Why do I have house flies in my carport?
Is it possible that these are not your regular house flies but instead something called a cluster fly?



I've seen these flies make a nuisance of themselves in the ceiling of one house of a friend.  He had to get it fumigated.  After that, no problems.  

Is your carport right next to your house?  is the light attached to the carport or to the house?  Could there be a little nest in there somewhere?