Fruit flies, though small, are a large pest problem especially in kitchen and food preparation areas.  The reason they pose such a threat is simple, they land on trash, feces, and rotting food, these substances stick to their feet and then they land on your clean dishes and food preparation surfaces.  One of the biggest issues with this, is they have been proven to spread E. coli to humans, which is a very dangerous food-borne illness.  Fruit flies are no small problem either, they can quickly get out of hand causing an infestation in your home or business.  Female fruit flies can deposit up to 500 eggs at a time, meaning they can produce thousands of offspring in just a couple of weeks.