When I'm canning lots of fruits, fruit flies are an absolute menace because I generally don't keep the fruits in the fridge for the day or so it might take me to prepare to put everything up.
Here's how to make an easy, natural, non-toxic trap for fruit flies. I got this "recipe" from a vendor at a farmers market a few years ago and have used it ever since. During my canning periods I can catch upwards of 40-50 in a single night. This is an incredibly effective method to catch and dispatch these flying pests.
- small glass jar (8-12 ounces)
- apple cider vinegar, red wine vinegar might also work
- 2 drops of dish soap
- tap water
Pour about 1/2 inch of vinegar into the jar. Add a couple of drops of dish soap, then fill the jar to the top with tap water. It doesn't matter if the water foams. Place the jar next to your problem area.
Why does this work? Fruit flies are attracted to the fermented scent of the vinegar (you won't notice it). They land on the surface of the water to feed but because the surface tension has been reduced by the addition of the soap to the water, they sink like teensy pebbles.
In my experience the traps work indefinitely. When they get unsightly due to their effectiveness, dump the liquid and start a new trap.