Cobweb spiders were found in 100% of homes in a recent
survey in North Carolina.
Last year an article was published by Matthew Bertone and colleagues at North Carolina State University about arthropods found in homes. The only organism found in 100% of the homes and over 90% of the basements surveyed was spiders. The only other organisms that came close were flies and ants and carpet beetles. By contrast, German cockroaches were found in only 6% of homes and fleas in 10% of homes.
Source: Insects in the City