Past 4 weeks these flies have arrived, they're small and fast and don't seem to care about traps or UV zappers. They're everywhere! One person has suggested Lesser House Fly - any other expert options please?

to NGA!

What is your zone? Here in zone 5a (microclimates of 4b) where we get frost in September, the flies start swarming by the hundreds of thousands onto our house (I'm not kidding) this time of year. They stick to our house, trying desperately to get inside, because they sense the frost coming, and they're trying to find warmth. The outside walls of the house sometimes look like they are moving with how many flies are on them. The frost kills them off before long, so we don't do anything to kill them ourselves.