If the floor was recently sealed the bugs may have laid eggs before the sale. They hatched and bored their way out. I think some borax based products will prevent further infestation (and is relatively non-toxic, to humans) but not what's already in the wood. The beetles like some wood better than others and some only infest at ceratin moisture content.

You might want to check the Wood Web on this one , Dr. Gene Wenghert (sp?) knows it all concern PPBs.