05/01/2026
Are the pesky bot flies bothering your horse? Hereβs what you need to knowβ£
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Adult bot flies are brown, hairy, bee-like insects. Their sole purpose as adults is to mate and lay eggs - they do not bite or feed.
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Female bot flies hover around the horse and rapidly glue eggs to individual hairs, most commonly on the legs. Although the fly isnβt biting, this fast, buzzing behaviour is why horses often react strongly by stamping, kicking, or running. Once eggs have been laid, the adult bot fly dies soon after (often within days).
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Warmth, moisture, or licking causes the eggs to hatch, allowing larvae to enter the horseβs mouth. After developing in the mouth for several weeks, the larvae migrate to the stomach, where they attach and remain over winter. After approximately 10 months, they detach, pass out in the manure, burrow into the soil, and eventually emerge as adult flies completing the life cycle.
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As the larvae migrate, they can irritate the mouth and surrounding tissues. While many horses show no obvious outward signs, even with heavy infestations, the presence of larvae in the stomach can contribute to gastric irritation and ulceration. Higher parasite burdens may increase the risk of discomfort and, in severe cases, colic.
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βοΈ Remove bot eggs regularly using a bot knife or similar tool.
βοΈ Remove eggs in an area where your horse cannot graze and ingest them.
βοΈ Horses are best wormed for bot flies in late Autumn to early Winter, when larvae are established in the stomach and treatment is most effective.
βοΈ Always include bot treatment as part of a strategic, vet-guided parasite program.
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Even if you worm for bot flies, removing eggs is still important. Worming treats larvae inside the horse, while egg removal prevents new ones entering.
π‘ππ‘π§ππ₯ππ¦π§ππ‘π ππππ§ - Adult bot flies donβt bite or feed because they have no functional mouthparts, they live briefly on stored energy purely to reproduce!
