You can get rid of flies in your house by for instance sealing up all entry points or small openings where they could be passing through,get rid of any spoil t food or garbage in the house as this attracts flies. Using insect cide spray can be another alternative in case all the other methods have not worked out. Check out http://www.getridofthings.com/pests/flies/get-rid-of-house-flies.htm for more information.
Are you baiting rats? If they die in your attic, cellar, walls etc.. that is now nothing more than a half a pound of decomposing flesh that will soon be a boiling mass of maggots aka baby housefly.if they appear out of nowhere with all entry point closed, with bright green butts as well as slow and no fear of humans with swatter, guess what....i smell a rat, chipmunk, cat