BOT-FLIES
- a common summer annoyance, we find out what they actually do
and how to deal with them.
Article by SHNZ
-
Information
sourced from "Parasites and Horses" by NZ Equine Research Foundation.
Bot-flies resemble a large honey bee - they are about 2 to 3 inches long, dark coloured, slightly hairy, and have one set of wings. They are a very common horse parasite and are active during the warmer summer months - their arrival usually easily noted by your horse's sudden tail swishing, stamping, tossing their head and short bursts around the paddock as they try to avoid these large flies buzzing around their legs.
Bot-flies do not actually bite or sting your horse, but instead try to lay their eggs on the hairs of your horse - quite cleverly they usually aim for the legs and lower body hairs where your horse often scratches or rubs their head. From here they can be licked up and into your horses mouth where they journey through into the stomach and are later passed out with the dung as a well grown larva to form into an adult fly and begin their lifecycle all over again.
| Bots spend several weeks inside your horses mouth (which can cause some soreness and irritation) before travelling into the stomach, where they remain for around 10 months feeding and growing. When they are passed out, they leave a small pit where they have been attached to the stomach wall. While it is not known for certain how serious the effects of larger larvae living inside the stomach are, it is of course certainly not doing any good and if large numbers are involved it can lead to some discomfort or unthriftiness, and, more rarely, stomach abcesses or ulcers. |
 Bot eggs on a horses fetlock |
If you are finding the tell-tale small yellow eggs on your horses coat you can:
- use a bot knife or clippers to remove the eggs to at least help reduce the number being taken in by your horse
- regularly remove the manure from your horse paddocks (adult flies emerge from the dung after about 2 to 6 weeks so bear in mind that removing the manure is only moving the source of new adults bots about to hatch to a different location, yet still useful)
- and make sure you use a worming treatment that is effective against bots (check the packet as not all wormers treat for bots). Ideal timing is to use the specific bot-fly wormer once the adult flies have dissapeared when the weather starts getting cooler (around May) as this will treat the larvae currently in the stomach and no further eggs are likely to be laid - until next summer!
If you notice your
horse being bothered by a bot-fly, you will actually find they are quite
dozy and easy to catch or swat to the ground before firmly placing your
foot overtop - they do not bite or sting and are harmless to humans, and
your horse will be pleased no end!