I have killed about 50 beings this week, and I did it with vinegar, honey, and dish liquid.
The beings are called drosophila or fruit flies. If you want to kill fruit flies by the dozen because it's easy to get an infestation in the summer months, here's how it's done.
Take a cup or glass (can be a plastic party cup), pour a small quantity of vinegar in the glass along with a drop of honey and a drop of dish liquid. Put it out in an area which is infested and leave it for a couple hours. you are likely to find anywhere from a few to lots and lots of fruit flies laying at the bottom of the vinegar solution.
This method is environmentally sound and avoids the use of poison.
Do you have a better way of becoming a murderer of fruit flies?
My method on what you will need.
1 Solo cup
1 rubber band
1 plastic bag or cling wrap
1 pencil or pen
A dash of OJ or any type of juice.
Pour a half inch of juice into the solo cup.
Put plastic bag or cling wrap over the top of the cup. Make sure the bag is tight over the top.
Secure cling wrap or bag with rubber band.
Poke about 6 holes with a pen or pencil through the plastic. They can get in but can't get out. (the juice compels them to keep going deeper into the cup of doom)
Be amazed on how many of those little buggers you will catch in two days time.
Keep rubber band and dispose of cup/plastic.
I did the cling wrap and rubber band thing for a while because that was the method I found on the Internet, but then tried it without. The cling wrap is totally unnecessary it turns out. IN FACT, some of the flies are so dumb that they may not figure out how to get in because of the cling wrap. Get rid of the cling wrap. Why would they want to get out anyway? There's sweet stuff at the bottom. The main thing is, though, you need to use the dish liquid. Just a drop is plenty. Why? Because it breaks up the surface tension. The bugs are used to actually being able to put their front legs on the surface and their weight being supported. Break up the surface tension and OOPS!...they're taking a bath from which there is no return.
Infestation of flies? This is a far more serious problem, and the flies are simply a symptom. You have in fact, most probably been possessed by a demon of Beelzebub (Lord of the flies). You will need :-
Call your local Catholic Exorcist and speak in tongues ('Google translator' can help, here). Break into English from time to time to say "Help me!" and "need exorcism", just to emphasise your message. Leave the door unlocked, set the camera to 'record', start the tape or CD, don your nightshirt and await your deliverance.
Once the process is complete, dispose of the priestly corpses responsibly, and make a film from the recording. Sell the rights to the film. Use the money to purchase the necessary ingredients to follow either Unseen or Morgan's directives above, and then follow them carefully.
Then, and only then, will you be free.
I'm thinking one good reason for the cling wrap is to slow down evaporation. I just add a little more vinegar and/or water every few days and change it entirely when it gets too disgusting. I'm going away for a few days so I may use the cling wrap + holes thing while I'm gone.
I stood in the kitchen this am and while I was making breakfast I saw two flies crawl down the sides and commit suicide. That was in 10 minutes. They made no attempt whatsoever to fly out.
Now, I always add a drop of honey, maple syrup, agave nectar, or a small amount of cane sugar. I'll have to experiment to see if that's even necessary because other names for fruit flies are vinegar flies and wine flies.
Fruit fly gestation takes 3-4 days, so if you change your garbage pail every 2 days, as I usually do because that's how often I scoop my cat's litter box, then that isn't the source. Other sources can be your kitchen drain or (super yuck) your kitchen towel. If they lay eggs in your kitchen drain, which almost certainly has a trap to keep sewer smells out of your kitchen, normal daily dishwashing activities should wash the eggs and larvae down the drain.
My sister's husband laughed at my brother's wife for washing out used beer and wine bottles, but seriously, this may be where they are breeding in houses that are otherwise very well-kept. People who recycle often keep bottles around and take them to a recycling center every week. Maybe even every month. A bottle with a few drops of beer or wine (or sugary soda, I suppose) could be a great breeding place for these pests.
In the meantime, consider putting that kitchen towel away where the flies can't get at it when not in use. Or change it out every day or two and sanitize it before putting it in the laundry basket (perhaps a solution of chlorine bleach and water).