Most spiders in the US are harmless with the exception of the Brown Recluse Spider or Violin (brown with a violin marking on its head), the Black Widow Spider (shiny black with a red hourglass on its abdomen) and the Funnel Spider (with yellow markings).   The Brown Recluse and Black Widow Spiders are found in the Southern and Western States and tend to live in dark, undisturbed areas.