fruit fly trap.

Few things are more annoying than fruit flies buzzing around a kitchen.  They are too small to swat and their presence makes a kitchen feel "dirty". 

Some Not-So-Fun Facts:
Fruit flies are common in homes, restaurants, supermarkets and wherever else food is allowed to rot and ferment. Adults are about 1/8 inch long and usually have red eyes. The front portion of the body is tan and the rear portion is black. Fruit flies lay their eggs near the surface of fermenting foods or other moist, organic materials. Upon emerging, the tiny larvae continue to feed near the surface of the fermenting mass. This surface-feeding characteristic of the larvae is significant in that damaged or over-ripened portions of fruits and vegetables can be cut away without having to discard the remainder for fear of retaining any developing larvae. The reproductive potential of fruit flies is enormous; given the opportunity, they will lay about 500 eggs. The entire life cycle from egg to adult can be completed in about a week.

Fruit flies are especially attracted to ripened fruits and vegetables in the kitchen. But they also will breed in drains, garbage disposals, empty bottles and cans, trash containers, mops and cleaning rags. All that is needed for development is a moist film of fermenting material. Infestations can originate from over-ripened fruits or vegetables that were previously infested and brought into the home.
From article by Michael F. Potter, Extension Entomologist
University of Kentucky College of Agriculture

I feel a little sick after reading that.  Rid your home & kitchen of these annoying pests by LOCATING AND ELIMINATING ALL POTENTIAL BREEDING AREAS.  This means that any produce that is over-ripe, cracked or damaged needs to be sealed in a Ziplock bag or thrown away.  We must prevent the fruit flies from laying more eggs on the fermenting food - and starting the whole cycle over.  (My apologies that this post is creepy to read.)

Once you have done a LOCK DOWN on all sketchy fruits and veggies in your kitchen, you can make a little "fruit fly trap" with some common ingredients.

Set out a dish containing wine + vinegar + Dawn dish soap.  And say good riddance to the little pests.