Black widows are the most venomous spider in North America. Their venom is about 15 times stronger than rattlesnake venom, and uses a chemical called alpha-latrotoxin to overwhelm nerve cells and cause immense pain. When the alpha-latrotoxin reaches a person’s nerve cell, the nerve dumps all of its signaling chemicals at once, overwhelming its neighbors. In addition to pain, the a bite can cause swelling around the wound, severe cramping, sweating and chills. But spiders are much smaller than sn