I got a non-toxic fly trap at CAL-Ranch called Pop or something. They recycle old 2 liter pop bottles with a trap thingie on top and the rest of the pop bottle on the bottom. You fill the pop bottle to the line they have marked and then put the attractant in the water, and then put the top on. It's non toxic. Only fair to warn you that you don't want to add the attractant to the water in your house. The smell is very pukey. I'd describe it as essence of rotting road kill magnified about 10,000 times. It's not noticeable outside but doesn't disperse as quickly indoors.
I hung it out one afternoon and looked at it the next morning and there was a layer of dead flies about 1/2" thick floating in the bottle and a couple dozen buzzing inside the trap. I guess they get tired and drown. Several days later the bottle was completely full of dead flies. I had no idea there were that many flies in the whole county, let alone the town. I loathe flies so I enjoyed watching the dead flies pile up inside the bottle.
I liked it so much I went and got a few more refills. they're about $2, and last until the bottle is pretty much full.
I can't use sticky strips out here because it's windy.
