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


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