I think it is no exaggeration to call it an infestation. Now, and it's happened a couple of times before, we have been hit by a sudden plague of large flies. In the past couple of days I've probably killed around 50-60, which hasn't been difficult as - unlike most flies - these react slowly if at all to an impending whack. They don't gradually build up in numbers. One day they weren't there, the next day they were.

 

Has anyone else had the same problem. Curiously, they appear mostly in only one room, which is all-white and might be an attraction. It does have open access to upstairs although I've found none up there. Apart from up there, I can't really see where they could have originated from or gained entry to my fortress.

Edited April 11, 20215 yr by Bangkok Barry

There well may be a dead animal or dumped garbage somewhere near-by.  A concentration of flies such as you describe usually means a single concentration of maggots have metamorphized into fly's in close proximity to where they are seen.

I had this same condition a couple of years back. I called the pest control people and they found a place (nest?) where the larva were hatching. He also told us to heavily disinfect all the house bins, inside and out and wash all surfaces in  a disinfectant solution.  It was  pain but It all cleared up in one day.  I am fanatic now about not leaving any food scraps/crumbs, paper wrappings from food,  around that they can feed on.  Same for keeping the small ants at bay. 

heavily disinfect all the house bins