This spider is found in many parts of the U.S.A. and has extended its range to the northern states. It often hides under stones and in dark corners inside buildings. It has a leg span of about 2.5 cm (1 inch) and a peculiar violin-shaped design of the back. Its venom may cause severe mechanical damage expressed in necrotic lesions. It destroys the walls of blood vessels causing nasty skin ulcers that take long to cure. Fatal bites are rare.