Black widow spiders are not aggressive theually exy are shy bue will bite instinctively when touched or threatened. The female inflicts a seriously poisonous bite which can be fatal. The bits causes extreme pain which usually extends to the abdominal muscles, where it localizes. A person bitten by this spider should call a doctor immediately. Black widow spiders seldom appear in living quarters of homes but are often found in basements beneath lawn benches or porches, and in garages, tool sheds, old lumber piles, trash piles, sand boxes, and outdoor toilets.