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Here’s an Instructable on how to make an old school fly trap from a 2 liter bottle and a leftover food container.

Fly Trap – Link

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.



  1. garyfixler says:

    I made an inverted version of this when I was having a really bad nat problem about a year ago. It was suggested to me by a friend. I took a 20oz. Diet Coke bottle, cut the bottle in half just above the label, before it starts curving in toward the cap. Then I took off the cap, flipped the cone upside down, stuck it back in the bottle, and electrical taped around the top.

    Then I poured in about 1″-2″ of beer, and put in the affected area. I wiped the funnel, because just the drops of beer there were enough to feed the gnats for days, and I wanted them to have to go inside. You can pour the beer in before taping in the cone to skip that step.

    A few gnats would occasionally fly to the middle, and work their way back out, but they pretty much all ended up back in there, like the drunkards they are. I liked how simple the concept, and build were. I made a 2-liter version later for another affected area. You’d think I was leaving food out, but the place was clean. I don’t know why I had so many gnats suddenly, in 2 different rooms, but this method captured several hundred.

  2. hppyfngy says:

    Try this. Take a wine glass, (or whatever glass,) and put a bit of wine, beer, juice, anything sugary in the bottom. (I think wine works best, as the little buggers die.) Cover with cellophane and poke a small hole in the cellophane with a pencil. Place in the affected area.

    Gnats will go in and they won’t come out. Simple yet effective.

  3. timo says:

    I find that a glass bowl or cup filled with fermenting yeast (yeast in warm water with sugar -as used in making bread) works well too.

  4. Logan says:

    Thanks guys!