, continuing life cycle. The larva that has matured will exit the horse through its manure than grow into flys.

Preventative Measures

A preventative measure is removing the eggs from the horses hair before they turn into larve. Removing the bot fly eggs can be done by using a grooming block or bot knife:

A bot knife is a curved blade with a serrated edge. The knife is gently placed above the egg and than pushed downward in the direction the hair grows. Be sure to remove the eggs in a location where horses do not graze or eat, to prevent the dropped eggs from being consumed.

A grooming block is a hard, porous block. The grooming blocks edge is placed above the egg and than pushed downward in the direction the hair grows.


Bot fly eggs will still enter the horse throughout the season. Some eggs will be hidden during removal or the horse will have licked or rubbed itself before the eggs were removed using a bot knife or grooming block. Deworming kills the internal larvae. Consult your vet on types of dewormer and your horses deworming needs.

Reducing the number of parasite bot eggs entering your horse can be done by manually removing the eggs from the horses hair. The bot knife and grooming block are tools remove bot eggs before they enter the horse.

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