The Horsefly Trap

The Horsefly Trap

By Dan Owsley

Horsefly TrapI built a horsefly trap recently and documented the results.  Day 1 killed 146 horseflies. Day 2 killed 375! We either have a terrible horsefly problem or it’s a great trap.  How it works is simple. Horseflies are visual hunters. From a distance the black bag looks like something to bite, they do a fly over and are deflected into soapy water and drown within a few seconds.  The 7 day total was 1,697 Horseflies killed! They are big (1″ long) and easy to count. They need to be cleaned out every day so they won’t rot.

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The leg configuration can be whatever you like. I just made mine so it would be easy to move and change the bag. The plexiglass needs to be kept clean and free of scratches. We have high humidity in our area so I squeegy the dew off the plexiglass every morning.  Notice the image depicting the saw cuts in the 2×4 that holds the plexiglass. They are at 45 degree angles about an inch deep. The plexiglass fits tight enough that I didn’t need to fasten it in any way. The bag I use is a 55 gallon trash bag from Sam’s Club. It holds about a 5 gallon bucket of water with a big squirt of liquid dish soap.

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Make sure and set this in an open area where the horse flies can see it from a distance. You may need to move it around until you find the “sweet spot”. Clean it out with a cat litter scoop or large slotted spoon. Be sure to paint the top board a dark color so the light color of the wood won’t reflect in the plexiglass and make it visible to the flies.

UPDATE: Dan Fowler from Tennessee sent me a video of his set-up catching Horseflies. He caught over 6,300 in one week!

Dan Owsley, who invented the Horsefly Trap, would love to hear from anyone who follows his plans and builds the trap, and would enjoy seeing photos.  Contact Dan by email:


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