In spending time around horses you have likely noticed the creamy white bot eggs ‘glued’ to the animal’s hair during late summer and early autumn.
These eggs can be found anywhere in the horse’s body but will be most plentiful on the hair of the forelegs, shoulders and around the lips. Eggs are deposited by the bot fly and nose bot fly, respectively. The scientific genus name of these flies is Gasterophilus.
Once the eggs are laid, they will hatch in 5-7 days either spontaneously or as a result of stimulation through licking and self grooming by the horse. The larvae crawl or are transferred to the tongue during this licking. They penetrate the tongue and cheek tissue and reside here for approximately one month after which they pass to the stomach.
Upon entering the stomach, they attach themselves to the stomach’s lining or they pass into the small intestine and attach there. The attachment of the larvae to the tissue produces a mild irritation which results in erosions and ulcerations at this site. The larvae remain attached and develop for 10-12 months before they are passed out of the body with the horse’s manure. Occasionally horse owners will report seeing the bot fly larvae in their horse’s manure. These larvae are cylindrical in shape and are reddish orange in color. In 1-2 months adult bot flies will emerge from the developing larvae and the cycle will repeat.
What is the significance of bot infestation to the overall health of the horse?
Adult flies are an annoyance during the summer as they approach horses to lay their eggs particularly those that lay eggs on the horse’s head. On a rare occasion an animal will experience pain upon eating when the larvae are present in the tongue and cheek tissue during their development. Most horses suffer no outwardly ill effects from having the bots attached to the stomach lining. Since the bot flies are so common, it would be assumed in temperate climates that most animals are infected with the bot larvae by summer’s end.
Deworming with a product labeled effective in treating bots after autumn frosts or during the winter months will eliminate an infection. In milder climates, additional treatments may be required. Treating provides an additional benefit of reducing that adult bot fly population.
Another treatment option that has been reported recommends vigorous sponging of the areas where bot eggs exist on the hair with a warm water solution containing an insecticide. The warmth will stimulate the eggs to hatch. The insecticide that is present serves to kill newly hatched larvae.
Using both treatment options simultaneously would be acceptable. Deworming with an approved product though is the only method that will rid a horse of bots that have already reached its mouth. Looking for Equine Supplies? For Complete Equine Listing |
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