This really works! I was searching for a way to get rid of the black flies from all the poo ! I have ducks chickens and now geese! Poo poo and more poo! So flies were outta control !!! I came upon this thread and went and got 12 vanillaroma scented tree air freshners ASAP. I have an 8/8 coop so I hung 3 in there and 6 outside in my backyard in various tree limbs - boom! No more flies! It was amazing!!! Even after rain 3 -4 x you can still smell the vanilla in my backyard! It's 10 days strong so far and in a few more days ill change to new ones . It's AWESOME!