House spiders belong to a species in the Tegenaria group, according to GreenNature.com. This species group includes the hobo spider, domestic and common house spider and the giant house spider. The hobo spider is the most dangerous in this group, but is found mostly in the Pacific Northwest.

Brown recluse spiders, also called violin spiders or fiddleback spiders, contain venom that can cause serious injury and death. These spiders are found mainly in the central Midwestern states southward to the Gulf of Mexico.

The brown widow spider, or Latrodectus geometricus, is one of five widow spider species found in the United States. More than 30,000 species of spiders exist, but only a few can inflict a serious bite and produce venom harmful to humans, according to Dr. James H.