If you have been seeing small flies or gnats in your kitchen, they're probably fruit flies. Fruit flies can be a problem year round, but are especially common during late summer/fall because they are attracted to ripened or fermenting fruits and vegetables.
Also known as vinegar flies and are widely used for biological research because they breed quickly and are easy to sustain. There can be confusion surrounding the term fruit flies with several species such as Tephritidae and Ceratitis capitata also termed fruit flies, however Drosophila melanogaster refers to the common fruit fly.