Snakes are among the most frightening animals to humans, and because of this fear many people would sooner try to destroy these animals than understand their benefits to the environment. Snakes are beneficial in that they eat pest insects and rodents, helping to control the populations of animals that can be nuisances to humans. Only about one-tenth of all snakes are venomous, and not all of the venomous snakes are dangerous, or even deadly, to humans. Most snakes are completely harmless. And poisonous snakes do not hunt people; they bite when they are handled, stepped on, or otherwise disturbed. Their venom is most often used on their prey, not on people.
There are about 20 species of poisonous snakes in the United States, mostly rattlesnakes, cottonmouths (also called water moccasins), coral snakes, and copperheads. Many venomous snakes (with coral snakes as one exception) are categorized as pit vipers because they have pits on their heads between their eyes and nostrils. These pits help the snakes detect heat, making it easier for them to locate prey. Most venomous snake bites are treatable and don't result in any lasting problems. The deaths that do occur from snake venom frequently happen because the person was unable to get to a hospital soon enough. If a snake bite occurs, try to get to a hospital as soon as possible. In the meantime, a bandage can be wrapped lightly around the area just above the bite, and the limb where the bite occurred should be moved as little as possible.