Smarter Than the Average Fruit Fly

Every summer the little pests invade my kitchen.  All it takes is an apple core in the trash or maybe even a lone piece of peel left in the sink.  Or maybe they are misnamed and the asparagus ends, the avocado pit and the potato and carrot peelings are just as enticing to them.  The summer heat does the rest and I soon have a cloud of them writhing over the sink. 

You can off a few of them by clapping your wet hands in the middle of the cloud, but that's a pretty inefficient method.  So every year I consult the wisdom of the internet for advice on how to get rid of them.  I'm never very convinced of the advice -- vinegar? -- so my attempts to apply it are rather halfhearted and I don't stick it out very long.  I usually end up just taking out the trash and subjecting the kitchen sink, garbage can and garbage disposal to extreme sterilization, which eventually works.

But this year I decided to give the internet advisors a better trial, and ended up combining a few of the suggestions into one. Burning incense and sucking them up into a hair dryer or a vacuum are methods of extermination mentioned but I decided to go with the baited trap instead.  Rotting fruit and apple cider vinegar are the main lures suggested on the web but also wine and beer.   So I started with a small bowl of water with a splash of apple cider vinegar in it, absurd though the idea of catching flies with vinegar strikes me.   Not really believing it would work I added a pinch of sugar and a tiny piece of apple and felt more optimistic about it as a lure.  It's not clear if the flies are to drown in the liquid or be killed by its toxicity or what, but I started with water assuming maybe the former and not wanting to waste my cider vinegar.  The advisors also tell you that dish soap will kill them, and that they can't detect it, so I added a drop of that too.  One suggests cutting off the corner of a plastic bag and rubber-banding it to a glass of your chosen lure, the idea being that the flies will be drawn down into the hole, attracted by their sense of smell, and not be able to find their way out, not being terribly bright.  My adaptation of that advice was to cut a small hole, about a third of an inch or so, in the middle of a piece of clear clingy plastic wrap and stretch it tight over the rim of my little bowl.  Left it on the counter near the sink.

Nothing happened the first day.  The second day I had about four flies dead in the liquid.  A couple days later there were a dozen, a few days after that over twenty and now after a couple of weeks the count is in the forties. 

The method works. 

What I'd like to know now is which elements of the method work.  Does the vinegar really lure them?  Could I dispense with the sugar and the apple piece?  I'm pretty sure of the dish soap and I'd rather poison them than have them drown, perhaps a misguided mercy.  Is the plastic wrap necessary or would they dive right into the lethal mix without it?

Later: It's now about a week after my last report and the liquid is so cloudy I can't see the flies at the bottom of the bowl.  But one thing for sure is that they aren't writhing over the sink any more.  I guess I could throw out the cloudy water and start over but why mess with a good thing?  I think I'll wait to see if the kitchen remains free of them before making any changes.  Not being up to conducting the scientific experiments necessary to finding out if there is a simplest most streamlined trap, since I know this combo works I'm going to keep this recipe for now.