Instructables
Picture of How to Create a Fool-Proof Gnat Trap
I was so frustrated from swatting at gnats every day in my house. I had them go up my nose, in my mouth and eyes, and actually bite me so hard once that I yelled. We didn't keep much, if any, food out on the counter, so the gnats even resorted to getting in our diaper pail! Talk about disgusting - poop-fed gnats going in your eyes and biting you. It doesn't get much worse than that. Even my two year old son started mimicking my swatting and trying to catch them out of the air with a loud clap. I tried several iterations of this trap, and finally hit the jackpot with the one in this instructable.

You'll have some fun when you notice gnats on the fruit. Give the plastic a flip and the gnat will fly into the corner between the bowl and the plastic. If you get good enough, you can smash them without putting a finger hole in the plastic!

Step 1: Gather your gear

What's needed:

 - A serving bowl or large salad bowl. I chose a 9 inch salad bowl, about 2 1/2 inches deep.
 - A small fruit cup, shorter in height than the large bowl. This is very important.
 - Fresh fruit, approximately 1/4 cup. I have used banana with great success, but used grapes for this instruction
 - 2 cups of water
 - Liquid dish soap
 - Cellophane wrap (I used Saran Wrap)
 - Serrated knife
 - Food coloring (optional)

Step 2: Put water in the large bowl

Picture of Put water in the large bowl
In the large bowl, put approximately 2 cups of water, such that there is at least 1 inch of water in the bowl. You can add a drop or two of food coloring now if you desire.

Step 3: Add fruit to the small bowl

Picture of Add fruit to the small bowl
Cut up some fresh fruit for your enemy to dine on. Bananas are best but I'm out, so I'm giving grapes a try. DO NOT add water to the small bowl; this will cause the fruit to rot much too quickly.

Step 4: Place the small bowl into the large bowl

Picture of Place the small bowl into the large bowl
 
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HarpAngel9995 months ago

Nicely done, however, I think it might be important to note that those are, in fact, fruit flies, and this method (the bait at least) won't work with gnats (like the ones that hang around potted plants) because they aren't eating, or laying their eggs there (Believe me, I've tried)
One other thing that might be helpful, flying insects (excluding beetles) can't fly if their wings get wet, though I find it most successful with oils or rubbing alcohol. It can be hard to kill just one, at least with your hands, but it isn't too hard to spray the nasty little buggers with a spray bottle (it's important not to use an aerosol bottle, because insects (like flies) can feel the movement of the air and avoid your death ray).
But pretty much, you can hit them more easily in mid air with a mist of liquid, they they plummet to the earth, where they have a MUCH harder time getting away, so you can smoosh them. OR if you use rubbing alcohol, at least with small insects, one spray will at least send them down and mostly incapacitate most movement, and generally a second should send them to the afterlife. I think it actually causes them to shrivel up, because their cells burst or something. But I do know it works. Better yet, this stuff won't leave residue (besides a dead insect carcass). It evaporates super quickly and is generally safe on surfaces as long as you don't soak them (even small amounts on live plants can be okay)

sickdevotee637 months ago

Thanks i really need this

ironsmiter2 years ago
so, make sure the fruit bowl is shorter than the water bowl i presume?
otherwise, the plastic wrap would seal it off.

in a few days, you have a bowl full of dead gnats, and a bunch of hatching baby gnats on the fruit?
jetich (author)  ironsmiter2 years ago
You're correct about the smaller bowl being shorter. It doesn't have to be much shorter, just the height of a gnat. :) I haven't seen any hatches on the fruit yet, just a bunch of dead ones in the water. Check out my update picture at the end, just added.
It doesnt seem like the smaller bowl is sealed off, so yeah i think it would make sense to assume the smaller one is shorter than the larger one. And the idea of the plastic wrap is like how a fly cant seem to fly out a window properly. They just miss and miss because theres no accuracy in their flight. So they will just fly around get really tired and fall down into the soapy water, sink and die.

Im assuming the plastic wrap doesnt quite seal off the smaller bowl. Id imagine the same lack of accuracy would apply. Assuming the bowl is anywhere from a centimeter or so from the top of the smaller bowl, it would give the smell of the fruit causing the flies to find it, but make it difficult to actually get to and lay eggs.