Your welcome.
I've seen the pop bottle trap all over the web, but no suggestions on what to put in it worked well. I had a buddy that quit drinking so I confiscated all his beer. I don't drink myself, so I came up with this use for it. I get an inch or more of flies each season in each trap...
Instead of Golden Malren, which is toxic, that your chickens could eat the poisoned flies. I use a beer trap, I use the below that I hang up out of the reach of chickens. Rotting beer stinks, that attracts the fly's and when they drink it, the alcohol kills them.