Eradicating Horse Fly Pests


As everyone who has ridden a horse knows, one of the most annoying things are the flies that constantly buzz around them. And they are more than just annoying for horse owners since dealing with them is a constant and costly battle to ensure that your horse isn’t miserable or develop infections and diseases due to them.

I attended the Osuna Committee meeting last week, and member and local vet Anthony Alario was talking up a relatively new control mechanism called feed through fly control.

Traditional Fly Control

When I used to own a commercial barn, we had a piped fly spray system that would shower each stall with pesticide on a regular basis to keep the flies in check. You’d know when it went off since everyone would flee the barn. I have no idea how this affected the health of either people or horses, but flies are such a problem we felt we had no choice.


Each cross tie area would also be well stocked with pump spray fly repellent. It was all quite “sub optimal”!

Feed Through Fly Control

Feed through fly control (also called Insect Growth Regulators, IGRs) uses the horse as a conduit to deliver a fly maturation inhibitor into horse poop. When flies lay their eggs in such inviting places, the chemical acts on the developing flies to prevent them from maturing into adults. Within six week of using this product, fly population is decimated.

Feed through fly control does not get metabolized by the horse and it isn’t a pesticide. The horse is effectively a giant mixing vat and applicator for the product. The active ingredient only affects specific insects and is ignored by mammalian digestive systems.

All horses in a barn must be fed the product to be effective. The cost (for Solitude, the most expensive type of feed through) is less than $0.50/day per horse, or about $15/month/horse. You just add it to the feed when you add other supplements.

Anthony Alario uses Solitude with his horses and finds it to be very helpful. He also says that he had “excellent results” years ago back East, in an equestrian area, where there was broad municipal encouragement for all horse owners to use feed through fly control.

Fly Predators

Local equestrian Rochelle Putnam advocates for the use of fly predators. She gets a new package of predators every month, releases them, and finds they keep the fly pest population under control. Alario cautions that you must release these predators on a constant 28 day cycle to maintain effectiveness.

Good Solutions

If I owned a barn again, I’d definitely be using one of these fly control mechanisms. Commercial barn owners can put into their contracts that whatever kind of fly control mechanism they use is mandatory for all horses. Considering the cost and unknown harmful effects of traditional pesticides, this seems like a no brainer to me.


Solitude, feed through fly control: Amazon Link. Smartpak Link.

SimpliFly, feed through fly control: Amazon Link, Smartpak Link.

Arbico Organics, fly predators: Link.

Spalding Labs, fly predators: Purchase link.