And now for a non-neutrino question!

I've noticed that there are quite a few spiderwebs (both spidered and without) in my basement and attic, areas where there are little-to-no flying insects of any kind. Evolutionarily speaking, isn't this a terrible survival strategy?

Also, roughly how long does it take for the "average" house spider to starve to death? Asked another way, what is the daily/weekly/monthly caloric intake requirements of a web-spinning spider? I assume they can shift into a semi-hibernation state while waiting for a hapless arthropod to fly into their web.

One last question, if a spider has chosen a terrible web location and is about to starve, will they ever retreat to a more optimal location? Does this account for the large number of abandoned cobwebs you encounter in a low-traffic area, such as a crawl space or attic?

Thanks!