This tip came from desperation. We had an infestation of gnats while we were off for the weekend. The house was thick with them. After the chemical sprays that didn't work forced us out of the house, I turned to Google. I learned from many people a tip that I had to pass on.
Take a cup and pour some apple cider vinegar in it. Put in just a couple drops of liquid dish soap or cooking oil to break the surface adhesion from the water. The gnats will dive in and and drown. The photo shows a piece of apple, since I only had regular vinegar. It worked as well. They love fruit, so entice them in any way you can. It took two days but the proof is in the pudding, so to speak.
Hope it helps.
By Poor But Proud from Sweet Home, OR
Apple cider vinegar and dish soap really works for catching gnats. It's like a lure - they flock to it like it's honey.
Can you use white vinegar and Ivory dish soap? (07/29/2010)
I found adding fruit juice increased the number of gnats floating dead in the saucer. (07/30/2010)
I am going to try this out on my patio to see it if it will help with the pesky no see-ums. Thanks! (07/30/2010)
It's a great weed killer, too. Works faster than the commercial weed killers, and it's cheaper! (07/30/2010)
For anyone that has trouble with gnats, those pesky flying (and yes they will bite) insects, then the answer to my prayers to get rid of them is to use a little apple cider vinegar and a couple drops of Dawn (or any brand) of dish washing liquid. Mix it up by swirling the bowl around as not to create bubbles.
Then just set the bowl on the counter or anywhere you are having the problem with them. I tried it myself earlier today and within 5 minutes there were about 20 in the bowl that had drowned. Their family members and friends were hanging around sitting on my paper towel holder watching and within about 20 minutes there were about 100 or so in the mixture. I waited about 30 more minutes and there were so many in the bowl you could no longer see any of the liquid left and there were 100's of bodies in there. I disposed of this mixture and made a fresh batch to leave overnight.
I am hoping that when I get up in the morning the rest of them have gone to their "vinegary" soap grave. If you are having these same problems give this a try. Hope it will work as well for your problem as it did for mine.
Source: Found this tip on thriftyfun.com
By Betsy from Mooresville, NC
This works for fruit flies as well. (07/17/2008)
Timely info: They have been fogging my kitchen for days. I remembered the vinegar but not the dishwashing liquid. Can't wait to get home to try it! (07/17/2008)
By Kathy S
How much vinegar should I put in the bowl for every couple of drops of soap?