Horse Flies and Other Pests

Oppressive heat and biting flies require that the horses stay in the barn at Ballentine’s Horse Heaven during the hot summer months. Horse flies pose a constant irritation and potential health problems. Outside in the pasture the flies are merciless, buzzing around the animals, landing and biting. The horses soon become annoyed by the constant attack and stand just outside the barn door waiting to get away from the ornery insects.

Johnn maintains an area in each stall where fly parasites breed and feed on the larva of pest flies which lay eggs in manure. Fly parasites are gnat-sized, nocturnal, burrowing insects which reproduce by laying their eggs in the pupa of other flies. The fly parasites kill pest flies before they hatch thus reducing their population. The system works pretty well and has eliminated most of the flies in the barn. The problem comes when we saddle up and leave the barn for a ride through the countryside.

Fly spray doesn’t do much to dissuade deer flies and horse flies seeking blood to lay their eggs. They are short-horned flies which use their maxillae and mandibles in a scissor like motion to slice open their victim, drink the blood then fly off to lay their eggs. Horse flies also prey on humans and for those of us who have been bitten realize the insect’s bite is no joking matter. The open wound left by the insect bite provides an ideal place for infection. Additionally, horse flies are known to transmit Anthrax to horses and other livestock.

The biting flies have extremely good vision and locate their victims through sight rather than smell. Large dark objects attract them and as we move down the road, especially in the open near fields of tall grass, the flies make a beeline for the horse; circling, briefly landing then circling again for a another attack. The horse fly’s loud buzzing coupled with their agile flight maneuvers cause both rider and horse to become nervous. The flies hover just out of striking distance then quickly land on the rump, belly or neck of the horse. The insects can follow an animal for miles.

Yesterday, I met Anne Shaffer for an evening ride and brought with me an aquarium fish net which I purchased at Wal-Mart. I saddled up and gripped tightly to the net as we headed up the road. Earlier in the day, I read about short-horned flies in Stephen Marshall’s book about insects. He explained that entomologists sometimes use their collecting nets to capture and kill deer flies which attack from above and hover over a hiker’s head. This gave me the idea that a small net might help me capture and kill the huge Black Horse Flies which hover around the horse’s tail and manes often just out of reach.

“There’s one,” said Anne watching to see if I would catch it.

I saw the insect resting for a moment on Pepper’s rump near her tail. I quickly placed the net over the insect but had difficulty squishing the bug. I let the rein rest on Pepper’s neck and reached around with my other hand to grab the insect when to my surprise the horse fly wiggled out from under the net and flew off.

“It’s not as easy as I thought,” I said.

Before I could capture another horse fly with the net, Pepper swished the insect away with her tail. As we proceeded up the road, I finally managed to get a fly in my net and squished the bug. Anne just squished the pests with her hand and between the two of us we killed over ten horse flies. Once we reached the woods the sun began to set and the flies were less active. It wasn’t long before we returned to the barn and put the horses out to pasture for the night, glad to finally be rid of the flies.

Simon and Schuster’s Guide to Insects, Dr. Ross H. Arnett, Jr., Dr. Richard L. Jacques, Jr., published Simon & Schuster, Inc. 1981; The Audubon Society Field Guide to North American Insects & Spiders, Lorus & Margery Milne, Alfred A Knopf, Inc, 1980; Insects Their Natural History & Diversity, Stephen A. Marshall, pg 395-396, Firefly Books, Ltd, 2006;

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2 Responses to Horse Flies and Other Pests

  1. Sandy Mack says:

    I remember those BIG Buffalo flies the most from my years of having my horses
    at Ballentines. Those things land most often on the rump, and bite a sizeable
    hole causing horses to panic and bolt. You can see them coming-they really stand out-and they don’t travel in groups. We could ride for a while and not have any of them,
    and then-BANG-one would be on a horse’s rump. Bucking bronco time….We don’t have them in MN, thank heavens….

    • Pat Miran says:

      You’re right! – They are hard to forget. This year they were especially horrible and fly spray doesn’t work on them. You are so lucky there aren’t any in MN. Thanks for the great comment.

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