The plumber was over to assess how bad the drainage system of the house is, and as he was about to leave, I suddenly remembered I had a couple of these guys and their larvae captive and thought he might be able to tell me something about them.

His attitude had been light up until that point despite the fact that the piping is broken and will require front yard excavation to fix it, but as soon as I mentioned these guys, he got very serious, and immediately started firing questions at me as to exactly what kind of fly, so I showed him.

He took one look and said that these flies are ALWAYS a sign of a pipe broken under the house. Just what we wanted to hear. I'm VERY glad I'm renting, but I am renting the basement, which of course would be the site of mass destruction in that instance. He explained that the larvae live in a slimy pocket of dirt that forms near a crack in the pipe, and the flies come up through cracks in the foundation.

I had never heard this before and was wondering if anyone here could verify or deny. I know that I mostly find the flies in the bathroom, and that all larvae I've found have been in the shower. The basement is carpeted, so it seems it would be difficult for them to come up from cracks in the foundation, through carpet, though there is a huge crack running across my living space under the carpet. And that does make it seem likely that, in the shifting of the house, a pipe could have gotten broken.

We couldn't get a clear answer out of him as to whether this was catastrophic and would require the basement to be dug up, but in the end it really sounded like what it came down to was that, if nothing was done, we'd just continue to have flies, but there might not be much that would happen in the way of drainage badness.

If that's the case, my landlady is very happy to have someone like me, who doesn't mind having cute flies around, as a tenant. ;-)