April Showers bring May … FLIES! A serious problem deserves serious consideration. With changes in climate occurring, scientists note that flies are finding a more hospitable environment almost everywhere, and most certainly in Florida, with its mild climate and large areas of wetland. Disease accompanies flies.

Know Thy Enemy

In Florida, there are 35 species of flies that fall within the family Tabanidae. For Jeopardy fans and those of you seeking to dazzle cocktail party companions with erudite conversation, horse flies fall in the genus Tabanus, deer flies in the genus Chrysops,and the yellow fly, Diachlorus ferrugatus. You and your horse will feel the bite of the yellow fly! Females are the biters. Males stick to pollen and nectar.

Flies prefer laying in areas of aquatic vegetation, but when they can’t find that, any vertical surface will do as long as it’s over wet ground favorable to the development of larvae. Eggs start out a creamy white color but darken to gray and black. They’re cylinder shaped, laid in clumps and clusters and measure 1 to 2.5 mm in length.

In five to seven days, larvae hatch and remain in the soil from a couple of weeks, in ideal warm conditions, to 30 days or longer in cool areas, eventually migrating to the upper 2.5 to 5.0 cm of soil where they turn into pupa. As many as 120 larvae per square yard of pasture have been found, according to the University of Florida. Once they reach the pupa stage, wings and legs emerge and it’s game on. The cycle of mating and preying on animals begins again.

Tabanids wait in the shade and under bushes and trees for their targets. Sight, odor, and carbon dioxide play a role in attracting the flies. They love dark moving targets. Peak snack time begins at sunrise and lasts three hours. The next high intensity feeding period begins two hours before sunset. During prime dining time, these invaders attack the face, abdomen, neck, and legs of horses, penetrating the skin with a scissor like action.

Although common pests, they can result in uncommon diseases, like Tularemia, Loa loa, and Anthrax. Google these maladies. You don’t want them. Your horse doesn’t want them. They are article topics unto themselves.

Twenty to thirty flies feeding for six hours can consume up to 100cc of blood. They can cause weight loss and lower milk production in mares.


Fighting flies is not a battle for the faint of heart. It’s ongoing. It’s a slog. Most experts will tell you that there are no effective programs for controlling flies. They’re talking total elimination. After all, in tropical and sub-tropical regions 20 generations can occur in a year.

As a horse owner, you must remain vigilant. Persistence overcomes resistance.

Weeds and tall grasses are the perfect place for flies to hideout while they wait for your horse. Keep weeds mowed down around buildings and pastures.

Mow and drag pastures frequently!

Don’t leave the manure spreader next to the barn while you fill it up. Run it weekly to keep from creating a fly breeding orgy on wheels.

You have some native helpers, too. Cattle egrets and killdeer feast on tabinids.

Eggs of tabinids are parasitized by Hymenoptera families, like Trichogrammatidae, Scelionidae and Chalcidae. In layman’s terms, these are basically tiny wasps. Additionally, nest building wasps prey on tabinids. Some ants also attack fly larvae.

More and more people are becoming fans of commercially delivered fly predators, like Spalding Fly Predators. They enhance the native army of insect predators who are already attacking the fly population like those mentioned above.

As fate would have it, not all solutions work on all types of flies. Fly predators usually don’t have any impact on deer flies, for example. In this case, many people turn to fly traps. They can be purchased, or they can be homemade. A myriad of directions exists online for making fly traps. All are basically the same and can be constructed in five minutes.

  • All you’ll need is a plastic bottle (think water bottle or soft drink bottle)
  • a tool to cut the bottle
  • some rancid contents to use for bait
  • water
  • heavy duty tape
  • string if you wish to hang the trap
  • something to add to the water to disrupt wing function of the fly once he’s in there. This could be anything from a little liquid dish soap to a couple of tablespoons of baby oil.

Just cut the cone shaped top from the bottle. Later, you will invert it back on the bottle so that it becomes a funnel for flies to enter the bottle.

Add bait to bottle (some suggest raw shrimp or chicken– any disgusting fly attractant).

Fill bottle about one third full of water.

Add a couple of tablespoons of liquid soap or oil.

Invert top of bottle so that it acts as a funnel for flies to enter bottle and tape it to the lower section of the bottle.

You can tape string to the bottle and hang or place down low. Some suggest not hanging higher than four feet.

Fly Sprays

When it comes to fly sprays, finding an effective one can be confusing and costly.

Leslie Anne Johnson did a study analyzing the effectiveness of different fly sprays for her Masters thesis at the University of Tennessee in 2013. In it, she compared three fly sprays: Farnam’s Endure, Eqyss Marigold, and Gordon’s Permethrin.

Endure contains pyrethrin, cypermethrin, piperonyl butoxide, and butoxy polypropylene glycol and claims to be effective for fourteen days. Since some bugs have developed genetic immunity to pyrethrin, which is a synthetic copy of the natural compound pyrethrum found in chrysanthemums, Farnam adds cypermethrin. This depresses nerve impulses in insects. Piperonyl butoxide is added as a synergist for pyrethrins to increase effectiveness. Butoxy polypropylene glycol, first registered with the Environmental Protection Agency in the 1960’s, is supposed to repel just about every insect that torments a horse.

With this product, if the insect is immune to one substance, no worries; another one will get him.

In her study, Endure won out, with horses having a mean number of 30 flies per horse over a 30 minute period. Eqyss Marigold came in second, with 48 flies on the horse in a 30 minute interval, and Gordon’s Permethrin had a mean of 60 flies per 30 minute interval. Incase you’ve ever thought that your fly spray is no more effective than water, horses sprayed with water entertained about 105 flies per 30 minute interval.

Fly sprays that contain a little oil are understandably a little more expensive. Many people suggest adding a couple of ounces of Skin So Soft or baby oil to fly spray. Oil bogs down bugs, and they avoid it. Spray lasts longer and doesn’t evaporate.

There are lots of recipes for homemade fly spray. Experiment and see if you find one that’s fly effective and cost effective.


You can’t go wrong with fly masks, although they cause horses to sweat behind the ears and rub. Therefore, check daily and groom your horse’s face. He’ll love you even more.

Fly sheets are also an option, although the don’t protect the legs or belly.


When it comes to fly control and prevention, rely on basics. Manage pasture mowing and manure spreading, spray your horse before peak feeding times, watch and treat ulcerations caused by flies under the abdomen and around ears to prevent disease and infection. And if you should concoct that perfect homemade remedy? Start shopping for that made Grand Prix horse, get that new custom carriage, and plan your next cruise. You’ll have solved the mystery of the ages.