General Question

XCNuse's avatar

Does a bag of water really work against flies?

Asked by XCNuse (1197points) July 6th, 2008

I know it’s an old wives tail, but has anyone heard or actually tested it themselves, does water in a plastic bag hanging really keep flies away or is it just something someone came up with and everyone started doing it?

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17 Answers

gailcalled's avatar

Only one way to find out….let us know. None of the “everyones’ that I know are doing this

thebeadholder's avatar

@programin: huh??? I’m lost. I guess that’s what happens when you take a day off!

gailcalled's avatar

Our village idiot is back or in another incarnation. Check his original, clever and beautifully-thought out profile and his date of joining or rejoining.

eenerweiner's avatar

We have family reunion every year at my cousins lake house and after one very fly filled reunion she tried the bags of water, The next year there was no fly problem. However, I do not know if that was due to the bags of water or the fact that it was a year later and a difference in the fly population in general.

marinelife's avatar

It is hard to find any scientific study of this practice. This study did not yield promising results:

“When Mike Stringham, professor of entomology at North Carolina State University, investigated the use of clear plastic water bags as a fly deterrent, he encountered just such a situation.

Stringham conducted a 13-week field trial by installing commercial, water-based optical fly repellants on two egg farms. Stringham measured the fly activity based on the spots of regurgitated material the flies left after feeding. He concluded that areas equipped with water bags actually experienced higher levels of housefly activity.

However, the study was not conducted under natural lighting conditions. Its purpose was to determine whether the water bags could be used to decrease fly populations on egg farms. The study didn’t explore the possibility that direct sunlight increased the water bags’ efficiency.

So do bags of water lower the number of houseflies around homes and restaurants? There are reasonable explanations that argue yes and significant evidence that proves no.”

AstroChuck's avatar

We need Adam and Jamie to test this one.

marinelife's avatar

@Ac I kept thinking I would see that they had. Can we email and suggest it?

ebenezer's avatar

Marina- I would like to hear one of those “reasonable explanations”. Are those available?

playthebanjo's avatar

the bags work, but they don’t just hang there. You have to swing it like a weapon and hit the fly with it.

marinelife's avatar

@Ebenezer The rationales (which as shown above don’t work) go something like this:

“Why Flies and Water Bags Just Can’t Get Along

The water bag method of fly repellant has many supporters, from restaurant owners to backyard grill-masters. Many success stories ranging from the mild to the miraculous litter the Internet.

So how does the method drive flies away? Some insist the flies perceive the clear liquid as the surface of a body of water. Others claim the insect flies away at the sight of its own magnified reflection. But the most popular reasoning that pops up among entomologists and patent-filing entrepreneurs is simple light refraction.

Refraction takes place when a clear or opaque object, such as a piece of glass or a bag of water, alters the course and velocity of light. The rays of light, which normally travel in a straight line, bend. This effect is responsible for a number of optical illusions, such as mirages, that occasionally baffle humans as well. For more information on refraction, read How Light Works.

In theory, refraction can be just as confusing for some species of insect, especially the housefly. It boasts a highly sensitive array of eyes which allow it to see in multiple directions at once.

The insect’s head mostly consists of a pair of large complex eyes, each of which is composed of 3,000 to 6,000 simple eyes. These eyes can’t move or focus on objects like human eyes, but they provide the fly with a mosaic view of the world around them. Each simple eye provides one small piece of the puzzle, much like the way a screen’s pixel delivers one detail of the larger picture.

A housefly bases its sense of direction on the direction sunlight comes from. Some entomologists believe that when these complex, sensitive eyes experience refracted light, the insect becomes confused and flies away.”

judochop's avatar

we do this at our doorways into our house. We leave our doors open in the summer. It does not keep them away 100 percent but I do know that it helps out a ton. We keep water bags up almost all year. Many bars and resturants do the same in our neighborhood.

scamp's avatar

Even if it works, you’d just be trading a fly problem for mosquitoes! Unless of course we are talking about closed bags of water.

marinelife's avatar

@scamp yes, the suggestion is Ziplock bags.

ebenezer's avatar

marina- thanks for the follow up. I am not sure those are very convincing explanations, but explanations nonetheless.

As always it seems a little personal testimonial is enough to convince some people…

Maybe a disco ball would keep even more varmints away, while possibly attracting bigger ones.

marinelife's avatar

@ebenezer Surely the disco ball, as the ultimate expression of the compound eye of the fly, would appear godlike to them and attract them for worship? ;)

XCNuse's avatar

nono, make a disco ball, and instead of mirrors, make directional lights that are those fly zappers….

woa that’d be awesome, until you see the pile of flies underneath it lol

raymondholbert's avatar

well i have never herd of such a thing but i was at a fish camp today 07–02-09 and i was talking to the owner on the outside at the entrance door and i kept looking at these plastic bags half full of water with a penney in them and i finally had to ask what they where for and she said it was to keep the flys away.
they have a cricket box outside and they always drawed flies and stayed all around the front door and someone had told her about the ziplock bags and she tryed it and she has not had a fly problem since !
so here i am on the internet this afternoon and doing a google search on this and 98% has been positive , so i will be trying it tomorrow.

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