First thought: move the bananas to the kitchen.
Second thought: you sure they are fruit flies? They really are attracted to fruit mostly (gases they give off). Have you tried pesticides for where you think they are coming from? Tacky fly strips for a week might break the reproductive cycle.
Second thought: you sure they are fruit flies? They really are attracted to fruit mostly (gases they give off). Have you tried pesticides for where you think they are coming from? Tacky fly strips for a week might break the reproductive cycle.