well if you knock it down before they're done with it they may just start rebuilding it. I just let them hatch and then take the nest down. They don't necessarily come back to the same spot, but they might. We have a problem with wolf spiders here, and anything that kills those evil things is ok with me.
Big Cy.... We've been getting rain for the past week and have at least a week to go, I was just on mosquito patrol earlier. Half the yard is flooded though so I'm expecting a big crop of them soon. Those dragonflys had better get to work!