Flies Love Yarrow

I discovered something yesterday while sitting on my deck. Take a close look at the photos..see the flies??? They seem to love this Yarrow plant. Yuck...I am pulling the darn thing up, I was going to anyway, we are tearing up the deck to pour a concrete patio. It's a shame because this plant really does have a beautiful flower. With the thought of possibly moving it to another location in my yard, after seeing the flies, it is going in the trash pronto!

Take a look at this big fella.....I detest flies! Can anyone tell me a fly's purpose in life??? I can't think of one good thing.