Chemical Free Fly Control for Horse Properties

If there is one pest that could be crowned “Kings of Irritation” to our equine friends it would be those ever-present menaces – flies.

Every year millions of dollars are spent by horse owners all over the world on chemical sprays of every kind, both organic and inorganic, to keep those pesky pests off their horses, along with the many hours spent applying said sprays. Even then, not every chemical seems to work on every horse, so the industry has created multiple chemical options to address the issue.

I can always tell a horse owner in a feed store by the smell of fly spray on their clothes. It never really goes away no matter how much you wash your hands. The lingering spray in the air always falls on your clothes or boots so that when you stand next to me in the cash register line at the Co-op I will always be able to smell that sweet smell of fly spray on you. Sorry, but it’s true. So if you want to avoid the cost and hassle of chemical fly controls – as well as detection by discerning fellow horse owners in the check-out line – there are some things you can do to manage flies biologically.

Turn Flies into Prey

Flies, like most other things on this planet, have natural predators. In the world of mammals humans have natural predators in bears (more on that in a future article) and in the insect world flies have natural predators in tiny, biteless, and completely stingless parasitic wasps commonly referred to in the horse world as “fly predators”.

Fly predators kill their prey while the flies are in the developing stages on the ground. The female fly lays her eggs on decomposing organic material, and very soon after the microscopic fly maggot burrows its way into the material and forms a cocoon. The fly predator seeks out her prey and when she sees these cocoons she deposits her eggs inside the cocoon, preventing the adult fly from hatching.

The only drawback to using fly predators is that they have a very short life span and the adult fly lays eggs at a faster rate than the fly predator. This all means you must continually replenish your supply of fly predators as the season progresses.

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Violet-green Swallow

Attract Birds and Bats

Another inexpensive method for controlling flies is to attract other natural predators such as birds and bats. This can be done by providing the targeted predators – specifically the Violet-Green Swallow, the Barn Swallow, and bats – with houses situated in favorable spots around your property.

Violet-Green Swallows need a house because they will not build nests in barn structures like their cousin Barn Swallows. Also unlike their cousin, they do not generally poop below their house, keeping their surroundings cleaner. Violet-Green Swallow houses must have an oval shaped opening rather than round, and should not have a perch in order to prevent predators from attacking their nests. Violet-Green Swallows first appear in early May, lay a brood, then move on by mid-July. However, while the Violet-green Swallow will leave by mid-July, the Barn Swallow may lay a second brood and will hang around until mid-September.

The nice thing about both birds is that they will eat their entire body weight in flies every day. On average, these fellows weigh in around 0.63 ounces while a typical fly weighs 0.0004 ounces – that’s a daily diet for the swallow of 1,575 flies! So, the more swallows you attract, the more flies they can consume.

However, if you want to pull out the big flying guns in this battle, attract bats. They consume 500 to 1,000 flies, mosquitoes and other flying insects…an hour! Since bats typically feed 8 hours a night, that means the average bat will consume from 4,000 to 8,000 flying insects a night. Bat houses can be bought commercially or easily constructed using commercial plans, and should be located also on the south or west side of your structures. They also need a reliable water source nearby…no doubt to wash down all those flies!

Manage Manure

At the same time you can attack flies directly using their natural predators, you can also control fly propagation by controlling the host for all their egg laying – your horse’s manure.

Building and using a compost bin is an essential weapon against parasites and pests on any horse property. It can be as simple as creating a pile and making sure it is covered to building an elaborate, forced air system with a roof and removable cover.

The key to making good compost comes down to three basics – moisture, air and temperature. The manure must always be the moisture of a damp sponge (not wet, but damp) and enough air, either from turning the pile at intervals or using a forced air system, to allow the microbes to do their job at breaking down the organic material in the manure. And the most important factor of the three is temperature. It is important that the internal temperature of the manure pile reach at least 130 degrees Fahrenheit (F) for at least 3 to 15 days depending on how your pile is constructed to kill off all the fly eggs present.  

By using these good, chemical free fly controls you will not only go a long way in reducing exposure to chemicals to yourself and your horse and save time and money in the barn from applying horse spray, but you will also smell a whole lot better in the check-out line.