Alright, so I’m always willing to try a new remedy for fly control…

This one I heard about from a reader when I wrote about being swarmed by mosquitoes.

She told me that she hadn’t tried it, but had heard that if you put 4 shiny copper pennies (shiner the better, she said) in a baggie filled with water, and then hung those on fences (or on your patio if you were having a party…) – the flies would not come around the horses.


I wondered about the science behind this and found a snippet on the Internet:

It’s all in the reflection: When you have millions of molecules present, like in that clear, plastic bag, it creates its own prism effect. Flies have “compound eyes,” i.e. they see multiple images (whereas we see only one), but compound eyes cannot focus, so flies also see blurry images.  To our winged little predator, that bag of water and its copper pennies appear, as one Google commenter described, like “a zillion disco balls,” reflecting lights, colors, and movement in a dizzying array.

OK, sounded plausible.


I thought that this would be an easy enough experiment for me to test.  I had all the ingredients already…

Baggies:  check

Water:  check

Pennies:  sort-of, I had some Valentine’s Day Love Tokens (large and silver and shiny) and a few pennies that were kind-of dull…

Something to tie with:  check

Ingredients... I later added shiny pennies



I filled my baggies with water, dropped a love token inside and zipped them back up.


I wasn’t quite happy with the refraction.  The Love Token wasn’t really catching the light in any way.

So, I went into the house and raided all of my coin jars to find 16 shiny pennies.  (I figured I would do 4 bags so I needed 16 pennies.)

OK, I had the pennies and resumed filling baggies with water.  I added 4 copper pennies to each baggie and kept the shiny Love Token just in case they were working by only flies would notice.

I then used some baling twine to hang the baggies on the fences.

I hung them on Finn and BG's fenceline

I chose the most fly intense spots.

1)  The fenceline where Finn and BG eat.

2)  The fenceline where Bodhi eats.

I huge two baggies about 8 feet apart on either side of where Finn and BG eat.  I tried to find the sunniest spots so the light would catch the coins inside of the water.

I then went to Bodhi’s pasture and did the same.  Both of his baggies were in direct sunlight but facing in a different direction.

The baggies on Bodhi's fenceline. (Note the wild turkeys in Bodhi's pasture.)



I wondered to myself if the sun – at different times of the day – would work differently with this experiment.

Clearly, if I had a NS fence, the sunlight would hit the baggies differently than an EW fenceline.

*Yes, there were videos online demonstrating this (so silly, most of them…) but none that I found discussed the direction of the fence or sunlight as an issue…

Anyway, Finn’s fenceline goes EW and Bodhi’s goes NS.

As you can see, there are no flies on Finn's muzzle (which is good but they are on his shoulder which is very nearby...



I took these photos around 5:30pm.

As you can see here, Finn’s muzzle is free of flies!  But, he has flies on his shoulder which is not too far away from his muzzle and the baggie…

As you can see here, Bodhi has a ton of flies all over this muzzle.

Bodhi has flies all over his muzzle. Clearly the bags are not working on his fenceline.




The next day, all the bags had been bitten and destroyed.  Luckily, the coins were all on the ground and no one had eaten the plastic or the coins.

For me, I’m thinking I would have to have put the baggies up in a high tree – which would be too far away to do any good.

Or, I’d have to hang them every 2 feet like a string of lights at a Mardi Gras party…


I’m thinking I still like my THE BALM (from Equi-Spa) as my go-to fly repellant around their muzzles…

To me, this coin in the baggie fly repellant system would be way too much trouble for the little bit of relief.

I don’t know – maybe I did it wrong or maybe the light wasn’t coming from the correct direction for Bodhi’s pasture.  Dunno.

Maybe the best use would be at a human party where the guests wouldn’t bite the baggies!

HORSE AND MAN is a blog in growth… if you like this, please pass it around!



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HORSE AND MAN is a blog in growth... if you like this, please pass it around!

5 comments have been posted...

  1. Janet Ortega

    This was a funny experiment, especially at the end with the bags bitten LOL. I use Smartpak Bugoff. After a month of preload, the flies stay off the horses altogether. It’s got garlic, DE and a few other herbs in it and the horses love the taste although the garlic is pretty strong when they’re munching it lol. I’m also using IGR (insect growth regulator) pellets this year to see if I can reduce or eliminate the fly population. So far we’ve had more rain than last year which means more flies and the fly population is way down. Another month or less it should be significantly reduced.

  2. Cresca

    I have heard about this but the bags are hung in the entrance to the stall doors. My horses hang in their stalls with fans all day when it’s buggy and hot. I have not tried it yet but if I did I would consider old CD’s instead of coins. Seems they are very shiny and would give considerable refraction.

  3. Arliss

    Interesting, and admirably scientific! But you had me at “love tokens.” Hilarious! And also: “The next day, the bags had all been bitten and destroyed.”

  4. sue tyrkus

    Thanks for trying this out, Dawn…I thought I’d give it a try this summer, but was skeptical, too, as to how many baggies, pennies, direction and placement, etc. It sounded too good to be true. Will attempt to get The Balm, here in Canada. :)

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