black flies?

[Davzbeez]

New beek of two hives here.  :D  I have noticed lots of black flies (house flies) on the outer cover of my hives during the middle of the day.  They don't seem to be doing much of anything.  Are they attracted by the smell of the hive?  Or perhaps the smell of the sugar water I'm feeding inside?  Thoughts? :?:

[Hi-Tech]

My guess would be both as well as the color if your hives are white. I also get a lot of flies but my hives are in a cow pasture so there are a lot of flies around. I wouldn't worry about it....