I promise you...this is the BEST solution EVER. I've tried everything suggested. The method I'm going to describe has caught easily 300 flies in the past day (GROSS!!!!!!)
I make protein shakes every day. I add banana to my protein shake after blending it in my magic bullet. Well, as you know, you can't get every ounce of food out of the container. I put the remains of the blended banana in the magic bullet container in a big gallon size ziploc bag along with the peel of an eaten banana. You'd think every fly was getting paid $1000 to land there cause it's IMMEDIATE and they all swarm there. Using the ziploc bag is the BEST option. It's easy for the bugs to go in...and it's easy to zip QUICKLY so they don't get away. (The flies were crawling out of any other "funnel" that I used). I've done this about 5 times since yesterday, and I think I'm finally starting to near the end of the problem! I had no idea how many there were in my house. Also, one last bit of advice...you need to empty it several times a day so you can start over again and again. It's the only way to catch them all. (and you have to do it often since they reproduce so quickly).
Another option is using old banana (after having been blended in a blender there were remains