Horse Bot Fly Infections

Horse Bot Fly Infestation

Welcome to summer, season of the horse bot fly. These flies lay eggs on your horse's legs. The eggs make your horse's legs itch. Your horse licks at them and the eggs end up in your horse's stomach lining. Cozy in your horse's interior,

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these parasites spend the winter turning into larvae, robbing your horse of nutrients and possibly causing stomach ulcers. They spend the winter waiting for the bright Spring day when they pass out of your horse in her stool, hatch and turn into more bot flies.

How to break this cycle? Remove the horse bot fly eggs that appear on your horses legs before your horse swallows them. The eggs are small (1/16" long) and yellow. They look like weed seeds but don't budge when you try to brush them off with your fingertips.

What you'll need:
Bot Block, Bot Knife or Safety Razor
Worming Medicine
Fly Leg Wraps (available from StateLineTack.com)
Fly Repellent

Step 1: Keep fly repellent on the horse throughout the summer. In July and August, be sure to apply the repellent to the legs. Don't neglect the fetlocks and pasterns. As an alternative, consider fly leg wraps. Fly leg wraps are helpful if you can't reapply fly sprays as often as needed.

Step 2: Remove bot eggs from a horse's legs any time you see them — at least once a day.

• Use a bot block or grooming stone to remove bots. A bot block is a rough, porous stone that rubs the eggs off the horse's leg.

• You can also remove bots with a bot knife. The knife has serrated edges and is shaped to get at those hard-to-reach places on your horse's legs. Use a downward motion.

• Finally, you can use an old disposable safety razor. Again, use a downward motion.

Step 3: Whatever device you use, do not scrape eggs off in an area where your horse grazes. The eggs will drop into the grass and you horse will eat them while grazing.

Step 4: Worm your horse one month after the last killing frost.

Step 5: Worm your horse again in the spring to catch any late-migrating bot larvae.

Step 6: Select a wormer that contains ivermectin or moxidectin to kill the larvae that reach the stomach. Many wormers that kill strongyles do not kill bots. All horses in the herd should be treated for bots, not just those with visible bot eggs. Ivermectin and moxidectin are also effective against a wide range of internal parasites, so they are excellent deworming products to use in winter.

There is some evidence that applying Tea Tree oil to your horse's legs creates a barrier that prevents the eggs from sticking.

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