Bait recipe: egg sugar and yeast
For the Attractant I use a packet of yeast, a couple eggs, quarter cup milk, and a tablespoon of sugar. seems to work good and stays in liquid form for a few days in 80 degree temperature days. I just top it off with water every few days. its been about 3 weeks now and still have them filled with the original solution. The other part is getting the trap in the right location, a sunny area 3 to 4 feet off the ground seems to work for me. yet still one of my trap gets 1000's of more fly's then the other two. so location is still key, if you not catching them in one location then move to a new location until you start to see fly's getting trapped.