Flies? do they nest?

Question

I have suddenly got an unusual amount of flies in my house, quite large ones, i dont know where they are coming from..even with the windows closed, they are appearing, mostly around my back patio doors...could i have some sort of nest? Do flies nest? I am starting to get the creeps!!

Answer 1

help there is somthing dead halfway up  our chimney we now have maggots falling down it it is impossible to reach from top or bottom as its all blocked up except a small hole how long will this last cani spray somthing up there?????