Horseflies: Why they’re the worst and what you can do about it

Why do their bites hurt so bad? Why won’t they just die when you smack the crap out of them? Today we answer your most burning horsefly questions.

Do horseflies serve a purpose in the animal kingdom or were they just put on this earth to make me and my horses miserable?

Great question. When I think of horseflies, I think of the big, nasty, bullet-shaped monster-bugs that seem to enjoy eating my horse alive, but there actually roughly some 4,500 species belonging to the horsefly family (Tabanidae). They live all over the world, pollinating flowers and, in their spare time, driving people and livestock insane. Other reasons to hate them: They’re vectors of disease, notably Equine Infectious Anemia, and left uncontrolled 20-30 horseflies can drain almost a third of a pint of blood from their victims in as little as six hours.

This person really, really, really does not like horseflies:

Why does it hurt like crazy when they bite you?

Under a microscope their mandibles look like jagged saws, which they use to rip and slice the flesh apart. The bigger the hole, the more blood they can ingest. Only female horseflies feed on mammalian blood (the males stick to pollen and nectar), so when one attacks you can use the “b” word with confidence.

This brave soul filmed a horsefly gnawing a hole in his arm:

I’ll slap one really hard but it just gets disoriented for a minute then comes back for more. WHY WON’T IT JUST DIE?!?!?

The life span of a horse fly is only a few days, but by God, they’re determined to make those few days count–so smack hard and aim true. They are not easily deterred from attacking, and they’ll even chase their intended targets.

This cartoon, featuring the song “You Can’t Shoo a Horsefly No Matter How You Try,” is pretty accurate:

 Make it stop!

We can’t, unfortunately. Horseflies are here to stay until the weather cools off. In the meantime, try to avoid them–they prefer wooded, wet areas, like creeks and ponds, and are most active during the hottest part of the day. I used to run a farm that was a horsefly nightmare in August and September–here are a few of our most successful survival tactics:

  • Limit riding and turnout to morning and evening when possible.
  • Fly spray and fly predators are a good start, but during horsefly season a fly sheet is invaluable.
  • When riding and working around your horse, stay alert–you never know when it might buck, kick out or swing its head around to rid itself of an offending attacker.
  • Horseflies are attracted to dark colors so keep that in mind when dressing.

Or, you could just take this young rider’s approach: Attack back!

Good luck, and Go Riding!


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