Bot Flies

We had Bot flies when I was a kid, and actually hadn't seen one in years and years until I noticed the eggs on Skip's legs when he was at Cara's place. I asked her to remove them before we brought him to the boarding barn; we didn't need an outbreak there!

Bot flies look a bit like skinny honey bees. One or several flies will hover around the horse's legs and body and dive in to attach their eggs to the hair strands. Bot flies don't sting like a bee, or bite like a horse fly. They are basically little flying egg laying machines and they dart at the horse repeatedly, attaching each egg to a single hair. If you see one, kill it!

Bot flies don't normally lay eggs around the head and ears, so a fly bonnet won't be much help. One species of bot lays eggs around the horse's nose. It's hard to protect your horse from these. Bots also lay eggs on the horse's mane, legs, shoulders and flanks, so insect repellents and fly sheets may help.

Don't worry that you or the horse will get bit or stung if you swat this fly. More likely you'll be disgusted by a smear of yellowish eggs on your hand or horse. If this happens, wash the eggs off your hands or horse, but don't let them fall where the horse may accidentally ingest them.

There are lots of ideas out there about the best way to remove bot eggs. If there's just a few eggs, you can pick them off with your fingernails. Wiping mineral oil or petroleum jelly over the eggs is supposed to suffocate them, killing them before they hatch. This leaves a greasy mess, but is harmless to the horse—and possibly the bot eggs too. Kerosene and diesel are not good for your horse, so don't use these. Sponging the eggs with warm water is supposed to pull the eggs off as if the horse is licking it's coat, but I've never seen this to be effective. Pulling a block of pumice stone over the areas where eggs have been laid helps pull them off the hair. In 4-H in the mid-60s we used a straightened coat hanger with a cotton swab dunked in alcohol, lit, and then burned them off. Now I can't believe my horse stood for that, and that we actually did that.

The easiest way to pull the eggs off is with a knife blade, special bot knife or scissor blade. I just open my scissors wide and use one blade to scrape the eggs off. Be careful to keep the blade almost flat against the horse's skin. You don't want to accidentally cut your horse or yourself. Pull the blade down in the direction of the hair growth and the eggs come off easily. Sweep up any dropped eggs and put them in the garbage where horse's won't eat them. Or burn them.

De-worming medication that contains Ivermectin or Moxidectin will kill internal bot larvae. These medications also kill other internal parasites, so can be used in place of your regular product. Give your horse this medication after the first hard frost that kills the insects in the autumn. Administer it again in early spring to kill any remaining bot larvae in your horse's system before they are expelled with the manure and develop into mature flies that will begin the bot's life cycle again.

He's been working on the Blacks, and part of this is getting rid of the eggs on their legs.