# Anti-fly bags. Filled with water. Do they work? **URL:** \ **Category:** Factual Questions\ **Created:** [July 24, 2011, 8:56pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208 "2011-07-24T20:56:10Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![TXCowboy](https://avatars.discourse-cdn.com/v4/letter/t/76d3ee/32.png) [@TXCowboy](https://boards.straightdope.com/u/TXCowboy)\ **Post date:** [July 27, 2011, 6:00pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/21 "2011-07-27T18:00:33Z")
> [@chiroptera](#): > > I am going to try this on my back porch. I get a vortex of flies there, and since the four dogs do an awful lot of coming and going I often get flies in the house. Two things I’ve been doing that half-assed help: spritz the back door and screen door with vinegar, and keep a fan going in the kitchen - seems flies don’t like any sort of breeze. > > \*\*One-gallon ziplock bags, check. Do you hang them with clothesline pegs, or what? \*\* > I’m guessing the point of ther pennies is to add to the reflective value of the bags. I hung mine up by putting a marble sized rock inside the bag, filled with water and sealed, then with the rock in the corner of the bag, wrapped and tied string around bag, under the rock. (The string traps the rock in the corner of the bag, the rock keeps the bag from slipping through loop of string) ---
**Author:** ![Enilno](https://avatars.discourse-cdn.com/v4/letter/e/58f4c7/32.png) [@Enilno](https://boards.straightdope.com/u/Enilno)\ **Post date:** [July 27, 2011, 6:14pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/22 "2011-07-27T18:14:19Z")
Maybe the idea of adding the penny is to slow microbial growth? Don’t know how well it’ll actually work but copper has some [anti-microbial](http://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper) properties. ---
**Author:** ![PapSett](https://avatars.discourse-cdn.com/v4/letter/p/ecc23a/32.png) [@PapSett](https://boards.straightdope.com/u/PapSett)\ **Post date:** [July 28, 2011, 1:28pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/23 "2011-07-28T13:28:34Z")
After reading this thread I decided to try it yesterday; I always had hoards of flies hanging around my back door, just waiting to dash in when I let dogs in & out. Hung the bag on the awning yesterday- as of today, NO FLIES trying to get in! So far, so good! ---
**Author:** ![PlainJain](https://avatars.discourse-cdn.com/v4/letter/p/5daacb/32.png) [@PlainJain](https://boards.straightdope.com/u/PlainJain)\ **Post date:** [July 28, 2011, 3:01pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/24 "2011-07-28T15:01:38Z")
> [@C\_K\_Dexter\_Haven](#): > > See: [http://www.straightdope.com/columns/read/1956/whats-the-purpose-of-bags-of-water-hanging-in-restaurants](http://www.straightdope.com/columns/read/1956/whats-the-purpose-of-bags-of-water-hanging-in-restaurants) Conspicuous lack of cites there. 🙂 ---
**Author:** ![Hilarity\_N.Suze](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hilarity_n.suze/32/6223_2.png) [@Hilarity\_N.Suze](https://boards.straightdope.com/u/Hilarity_N.Suze)\ **Post date:** [July 28, 2011, 3:24pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/25 "2011-07-28T15:24:30Z")
Okay, folks, here’s a data point! A couple of flies sighted since hanging the bag, but nothing like before. Of course there are a lot of uncontrolled variables. On the day we killed 7 flies, we had meat on the table. The next day, when two flies were sighted and none were killed, we were eating vegetarian. Since individual flies tend to be kind of indistinguishable unless there’s one little one and one REALLY BIG one, we can really only count corpses. Unfortunately as hit men we kind of suck. It’s possible that some days our aim is just bad. I can see that this is pretty hard to field test. But it looks like it’s actually working. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [July 28, 2011, 3:43pm UTC](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208/26 "2011-07-28T15:43:46Z")
> [@C\_K\_Dexter\_Haven](#): > > See: [http://www.straightdope.com/columns/read/1956/whats-the-purpose-of-bags-of-water-hanging-in-restaurants](http://www.straightdope.com/columns/read/1956/whats-the-purpose-of-bags-of-water-hanging-in-restaurants) Back in the dusty, musty recesses of my aging memory, I seem to recall challenging this report by “Doug” (which Doug?), but it probably isn’t worth my time to seach for “water” in 12 years of SDMB files. This staff report reads like an Onion article. Surely Doug, or Shirley, can’t be serious. [Previous page](https://boards.straightdope.com/t/anti-fly-bags-filled-with-water-do-they-work/590208.md?page=1)