The exterminator's coming next week, but any idea what this might be?

Question

So my house has been swarmed by flies by all the windows! The weird part, though, is that they're all dead. Flies get into the house somehow, through a couple of closed windows in the living room and family room, but they drop dead within minutes. We've called the exterminator, and he's coming next week.

Still, any ideas about this?

Answer 1

if you have an older house they will get in around the window frames,old farm houses seem to be bad for this.they only live for a while then die,they collect at the windows because of the light,

i have a new house but someone not so handy added a window to a bedroom on the second floor and did not seal or cap the window properly that room had a lot of flies in it.they like to be warm at night and in around the windows is warm