Lord of the Flies. Every year since I moved into this house, I get about a two week period in the summer where fruit flies gather on the bedroom wall. I catch and kill them (they are very fast), but more take their place until they are suddenly gone. I have long suspected they were hanging around because of the rotting pears in the backyard, but was too lazy to do more than whatever the mower could do. This year, I was diligent and removed pears from the ground every single day until they were all gone. And, no flies this year!