Bot Flies and Bot Fly Egg Removal

Equine Parasite Management

Ivermectin to the Rescue!

Bot Flies and Bot Fly Egg Removal
Equine Parasite Management and Ivermectin to the Rescue!

By Karen Griffith - Equine Nutritional and Farm Management Consultant

© 2007, Karen Griffith. All rights reserved.
To reprint this article call (740) 992-5782 or e-mail griffith@frognet.net

As open agricultural space decreases, your own worming and management regime comes into attack. As equine owning neighbors are encroaching closer to your property, keep in mind that your own worming program may become inadequate. Bot flies are a threat that needs to be addressed. Even if you have used a rotational worming program that includes Ivermectin, your neighbors may not. With the advantage of flight, the adult bot fly can migrate to your farm with ease.

Many people do not know that one female adult bot fly can lay from 300 to 1000 eggs in her short life span. (If you see something that looks like a honey bee hovering around your horses legs or chin, feel free to snatch this critter out of the air, crush it and throw it into your trash can. Don't throw the crushed bot fly on the ground where your horse may pick it up in any feeding, i.e. pasture, hay, or grain. If the horse eats the bot fly, he could ingest the mature, unlaid eggs of the dead bot fly.)

The adult bot fly has no other goal in life than to lay eggs. It may look like a honey bee, but it has no moving mouth parts to bite or eat and no stinger to sting. It's soul life function is to lay it's eggs on the hair of your horse in order to reproduce itself.

Those little tan specks you see attached to the hairs on your horses legs, flanks, shoulders, mane, and chin are the eggs of the bot fly and need to be removed. Some folks recommend sponging the areas where the bot fly eggs are attached with warm water (115°-120° F) to stimulate some eggs to hatch, then wash away the small larvae. I've never found this to be effective.

Some say that Vaseline applied to the areas covered by the eggs will suffocate the eggs and they will die. That sounds fine in theory, but who wants a Vaseline covered horse with all of the dirt and debris that would inevitably stick to the grease! (Not a pretty picture...)

There are commercial "bot scrapers" available. They resemble a rough, porous stone. When rubbed with the lay of the hair, the eggs are removed.

I find the best and most simple removal method to be an old fashioned razor used to scrape these invaders off your horse. Make sure when you do this, you have the horse in an area where he or his buddies will never be eating (i.e. a gravel driveway away from your pasture). Or, stand your horse on a tarp, scrape the eggs, and then take the tarp away to be cleaned where no livestock will be eating in the future. (If your horse or pony has never walked across a tarp before, you might want to head over to that driveway that I mentioned! A "tarp walking" training session should be in order for your horse as a general rule.)

If you don't remove these eggs, the horse will lick his legs and flanks or scratch and lick his buddies mane or shoulder and your horse will have taken in more invaders. Your horse's saliva provides the enzymes, moisture, and temperature that allows the egg to release it's tiny larvae from the hair to which it was attached and be ingested by your horse. These larvae then spend about a month burrowed in the mouth of the horse where they evolve. They are then swallowed during a larval growth stage and attach to your horses stomach lining.

Picture, again, the number of tiny specs you have seen attached to all of the hairs on your horse. Now picture that number of bot larvae with very sharp mouth parts, lined up side by side, top to bottom, attached and almost covering the entire lining of your horse's stomach. Imagine the lining of your horse's stomach covered with these hungry, developing invaders at the onset of winter. How can you expect your beautiful, shiny partner to have enough available stomach lining to digest that perfect diet and expensive food with which you are providing him? How can he accomplish the tasks to which you aim? Imagine the lack of open stomach lining available to your loyal partner. These hungry little critters (unless disrupted by a good dewormer - antelthelmic) will stay attached to the stomach lining of your dependable partner until spring. (They can stay attached to the stomach for 8-10 months, causing the stomach lining to become ulcerated and inflamed. Actual stomach ruptures from heavy bot infestations have occurred.)

The bot larvae will then release their hold on the stomach lining, pass through the small and large intestines, and are deposited with the manure into your pasture. The bot is now in the pupae form and burrows down through the manure and into the soil. They will then mature and emerge as adult bot flies.

Keep in mind how many of these deposited eggs there were on the hairs of your horse's legs, shoulders, mane, flank and chin, each forming another adult bot fly who will each lay another 300 to 1000 eggs.

