The interesting thing about this poll to me is the distinction between "eh, no big deal" and "time to take pest-control measures". To me, the answer would usually be both; as in, it's no big deal to have to take pest-control measures, it's part of the regular upkeep of a dwelling unless you happen to live in an insanely lucky climate.

Well, for example: we occasionally see stray tiny little ants in the playroom, which opens up onto our garden. If there aren't a lot of them, and they don't seem to be going after something in particular, I just keep my eye out. I figure they wandered in from outside and will wander back out again, and that's usually what happens. That's how I feel about the occasional housefly too. I wouldn't rush out to get poison spray. But if I had ants in the pantry, or a housefly problem, then I would take steps.