Another effective way to get rid of them is to get a jar, like this says, and pour in karo syrup (about a third karo). Cut up a hot dog and put a few small chunks in the karo. Poke small holes in the lid of the jar or saran paper. The flies get in the jar and stick to the hotdog pillars bc of the karo.
I will warn you. This is extremely effective and you'll have a layer of fly bodies. It's a bit dark if you watch it.
Another effective way to get rid of them is to get a jar, like this says, and pour in karo syrup (about a third karo). Cut up a hot dog and put a few small chunks in the karo. Poke small holes in the lid of the jar or saran paper. The flies get in the jar and stick to the hotdog pillars bc of the karo.
I will warn you. This is extremely effective and you'll have a layer of fly bodies. It's a bit dark if you watch it.