They are harmless. But, to find the odd one crawling around the house is a surprising thing. Usually they are brought in with our clothes, are if they are hanging on the door they somehow fly in, maybe with the wind. As, the house is sealed very tight here, which is a good thing.
Once inside the house, there is no food for them. They just will eventually, whither away. I doused them a year ago with soap and water, as they say that is enough to kill them. It does work, but it seems to be a temporary matter of remedy.
I seen the neighbor today, hire a pest control professional to clean up around his house. I am unsure of the spray he uses, but he did tell me he had big problems with them. I will evaluate the situation in the near future, as working night shifts, it is hard to check up on where they could be hiding...
Sometimes the bugs wins over the humans.. For a short while, we hope... Till next time ..