The three most poisonous spiders in the United States. Are the widow, the recluse, and the hobo spider. But the hobo spider actually not poisonous, that's based on other information that's old and I will explain it in another video. But the scorpion, which is found in the United States, and is an arachnid, is dangerous. So the three most poisonous arachnids in the United States today are the widow, the recluse and the scorpion.