Do water bags keep flies away?

aargh57

Critical Thinker
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I was in an outdoor resaraunt today and we noticed some bags hanging around filled with water. When asked we were told they kept flies away by blinding the flies eyes. I thought this to be a little nutty so I did a search and found this:
http://www.straightdope.com/mailbag/mwaterbags.html

that claimed it did in fact work. Anyone have any info on this. Thanks.
 
That's new to me. But it makes sense, the way the article explains it... I suppose the only way to find out would be to test it. :)
 
I've seen those around at some places. The problem is that typically there are so many other pests flying about besides houseflies that the user will go to another solution to try to handle all the pests. I've no evidence one way or another, but it's certainly an easy enough experiment to run.
 
i read the title as water BUGS, not bags, and i wondered what the hell a water strider could possibly do against flies.
 
I once worked on a dive boat that was doing work around bridge piers. Pier 57 was the hot spot for flies - there were untold numbers of them. One morning the crew brought every fly repellant/killer they could get their hands on to try and combat them (not an exaggeration - they showed up with shopping bags full of stuff), even, yes, jugs of water.

Didn't do a damn bit of good. Nothing repelled them, and you'd spend hours killing flies and have just as many as when you started. Best way to get rid of them was to leave the area and go somewhere there weren't any flies. Gads, we hated that pier.
 
EdipisReks said:
i read the title as water BUGS, not bags, and i wondered what the hell a water strider could possibly do against flies.
Click to expand...

What striders are actually the messiahs of the bug world, and flies do fear them. I mean, walking on water, that's a miracle!
 
I thought the bag of water would be spherical, and thus provide some contrasty reflection when light falls on it.

If it is clear and transparent plastic bags, then it would look very much like glass. I recall someone telling me flies are attracted to glass door or window.

Check this out. It teaches a method to catch fly using a drinking glass, based on the theory that a fly is attracted to light.
http://entowww.tamu.edu/extension/bulletins/uc/uc-023.html

Look at the diagram of this one.http://bitingflies.com/newsleaf.html
This one uses a spherical ball to attract flies. Although it says it just use the ball as a dark object, it seems apparent that the spherical ball provides good contrast when lights falls on it.
The fly are then lured to fly up by the sunlight up into the glass container.
 
Dang! Them Aggies is gittin' good! They done figgered how to catch flies without usin' no 12 gauge!
Sure saves on fixin' the trailer.

(Jyera- ignore me. Too much coffee).:D
 
Another mystery solved....

tim and I pondered about this in the Grand Canyon earlier in the year when we saw the bags in the cafe/gift shop/waiting room.



DSC04847.jpg
 
Jyera said:
I thought the bag of water would be spherical, and thus provide some contrasty reflection when light falls on it.

If it is clear and transparent plastic bags, then it would look very much like glass. I recall someone telling me flies are attracted to glass door or window.

Check this out. It teaches a method to catch fly using a drinking glass, based on the theory that a fly is attracted to light.
http://entowww.tamu.edu/extension/bulletins/uc/uc-023.html

Look at the diagram of this one.http://bitingflies.com/newsleaf.html
This one uses a spherical ball to attract flies. Although it says it just use the ball as a dark object, it seems apparent that the spherical ball provides good contrast when lights falls on it.
The fly are then lured to fly up by the sunlight up into the glass container.
Click to expand...

Wait a minute. According to that, the light contrast attracts horseflies. So maybe the water bags scare houseflies and attract horseflies. Great. I'm just gonna put up a strobe.
 
I was disappointed by the Straight Dope article. I think I recall a lively discussion about it at the message boards over there, which I can't find now. It was pointed out that flies seem to have no problem hanging around tables, lighting right next to a glass full of water. If these bags 15 feet away are supposed to scare them off, why aren't the phased by a glass of water right next to them?

It's just not plausible to me. Unless there has been a quality study showing that it really works, without a plausible mechanism, it is likely a false belief.

A couple of weeks ago I was visiting my relatives in New Mexico, and they're having an unusual influx of flies. There was this bag of water hanging above the doorway, which started a discussion of how they've seen it in restaurants, and of course I expressed the skeptical view. Their view was that since restaurants do it, it must work, and someone said something that it's surprising. I said "It's not surprising to me - people believe all kinds of silly things."

Which wasn't the right thing to say. I wish I had instead asked my niece how she could determine for herself why it really works, how you could control for confounding variables, etc. That would have been much better. Then I could move on to the point that probably no one has ever tested out the idea with proper controls, and how unlikely it is to work because of that.
 
Yeah, I didn't find too much in that article either but I find I'm still gullible in ways. What I mean is my first inclination about the fly bag thing was "B.S.", then I read the article in the StaightDope thing and thought "Oh, that makes sense". Sometimes I think I'm very critical at first but then once I see something that I believe is credible I tend to embrace that. Anyway, the bags do look a little tacky anyway if you ask me and I still have my doubts.
 
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