Perhaps one of the most widely known dangerous spiders in the United States, black widow spiders have definitely earned their reputation. The most distinct thing about them is their red hourglass symbol on their abdomen. They are also known for their dangerous bites, which can cause severe damage to someone’s health. The females are the more aggressive of the black widow gender, as they get very protective of their nests and eggs. Symptoms of a black widow bite include, severe muscle pain, cramps, increased heart rate and blood pressure, and muscle spasms. They are not generally fatal, but can be very painful and can last for several days. If you want to prevent black widows from showing up in and around your home, make sure to clear out any cluttered areas, as they are drawn to places where they can easily hide, such as basements, barns, and garages.