Of the spider species commonly seen in homes, only a few are reported to bite. In fact, researchers have demonstrated that over 80 percent of suspected spider bites are attributable to other insects, ticks or disease.
Though spider bites are not as frequent as commonly thought, 60 of the more than 3,000 spider species in the United States do cause medially significant bites and should be avoided. These spiders, including the black widow, brown recluse and common sac spider, are not aggressive and shy away from human contact. However, they bite in self-defense if they are cornered, mishandled or injured.