run, janelle, run!

15 Interesting facts about horseflies

Like most other runners, I LOVE trail running. There’s just something incredibly soothing to it all once I feel the tread of dirt and gravel beneath my feet. And on most days, I’m left alone to enjoy the peace and quiet- until the warmer months start to hit. That’s when I really start picking up the pace of my trail runs…partly because of the euphoria of my runner’s high, but mostly because I’m being chased by vampire-like, blood-sucking demon flies.

When we run, we put up with a lot of annoying things, but nothing is more annoying (and painful) than horseflies. And chances are pretty decent that if you’ve been running in wooded areas lately, you’ve been chased and assaulted by these archfiends. All of the pain and swelling aside, the following are some interesting and perhaps useful tips that I’ve managed to compile about these painfully pesky pests.

[image by Thomas Shahan on flickr]

I bet you didn’t know that….

  1. Horseflies are among the world’s largest flies. They belong to the tabanidae family.
  2. Horseflies are located around the world, with the exception of extreme northern and southern latitudes.
  3. There are roughly 3,000 species of horseflies in the world, with 350 different species within North America alone.
  4. Horseflies can be as large as 1 ¼ inches in length.
  5. They are equipped with scissor-like mandibles that tear and cut. When viewed under a microscope, the mouth parts of a female horse-fly look like jagged saw blades.
  6. The bite is painful because the females actually cut a hole into the skin in order to soak up the blood that comes out.
  7. Horseflies are generally found near areas that contain water and/or livestock, both of which are food sources.
  8. Male horseflies feed on pollen and nectar only as they do not have the mouth parts required for blood feeding.
  9. If you are bitten by a horse-fly, it’s a female. Female horseflies feed on the blood of mammals in order to assist in egg development.
  10. Horse-fly eggs are laid on plants in or near water. Once they hatch, they will spend between 1-2 years growing in moist soil or water.
  11. Adult horseflies only live for a few days.
  12. Left uncontrolled, 20-30 horseflies can drain almost a third of a pint of blood from their victims in as little as 6 hours.
  13. Horseflies go by many names. In Canada, they are referred to as ‘bull dog flies’ while in Australia, they are referred to as ‘March flies’.
  14. In the United States, horseflies do not usually appear in full force until the summer months.
  15. You can avoid horseflies by running during the cooler part of the day as they are not as active. They are also less active on windy days.

[image by Radu P on flickr]

I never run faster than when I’m being chased by horseflies…kinda’ makes me think of the PRs I might have had in college if someone had released a swarm of those blood-sucking fiends at the start line…  -jv


6 thoughts on “15 Interesting facts about horseflies

  1. Chilly B

    That is truely disgusting! I never ever knew that horseflys suck blood or that they would even bite you. I just knew they were big as HELL and hung around..well Horses and CRAP!!! You just scared the living daylights outta me about horseflys!!! EWWHHH!!!!!

  2. janelle Post author

    lol…Yeah- after being chased for half of my run today, I came back and decided to do a little reading…Those flies are no joke!

  3. Action Jackson

    Very Interesting article Janelle! Can’t say as I have ever been chased by them, but then again i have never been running at umstead.

  4. Paul Whitcomb

    I just moved to the mountains of western Maine and I’m being buzzed and chased by a type of horsefly that they call “mooseflies” around here.
    I haven’t been bitten, yet, but am going to start wearing my long, base layer pants, as well as my normal long-sleeve tech shirt that I’d be wearing up here anyways, because of the cool temps. I hear they can bite through fabric.., let’s hope that’s not true.
    I’ve also been reading about the colors they are attracted to, so waht I plan on getting is blue “party hats” that I will wear over my Headsweats Coolmax Shorty. The blue, conical party will be covered in “tanglefoot”, an adhesive.
    (I can’t believe that these things are too smart for us to out-think).
    Also, if deerflies are your only problem, you can buy Tred-Not deerfly patches for the back of your cap. Running with a Coolmax cap is surprisingly pleasant.

  5. Marina

    I’m from Cape Town, South Africa. I moved to the eastern coast in the US a few years ago. Here in Virginia, there are very many horseflies. I had never seen one before. These 1inch plus size buggers do chew through clothes. My husband went paddle boarding on the Poquoson river a couple weeks ago and he had one chasing him and it bit through his BLACK rash guard ( a colour they love apparently) in two places and the welts were huge!
    And they do not give up, he jumped in the water to get away but it waited for him and followed him for a while! Freaked him out!

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