These spiders can be found all over the United States. Their bite has been known to destroy the walls of blood vessels and leave large skin ulcers. The bites can take months to heal, and if left untreated, can lead to a painful death. Want to avoid these things? Try and stay away from caves, storage areas, and attics. These guys are also known as “Violin Spiders” because of the dark violin shape that can be found on its back.