You would think we shouldn't be bothered with flies this time of year. However, there is a specific fly called the Cluster Fly that is making his appearance in many homes in the tri-state area.
Cluster flies tend to hibernate between the wall studs or floor joists.
When they become active they usually find a small opening around the window frame thus we tend to spot sometimes mass swarms on the window itself. These flies are sluggish and make an irritating buzzing noise while they spin around. Don't attempt to squash the flies because they can leave a greasy spot on upholstery, carpets and wood surfaces. The only good thing about cluster flies is that they don't bite. When the days shorten in the summer their biological clock says find a good resting place which means the attic, unused rooms, wall voids like I mentioned, basements and even tree holes.