If you worm your horse with an effective wormer, (i.e. Ivermectin products work great!) you will loosen these critters from the stomach lining prior to their ability to mature. They will pass through your horse harmlessly, and end this dangerous cycle.

If you are an old timer in the horse business, your will remember how toxic the old drugs were that eliminated bots. Some were worse on the horse than the infestation of bots themselves. We are a lucky bunch today. With the advent of Ivermectin, bot removal is a relatively easy task in our equine friends. Make sure if you haven't wormed your horse for bots up to this point, that you do so 30 days after the first killing frost in your part of the country. No further eggs will be laid on your horse, as the adult flies will have frozen to death. Immediately, after the first killing frost, make sure that you remove the bot fly eggs currently present on the hairs of your horse. This will allow the bots that have burrowed into your horse's mouth to have time to migrate to your horse's stomach where the Ivermectin will effectively eliminate these parasites. (Keep in mind that Ivermectin will kill some of these burrowed larvae in the mouth.) This will break the reproductive cycle of this taxing parasite. Once you have removed all of the eggs which will prevent your horse's intake of new parasites, and have used a boticide, i.e. Ivermectin, 30 days after the first killing frost, your own personal farm's problems have been solved for the year.

As I mentioned in the beginning of this article, the arrival of new and uneducated horse owners to your area is almost inevitable. Keep in mind the value of welcoming your new equine neighbors to your horse community and discussing the benefits of neighborhood wide control of the pests who threaten your mutual equine friends. Educate yourself on effective mosquito and fly control as well. You and your neighbors must work together for effective parasite and pest control whether they be spread through air, water or physically being brought to your farm.

P.S. For all of you scientific lingo folks, there are 3 species of the bot fly that target your horse.*The main difference in the species is where they choose to lay their eggs.

Three Species of Bot Fly:

1. Common horse bot - Gastrophilus intestinalis *Legs, sides, flanks
2. Throat bot - Gastrophilus nasalis *Under the head, neck, mane
3. Nose bot - Gastrophilus haemorrhoidalis *Muzzle
   
   

There, that little tidbit is out of the way.......

Bot Fly and Bot Fly Larvae Photo credits: J. F. Butler, Department of Entomology and Nematology, Cooperative Extension Service
Institute of Food and Agricultural Sciences, University of Florida, Gainesville

Karen Griffith - Equine Nutritional and Farm Management Consultant

Ohio State University - 1974

Karen has been doing equine and livestock nutritional and farm management consulting work all across the United States since the early 80's. She is a 1974 graduate of The Ohio State University, College of Agriculture, with a Bachelor of Science degree in Animal Science. She returned to obtain a second degree in Agricultural Education, and her Master's work is in Large Animal Nutrition and physiology.

Karen also has served as head research associate for the O.S.U. Surgical Research Department.

Professional equine articles by Karen Griffith have appeared in many top equine publications.

Karen served as Equine Science director for the Delaware City-County Joint Vocational School, Delaware, Ohio. She developed the curriculum for the program which included anatomy, nutrition, parasite control, reproductive physiology, stable and farm management, stallion and mare management, sales, farm promotion and advertising, western and English riding, and the breaking and training of young horses. She coached their horse judging team to a State Championship and Top National Status. During this busy time, Karen also served as coach and riding instructor for Ohio Wesleyan University in Delaware, Ohio.

Karen was a livestock nutritionist and field manager for the Furst-McNess Co., of Freeport, Illinois. Here she was responsible for the success and nutritional programs of over 100 dairy, beef, hog, and horse operations including the entire West Virginia State Farm Commission.

Karen was breeding top quality Paint horses before the Paint Horse Association was ever founded. Her first great foundation Paint mare was born in 1959. (The APHA was formed in 1963.) In 1973 when Atahi arrived on the scene, the bar was raised as to the quality of horses with "color". Her horses have been a major competitive factor in the industry. Karen's breeding program has produced some of the most successful horses and ponies to be found in North America to this date.
Want to see your farm turn a profit? Make your own breeding or sales operation profitable. To find out how to speak with Karen Griffith personally, click on the underlined text: Paint horses, paint stallions, equine nutrition information and farm management consulting.

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