Fruit flies got you down? Yes, they breed like crazy this time of year, coming home with your precious fruits and vegetables. But you don't need to suffer their annoyances; make a cheap trap that will end their reign in your kitchen forever.
The equipment list here is simple: Mason jar, hammer and nail, cheap beer. Drown those suckers before they ever get going. It's all natural, non-toxic, and all it'll cost you is a little beer.
• See the full instructions: How To: Make the Ultimate, Reusable Fruit Fly Trap at Curbly
Of course, if you're using a clear Mason jar you may want to put it somewhere out of sight in the kitchen. You can also wrap the jar in paper or aluminum foil, or use a non-transparent jar to hide all that drowned fly ickiness.
We have a few more pieces of info and good ideas on getting rid of fruit flies here:
• Fruit Flies! What They Are and How To Get Rid of Them
• Tips: Repel Fruit Flies with Rue
• Good Question: How To Get Rid of Fruit Flies?
(Images: Curbly)
TW Salt Mill by Wil...

Rather than buying cheap beer, I prefer to use about a 1/2" of cider vinegar in a small jar & add a couple of drops of dish soap. It lasts about a week & really traps the fruit flies super well. When I start to notice the fruit flies, I know it's time for a new batch.
Honestly, that type of trap has never worked for me. A lot of them drown, but others continue to breed at a fast pace so the population is never completely depleted. Somehow though, the last 2 summers I have managed to be fruit fly free though!
The #1 remedy is OCD cleanliness. If you keep your food properly put away (including fruit in the fridge until the buggers are gone), they'll go after food remnants other places: on countertops or cooking surfaces, the floor, dirty dishes, in the sink, and in the garbage.
Wash or put dirty dishes in the dishwasher pronto, wipe down any surface that might have had something splattered on it, and give your sink a thorough cleaning to make sure there's nothing rotting in the drain.
With those options gone, they'll focus on your delicious garbage. Every day, spray a little bit of a cleaning product with bleach into your garbage. They'll go in there to snack and never come back out.
It makes me think of those beer cans and bottles that end up in the recycling bucket with a smidgen of brew left in the bottom and smell so horrible come recycling emptying day. I wouldn't want to leave a jar of old beer sitting on the counter. Though, I've never had a fruit fly problem.
When I start to notice any fruit flies, I put a 1/2" of red wine vinegar (although as @tallsarah said, I'm sure cider vinegar would work) in a juice glass, then I take a piece of paper and twirl it into a cone shape, drop the cone (pointy-end down) in the juice glass and voila.
They're drawn to the vinegar, they go down the hole, and then they can't seem to find their way out! Magic...
using a water or soda bottle with apple cider vinegar and a little dish soap and water works like a charm and is super easy to make! I don't even tape it and then when it gets full of dead flies I rinse it out and re-fill it. haven't had any problems with the smell either as I only put a little bit of the apple cider vinegar.
http://articles.directorym.com/DIY_Fruit_Fly_Trap-a1072374.html
I recently moved into a new home. A neighbor told me she'd had a terrible fruit fly problem a few years ago. A friend gave her a tip, she's used it and they've never come back.
Each evening she washes out her sink. That's it. So every evening I put a squirt of the detergent you use for washing dishes by hand into the sink and lather it all around with my scrubber/sponge. I rinse it out. This takes perhaps 30 seconds. I've never seen a fruit fly in my house.
I used to use the fruit fly trap I saw on here, but I found an easier way:
an inch or so of red wine/balsamic vinegar
1 or 2 drops of dish detergent
an inch of water
Just put it in a glass - no need to cover it or make cone traps. They'll flock to it, and the detergent will make them sticky so they can't fly out. HA!!!
And for the record, last summer I had a horrible fruit fly problem. I cleaned and bleached the hell out of my kitchen, but it didn't work. Don't think you're kitchen is a hellhole just because you have fruit flies; sometimes, they just happen.
I will second the paper cone and cider vinegar trap. I just use a tall glass and pop the cone in. Works like a charm.
I keep the compost bucket with the lid a bit open on the floor, and the fruit flies hang out down there.
Having said that--last summer fruit flies were everywhere no matter what I did and this year they aren't. They seem to go in cycles.
I usually just raid my fridge for some small nibbles of fruit, along with some water sugar placed in a ceranwrap-covered cup (with holes). This usually catches the fruitflies.
But really the best advice is akay's: just keep everything clean during the summer. I try to take my trash out frequently, and tend to have less fresh flowers during the summer.
Rice vinegar works, too... we found out the hard way the bottle was left open a smidge. There were tons of fruit flies floating around in there. Gross.
Beer in a jar works extremely well!