Crawl spaces can be a breeding ground for many bugs and rodents. They often are just a wet area that is unusable for homeowners.  What we do is make the area more suitable for storage and easier to perform work.  We install drain tile around the complete perimeter and across the middle. We then tie it into a sump pit and install a pump, which carries a lifetime warranty.  We install 4 inches of pea stone and 6 mil visqueen and remove all the dirt and debris out of the crawlspace.  We install insulation on the exposed wall, and also install vents.  We tuck point all mortar joints and cracks in the wall and inspect the footing for cracks and deterioration.