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Bags of water to repell flies

  1. Jun 7, 2010 #1
  2. jcsd
  3. Jun 7, 2010 #2
    I have seen this in action and could not argue with seemingly good results. The flies tended to steer clear of the bags. The bags I have seen always had a penny in them though.
    A old women that worked at my school said that it tricks the flies into thinking it is a hornet nest.

    Not the most scientific input.
  4. Jun 7, 2010 #3
    I have little confidence in this, but I can imagine it working for houseflies. That said, what do you want to keep away most? Hornets, and mosquitoes, and neither of those are going to give a fig about a sack of water.

    That said, I'd need to see a really REALLY good series of studies to buy this one, but if it works for you, I can't see the harm. Everyone has bags, and pretty much anyone worried about houseflies has water to spare, so... what the hell? Light up the citronella, spritz the DDT, light up the CO2 trap, and fill dem bags! Those flying bastards won't know what to do. :wink:
  5. Jun 8, 2010 #4
    The only problem I had with the experiment in the reference is the flies were confined to a small area. The purpose of the bags is to keep the flies away from where you are sitting/eating, not kill or drive them away completely. The flies may have shown more activity due the fact they were agitated by the bag. This may have translated to them maintaining a wider distance from the bag than they would if the bag was not there. Just saying...
    The experiment didn't really confirm or refute anything.
  6. Jun 8, 2010 #5
    Thats not a bad idea, I'll do the same. Lets have a real fact finding mission here. We'll get to the bottom of this. FOR PHYSICS FORUMS AND THE WORLD AS A WHOLE WE'LL ANSWER THIS ONCE AND FOR ALL!!!!!
  7. Jun 8, 2010 #6
    Even if they are avoiding the bag, how big of an area will they avoid? Will they just not land on the bag? If so, that doesn't help much.
  8. Jun 8, 2010 #7
    Something we can find out...
    Although, if it only prevented flies landing on the bag, why would the idea persist this long?
  9. Jun 8, 2010 #8
    It may not even do that, yet keep persisting.
  10. Jun 8, 2010 #9
    Here's an easy way to test it. Take some dog crap and place it in an area and count how many flies come to it over the course of 10 minutes or so. Then move the sample, and put the bags up and replace it and see if the number drops.
  11. Jul 1, 2010 #10
    I used to keep bees.

    One thing that's sure gonna get you stung is static electricity. That's how bee venom is collected - with a rubber sheet stretched over a jar.

    It's possible that static charged bags of water (dry outside of course) might upset flies.

    Maybe balloons would work better?
  12. Jul 1, 2010 #11
    I love to BBQ in my backyard and am getting tired of all of the flies. I have sprays and fly strips but they don't work that well. I would be willing to give this water bag method a try but no one has provided details:
    What kind of bag? Clear Ziploc style? How full of water? Do I close the bag or leave it open? How do I hang a bag of water? Nails, string? If it's too heavy with water, it might just rip and fall down. Hang it in direct sunlight or not? Should I add anything to the water? Salt? Bleach?
    If light refraction is the key, do any other clear liquids refract light more than water?

    If people make suggestions I would be willing to try this at home while I BBQ. I just don't want to be known as the crazy water-bag man with 20-30 bags of water hanging from his patio!:uhh:
  13. Jul 1, 2010 #12


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    They sell the disposable bags and it contains something that attracts he flies. Amazing how well they work! I used to get mine at the local feed shop, they're used in barns. The bags of water don't repel flies, it attracts them and they fall into the bag and drown.

    I don't think closed bags of water will repel flies.
  14. Jul 1, 2010 #13
    Oh i see. I was thinking that if it was the refraction of the light disturbing the flies then it wouldn't matter if the bags were open or closed.

    Where can I buy some of these commercially manufactured bags? I haven't seen anything in Walmart. There are no feed shops around here.
  15. Jul 1, 2010 #14
    I had another question regarding the flies themselves. On my patio, flies(perhaps 5 to 10 of them at a time) just fly in circles, like planes in a holding pattern over an airport. I've sat there for an hour before, watching them. They don't land on anything or fly away. They just go in endless circles.
    What is their deal?
    I've considered the notion that they may be mating, but I can't recall ever seeing two of them fly together. I have seen them occasionally bump into each other. Could it be a "bump and run" mating thing?
  16. Jul 1, 2010 #15


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    You can get them from amazon.com

    Last edited by a moderator: May 4, 2017
  17. Aug 16, 2010 #16
    If thrown at the flies with sufficient velocity and repetition, I can certainly see how they'd keep the flies away.

    I'd imagine you'd keep Glad in a pretty penny, though.

    Speaking of pennies, though, the lady who thought they may confuse it with a hornets' next may actually have something.
  18. Aug 16, 2010 #17


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    Time flies. If your stopwatch is reliable enough.
  19. Sep 6, 2010 #18
    I saw at a BBQ stand a bunch of clear plastic bags of water hanging from the rafters,out side under the overhanging roof, where the order window is. I asked about it, but I noticed there still was some flies around there. Maybe there would have been more flies if it really works. I didnt stick aound, just drove off with the food. I can see why at least some flies would want to stay there. Great food.
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