Black flies vs Horse Flies (and a few other horse biting insects)

Black flies vs horse flies (and other horse biting insects)

Finally the warmer weather is here and it’s that wonderful time of the year when we all spend more time with our horses.  However, with all this and longer evenings comes the dreaded problem of flies, midges and many other sorts of biting insects. Unfortunately, hot weather and flies go hand-in-hand where horses are concerned. The problem being that flies attack horses in so many different ways means you've got to be prepared for them. If you know how to deal with a fly problem it makes it a lot easier to cope and this in turns means both horse and owner can appreciate the warmer weather than much better. Read on to learn more.

The Many Ways Flies Attack Horses

Biting flies are a real menace around horses and can be the cause of many an accident. Flies pierce the skin and then feed on the horse's blood – this naturally irritates the horse and some may even take off to get away from the bite!

Flies also gather around a horse's eyes, mouth, nose and other very sensitive areas of the body. These flies secrete all sorts of things which cause more irritation to horses – they are a real nuisance both for horse and rider!

Fly bites can cause an allergic reaction in horses – something to be really careful of when out riding or even when competing – the hotter a horse gets, the more they sweats which then attracts even more flies making the situation even worse!

The Worst Flies To Watch Out For

Horse Flies

Anyone who has spent any time around horses knows about the worst offender of all – the horsefly (Tabinidae). These pesky pests appear as soon as the weather heats up – around June and thereafter until the weather gets cooler again. They are busiest on warmer, sultry days and are commonly found around woodland or moist areas. These insects can really attack horses, biting their tummies, legs, necks and withers. They will also bite anyone who happens to be around horses at the time.  So watch out!

Horse fly bites are nasty and come up like lumps with a characteristic ulcer looking middle to them. The best way to avoid your horse having to cope with these symptons, is to keep them in during the day when you know there are horse flies about. Horse flies don't like dark areas and will not follow a horse into a dark stable.

Unfortunately, horse flies are resilient insects which means many home-made insect repellents don't work that well on them.  However, if you can find anything that contains pyrethroids (Permethrin or Cypermethrin), this does work pretty well.

Black Flies

Black flies (Simuliidae) in the summer can be a real problem for both horses and their riders as well as horses grazing in paddocks during the day. They are little flies – around 2mm to 5mm in size and they breed really quickly in flowing water. The flies first appear at dawn and then again at dusk, when the weather starts to warm up in the spring and early summer. The best way to avoid them annoying your horse is to make sure your horse is stabled when the sun comes up and then again at sunset.

Black flies are really annoying and feed around a horse's face – they particularly like ears which can drive horses crazy. However, they also bite horse's necks and their bellies, leaving painful lumps which bleed and then scab over – this of course attracts more flies making the situation even worse.

The best way to deal with black flies is to get hold of some sort of synthetic pyrethroid fly  spray which acts as a good deterrent. However, physical barriers like ear nets and oil based products work well too. One popular solution contains oil of citronella which puts flies off landing on horses in the first place. The other thing to use is petroleum jelly (Vaseline) which you can apply to the inside of your horse's ears to stop the flies from biting them – making sure you do this very gently and remember some horses do not like their ears being touched!


Midges (Culicoides) are tiny flying nuisances that are only 1mm-3mm long. They hover in swarms first thing in the morning and then again as the sun sets at dusk. They lay their eggs in still water which means you have to avoid creating any stagnant areas in a yard and to avoid having horses out in paddocks that are too near to any still water – the perfect breeding ground for midges to thrive in!

There are a few different species of midges and they feed on various parts of a horse's body. More commonly, horses are seen to rub away both their manes and the tops of their tails which can exacerbate another condition called sweet itch – this is when horses are allergic to insect bites and can rub themselves raw which then gets infected and extremely painful.

An effective way of keeping midges at bay is to use insect repellents that are ‘permethrin’ based and to apply them late in the afternoon.  Again, any oil based product is useful at preventing the midges from biting and causing all the damage.  By far the best way to prevent your horse from being attacked by midges, is to bring them in just before dusk. Another good method of keeping midges at bay is to use a fly sheet. These can be very useful at keeping the midges away from your horse when they attack the most.

Stable Flies

Stable flies are really annoying. They lay their eggs in anything moist found around a yard which is why it's so important to make stable hygiene such a high priority. These flies feed around horse's legs and bellies where they bite causing a lot of irritation and painful wheals which have scabs in the centre.

The best way to avoid having too many stable flies around a yard is to keep everything as clean as possible. However, hanging fly traps helps and using a fly repellent containing ‘permethrin’ is also an effective deterrent. You need to spray your horse's legs – making sure you do so carefully and without spooking your horse. If they object to the spray, then spray the repellent on a sponge and wipe the legs over with the repellent and do so several times a day.

In summary...

We all love the summer, it's a wonderful time of year for both riders and horses. However, the eternal fly problem can turn a great day into a real disaster if you're not ready and able to cope with the situation. Being prepared with all the right repellents goes a long way when it comes to enjoying what is the best time of the equine year!

Look out for our other articles to help you cope with the flies over the Summer months…

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Kim Horton

Co-Founder of EQUUS and a keen equestrian, when Kim's not at her desk she's with her horse, Waldo.


  • Lesley Gibbins posted on April 12 2018 at 07:04 PM

    I found this topic very interesting

  • Lesley Gibbins posted on April 12 2018 at 07:04 PM

    I found this topic very interesting

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